Adding upstream version 6.0.4-dfsg.upstream/6.0.4-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 4115 insertions, 0 deletions

diff --git a/src/VBox/Runtime/common/fuzz/Makefile.kup b/src/VBox/Runtime/common/fuzz/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/common/fuzz/Makefile.kup
diff --git a/src/VBox/Runtime/common/fuzz/fuzz-observer.cpp b/src/VBox/Runtime/common/fuzz/fuzz-observer.cpp
new file mode 100644
index 00000000..343a29e9
--- /dev/null
+++ b/src/VBox/Runtime/common/fuzz/fuzz-observer.cpp
@@ -0,0 +1,1331 @@
+/* $Id: fuzz-observer.cpp $ */
+/** @file
+ * IPRT - Fuzzing framework API, observer.
+ */
+
+/*
+ * Copyright (C) 2018-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/fuzz.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/ctype.h>
+#include <iprt/dir.h>
+#include <iprt/err.h>
+#include <iprt/env.h>
+#include <iprt/file.h>
+#include <iprt/md5.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/path.h>
+#include <iprt/pipe.h>
+#include <iprt/poll.h>
+#include <iprt/process.h>
+#include <iprt/semaphore.h>
+#include <iprt/stream.h>
+#include <iprt/string.h>
+#include <iprt/time.h>
+#include <iprt/thread.h>
+
+
+/** Poll ID for the reading end of the stdout pipe from the client process. */
+#define RTFUZZOBS_EXEC_CTX_POLL_ID_STDOUT 0
+/** Poll ID for the reading end of the stderr pipe from the client process. */
+#define RTFUZZOBS_EXEC_CTX_POLL_ID_STDERR 1
+/** Poll ID for the writing end of the stdin pipe to the client process. */
+#define RTFUZZOBS_EXEC_CTX_POLL_ID_STDIN  2
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/** Pointer to the internal fuzzing observer state. */
+typedef struct RTFUZZOBSINT *PRTFUZZOBSINT;
+
+
+/**
+ * Observer thread state for one process.
+ */
+typedef struct RTFUZZOBSTHRD
+{
+    /** The thread handle. */
+    RTTHREAD                    hThread;
+    /** The observer ID. */
+    uint32_t                    idObs;
+    /** Flag whether to shutdown. */
+    volatile bool               fShutdown;
+    /** Pointer to te global observer state. */
+    PRTFUZZOBSINT               pFuzzObs;
+    /** Current fuzzer input. */
+    RTFUZZINPUT                 hFuzzInput;
+    /** Flag whether to keep the input. */
+    bool                        fKeepInput;
+    /** Flag whether a new input is waiting. */
+    volatile bool               fNewInput;
+} RTFUZZOBSTHRD;
+/** Pointer to an observer thread state. */
+typedef RTFUZZOBSTHRD *PRTFUZZOBSTHRD;
+
+
+/**
+ * Internal fuzzing observer state.
+ */
+typedef struct RTFUZZOBSINT
+{
+    /** The fuzzing context used for this observer. */
+    RTFUZZCTX                   hFuzzCtx;
+    /** Temp directory for input files. */
+    char                       *pszTmpDir;
+    /** Results directory. */
+    char                       *pszResultsDir;
+    /** The binary to run. */
+    char                       *pszBinary;
+    /** Arguments to run the binary with, terminated by a NULL entry. */
+    char                      **papszArgs;
+    /** Number of arguments. */
+    uint32_t                    cArgs;
+    /** Maximum time to wait for the client to terminate until it is considered hung and killed. */
+    RTMSINTERVAL                msWaitMax;
+    /** The channel the binary expects the input. */
+    RTFUZZOBSINPUTCHAN          enmInputChan;
+    /** Flag whether to shutdown the master and all workers. */
+    volatile bool               fShutdown;
+    /** Global observer thread handle. */
+    RTTHREAD                    hThreadGlobal;
+    /** The event semaphore handle for the global observer thread. */
+    RTSEMEVENT                  hEvtGlobal;
+    /** Notification event bitmap. */
+    volatile uint64_t           bmEvt;
+    /** Number of threads created - one for each process. */
+    uint32_t                    cThreads;
+    /** Pointer to the array of observer thread states. */
+    PRTFUZZOBSTHRD              paObsThreads;
+    /** Timestamp of the last stats query. */
+    uint64_t                    tsLastStats;
+    /** Last number of fuzzed inputs per second if we didn't gather enough data in between
+     * statistic queries. */
+    uint32_t                    cFuzzedInputsPerSecLast;
+    /** Fuzzing statistics. */
+    RTFUZZOBSSTATS              Stats;
+} RTFUZZOBSINT;
+
+
+/**
+ * Stdout/Stderr buffer.
+ */
+typedef struct RTFUZZOBSSTDOUTERRBUF
+{
+    /** Current amount buffered. */
+    size_t                      cbBuf;
+    /** Maxmium amount to buffer. */
+    size_t                      cbBufMax;
+    /** Base pointer to the data buffer. */
+    uint8_t                     *pbBase;
+} RTFUZZOBSSTDOUTERRBUF;
+/** Pointer to a stdout/stderr buffer. */
+typedef RTFUZZOBSSTDOUTERRBUF *PRTFUZZOBSSTDOUTERRBUF;
+
+
+/**
+ * Worker execution context.
+ */
+typedef struct RTFUZZOBSEXECCTX
+{
+    /** The stdout pipe handle - reading end. */
+    RTPIPE                      hPipeStdoutR;
+    /** The stdout pipe handle - writing end. */
+    RTPIPE                      hPipeStdoutW;
+    /** The stderr pipe handle - reading end. */
+    RTPIPE                      hPipeStderrR;
+    /** The stderr pipe handle - writing end. */
+    RTPIPE                      hPipeStderrW;
+    /** The stdin pipe handle - reading end. */
+    RTPIPE                      hPipeStdinR;
+    /** The stind pipe handle - writing end. */
+    RTPIPE                      hPipeStdinW;
+    /** The stdout handle. */
+    RTHANDLE                    StdoutHandle;
+    /** The stderr handle. */
+    RTHANDLE                    StderrHandle;
+    /** The stdin handle. */
+    RTHANDLE                    StdinHandle;
+    /** The pollset to monitor. */
+    RTPOLLSET                   hPollSet;
+    /** The process to monitor. */
+    RTPROCESS                   hProc;
+    /** Execution time of the process. */
+    RTMSINTERVAL                msExec;
+    /** Current input data pointer. */
+    uint8_t                     *pbInputCur;
+    /** Number of bytes left for the input. */
+    size_t                      cbInputLeft;
+    /** The stdout data buffer. */
+    RTFUZZOBSSTDOUTERRBUF       StdOutBuf;
+    /** The stderr data buffer. */
+    RTFUZZOBSSTDOUTERRBUF       StdErrBuf;
+    /** Modified arguments vector - variable in size. */
+    char                        *apszArgs[1];
+} RTFUZZOBSEXECCTX;
+/** Pointer to an execution context. */
+typedef RTFUZZOBSEXECCTX *PRTFUZZOBSEXECCTX;
+/** Pointer to an execution context pointer. */
+typedef PRTFUZZOBSEXECCTX *PPRTFUZZOBSEXECCTX;
+
+
+/**
+ * A variable descriptor.
+ */
+typedef struct RTFUZZOBSVARIABLE
+{
+    /** The variable. */
+    const char                  *pszVar;
+    /** Length of the variable in characters - excluding the terminator. */
+    uint32_t                    cchVar;
+    /** The replacement value. */
+    const char                  *pszVal;
+} RTFUZZOBSVARIABLE;
+/** Pointer to a variable descriptor. */
+typedef RTFUZZOBSVARIABLE *PRTFUZZOBSVARIABLE;
+
+
+/**
+ * Initializes the given stdout/stderr buffer.
+ *
+ * @returns nothing.
+ * @param   pBuf                The buffer to initialize.
+ */
+static void rtFuzzObsStdOutErrBufInit(PRTFUZZOBSSTDOUTERRBUF pBuf)
+{
+    pBuf->cbBuf    = 0;
+    pBuf->cbBufMax = 0;
+    pBuf->pbBase   = NULL;
+}
+
+
+/**
+ * Frees all allocated resources in the given stdout/stderr buffer.
+ *
+ * @returns nothing.
+ * @param   pBuf                The buffer to free.
+ */
+static void rtFuzzObsStdOutErrBufFree(PRTFUZZOBSSTDOUTERRBUF pBuf)
+{
+    if (pBuf->pbBase)
+        RTMemFree(pBuf->pbBase);
+}
+
+
+/**
+ * Clears the given stdout/stderr buffer.
+ *
+ * @returns nothing.
+ * @param   pBuf                The buffer to clear.
+ */
+static void rtFuzzObsStdOutErrBufClear(PRTFUZZOBSSTDOUTERRBUF pBuf)
+{
+    pBuf->cbBuf = 0;
+}
+
+
+/**
+ * Fills the given stdout/stderr buffer from the given pipe.
+ *
+ * @returns IPRT status code.
+ * @param   pBuf                The buffer to fill.
+ * @param   hPipeRead           The pipe to read from.
+ */
+static int rtFuzzObsStdOutErrBufFill(PRTFUZZOBSSTDOUTERRBUF pBuf, RTPIPE hPipeRead)
+{
+    int rc = VINF_SUCCESS;
+
+    size_t cbRead = 0;
+    size_t cbThisRead = 0;
+    do
+    {
+        cbThisRead = pBuf->cbBufMax - pBuf->cbBuf;
+        if (!cbThisRead)
+        {
+            /* Try to increase the buffer. */
+            uint8_t *pbNew = (uint8_t *)RTMemRealloc(pBuf->pbBase, pBuf->cbBufMax + _4K);
+            if (RT_LIKELY(pbNew))
+            {
+                pBuf->cbBufMax += _4K;
+                pBuf->pbBase   = pbNew;
+            }
+            cbThisRead = pBuf->cbBufMax - pBuf->cbBuf;
+        }
+
+        if (cbThisRead)
+        {
+            rc = RTPipeRead(hPipeRead, pBuf->pbBase + pBuf->cbBuf, cbThisRead, &cbRead);
+            if (RT_SUCCESS(rc))
+                pBuf->cbBuf += cbRead;
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    } while (   RT_SUCCESS(rc)
+             && cbRead == cbThisRead);
+
+    return rc;
+}
+
+
+/**
+ * Writes the given stdout/stderr buffer to the given filename.
+ *
+ * @returns IPRT status code.
+ * @param   pBuf                The buffer to write.
+ * @param   pszFilename         The filename to write the buffer to.
+ */
+static int rtFuzzStdOutErrBufWriteToFile(PRTFUZZOBSSTDOUTERRBUF pBuf, const char *pszFilename)
+{
+    RTFILE hFile;
+    int rc = RTFileOpen(&hFile, pszFilename, RTFILE_O_CREATE | RTFILE_O_WRITE | RTFILE_O_DENY_NONE);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTFileWrite(hFile, pBuf->pbBase, pBuf->cbBuf, NULL);
+        AssertRC(rc);
+        RTFileClose(hFile);
+
+        if (RT_FAILURE(rc))
+            RTFileDelete(pszFilename);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Replaces a variable with its value.
+ *
+ * @returns VINF_SUCCESS or VERR_NO_STR_MEMORY.
+ * @param   ppszNew             In/Out.
+ * @param   pcchNew             In/Out. (Messed up on failure.)
+ * @param   offVar              Variable offset.
+ * @param   cchVar              Variable length.
+ * @param   pszValue            The value.
+ * @param   cchValue            Value length.
+ */
+static int rtFuzzObsReplaceStringVariable(char **ppszNew, size_t *pcchNew, size_t offVar, size_t cchVar,
+                                          const char *pszValue, size_t cchValue)
+{
+    size_t const cchAfter = *pcchNew - offVar - cchVar;
+    if (cchVar < cchValue)
+    {
+        *pcchNew += cchValue - cchVar;
+        int rc = RTStrRealloc(ppszNew, *pcchNew + 1);
+        if (RT_FAILURE(rc))
+            return rc;
+    }
+
+    char *pszNew = *ppszNew;
+    memmove(&pszNew[offVar + cchValue], &pszNew[offVar + cchVar], cchAfter + 1);
+    memcpy(&pszNew[offVar], pszValue, cchValue);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Replace the variables found in the source string, returning a new string that
+ * lives on the string heap.
+ *
+ * @returns IPRT status code.
+ * @param   pszSrc              The source string.
+ * @param   paVars              Pointer to the array of known variables.
+ * @param   ppszNew             Where to return the new string.
+ */
+static int rtFuzzObsReplaceStringVariables(const char *pszSrc, PRTFUZZOBSVARIABLE paVars, char **ppszNew)
+{
+    /* Lazy approach that employs memmove.  */
+    int     rc        = VINF_SUCCESS;
+    size_t  cchNew    = strlen(pszSrc);
+    char   *pszNew    = RTStrDup(pszSrc);
+
+    if (paVars)
+    {
+        char   *pszDollar = pszNew;
+        while ((pszDollar = strchr(pszDollar, '$')) != NULL)
+        {
+            if (pszDollar[1] == '{')
+            {
+                const char *pszEnd = strchr(&pszDollar[2], '}');
+                if (pszEnd)
+                {
+                    size_t const cchVar    = pszEnd - pszDollar + 1; /* includes "${}" */
+                    size_t       offDollar = pszDollar - pszNew;
+                    PRTFUZZOBSVARIABLE pVar = paVars;
+                    while (pVar->pszVar != NULL)
+                    {
+                        if (   cchVar == pVar->cchVar
+                            && !memcmp(pszDollar, pVar->pszVar, cchVar))
+                        {
+                            size_t const cchValue = strlen(pVar->pszVal);
+                            rc = rtFuzzObsReplaceStringVariable(&pszNew, &cchNew, offDollar,
+                                                                cchVar, pVar->pszVal, cchValue);
+                            offDollar += cchValue;
+                            break;
+                        }
+
+                        pVar++;
+                    }
+
+                    pszDollar = &pszNew[offDollar];
+
+                    if (RT_FAILURE(rc))
+                    {
+                        RTStrFree(pszNew);
+                        *ppszNew = NULL;
+                        return rc;
+                    }
+                }
+            }
+        }
+    }
+
+    *ppszNew = pszNew;
+    return rc;
+}
+
+/**
+ * Prepares the argument vector for the child process.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   pExecCtx            The execution context to prepare the argument vector for.
+ * @param   paVars              Pointer to the array of known variables.
+ */
+static int rtFuzzObsExecCtxArgvPrepare(PRTFUZZOBSINT pThis, PRTFUZZOBSEXECCTX pExecCtx, PRTFUZZOBSVARIABLE paVars)
+{
+    int rc = VINF_SUCCESS;
+    for (unsigned i = 0; i < pThis->cArgs && RT_SUCCESS(rc); i++)
+        rc = rtFuzzObsReplaceStringVariables(pThis->papszArgs[i], paVars, &pExecCtx->apszArgs[i]);
+
+    return rc;
+}
+
+
+/**
+ * Creates a new execution context.
+ *
+ * @returns IPRT status code.
+ * @param   ppExecCtx           Where to store the pointer to the execution context on success.
+ * @param   pThis               The internal fuzzing observer state.
+ */
+static int rtFuzzObsExecCtxCreate(PPRTFUZZOBSEXECCTX ppExecCtx, PRTFUZZOBSINT pThis)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZOBSEXECCTX pExecCtx = (PRTFUZZOBSEXECCTX)RTMemAllocZ(RT_UOFFSETOF_DYN(RTFUZZOBSEXECCTX, apszArgs[pThis->cArgs + 1]));
+    if (RT_LIKELY(pExecCtx))
+    {
+        pExecCtx->hPipeStdoutR     = NIL_RTPIPE;
+        pExecCtx->hPipeStdoutW     = NIL_RTPIPE;
+        pExecCtx->hPipeStderrR     = NIL_RTPIPE;
+        pExecCtx->hPipeStderrW     = NIL_RTPIPE;
+        pExecCtx->hPipeStdinR      = NIL_RTPIPE;
+        pExecCtx->hPipeStdinW      = NIL_RTPIPE;
+        pExecCtx->hPollSet         = NIL_RTPOLLSET;
+        pExecCtx->hProc            = NIL_RTPROCESS;
+        pExecCtx->msExec           = 0;
+        rtFuzzObsStdOutErrBufInit(&pExecCtx->StdOutBuf);
+        rtFuzzObsStdOutErrBufInit(&pExecCtx->StdErrBuf);
+
+        rc = RTPollSetCreate(&pExecCtx->hPollSet);
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTPipeCreate(&pExecCtx->hPipeStdoutR, &pExecCtx->hPipeStdoutW, RTPIPE_C_INHERIT_WRITE);
+            if (RT_SUCCESS(rc))
+            {
+                RTHANDLE Handle;
+                Handle.enmType = RTHANDLETYPE_PIPE;
+                Handle.u.hPipe = pExecCtx->hPipeStdoutR;
+                rc = RTPollSetAdd(pExecCtx->hPollSet, &Handle, RTPOLL_EVT_READ, RTFUZZOBS_EXEC_CTX_POLL_ID_STDOUT);
+                AssertRC(rc);
+
+                rc = RTPipeCreate(&pExecCtx->hPipeStderrR, &pExecCtx->hPipeStderrW, RTPIPE_C_INHERIT_WRITE);
+                if (RT_SUCCESS(rc))
+                {
+                    Handle.u.hPipe = pExecCtx->hPipeStderrR;
+                    rc = RTPollSetAdd(pExecCtx->hPollSet, &Handle, RTPOLL_EVT_READ, RTFUZZOBS_EXEC_CTX_POLL_ID_STDERR);
+                    AssertRC(rc);
+
+                    /* Create the stdin pipe handles if not a file input. */
+                    if (pThis->enmInputChan == RTFUZZOBSINPUTCHAN_STDIN || pThis->enmInputChan == RTFUZZOBSINPUTCHAN_FUZZING_AWARE_CLIENT)
+                    {
+                        rc = RTPipeCreate(&pExecCtx->hPipeStdinR, &pExecCtx->hPipeStdinW, RTPIPE_C_INHERIT_READ);
+                        if (RT_SUCCESS(rc))
+                        {
+                            pExecCtx->StdinHandle.enmType = RTHANDLETYPE_PIPE;
+                            pExecCtx->StdinHandle.u.hPipe = pExecCtx->hPipeStdinR;
+
+                            Handle.u.hPipe = pExecCtx->hPipeStdinW;
+                            rc = RTPollSetAdd(pExecCtx->hPollSet, &Handle, RTPOLL_EVT_WRITE, RTFUZZOBS_EXEC_CTX_POLL_ID_STDIN);
+                            AssertRC(rc);
+                        }
+                    }
+                    else
+                    {
+                        pExecCtx->StdinHandle.enmType = RTHANDLETYPE_PIPE;
+                        pExecCtx->StdinHandle.u.hPipe = NIL_RTPIPE;
+                    }
+
+                    if (RT_SUCCESS(rc))
+                    {
+                        pExecCtx->StdoutHandle.enmType = RTHANDLETYPE_PIPE;
+                        pExecCtx->StdoutHandle.u.hPipe = pExecCtx->hPipeStdoutW;
+                        pExecCtx->StderrHandle.enmType = RTHANDLETYPE_PIPE;
+                        pExecCtx->StderrHandle.u.hPipe = pExecCtx->hPipeStderrW;
+                        *ppExecCtx = pExecCtx;
+                        return VINF_SUCCESS;
+                    }
+
+                    RTPipeClose(pExecCtx->hPipeStderrR);
+                    RTPipeClose(pExecCtx->hPipeStderrW);
+                }
+
+                RTPipeClose(pExecCtx->hPipeStdoutR);
+                RTPipeClose(pExecCtx->hPipeStdoutW);
+            }
+
+            RTPollSetDestroy(pExecCtx->hPollSet);
+        }
+
+        RTMemFree(pExecCtx);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    return rc;
+}
+
+
+/**
+ * Destroys the given execution context.
+ *
+ * @returns nothing.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   pExecCtx            The execution context to destroy.
+ */
+static void rtFuzzObsExecCtxDestroy(PRTFUZZOBSINT pThis, PRTFUZZOBSEXECCTX pExecCtx)
+{
+    RTPipeClose(pExecCtx->hPipeStdoutR);
+    RTPipeClose(pExecCtx->hPipeStdoutW);
+    RTPipeClose(pExecCtx->hPipeStderrR);
+    RTPipeClose(pExecCtx->hPipeStderrW);
+
+    if (   pThis->enmInputChan == RTFUZZOBSINPUTCHAN_STDIN
+        || pThis->enmInputChan == RTFUZZOBSINPUTCHAN_FUZZING_AWARE_CLIENT)
+    {
+        RTPipeClose(pExecCtx->hPipeStdinR);
+        RTPipeClose(pExecCtx->hPipeStdinW);
+    }
+
+    RTPollSetDestroy(pExecCtx->hPollSet);
+    char **ppszArg = &pExecCtx->apszArgs[0];
+    while (*ppszArg != NULL)
+    {
+        RTStrFree(*ppszArg);
+        ppszArg++;
+    }
+
+    rtFuzzObsStdOutErrBufFree(&pExecCtx->StdOutBuf);
+    rtFuzzObsStdOutErrBufFree(&pExecCtx->StdErrBuf);
+    RTMemFree(pExecCtx);
+}
+
+
+/**
+ * Runs the client binary pumping all data back and forth waiting for the client to finish.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_TIMEOUT if the client didn't finish in the given deadline and was killed.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   pExecCtx            The execution context.
+ * @param   pProcStat           Where to store the process exit status on success.
+ */
+static int rtFuzzObsExecCtxClientRun(PRTFUZZOBSINT pThis, PRTFUZZOBSEXECCTX pExecCtx, PRTPROCSTATUS pProcStat)
+{
+    rtFuzzObsStdOutErrBufClear(&pExecCtx->StdOutBuf);
+    rtFuzzObsStdOutErrBufClear(&pExecCtx->StdErrBuf);
+
+    int rc = RTProcCreateEx(pThis->pszBinary, &pExecCtx->apszArgs[0], RTENV_DEFAULT, 0 /*fFlags*/, &pExecCtx->StdinHandle,
+                            &pExecCtx->StdoutHandle, &pExecCtx->StderrHandle, NULL, NULL, &pExecCtx->hProc);
+    if (RT_SUCCESS(rc))
+    {
+        uint64_t tsMilliesStart = RTTimeSystemMilliTS();
+        for (;;)
+        {
+            /* Wait a bit for something to happen on one of the pipes. */
+            uint32_t fEvtsRecv = 0;
+            uint32_t idEvt = 0;
+            rc = RTPoll(pExecCtx->hPollSet, 10 /*cMillies*/, &fEvtsRecv, &idEvt);
+            if (RT_SUCCESS(rc))
+            {
+                if (idEvt == RTFUZZOBS_EXEC_CTX_POLL_ID_STDOUT)
+                {
+                    Assert(fEvtsRecv & RTPOLL_EVT_READ);
+                    rc = rtFuzzObsStdOutErrBufFill(&pExecCtx->StdOutBuf, pExecCtx->hPipeStdoutR);
+                    AssertRC(rc);
+                }
+                else if (idEvt == RTFUZZOBS_EXEC_CTX_POLL_ID_STDERR)
+                {
+                    Assert(fEvtsRecv & RTPOLL_EVT_READ);
+                    rc = rtFuzzObsStdOutErrBufFill(&pExecCtx->StdErrBuf, pExecCtx->hPipeStderrR);
+                    AssertRC(rc);
+                }
+                else if (idEvt == RTFUZZOBS_EXEC_CTX_POLL_ID_STDIN)
+                {
+                    /* Feed the next input. */
+                    Assert(fEvtsRecv & RTPOLL_EVT_WRITE);
+                    size_t cbWritten = 0;
+                    rc = RTPipeWrite(pExecCtx->hPipeStdinW, pExecCtx->pbInputCur, pExecCtx->cbInputLeft, &cbWritten);
+                    if (RT_SUCCESS(rc))
+                    {
+                        pExecCtx->cbInputLeft -= cbWritten;
+                        if (!pExecCtx->cbInputLeft)
+                        {
+                            /* Close stdin pipe. */
+                            rc = RTPollSetRemove(pExecCtx->hPollSet, RTFUZZOBS_EXEC_CTX_POLL_ID_STDIN);
+                            AssertRC(rc);
+                            RTPipeClose(pExecCtx->hPipeStdinW);
+                        }
+                    }
+                }
+                else
+                    AssertMsgFailed(("Invalid poll ID returned: %u!\n", idEvt));
+            }
+            else
+                Assert(rc == VERR_TIMEOUT);
+
+            /* Check the process status. */
+            rc = RTProcWait(pExecCtx->hProc, RTPROCWAIT_FLAGS_NOBLOCK, pProcStat);
+            if (RT_SUCCESS(rc))
+                break;
+            else
+            {
+                Assert(rc == VERR_PROCESS_RUNNING);
+                /* Check whether we reached the limit. */
+                if (RTTimeSystemMilliTS() - tsMilliesStart > pThis->msWaitMax)
+                {
+                    rc = VERR_TIMEOUT;
+                    break;
+                }
+            }
+        } /* for (;;) */
+
+        /* Kill the process on a timeout. */
+        if (rc == VERR_TIMEOUT)
+        {
+            int rc2 = RTProcTerminate(pExecCtx->hProc);
+            AssertRC(rc2);
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Runs the fuzzing aware client binary pumping all data back and forth waiting for the client to crash.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_TIMEOUT if the client didn't finish in the given deadline and was killed.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   pExecCtx            The execution context.
+ * @param   pProcStat           Where to store the process exit status on success.
+ */
+static int rtFuzzObsExecCtxClientRunFuzzingAware(PRTFUZZOBSINT pThis, PRTFUZZOBSEXECCTX pExecCtx, PRTPROCSTATUS pProcStat)
+{
+    rtFuzzObsStdOutErrBufClear(&pExecCtx->StdOutBuf);
+    rtFuzzObsStdOutErrBufClear(&pExecCtx->StdErrBuf);
+
+    int rc = RTProcCreateEx(pThis->pszBinary, &pExecCtx->apszArgs[0], RTENV_DEFAULT, 0 /*fFlags*/, &pExecCtx->StdinHandle,
+                            &pExecCtx->StdoutHandle, &pExecCtx->StderrHandle, NULL, NULL, &pExecCtx->hProc);
+    if (RT_SUCCESS(rc))
+    {
+        /* Send the initial fuzzing context state over to the client. */
+        void *pvState = NULL;
+        size_t cbState = 0;
+        rc = RTFuzzCtxStateExport(pThis->hFuzzCtx, &pvState, &cbState);
+        if (RT_SUCCESS(rc))
+        {
+            uint32_t cbStateWr = (uint32_t)cbState;
+            rc = RTPipeWriteBlocking(pExecCtx->hPipeStdinW, &cbStateWr, sizeof(cbStateWr), NULL);
+            rc = RTPipeWriteBlocking(pExecCtx->hPipeStdinW, pvState, cbState, NULL);
+            if (RT_SUCCESS(rc))
+            {
+                rc = RTPollSetRemove(pExecCtx->hPollSet, RTFUZZOBS_EXEC_CTX_POLL_ID_STDIN);
+                AssertRC(rc);
+
+                uint64_t tsMilliesLastSignal = RTTimeSystemMilliTS();
+                uint32_t cFuzzedInputs = 0;
+                for (;;)
+                {
+                    /* Wait a bit for something to happen on one of the pipes. */
+                    uint32_t fEvtsRecv = 0;
+                    uint32_t idEvt = 0;
+                    rc = RTPoll(pExecCtx->hPollSet, 10 /*cMillies*/, &fEvtsRecv, &idEvt);
+                    if (RT_SUCCESS(rc))
+                    {
+                        if (idEvt == RTFUZZOBS_EXEC_CTX_POLL_ID_STDOUT)
+                        {
+                            Assert(fEvtsRecv & RTPOLL_EVT_READ);
+                            for (;;)
+                            {
+                                char achBuf[512];
+                                size_t cbRead = 0;
+                                rc = RTPipeRead(pExecCtx->hPipeStdoutR, &achBuf[0], sizeof(achBuf), &cbRead);
+                                if (RT_SUCCESS(rc))
+                                {
+                                    if (!cbRead)
+                                        break;
+
+                                    tsMilliesLastSignal = RTTimeMilliTS();
+                                    for (unsigned i = 0; i < cbRead; i++)
+                                    {
+                                        ASMAtomicIncU32(&pThis->Stats.cFuzzedInputs);
+                                        ASMAtomicIncU32(&pThis->Stats.cFuzzedInputsPerSec);
+
+                                        if (achBuf[i] == '.')
+                                            cFuzzedInputs++;
+                                        else if (achBuf[i] == 'A')
+                                        {
+                                            /** @todo Advance our fuzzer to get the added input. */
+                                        }
+                                    }
+                                }
+                                else
+                                    break;
+                            }
+                            AssertRC(rc);
+                        }
+                        else if (idEvt == RTFUZZOBS_EXEC_CTX_POLL_ID_STDERR)
+                        {
+                            Assert(fEvtsRecv & RTPOLL_EVT_READ);
+                            rc = rtFuzzObsStdOutErrBufFill(&pExecCtx->StdErrBuf, pExecCtx->hPipeStderrR);
+                            AssertRC(rc);
+                        }
+                        else
+                            AssertMsgFailed(("Invalid poll ID returned: %u!\n", idEvt));
+                    }
+                    else
+                        Assert(rc == VERR_TIMEOUT);
+
+                    /* Check the process status. */
+                    rc = RTProcWait(pExecCtx->hProc, RTPROCWAIT_FLAGS_NOBLOCK, pProcStat);
+                    if (RT_SUCCESS(rc))
+                        break;
+                    else
+                    {
+                        Assert(rc == VERR_PROCESS_RUNNING);
+                        /* Check when the last response from the client was. */
+                        if (RTTimeSystemMilliTS() - tsMilliesLastSignal > pThis->msWaitMax)
+                        {
+                            rc = VERR_TIMEOUT;
+                            break;
+                        }
+                    }
+                } /* for (;;) */
+
+                /* Kill the process on a timeout. */
+                if (rc == VERR_TIMEOUT)
+                {
+                    int rc2 = RTProcTerminate(pExecCtx->hProc);
+                    AssertRC(rc2);
+                }
+            }
+        }
+    }
+
+    RTHANDLE Handle;
+    Handle.enmType = RTHANDLETYPE_PIPE;
+    Handle.u.hPipe = pExecCtx->hPipeStdinW;
+    rc = RTPollSetAdd(pExecCtx->hPollSet, &Handle, RTPOLL_EVT_WRITE, RTFUZZOBS_EXEC_CTX_POLL_ID_STDIN);
+    AssertRC(rc);
+
+    return rc;
+}
+
+
+/**
+ * Adds the input to the results directory.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   hFuzzInput          Fuzzing input handle to write.
+ * @param   pExecCtx            Execution context.
+ */
+static int rtFuzzObsAddInputToResults(PRTFUZZOBSINT pThis, RTFUZZINPUT hFuzzInput, PRTFUZZOBSEXECCTX pExecCtx)
+{
+    char aszDigest[RTMD5_STRING_LEN + 1];
+    int rc = RTFuzzInputQueryDigestString(hFuzzInput, &aszDigest[0], sizeof(aszDigest));
+    if (RT_SUCCESS(rc))
+    {
+        /* Create a directory. */
+        char szPath[RTPATH_MAX];
+        rc = RTPathJoin(szPath, sizeof(szPath), pThis->pszResultsDir, &aszDigest[0]);
+        AssertRC(rc);
+
+        rc = RTDirCreate(&szPath[0], 0700, 0 /*fCreate*/);
+        if (RT_SUCCESS(rc))
+        {
+            /* Write the input. */
+            char szTmp[RTPATH_MAX];
+            rc = RTPathJoin(szTmp, sizeof(szTmp), &szPath[0], "input");
+            AssertRC(rc);
+
+            rc = RTFuzzInputWriteToFile(hFuzzInput, &szTmp[0]);
+            if (RT_SUCCESS(rc))
+            {
+                /* Stdout and Stderr. */
+                rc = RTPathJoin(szTmp, sizeof(szTmp), &szPath[0], "stdout");
+                AssertRC(rc);
+                rc = rtFuzzStdOutErrBufWriteToFile(&pExecCtx->StdOutBuf, &szTmp[0]);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = RTPathJoin(szTmp, sizeof(szTmp), &szPath[0], "stderr");
+                    AssertRC(rc);
+                    rc = rtFuzzStdOutErrBufWriteToFile(&pExecCtx->StdOutBuf, &szTmp[0]);
+                }
+            }
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Fuzzing observer worker loop.
+ *
+ * @returns IPRT status code.
+ * @param   hThrd               The thread handle.
+ * @param   pvUser              Opaque user data.
+ */
+static DECLCALLBACK(int) rtFuzzObsWorkerLoop(RTTHREAD hThrd, void *pvUser)
+{
+    PRTFUZZOBSTHRD pObsThrd = (PRTFUZZOBSTHRD)pvUser;
+    PRTFUZZOBSINT pThis = pObsThrd->pFuzzObs;
+    PRTFUZZOBSEXECCTX pExecCtx = NULL;
+
+    int rc = rtFuzzObsExecCtxCreate(&pExecCtx, pThis);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    while (!pObsThrd->fShutdown)
+    {
+        char szInput[RTPATH_MAX];
+
+        /* Wait for work. */
+        rc = RTThreadUserWait(hThrd, RT_INDEFINITE_WAIT);
+        AssertRC(rc);
+
+        if (pObsThrd->fShutdown)
+            break;
+
+        if (!ASMAtomicXchgBool(&pObsThrd->fNewInput, false))
+            continue;
+
+        AssertPtr(pObsThrd->hFuzzInput);
+
+        if (pThis->enmInputChan == RTFUZZOBSINPUTCHAN_FILE)
+        {
+            char szFilename[32];
+
+            ssize_t cbBuf = RTStrPrintf2(&szFilename[0], sizeof(szFilename), "%u", pObsThrd->idObs);
+            Assert(cbBuf > 0); RT_NOREF(cbBuf);
+
+            RT_ZERO(szInput);
+            rc = RTPathJoin(szInput, sizeof(szInput), pThis->pszTmpDir, &szFilename[0]);
+            AssertRC(rc);
+
+            rc = RTFuzzInputWriteToFile(pObsThrd->hFuzzInput, &szInput[0]);
+            if (RT_SUCCESS(rc))
+            {
+                RTFUZZOBSVARIABLE aVar[2] = {
+                    { "${INPUT}", sizeof("${INPUT}") - 1, &szInput[0] },
+                    { NULL,       0,                      NULL        }
+                };
+                rc = rtFuzzObsExecCtxArgvPrepare(pThis, pExecCtx, &aVar[0]);
+            }
+        }
+        else if (pThis->enmInputChan == RTFUZZOBSINPUTCHAN_STDIN)
+        {
+            rc = RTFuzzInputQueryData(pObsThrd->hFuzzInput, (void **)&pExecCtx->pbInputCur, &pExecCtx->cbInputLeft);
+            if (RT_SUCCESS(rc))
+                rc = rtFuzzObsExecCtxArgvPrepare(pThis, pExecCtx, NULL);
+        }
+
+        if (RT_SUCCESS(rc))
+        {
+            RTPROCSTATUS ProcSts;
+            if (pThis->enmInputChan == RTFUZZOBSINPUTCHAN_FUZZING_AWARE_CLIENT)
+                rc = rtFuzzObsExecCtxClientRunFuzzingAware(pThis, pExecCtx, &ProcSts);
+            else
+            {
+                rc = rtFuzzObsExecCtxClientRun(pThis, pExecCtx, &ProcSts);
+                ASMAtomicIncU32(&pThis->Stats.cFuzzedInputs);
+                ASMAtomicIncU32(&pThis->Stats.cFuzzedInputsPerSec);
+            }
+
+            if (RT_SUCCESS(rc))
+            {
+                if (ProcSts.enmReason != RTPROCEXITREASON_NORMAL)
+                {
+                    ASMAtomicIncU32(&pThis->Stats.cFuzzedInputsCrash);
+                    rc = rtFuzzObsAddInputToResults(pThis, pObsThrd->hFuzzInput, pExecCtx);
+                }
+            }
+            else if (rc == VERR_TIMEOUT)
+            {
+                ASMAtomicIncU32(&pThis->Stats.cFuzzedInputsHang);
+                rc = rtFuzzObsAddInputToResults(pThis, pObsThrd->hFuzzInput, pExecCtx);
+            }
+            else
+                AssertFailed();
+
+            if (pThis->enmInputChan == RTFUZZOBSINPUTCHAN_FILE)
+                RTFileDelete(&szInput[0]);
+        }
+
+        ASMAtomicBitSet(&pThis->bmEvt, pObsThrd->idObs);
+        RTSemEventSignal(pThis->hEvtGlobal);
+    }
+
+    rtFuzzObsExecCtxDestroy(pThis, pExecCtx);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Fuzzing observer master worker loop.
+ *
+ * @returns IPRT status code.
+ * @param   hThread               The thread handle.
+ * @param   pvUser              Opaque user data.
+ */
+static DECLCALLBACK(int) rtFuzzObsMasterLoop(RTTHREAD hThread, void *pvUser)
+{
+    RT_NOREF(hThread);
+    int rc = VINF_SUCCESS;
+    PRTFUZZOBSINT pThis = (PRTFUZZOBSINT)pvUser;
+
+    RTThreadUserSignal(hThread);
+
+    while (   !pThis->fShutdown
+           && RT_SUCCESS(rc))
+    {
+        uint64_t bmEvt = ASMAtomicXchgU64(&pThis->bmEvt, 0);
+        uint32_t idxObs = 0;
+        while (bmEvt != 0)
+        {
+            if (bmEvt & 0x1)
+            {
+                /* Create a new input for this observer and kick it. */
+                PRTFUZZOBSTHRD pObsThrd = &pThis->paObsThreads[idxObs];
+
+                /* Release the old input. */
+                if (pObsThrd->hFuzzInput)
+                {
+                    if (pObsThrd->fKeepInput)
+                    {
+                        int rc2 = RTFuzzInputAddToCtxCorpus(pObsThrd->hFuzzInput);
+                        Assert(RT_SUCCESS(rc2) || rc2 == VERR_ALREADY_EXISTS); RT_NOREF(rc2);
+                        pObsThrd->fKeepInput= false;
+                    }
+                    RTFuzzInputRelease(pObsThrd->hFuzzInput);
+                }
+
+                rc = RTFuzzCtxInputGenerate(pThis->hFuzzCtx, &pObsThrd->hFuzzInput);
+                if (RT_SUCCESS(rc))
+                {
+                    ASMAtomicWriteBool(&pObsThrd->fNewInput, true);
+                    RTThreadUserSignal(pObsThrd->hThread);
+                }
+            }
+
+            idxObs++;
+            bmEvt >>= 1;
+        }
+
+        rc = RTSemEventWait(pThis->hEvtGlobal, RT_INDEFINITE_WAIT);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Initializes the given worker thread structure.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   iObs                Observer ID.
+ * @param   pObsThrd            The observer thread structure.
+ */
+static int rtFuzzObsWorkerThreadInit(PRTFUZZOBSINT pThis, uint32_t idObs, PRTFUZZOBSTHRD pObsThrd)
+{
+    pObsThrd->pFuzzObs   = pThis;
+    pObsThrd->hFuzzInput = NULL;
+    pObsThrd->idObs      = idObs;
+    pObsThrd->fShutdown  = false;
+
+    ASMAtomicBitSet(&pThis->bmEvt, idObs);
+    return RTThreadCreate(&pObsThrd->hThread, rtFuzzObsWorkerLoop, pObsThrd, 0, RTTHREADTYPE_IO,
+                          RTTHREADFLAGS_WAITABLE, "Fuzz-Worker");
+}
+
+
+/**
+ * Creates the given amount of worker threads and puts them into waiting state.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal fuzzing observer state.
+ * @param   cThreads            Number of worker threads to create.
+ */
+static int rtFuzzObsWorkersCreate(PRTFUZZOBSINT pThis, uint32_t cThreads)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZOBSTHRD paObsThreads = (PRTFUZZOBSTHRD)RTMemAllocZ(cThreads * sizeof(RTFUZZOBSTHRD));
+    if (RT_LIKELY(paObsThreads))
+    {
+        for (unsigned i = 0; i < cThreads && RT_SUCCESS(rc); i++)
+        {
+            rc = rtFuzzObsWorkerThreadInit(pThis, i, &paObsThreads[i]);
+            if (RT_FAILURE(rc))
+            {
+                /* Rollback. */
+
+            }
+        }
+
+        if (RT_SUCCESS(rc))
+        {
+            pThis->paObsThreads = paObsThreads;
+            pThis->cThreads     = cThreads;
+        }
+        else
+            RTMemFree(paObsThreads);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Creates the global worker thread managing the input creation and other worker threads.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal fuzzing observer state.
+ */
+static int rtFuzzObsMasterCreate(PRTFUZZOBSINT pThis)
+{
+    pThis->fShutdown = false;
+
+    int rc = RTSemEventCreate(&pThis->hEvtGlobal);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTThreadCreate(&pThis->hThreadGlobal, rtFuzzObsMasterLoop, pThis, 0, RTTHREADTYPE_IO,
+                            RTTHREADFLAGS_WAITABLE, "Fuzz-Master");
+        if (RT_SUCCESS(rc))
+        {
+            RTThreadUserWait(pThis->hThreadGlobal, RT_INDEFINITE_WAIT);
+        }
+        else
+        {
+            RTSemEventDestroy(pThis->hEvtGlobal);
+            pThis->hEvtGlobal = NIL_RTSEMEVENT;
+        }
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsCreate(PRTFUZZOBS phFuzzObs)
+{
+    AssertPtrReturn(phFuzzObs, VERR_INVALID_POINTER);
+
+    int rc = VINF_SUCCESS;
+    PRTFUZZOBSINT pThis = (PRTFUZZOBSINT)RTMemAllocZ(sizeof(*pThis));
+    if (RT_LIKELY(pThis))
+    {
+        pThis->pszBinary     = NULL;
+        pThis->papszArgs     = NULL;
+        pThis->msWaitMax     = 1000;
+        pThis->hThreadGlobal = NIL_RTTHREAD;
+        pThis->hEvtGlobal    = NIL_RTSEMEVENT;
+        pThis->bmEvt         = 0;
+        pThis->cThreads      = 0;
+        pThis->paObsThreads  = NULL;
+        pThis->tsLastStats   = RTTimeMilliTS();
+        pThis->Stats.cFuzzedInputsPerSec = 0;
+        pThis->Stats.cFuzzedInputs       = 0;
+        pThis->Stats.cFuzzedInputsHang   = 0;
+        pThis->Stats.cFuzzedInputsCrash  = 0;
+        rc = RTFuzzCtxCreate(&pThis->hFuzzCtx);
+        if (RT_SUCCESS(rc))
+        {
+            *phFuzzObs = pThis;
+            return VINF_SUCCESS;
+        }
+
+        RTMemFree(pThis);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsDestroy(RTFUZZOBS hFuzzObs)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+
+    RTFuzzObsExecStop(hFuzzObs);
+
+    /* Clean up all acquired resources. */
+    for (unsigned i = 0; i < pThis->cArgs; i++)
+        RTStrFree(pThis->papszArgs[i]);
+
+    RTMemFree(pThis->papszArgs);
+
+    if (pThis->hEvtGlobal != NIL_RTSEMEVENT)
+        RTSemEventDestroy(pThis->hEvtGlobal);
+
+    if (pThis->pszResultsDir)
+        RTStrFree(pThis->pszResultsDir);
+    if (pThis->pszTmpDir)
+        RTStrFree(pThis->pszTmpDir);
+    if (pThis->pszBinary)
+        RTStrFree(pThis->pszBinary);
+    RTFuzzCtxRelease(pThis->hFuzzCtx);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTFuzzObsQueryCtx(RTFUZZOBS hFuzzObs, PRTFUZZCTX phFuzzCtx)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(phFuzzCtx, VERR_INVALID_POINTER);
+
+    RTFuzzCtxRetain(pThis->hFuzzCtx);
+    *phFuzzCtx = pThis->hFuzzCtx;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTFuzzObsQueryStats(RTFUZZOBS hFuzzObs, PRTFUZZOBSSTATS pStats)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(pStats, VERR_INVALID_POINTER);
+
+    uint64_t tsStatsQuery = RTTimeMilliTS();
+    uint32_t cFuzzedInputsPerSec = ASMAtomicXchgU32(&pThis->Stats.cFuzzedInputsPerSec, 0);
+
+    pStats->cFuzzedInputsCrash  = ASMAtomicReadU32(&pThis->Stats.cFuzzedInputsCrash);
+    pStats->cFuzzedInputsHang   = ASMAtomicReadU32(&pThis->Stats.cFuzzedInputsHang);
+    pStats->cFuzzedInputs       = ASMAtomicReadU32(&pThis->Stats.cFuzzedInputs);
+    uint64_t cPeriodSec = (tsStatsQuery - pThis->tsLastStats) / 1000;
+    if (cPeriodSec)
+    {
+        pStats->cFuzzedInputsPerSec    = cFuzzedInputsPerSec / cPeriodSec;
+        pThis->cFuzzedInputsPerSecLast = pStats->cFuzzedInputsPerSec;
+        pThis->tsLastStats             = tsStatsQuery;
+    }
+    else
+        pStats->cFuzzedInputsPerSec = pThis->cFuzzedInputsPerSecLast;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTFuzzObsSetTmpDirectory(RTFUZZOBS hFuzzObs, const char *pszTmp)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszTmp, VERR_INVALID_POINTER);
+
+    int rc = VINF_SUCCESS;
+    pThis->pszTmpDir = RTStrDup(pszTmp);
+    if (!pThis->pszTmpDir)
+        rc = VERR_NO_STR_MEMORY;
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsSetResultDirectory(RTFUZZOBS hFuzzObs, const char *pszResults)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszResults, VERR_INVALID_POINTER);
+
+    int rc = VINF_SUCCESS;
+    pThis->pszResultsDir = RTStrDup(pszResults);
+    if (!pThis->pszResultsDir)
+        rc = VERR_NO_STR_MEMORY;
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsSetTestBinary(RTFUZZOBS hFuzzObs, const char *pszBinary, RTFUZZOBSINPUTCHAN enmInputChan)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszBinary, VERR_INVALID_POINTER);
+
+    int rc = VINF_SUCCESS;
+    pThis->enmInputChan = enmInputChan;
+    pThis->pszBinary    = RTStrDup(pszBinary);
+    if (RT_UNLIKELY(!pThis->pszBinary))
+        rc = VERR_NO_STR_MEMORY;
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsSetTestBinaryArgs(RTFUZZOBS hFuzzObs, const char * const *papszArgs, unsigned cArgs)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+
+    int rc = VINF_SUCCESS;
+    char **papszArgsOld = pThis->papszArgs;
+    if (papszArgs)
+    {
+        pThis->papszArgs = (char **)RTMemAllocZ(sizeof(char **) * (cArgs + 1));
+        if (RT_LIKELY(pThis->papszArgs))
+        {
+            for (unsigned i = 0; i < cArgs; i++)
+            {
+                pThis->papszArgs[i] = RTStrDup(papszArgs[i]);
+                if (RT_UNLIKELY(!pThis->papszArgs[i]))
+                {
+                    while (i > 0)
+                    {
+                        i--;
+                        RTStrFree(pThis->papszArgs[i]);
+                    }
+                    break;
+                }
+            }
+
+            if (RT_FAILURE(rc))
+                RTMemFree(pThis->papszArgs);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+
+        if (RT_FAILURE(rc))
+            pThis->papszArgs = papszArgsOld;
+        else
+            pThis->cArgs = cArgs;
+    }
+    else
+    {
+        pThis->papszArgs = NULL;
+        pThis->cArgs = 0;
+        if (papszArgsOld)
+        {
+            char **ppsz = papszArgsOld;
+            while (*ppsz != NULL)
+            {
+                RTStrFree(*ppsz);
+                ppsz++;
+            }
+            RTMemFree(papszArgsOld);
+        }
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsExecStart(RTFUZZOBS hFuzzObs, uint32_t cProcs)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(cProcs <= sizeof(uint64_t) * 8, VERR_INVALID_PARAMETER);
+    AssertReturn(   pThis->enmInputChan == RTFUZZOBSINPUTCHAN_FILE
+                 || pThis->pszTmpDir != NULL,
+                 VERR_INVALID_STATE);
+
+    int rc = VINF_SUCCESS;
+    if (!cProcs)
+        cProcs = RT_MIN(RTMpGetPresentCoreCount(), sizeof(uint64_t) * 8);
+
+    /* Spin up the worker threads first. */
+    rc = rtFuzzObsWorkersCreate(pThis, cProcs);
+    if (RT_SUCCESS(rc))
+    {
+        /* Spin up the global thread. */
+        rc = rtFuzzObsMasterCreate(pThis);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzObsExecStop(RTFUZZOBS hFuzzObs)
+{
+    PRTFUZZOBSINT pThis = hFuzzObs;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+
+    /* Wait for the master thread to terminate. */
+    if (pThis->hThreadGlobal != NIL_RTTHREAD)
+    {
+        ASMAtomicXchgBool(&pThis->fShutdown, true);
+        RTSemEventSignal(pThis->hEvtGlobal);
+        RTThreadWait(pThis->hThreadGlobal, RT_INDEFINITE_WAIT, NULL);
+        pThis->hThreadGlobal = NIL_RTTHREAD;
+    }
+
+    /* Destroy the workers. */
+    if (pThis->paObsThreads)
+    {
+        for (unsigned i = 0; i < pThis->cThreads; i++)
+        {
+            PRTFUZZOBSTHRD pThrd = &pThis->paObsThreads[i];
+            ASMAtomicXchgBool(&pThrd->fShutdown, true);
+            RTThreadUserSignal(pThrd->hThread);
+            RTThreadWait(pThrd->hThread, RT_INDEFINITE_WAIT, NULL);
+            if (pThrd->hFuzzInput)
+                RTFuzzInputRelease(pThrd->hFuzzInput);
+        }
+
+        RTMemFree(pThis->paObsThreads);
+        pThis->paObsThreads = NULL;
+        pThis->cThreads     = 0;
+    }
+
+    RTSemEventDestroy(pThis->hEvtGlobal);
+    pThis->hEvtGlobal = NIL_RTSEMEVENT;
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/common/fuzz/fuzz.cpp b/src/VBox/Runtime/common/fuzz/fuzz.cpp
new file mode 100644
index 00000000..a74d130b
--- /dev/null
+++ b/src/VBox/Runtime/common/fuzz/fuzz.cpp
@@ -0,0 +1,1217 @@
+/* $Id: fuzz.cpp $ */
+/** @file
+ * IPRT - Fuzzing framework API, core.
+ */
+
+/*
+ * Copyright (C) 2018-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/fuzz.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/avl.h>
+#include <iprt/ctype.h>
+#include <iprt/dir.h>
+#include <iprt/err.h>
+#include <iprt/file.h>
+#include <iprt/list.h>
+#include <iprt/md5.h>
+#include <iprt/mem.h>
+#include <iprt/path.h>
+#include <iprt/rand.h>
+#include <iprt/string.h>
+#include <iprt/time.h>
+#include <iprt/vfs.h>
+
+
+#define RTFUZZCTX_MAGIC UINT32_C(0xdeadc0de) /** @todo */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/** Pointer to the internal fuzzer state. */
+typedef struct RTFUZZCTXINT *PRTFUZZCTXINT;
+
+/**
+ * A fuzzing input seed.
+ */
+typedef struct RTFUZZINPUTINT
+{
+    /** The AVL tree core. */
+    AVLU64NODECORE              Core;
+    /** Node for the global list. */
+    RTLISTNODE                  NdInputs;
+    /** Reference counter. */
+    volatile uint32_t           cRefs;
+/** @todo add magic here (unused padding space on 64-bit hosts). */
+    /** The fuzzer this input belongs to. */
+    PRTFUZZCTXINT               pFuzzer;
+    /** Complete MD5 hash of the input data. */
+    uint8_t                     abMd5Hash[RTMD5_HASH_SIZE];
+    /** Size of the input data. */
+    size_t                      cbInput;
+    /** Input data - variable in size. */
+    uint8_t                     abInput[1];
+} RTFUZZINPUTINT;
+/** Pointer to the internal input state. */
+typedef RTFUZZINPUTINT *PRTFUZZINPUTINT;
+/** Pointer to an internal input state pointer. */
+typedef PRTFUZZINPUTINT *PPRTFUZZINPUTINT;
+
+
+/**
+ * Intermediate indexing structure.
+ */
+typedef struct RTFUZZINTERMEDIATE
+{
+    /** The AVL tree core. */
+    AVLU64NODECORE              Core;
+    /** The AVL tree for indexing the input seeds (keyed by the lower half of the MD5). */
+    AVLU64TREE                  TreeSeedsLow;
+} RTFUZZINTERMEDIATE;
+/** Pointer to an intermediate indexing state. */
+typedef RTFUZZINTERMEDIATE *PRTFUZZINTERMEDIATE;
+/** Pointer to an intermediate indexing state pointer. */
+typedef PRTFUZZINTERMEDIATE *PPRTFUZZINTERMEDIATE;
+
+/**
+ * The fuzzer state.
+ */
+typedef struct RTFUZZCTXINT
+{
+    /** Magic value for identification. */
+    uint32_t                    u32Magic;
+    /** Reference counter. */
+    volatile uint32_t           cRefs;
+    /** The random number generator. */
+    RTRAND                      hRand;
+    /** The AVL tree for indexing the input seeds (keyed by the upper half of the MD5). */
+    AVLU64TREE                  TreeSeedsHigh;
+    /** Sequential list of all inputs. */
+    RTLISTANCHOR                LstInputs;
+    /** Number of inputs currently in the tree. */
+    uint32_t                    cInputs;
+    /** The maximum size of one input seed to generate. */
+    size_t                      cbInputMax;
+    /** Behavioral flags. */
+    uint32_t                    fFlagsBehavioral;
+} RTFUZZCTXINT;
+
+
+/**
+ * Available mutators enum.
+ */
+typedef enum RTFUZZCTXMUTATOR
+{
+    /** Invalid mutator, not used. */
+    RTFUZZCTXMUTATOR_INVALID = 0,
+    /** Flips a single bit in the input. */
+    RTFUZZCTXMUTATOR_BIT_FLIP,
+    /** Replaces a single byte in the input. */
+    RTFUZZCTXMUTATOR_BYTE_REPLACE,
+    /** Inserts a byte sequence into the input. */
+    RTFUZZCTXMUTATOR_BYTE_SEQUENCE_INSERT,
+    /** Appends a byte sequence to the input. */
+    RTFUZZCTXMUTATOR_BYTE_SEQUENCE_APPEND,
+    /** Deletes a single byte from the input. */
+    RTFUZZCTXMUTATOR_BYTE_DELETE,
+    /** Deletes a sequence of bytes from the input. */
+    RTFUZZCTXMUTATOR_BYTE_SEQUENCE_DELETE,
+    /** Last valid mutator. */
+    RTFUZZCTXMUTATOR_LAST = RTFUZZCTXMUTATOR_BYTE_SEQUENCE_DELETE,
+    /** 32bit hack. */
+    RTFUZZCTXMUTATOR_32BIT_HACK = 0x7fffffff
+} RTFUZZCTXMUTATOR;
+/** Pointer to a mutator enum. */
+typedef RTFUZZCTXMUTATOR *PRTFUZZCTXMUTATOR;
+
+
+/**
+ * The fuzzer state to be exported - all members are stored in little endian form.
+ */
+typedef struct RTFUZZCTXSTATE
+{
+    /** Magic value for identification. */
+    uint32_t                    u32Magic;
+    /** Size of the PRNG state following in bytes. */
+    uint32_t                    cbPrng;
+    /** Number of input descriptors following. */
+    uint32_t                    cInputs;
+    /** Behavioral flags. */
+    uint32_t                    fFlagsBehavioral;
+    /** Maximum input size to generate. */
+    uint64_t                    cbInputMax;
+} RTFUZZCTXSTATE;
+/** Pointer to a fuzzing context state. */
+typedef RTFUZZCTXSTATE *PRTFUZZCTXSTATE;
+
+
+/**
+ * Mutator callback.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzer context instance.
+ * @param   pvBuf               The input buffer to mutate.
+ * @param   cbBuf               Size of the buffer in bytes.
+ * @param   ppInputMutated      Where to store the pointer to the mutated input success.
+ */
+typedef DECLCALLBACK(int) FNRTFUZZCTXMUTATOR(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated);
+/** Pointer to a mutator callback. */
+typedef FNRTFUZZCTXMUTATOR *PFNRTFUZZCTXMUTATOR;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static DECLCALLBACK(int) rtFuzzCtxMutatorBitFlip(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf,
+                                                 PPRTFUZZINPUTINT ppInputMutated);
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteReplace(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf,
+                                                     PPRTFUZZINPUTINT ppInputMutated);
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteSequenceInsert(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf,
+                                                            PPRTFUZZINPUTINT ppInputMutated);
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteSequenceAppend(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf,
+                                                            PPRTFUZZINPUTINT ppInputMutated);
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteDelete(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf,
+                                                    PPRTFUZZINPUTINT ppInputMutated);
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteSequenceDelete(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf,
+                                                            PPRTFUZZINPUTINT ppInputMutated);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/**
+ * Array of all available mutators.
+ */
+static PFNRTFUZZCTXMUTATOR const g_apfnMutators[] =
+{
+    NULL,
+    rtFuzzCtxMutatorBitFlip,
+    rtFuzzCtxMutatorByteReplace,
+    rtFuzzCtxMutatorByteSequenceInsert,
+    rtFuzzCtxMutatorByteSequenceAppend,
+    rtFuzzCtxMutatorByteDelete,
+    rtFuzzCtxMutatorByteSequenceDelete,
+    NULL
+};
+
+
+
+/**
+ * Tries to locate an input seed with the given input MD5 seed.
+ *
+ * @returns Pointer to the input seed on success or NULL if not found.
+ * @param   pThis               The fuzzer context instance.
+ * @param   pbMd5Hash           The MD5 hash to search for.
+ * @param   fExact              Flag whether to search for an exact match or return the next best fit if no match exists.
+ * @param   ppIntermediate      Where to store the pointer to the intermediate layer upon success, optional.
+ */
+static PRTFUZZINPUTINT rtFuzzCtxInputLocate(PRTFUZZCTXINT pThis, uint8_t *pbMd5Hash, bool fExact, PPRTFUZZINTERMEDIATE ppIntermediate)
+{
+    PRTFUZZINPUTINT pInput = NULL;
+    uint64_t u64Md5High = *(uint64_t *)&pbMd5Hash[RTMD5_HASH_SIZE / 2];
+    uint64_t u64Md5Low = *(uint64_t *)&pbMd5Hash[0];
+    PRTFUZZINTERMEDIATE pIntermediate = (PRTFUZZINTERMEDIATE)RTAvlU64Get(&pThis->TreeSeedsHigh, u64Md5High);
+    if (!fExact && !pIntermediate)
+        pIntermediate = (PRTFUZZINTERMEDIATE)RTAvlU64GetBestFit(&pThis->TreeSeedsHigh, u64Md5High, true /*fAbove*/);
+    if (!fExact && !pIntermediate)
+        pIntermediate = (PRTFUZZINTERMEDIATE)RTAvlU64GetBestFit(&pThis->TreeSeedsHigh, u64Md5High, false /*fAbove*/);
+
+    if (pIntermediate)
+    {
+        /* 2nd level lookup. */
+        pInput = (PRTFUZZINPUTINT)RTAvlU64Get(&pIntermediate->TreeSeedsLow, u64Md5Low);
+        if (!fExact && !pInput)
+            pInput = (PRTFUZZINPUTINT)RTAvlU64GetBestFit(&pIntermediate->TreeSeedsLow, u64Md5Low, true /*fAbove*/);
+        if (!fExact && !pInput)
+            pInput = (PRTFUZZINPUTINT)RTAvlU64GetBestFit(&pIntermediate->TreeSeedsLow, u64Md5Low, false /*fAbove*/);
+    }
+
+    if (ppIntermediate)
+        *ppIntermediate = pIntermediate;
+
+    return pInput;
+}
+
+
+/**
+ * Adds the given input to the corpus of the given fuzzer context.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzer context instance.
+ * @param   pInput              The input to add.
+ */
+static int rtFuzzCtxInputAdd(PRTFUZZCTXINT pThis, PRTFUZZINPUTINT pInput)
+{
+    int rc = VINF_SUCCESS;
+    uint64_t u64Md5High = *(uint64_t *)&pInput->abMd5Hash[RTMD5_HASH_SIZE / 2];
+    uint64_t u64Md5Low = *(uint64_t *)&pInput->abMd5Hash[0];
+
+    pInput->Core.Key = u64Md5Low;
+    PRTFUZZINTERMEDIATE pIntermediate = (PRTFUZZINTERMEDIATE)RTAvlU64Get(&pThis->TreeSeedsHigh, u64Md5High);
+    if (!pIntermediate)
+    {
+        pIntermediate = (PRTFUZZINTERMEDIATE)RTMemAllocZ(sizeof(*pIntermediate));
+        if (RT_LIKELY(pIntermediate))
+        {
+            pIntermediate->Core.Key = u64Md5High;
+            pIntermediate->TreeSeedsLow = NULL;
+            bool fIns = RTAvlU64Insert(&pThis->TreeSeedsHigh, &pIntermediate->Core);
+            Assert(fIns); RT_NOREF(fIns);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    if (RT_SUCCESS(rc))
+    {
+        AssertPtr(pIntermediate);
+        bool fIns = RTAvlU64Insert(&pIntermediate->TreeSeedsLow, &pInput->Core);
+        if (!fIns)
+            rc = VERR_ALREADY_EXISTS;
+        else
+        {
+            RTListAppend(&pThis->LstInputs, &pInput->NdInputs);
+            pThis->cInputs++;
+            RTFuzzInputRetain(pInput);
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Returns a random input from the corpus of the given fuzzer context.
+ *
+ * @returns Pointer to a randomly picked input.
+ * @param   pThis               The fuzzer context instance.
+ */
+static PRTFUZZINPUTINT rtFuzzCtxInputPickRnd(PRTFUZZCTXINT pThis)
+{
+    /* Generate a random MD5 hash and do a non exact localisation. */
+    uint8_t abDigestRnd[RTMD5_HASH_SIZE];
+    RTRandAdvBytes(pThis->hRand, &abDigestRnd[0], sizeof(abDigestRnd));
+
+    return rtFuzzCtxInputLocate(pThis, &abDigestRnd[0], false /*fExact*/, NULL /*ppIntermediate*/);
+}
+
+
+/**
+ * Clones a given input.
+ *
+ * @returns Pointer to the cloned input or NULL if out of memory.
+ * @param   pThis               The fuzzer context instance.
+ * @param   pvBuf               The buffer to clone.
+ * @param   cbBuf               Size of the buffer in bytes.
+ */
+static PRTFUZZINPUTINT rtFuzzCtxInputClone(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf)
+{
+    PRTFUZZINPUTINT pInpClone = (PRTFUZZINPUTINT)RTMemAllocZ(RT_UOFFSETOF_DYN(RTFUZZINPUTINT, abInput[cbBuf]));
+    if (RT_LIKELY(pInpClone))
+    {
+        pInpClone->cRefs    = 1;
+        pInpClone->pFuzzer  = pThis,
+        pInpClone->cbInput  = cbBuf;
+        memcpy(&pInpClone->abInput[0], pvBuf, cbBuf);
+    }
+
+    return pInpClone;
+}
+
+
+/**
+ * Creates an empty input seed capable of holding the given number of bytes.
+ *
+ * @returns Pointer to the newly created input seed.
+ * @param   pThis               The fuzzer context instance.
+ * @param   cbInput             Input seed size in bytes.
+ */
+static PRTFUZZINPUTINT rtFuzzCtxInputCreate(PRTFUZZCTXINT pThis, size_t cbInput)
+{
+    PRTFUZZINPUTINT pInput = (PRTFUZZINPUTINT)RTMemAllocZ(RT_UOFFSETOF_DYN(RTFUZZINPUTINT, abInput[cbInput]));
+    if (RT_LIKELY(pInput))
+    {
+        pInput->pFuzzer = pThis;
+        pInput->cRefs   = 1;
+        pInput->cbInput = cbInput;
+    }
+
+    return pInput;
+}
+
+
+/**
+ * Destroys the given input.
+ *
+ * @returns nothing.
+ * @param   pInput              The input to destroy.
+ */
+static void rtFuzzInputDestroy(PRTFUZZINPUTINT pInput)
+{
+    RTMemFree(pInput);
+}
+
+
+/**
+ * Destorys the given fuzzer context freeing all allocated resources.
+ *
+ * @returns nothing.
+ * @param   pThis               The fuzzer context instance.
+ */
+static void rtFuzzCtxDestroy(PRTFUZZCTXINT pThis)
+{
+    RT_NOREF(pThis);
+}
+
+
+/**
+ * Mutator callback - flips a single bit in the input.
+ */
+static DECLCALLBACK(int) rtFuzzCtxMutatorBitFlip(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZINPUTINT pInputMutated = rtFuzzCtxInputClone(pThis, pvBuf, cbBuf);
+    if (RT_LIKELY(pInputMutated))
+    {
+        int32_t iBit = RTRandAdvS32Ex(pThis->hRand, 0, (uint32_t)cbBuf * 8 - 1);
+        ASMBitToggle(&pInputMutated->abInput[0], iBit);
+        RTMd5(&pInputMutated->abInput[0], pInputMutated->cbInput, &pInputMutated->abMd5Hash[0]);
+        *ppInputMutated = pInputMutated;
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    return rc;
+}
+
+
+/**
+ * Mutator callback - replaces a single byte in the input.
+ */
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteReplace(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZINPUTINT pInputMutated = rtFuzzCtxInputClone(pThis, pvBuf, cbBuf);
+    if (RT_LIKELY(pInputMutated))
+    {
+        uint8_t *pbBuf = (uint8_t *)pvBuf;
+        uint32_t offByte = RTRandAdvU32Ex(pThis->hRand, 0, (uint32_t)cbBuf - 1);
+        RTRandAdvBytes(pThis->hRand, &pInputMutated->abInput[offByte], 1);
+        if (pbBuf[offByte] != pInputMutated->abInput[offByte])
+        {
+            RTMd5(&pInputMutated->abInput[0], pInputMutated->cbInput, &pInputMutated->abMd5Hash[0]);
+            *ppInputMutated = pInputMutated;
+        }
+        else
+            RTMemFree(pInputMutated);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    return rc;
+}
+
+
+/**
+ * Mutator callback - inserts a byte sequence into the input.
+ */
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteSequenceInsert(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated)
+{
+    int rc = VINF_SUCCESS;
+    if (cbBuf < pThis->cbInputMax)
+    {
+        size_t cbInputMutated = RTRandAdvU32Ex(pThis->hRand, (uint32_t)cbBuf + 1, (uint32_t)pThis->cbInputMax);
+        size_t cbInsert = cbInputMutated - cbBuf;
+        uint32_t offInsert = RTRandAdvU32Ex(pThis->hRand, 0, (uint32_t)cbBuf);
+        uint8_t *pbBuf = (uint8_t *)pvBuf;
+        PRTFUZZINPUTINT pInputMutated = rtFuzzCtxInputCreate(pThis, cbInputMutated);
+        if (RT_LIKELY(pInputMutated))
+        {
+            if (offInsert)
+                memcpy(&pInputMutated->abInput[0], pbBuf, offInsert);
+            RTRandAdvBytes(pThis->hRand, &pInputMutated->abInput[offInsert], cbInsert);
+            memcpy(&pInputMutated->abInput[offInsert + cbInsert], &pbBuf[offInsert], cbBuf - offInsert);
+            RTMd5(&pInputMutated->abInput[0], pInputMutated->cbInput, &pInputMutated->abMd5Hash[0]);
+            *ppInputMutated = pInputMutated;
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Mutator callback - appends a byte sequence to the input.
+ */
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteSequenceAppend(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated)
+{
+    int rc = VINF_SUCCESS;
+    if (cbBuf < pThis->cbInputMax)
+    {
+        size_t cbInputMutated = RTRandAdvU32Ex(pThis->hRand, (uint32_t)cbBuf + 1, (uint32_t)pThis->cbInputMax);
+        size_t cbInsert = cbInputMutated - cbBuf;
+        PRTFUZZINPUTINT pInputMutated = rtFuzzCtxInputCreate(pThis, cbInputMutated);
+        if (RT_LIKELY(pInputMutated))
+        {
+            memcpy(&pInputMutated->abInput[0], pvBuf, cbBuf);
+            RTRandAdvBytes(pThis->hRand, &pInputMutated->abInput[cbBuf], cbInsert);
+            RTMd5(&pInputMutated->abInput[0], pInputMutated->cbInput, &pInputMutated->abMd5Hash[0]);
+            *ppInputMutated = pInputMutated;
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Mutator callback - deletes a single byte in the input.
+ */
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteDelete(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated)
+{
+    int rc = VINF_SUCCESS;
+    if (cbBuf > 1)
+    {
+        uint32_t offDelete = RTRandAdvU32Ex(pThis->hRand, 0, (uint32_t)cbBuf - 1);
+        uint8_t *pbBuf = (uint8_t *)pvBuf;
+        PRTFUZZINPUTINT pInputMutated = rtFuzzCtxInputCreate(pThis, cbBuf - 1);
+        if (RT_LIKELY(pInputMutated))
+        {
+            if (offDelete)
+                memcpy(&pInputMutated->abInput[0], pbBuf, offDelete);
+            if (offDelete < cbBuf - 1)
+                memcpy(&pInputMutated->abInput[offDelete], &pbBuf[offDelete + 1], cbBuf - offDelete - 1);
+            RTMd5(&pInputMutated->abInput[0], pInputMutated->cbInput, &pInputMutated->abMd5Hash[0]);
+            *ppInputMutated = pInputMutated;
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Mutator callback - deletes a byte sequence in the input.
+ */
+static DECLCALLBACK(int) rtFuzzCtxMutatorByteSequenceDelete(PRTFUZZCTXINT pThis, const void *pvBuf, size_t cbBuf, PPRTFUZZINPUTINT ppInputMutated)
+{
+    int rc = VINF_SUCCESS;
+    if (cbBuf > 1)
+    {
+        size_t cbInputMutated = RTRandAdvU32Ex(pThis->hRand, 0, (uint32_t)cbBuf - 1);
+        size_t cbDel = cbBuf - cbInputMutated;
+        uint32_t offDel = RTRandAdvU32Ex(pThis->hRand, 0, (uint32_t)(cbBuf - cbDel));
+        uint8_t *pbBuf = (uint8_t *)pvBuf;
+
+        PRTFUZZINPUTINT pInputMutated = rtFuzzCtxInputCreate(pThis, cbInputMutated);
+        if (RT_LIKELY(pInputMutated))
+        {
+            if (offDel)
+                memcpy(&pInputMutated->abInput[0], pbBuf, offDel);
+            memcpy(&pInputMutated->abInput[offDel], &pbBuf[offDel + cbDel], cbBuf - offDel - cbDel);
+            RTMd5(&pInputMutated->abInput[0], pInputMutated->cbInput, &pInputMutated->abMd5Hash[0]);
+            *ppInputMutated = pInputMutated;
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    return rc;
+}
+
+
+static PRTFUZZCTXINT rtFuzzCtxCreateEmpty(void)
+{
+    PRTFUZZCTXINT pThis = (PRTFUZZCTXINT)RTMemAllocZ(sizeof(*pThis));
+    if (RT_LIKELY(pThis))
+    {
+        pThis->u32Magic         = RTFUZZCTX_MAGIC;
+        pThis->cRefs            = 1;
+        pThis->TreeSeedsHigh    = NULL;
+        pThis->cbInputMax       = UINT32_MAX;
+        pThis->cInputs          = 0;
+        pThis->fFlagsBehavioral = 0;
+        RTListInit(&pThis->LstInputs);
+
+        int rc = RTRandAdvCreateParkMiller(&pThis->hRand);
+        if (RT_SUCCESS(rc))
+        {
+            RTRandAdvSeed(pThis->hRand, RTTimeSystemNanoTS());
+            return pThis;
+        }
+
+        RTMemFree(pThis);
+    }
+
+    return NULL;
+}
+
+
+RTDECL(int) RTFuzzCtxCreate(PRTFUZZCTX phFuzzCtx)
+{
+    AssertPtrReturn(phFuzzCtx, VERR_INVALID_POINTER);
+
+    int rc = VINF_SUCCESS;
+    PRTFUZZCTXINT pThis = rtFuzzCtxCreateEmpty();
+    if (RT_LIKELY(pThis))
+    {
+        *phFuzzCtx = pThis;
+        return VINF_SUCCESS;
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCreateFromState(PRTFUZZCTX phFuzzCtx, const void *pvState, size_t cbState)
+{
+    AssertPtrReturn(phFuzzCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pvState, VERR_INVALID_POINTER);
+    AssertReturn(cbState > 0, VERR_INVALID_PARAMETER);
+
+    int rc = VINF_SUCCESS;
+    if (cbState >= sizeof(RTFUZZCTXSTATE))
+    {
+        RTFUZZCTXSTATE StateImport;
+
+        memcpy(&StateImport, pvState, sizeof(RTFUZZCTXSTATE));
+        if (   RT_LE2H_U32(StateImport.u32Magic) == RTFUZZCTX_MAGIC
+            && RT_LE2H_U32(StateImport.cbPrng) <= cbState - sizeof(RTFUZZCTXSTATE))
+        {
+            PRTFUZZCTXINT pThis = rtFuzzCtxCreateEmpty();
+            if (RT_LIKELY(pThis))
+            {
+                pThis->cbInputMax       = (size_t)RT_LE2H_U64(StateImport.cbInputMax);
+                pThis->fFlagsBehavioral = RT_LE2H_U32(StateImport.fFlagsBehavioral);
+
+                uint8_t *pbState = (uint8_t *)pvState;
+                uint32_t cInputs = RT_LE2H_U32(StateImport.cInputs);
+                rc = RTRandAdvRestoreState(pThis->hRand, (const char *)&pbState[sizeof(RTFUZZCTXSTATE)]);
+                if (RT_SUCCESS(rc))
+                {
+                    /* Go through the inputs and add them. */
+                    pbState += sizeof(RTFUZZCTXSTATE) + RT_LE2H_U32(StateImport.cbPrng);
+                    cbState -= sizeof(RTFUZZCTXSTATE) + RT_LE2H_U32(StateImport.cbPrng);
+
+                    uint32_t idx = 0;
+                    while (   idx < cInputs
+                           && RT_SUCCESS(rc))
+                    {
+                        size_t cbInput = 0;
+                        if (cbState >= sizeof(uint32_t))
+                        {
+                            memcpy(&cbInput, pbState, sizeof(uint32_t));
+                            cbInput = RT_LE2H_U32(cbInput);
+                            pbState += sizeof(uint32_t);
+                        }
+
+                        if (   cbInput
+                            && cbInput <= cbState)
+                        {
+                            PRTFUZZINPUTINT pInput = rtFuzzCtxInputCreate(pThis, cbInput);
+                            if (RT_LIKELY(pInput))
+                            {
+                                memcpy(&pInput->abInput[0], pbState, cbInput);
+                                RTMd5(&pInput->abInput[0], pInput->cbInput, &pInput->abMd5Hash[0]);
+                                rc = rtFuzzCtxInputAdd(pThis, pInput);
+                                if (RT_FAILURE(rc))
+                                    RTMemFree(pInput);
+                                pbState += cbInput;
+                            }
+                        }
+                        else
+                            rc = VERR_INVALID_STATE;
+
+                        idx++;
+                    }
+
+                    if (RT_SUCCESS(rc))
+                    {
+                        *phFuzzCtx = pThis;
+                        return VINF_SUCCESS;
+                    }
+                }
+
+                rtFuzzCtxDestroy(pThis);
+            }
+            else
+                rc = VERR_NO_MEMORY;
+        }
+        else
+            rc = VERR_INVALID_MAGIC;
+    }
+    else
+        rc = VERR_INVALID_MAGIC;
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCreateFromStateFile(PRTFUZZCTX phFuzzCtx, const char *pszFilename)
+{
+    AssertPtrReturn(phFuzzCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszFilename, VERR_INVALID_POINTER);
+
+    void *pv = NULL;
+    size_t cb = 0;
+    int rc = RTFileReadAll(pszFilename, &pv, &cb);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTFuzzCtxCreateFromState(phFuzzCtx, pv, cb);
+        RTFileReadAllFree(pv, cb);
+    }
+
+    return rc;
+}
+
+
+RTDECL(uint32_t) RTFuzzCtxRetain(RTFUZZCTX hFuzzCtx)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+
+    AssertPtrReturn(pThis, UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    AssertMsg(cRefs > 1 && cRefs < _1M, ("%#x %p\n", cRefs, pThis));
+    return cRefs;
+}
+
+
+RTDECL(uint32_t) RTFuzzCtxRelease(RTFUZZCTX hFuzzCtx)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    if (pThis == NIL_RTFUZZCTX)
+        return 0;
+    AssertPtrReturn(pThis, UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicDecU32(&pThis->cRefs);
+    AssertMsg(cRefs < _1M, ("%#x %p\n", cRefs, pThis));
+    if (cRefs == 0)
+        rtFuzzCtxDestroy(pThis);
+    return cRefs;
+}
+
+
+RTDECL(int) RTFuzzCtxStateExport(RTFUZZCTX hFuzzCtx, void **ppvState, size_t *pcbState)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppvState, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcbState, VERR_INVALID_POINTER);
+
+    char aszPrngExport[_4K]; /* Should be plenty of room here. */
+    size_t cbPrng = sizeof(aszPrngExport);
+    int rc = RTRandAdvSaveState(pThis->hRand, &aszPrngExport[0], &cbPrng);
+    if (RT_SUCCESS(rc))
+    {
+        RTFUZZCTXSTATE StateExport;
+
+        StateExport.u32Magic         = RT_H2LE_U32(RTFUZZCTX_MAGIC);
+        StateExport.cbPrng           = RT_H2LE_U32((uint32_t)cbPrng);
+        StateExport.cInputs          = RT_H2LE_U32(pThis->cInputs);
+        StateExport.fFlagsBehavioral = RT_H2LE_U32(pThis->fFlagsBehavioral);
+        StateExport.cbInputMax       = RT_H2LE_U64(pThis->cbInputMax);
+
+        /* Estimate the size of the required state. */
+        size_t cbState =   sizeof(StateExport)
+                         + cbPrng
+                         + pThis->cInputs * ((pThis->cbInputMax < _1M ? pThis->cbInputMax : _64K) + sizeof(uint32_t)); /* For the size indicator before each input. */
+        uint8_t *pbState = (uint8_t *)RTMemAllocZ(cbState);
+        if (RT_LIKELY(pbState))
+        {
+            size_t offState = 0;
+            memcpy(pbState, &StateExport, sizeof(StateExport));
+            offState += sizeof(StateExport);
+            memcpy(&pbState[offState], &aszPrngExport[0], cbPrng);
+            offState += cbPrng;
+
+            /* Export each input. */
+            PRTFUZZINPUTINT pIt;
+            RTListForEach(&pThis->LstInputs, pIt, RTFUZZINPUTINT, NdInputs)
+            {
+                /* Ensure buffer size. */
+                if (offState + pIt->cbInput + sizeof(uint32_t) > cbState)
+                {
+                    uint8_t *pbStateNew = (uint8_t *)RTMemRealloc(pbState, cbState + pIt->cbInput + sizeof(uint32_t));
+                    if (RT_LIKELY(pbStateNew))
+                    {
+                        pbState = pbStateNew;
+                        cbState += pIt->cbInput + sizeof(uint32_t);
+                    }
+                    else
+                    {
+                        rc = VERR_NO_MEMORY;
+                        break;
+                    }
+                }
+
+                *(uint32_t *)&pbState[offState] = RT_H2LE_U32((uint32_t)pIt->cbInput);
+                offState += sizeof(uint32_t);
+                memcpy(&pbState[offState], &pIt->abInput[0], pIt->cbInput);
+                offState += pIt->cbInput;
+            }
+
+            if (RT_SUCCESS(rc))
+            {
+                *ppvState = pbState;
+                *pcbState = offState;
+            }
+            else
+                RTMemFree(pbState);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxStateExportToFile(RTFUZZCTX hFuzzCtx, const char *pszFilename)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszFilename, VERR_INVALID_POINTER);
+
+    void *pvState = NULL;
+    size_t cbState = 0;
+    int rc = RTFuzzCtxStateExport(hFuzzCtx, &pvState, &cbState);
+    if (RT_SUCCESS(rc))
+    {
+        RTFILE hFile;
+
+        rc = RTFileOpen(&hFile, pszFilename, RTFILE_O_CREATE | RTFILE_O_WRITE | RTFILE_O_DENY_NONE);
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTFileWrite(hFile, pvState, cbState, NULL);
+            RTFileClose(hFile);
+            if (RT_FAILURE(rc))
+                RTFileDelete(pszFilename);
+        }
+
+        RTMemFree(pvState);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCorpusInputAdd(RTFUZZCTX hFuzzCtx, const void *pvInput, size_t cbInput)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(pvInput, VERR_INVALID_POINTER);
+    AssertReturn(cbInput, VERR_INVALID_POINTER);
+
+    /* Generate MD5 checksum and try to locate input. */
+    int rc = VINF_SUCCESS;
+    uint8_t abDigest[RTMD5_HASH_SIZE];
+    RTMd5(pvInput, cbInput, &abDigest[0]);
+
+    PRTFUZZINPUTINT pInput = rtFuzzCtxInputLocate(pThis, &abDigest[0], true /*fExact*/, NULL /*ppIntermediate*/);
+    if (!pInput)
+    {
+        pInput = (PRTFUZZINPUTINT)RTMemAllocZ(RT_UOFFSETOF_DYN(RTFUZZINPUTINT, abInput[cbInput]));
+        if (RT_LIKELY(pInput))
+        {
+            pInput->cRefs   = 1;
+            pInput->pFuzzer = pThis;
+            pInput->cbInput = cbInput;
+            memcpy(&pInput->abInput[0], pvInput, cbInput);
+            memcpy(&pInput->abMd5Hash[0], &abDigest[0], sizeof(abDigest));
+            rc = rtFuzzCtxInputAdd(pThis, pInput);
+            if (RT_FAILURE(rc))
+                RTMemFree(pInput);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+    else
+        rc = VERR_ALREADY_EXISTS;
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCorpusInputAddFromFile(RTFUZZCTX hFuzzCtx, const char *pszFilename)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszFilename, VERR_INVALID_POINTER);
+
+    void *pv = NULL;
+    size_t cb = 0;
+    int rc = RTFileReadAll(pszFilename, &pv, &cb);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTFuzzCtxCorpusInputAdd(hFuzzCtx, pv, cb);
+        RTFileReadAllFree(pv, cb);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCorpusInputAddFromVfsFile(RTFUZZCTX hFuzzCtx, RTVFSFILE hVfsFile)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(hVfsFile != NIL_RTVFSFILE, VERR_INVALID_HANDLE);
+
+    uint64_t cbFile = 0;
+    int rc = RTVfsFileGetSize(hVfsFile, &cbFile);
+    if (RT_SUCCESS(rc))
+    {
+        PRTFUZZINPUTINT pInput = (PRTFUZZINPUTINT)RTMemAllocZ(RT_UOFFSETOF_DYN(RTFUZZINPUTINT, abInput[cbFile]));
+        if (RT_LIKELY(pInput))
+        {
+            pInput->cRefs   = 1;
+            pInput->pFuzzer = pThis;
+            pInput->cbInput = cbFile;
+
+            rc = RTVfsFileRead(hVfsFile, &pInput->abInput[0], cbFile, NULL);
+            if (RT_SUCCESS(rc))
+            {
+                /* Generate MD5 checksum and try to locate input. */
+                uint8_t abDigest[RTMD5_HASH_SIZE];
+                RTMd5(&pInput->abInput[0], cbFile, &abDigest[0]);
+
+                if (!rtFuzzCtxInputLocate(pThis, &abDigest[0], true /*fExact*/, NULL /*ppIntermediate*/))
+                {
+                    memcpy(&pInput->abMd5Hash[0], &abDigest[0], sizeof(abDigest));
+                    rc = rtFuzzCtxInputAdd(pThis, pInput);
+                }
+                else
+                    rc = VERR_ALREADY_EXISTS;
+            }
+
+            if (RT_FAILURE(rc))
+                RTMemFree(pInput);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCorpusInputAddFromDirPath(RTFUZZCTX hFuzzCtx, const char *pszDirPath)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszDirPath, VERR_INVALID_POINTER);
+
+    RTDIR hDir;
+    int rc = RTDirOpen(&hDir, pszDirPath);
+    if (RT_SUCCESS(rc))
+    {
+        for (;;)
+        {
+            RTDIRENTRY DirEntry;
+            rc = RTDirRead(hDir, &DirEntry, NULL);
+            if (RT_FAILURE(rc))
+                break;
+
+            /* Skip '.', '..' and other non-files. */
+            if (   DirEntry.enmType != RTDIRENTRYTYPE_UNKNOWN
+                && DirEntry.enmType != RTDIRENTRYTYPE_FILE)
+                continue;
+            if (RTDirEntryIsStdDotLink(&DirEntry))
+                continue;
+
+            /* Compose the full path, result 'unknown' entries and skip non-files. */
+            char szFile[RTPATH_MAX];
+            RT_ZERO(szFile);
+            rc = RTPathJoin(szFile, sizeof(szFile), pszDirPath, DirEntry.szName);
+            if (RT_FAILURE(rc))
+                break;
+
+            if (DirEntry.enmType == RTDIRENTRYTYPE_UNKNOWN)
+            {
+                RTDirQueryUnknownType(szFile, false, &DirEntry.enmType);
+                if (DirEntry.enmType != RTDIRENTRYTYPE_FILE)
+                    continue;
+            }
+
+            /* Okay, it's a file we can add. */
+            rc = RTFuzzCtxCorpusInputAddFromFile(hFuzzCtx, szFile);
+            if (RT_FAILURE(rc))
+                break;
+        }
+        if (rc == VERR_NO_MORE_FILES)
+            rc = VINF_SUCCESS;
+        RTDirClose(hDir);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxCfgSetInputSeedMaximum(RTFUZZCTX hFuzzCtx, size_t cbMax)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+
+    pThis->cbInputMax = cbMax;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(size_t) RTFuzzCtxCfgGetInputSeedMaximum(RTFUZZCTX hFuzzCtx)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, 0);
+
+    return pThis->cbInputMax;
+}
+
+
+RTDECL(int) RTFuzzCtxCfgSetBehavioralFlags(RTFUZZCTX hFuzzCtx, uint32_t fFlags)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(!(fFlags & ~RTFUZZCTX_F_BEHAVIORAL_VALID), VERR_INVALID_PARAMETER);
+
+    pThis->fFlagsBehavioral = fFlags;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(uint32_t) RTFuzzCfgGetBehavioralFlags(RTFUZZCTX hFuzzCtx)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, 0);
+
+    return pThis->fFlagsBehavioral;
+}
+
+
+RTDECL(int) RTFuzzCtxCfgSetTmpDirectory(RTFUZZCTX hFuzzCtx, const char *pszPathTmp)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszPathTmp, VERR_INVALID_POINTER);
+
+    return VERR_NOT_IMPLEMENTED;
+}
+
+
+RTDECL(const char *) RTFuzzCtxCfgGetTmpDirectory(RTFUZZCTX hFuzzCtx)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, NULL);
+
+    return NULL;
+}
+
+
+RTDECL(int) RTFuzzCtxReseed(RTFUZZCTX hFuzzCtx, uint64_t uSeed)
+{
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+
+    RTRandAdvSeed(pThis->hRand, uSeed);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTFuzzCtxInputGenerate(RTFUZZCTX hFuzzCtx, PRTFUZZINPUT phFuzzInput)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(phFuzzInput, VERR_INVALID_POINTER);
+
+    uint32_t cTries = 0;
+    PRTFUZZINPUTINT pSrc = rtFuzzCtxInputPickRnd(pThis);
+    do
+    {
+        RTFUZZCTXMUTATOR enmMutator = (RTFUZZCTXMUTATOR)RTRandAdvU32Ex(pThis->hRand, 1, RTFUZZCTXMUTATOR_LAST);
+        PRTFUZZINPUTINT pInput = NULL;
+        rc = g_apfnMutators[enmMutator](pThis, &pSrc->abInput[0], pSrc->cbInput, &pInput);
+        if (   RT_SUCCESS(rc)
+            && VALID_PTR(pInput))
+        {
+            if (pThis->fFlagsBehavioral & RTFUZZCTX_F_BEHAVIORAL_ADD_INPUT_AUTOMATICALLY_TO_CORPUS)
+                rtFuzzCtxInputAdd(pThis, pInput);
+            *phFuzzInput = pInput;
+            return rc;
+        }
+    } while (++cTries <= 50);
+
+    if (RT_SUCCESS(rc))
+        rc = VERR_INVALID_STATE;
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzCtxMutateBuffer(RTFUZZCTX hFuzzCtx, void *pvBuf, size_t cbBuf, PRTFUZZINPUT phFuzzInput)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZCTXINT pThis = hFuzzCtx;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(phFuzzInput, VERR_INVALID_POINTER);
+
+    uint32_t cTries = 0;
+    do
+    {
+        RTFUZZCTXMUTATOR enmMutator = (RTFUZZCTXMUTATOR)RTRandAdvU32Ex(pThis->hRand, 1, RTFUZZCTXMUTATOR_LAST);
+        PRTFUZZINPUTINT pInput = NULL;
+        rc = g_apfnMutators[enmMutator](pThis, pvBuf, cbBuf, &pInput);
+        if (   RT_SUCCESS(rc)
+            && VALID_PTR(pInput))
+        {
+            *phFuzzInput = pInput;
+            return rc;
+        }
+    } while (++cTries <= 50);
+
+    if (RT_SUCCESS(rc))
+        rc = VERR_INVALID_STATE;
+
+    return rc;
+}
+
+
+RTDECL(uint32_t) RTFuzzInputRetain(RTFUZZINPUT hFuzzInput)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+
+    AssertPtrReturn(pThis, UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    AssertMsg(cRefs > 1 && cRefs < _1M, ("%#x %p\n", cRefs, pThis));
+    return cRefs;
+}
+
+
+RTDECL(uint32_t) RTFuzzInputRelease(RTFUZZINPUT hFuzzInput)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+    if (pThis == NIL_RTFUZZINPUT)
+        return 0;
+    AssertPtrReturn(pThis, UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicDecU32(&pThis->cRefs);
+    AssertMsg(cRefs < _1M, ("%#x %p\n", cRefs, pThis));
+    if (cRefs == 0)
+        rtFuzzInputDestroy(pThis);
+    return cRefs;
+}
+
+
+RTDECL(int) RTFuzzInputQueryData(RTFUZZINPUT hFuzzInput, void **ppv, size_t *pcb)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+    AssertPtrReturn(pThis, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppv, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcb, VERR_INVALID_POINTER);
+
+    *ppv = &pThis->abInput[0];
+    *pcb = pThis->cbInput;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTFuzzInputQueryDigestString(RTFUZZINPUT hFuzzInput, char *pszDigest, size_t cchDigest)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszDigest, VERR_INVALID_POINTER);
+    AssertReturn(cchDigest >= RTMD5_STRING_LEN + 1, VERR_INVALID_PARAMETER);
+
+    return RTMd5ToString(&pThis->abMd5Hash[0], pszDigest, cchDigest);
+}
+
+
+RTDECL(int) RTFuzzInputWriteToFile(RTFUZZINPUT hFuzzInput, const char *pszFilename)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszFilename, VERR_INVALID_POINTER);
+
+    RTFILE hFile;
+    int rc = RTFileOpen(&hFile, pszFilename, RTFILE_O_CREATE | RTFILE_O_WRITE | RTFILE_O_DENY_NONE);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTFileWrite(hFile, &pThis->abInput[0], pThis->cbInput, NULL);
+        AssertRC(rc);
+        RTFileClose(hFile);
+
+        if (RT_FAILURE(rc))
+            RTFileDelete(pszFilename);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTFuzzInputAddToCtxCorpus(RTFUZZINPUT hFuzzInput)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+
+    return rtFuzzCtxInputAdd(pThis->pFuzzer, pThis);
+}
+
+
+RTDECL(int) RTFuzzInputRemoveFromCtxCorpus(RTFUZZINPUT hFuzzInput)
+{
+    PRTFUZZINPUTINT pThis = hFuzzInput;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+
+    int rc = VINF_SUCCESS;
+    PRTFUZZINTERMEDIATE pIntermediate = NULL;
+    PRTFUZZINPUTINT pInputLoc = rtFuzzCtxInputLocate(pThis->pFuzzer, &pThis->abMd5Hash[0], true /*fExact*/,
+                                                     &pIntermediate);
+    if (pInputLoc)
+    {
+        AssertPtr(pIntermediate);
+        Assert(pInputLoc == pThis);
+
+        uint64_t u64Md5Low = *(uint64_t *)&pThis->abMd5Hash[0];
+        RTAvlU64Remove(&pIntermediate->TreeSeedsLow, u64Md5Low);
+        RTFuzzInputRelease(hFuzzInput);
+    }
+    else
+        rc = VERR_NOT_FOUND;
+
+    return rc;
+}
+
diff --git a/src/VBox/Runtime/common/fuzz/fuzzclientcmd.cpp b/src/VBox/Runtime/common/fuzz/fuzzclientcmd.cpp
new file mode 100644
index 00000000..701cdd0b
--- /dev/null
+++ b/src/VBox/Runtime/common/fuzz/fuzzclientcmd.cpp
@@ -0,0 +1,216 @@
+/* $Id: fuzzclientcmd.cpp $ */
+/** @file
+ * IPRT - Fuzzing framework API, fuzzed client command.
+ */
+
+/*
+ * Copyright (C) 2018-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/fuzz.h>
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+#include <iprt/buildconfig.h>
+#include <iprt/errcore.h>
+#include <iprt/getopt.h>
+#include <iprt/mem.h>
+#include <iprt/message.h>
+#include <iprt/stream.h>
+#include <iprt/string.h>
+#include <iprt/types.h>
+#include <iprt/vfs.h>
+
+
+/**
+ * Fuzzing client command state.
+ */
+typedef struct RTFUZZCMDCLIENT
+{
+    /** Our own fuzzing context containing all the data. */
+    RTFUZZCTX               hFuzzCtx;
+    /** Consumption callback. */
+    PFNFUZZCLIENTCONSUME    pfnConsume;
+    /** Opaque user data to pass to the consumption callback. */
+    void                    *pvUser;
+    /** Standard input VFS handle. */
+    RTVFSIOSTREAM           hVfsStdIn;
+    /** Standard output VFS handle. */
+    RTVFSIOSTREAM           hVfsStdOut;
+} RTFUZZCMDCLIENT;
+/** Pointer to a fuzzing client command state. */
+typedef RTFUZZCMDCLIENT *PRTFUZZCMDCLIENT;
+
+
+/**
+ * The fuzzing client mainloop.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing client command state.
+ */
+static int rtFuzzCmdClientMainloop(PRTFUZZCMDCLIENT pThis)
+{
+    int rc = VINF_SUCCESS;
+    bool fShutdown = false;
+
+    while (   !fShutdown
+           && RT_SUCCESS(rc))
+    {
+        RTFUZZINPUT hFuzzInput;
+
+        rc = RTFuzzCtxInputGenerate(pThis->hFuzzCtx, &hFuzzInput);
+        if (RT_SUCCESS(rc))
+        {
+            void *pv = NULL;
+            size_t cb = 0;
+            rc = RTFuzzInputQueryData(hFuzzInput, &pv, &cb);
+            if (RT_SUCCESS(rc))
+            {
+                char bResp = '.';
+                int rc2 = pThis->pfnConsume(pv, cb, pThis->pvUser);
+                if (RT_SUCCESS(rc2))
+                {
+                    rc = RTFuzzInputAddToCtxCorpus(hFuzzInput);
+                    bResp = 'A';
+                }
+
+                if (RT_SUCCESS(rc))
+                    rc = RTVfsIoStrmWrite(pThis->hVfsStdOut, &bResp, 1, true /*fBlocking*/, NULL);
+            }
+
+            RTFuzzInputRelease(hFuzzInput);
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Run the fuzzing client.
+ *
+ * @returns Process exit status.
+ * @param   pThis               The fuzzing client command state.
+ */
+static RTEXITCODE rtFuzzCmdClientRun(PRTFUZZCMDCLIENT pThis)
+{
+    int rc = RTVfsIoStrmFromStdHandle(RTHANDLESTD_INPUT, 0, true /*fLeaveOpen*/, &pThis->hVfsStdIn);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTVfsIoStrmFromStdHandle(RTHANDLESTD_OUTPUT, 0, true /*fLeaveOpen*/, &pThis->hVfsStdOut);
+        if (RT_SUCCESS(rc))
+        {
+            /* Read the initial input fuzzer state from the standard input. */
+            uint32_t cbFuzzCtxState;
+            rc = RTVfsIoStrmRead(pThis->hVfsStdIn, &cbFuzzCtxState, sizeof(cbFuzzCtxState), true /*fBlocking*/, NULL);
+            if (RT_SUCCESS(rc))
+            {
+                void *pvFuzzCtxState = RTMemAllocZ(cbFuzzCtxState);
+                if (RT_LIKELY(pvFuzzCtxState))
+                {
+                    rc = RTVfsIoStrmRead(pThis->hVfsStdIn, pvFuzzCtxState, cbFuzzCtxState, true /*fBlocking*/, NULL);
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = RTFuzzCtxCreateFromState(&pThis->hFuzzCtx, pvFuzzCtxState, cbFuzzCtxState);
+                        if (RT_SUCCESS(rc))
+                            rc = rtFuzzCmdClientMainloop(pThis);
+                    }
+
+                    RTMemFree(pvFuzzCtxState);
+                }
+                else
+                    rc = VERR_NO_MEMORY;
+            }
+        }
+    }
+
+    if (RT_SUCCESS(rc))
+        return RTEXITCODE_SUCCESS;
+
+    return RTEXITCODE_FAILURE;
+}
+
+
+RTR3DECL(RTEXITCODE) RTFuzzCmdFuzzingClient(unsigned cArgs, char **papszArgs, PFNFUZZCLIENTCONSUME pfnConsume, void *pvUser)
+{
+    /*
+     * Parse the command line.
+     */
+    static const RTGETOPTDEF s_aOptions[] =
+    {
+        { "--help",                            'h', RTGETOPT_REQ_NOTHING },
+        { "--version",                         'V', RTGETOPT_REQ_NOTHING },
+    };
+
+    RTEXITCODE rcExit = RTEXITCODE_SUCCESS;
+    RTGETOPTSTATE GetState;
+    int rc = RTGetOptInit(&GetState, cArgs, papszArgs, s_aOptions, RT_ELEMENTS(s_aOptions), 1,
+                          RTGETOPTINIT_FLAGS_OPTS_FIRST);
+    if (RT_SUCCESS(rc))
+    {
+        /* Option variables:  */
+        RTFUZZCMDCLIENT This;
+
+        This.pfnConsume = pfnConsume;
+        This.pvUser     = pvUser;
+
+        /* Argument parsing loop. */
+        bool fContinue = true;
+        do
+        {
+            RTGETOPTUNION ValueUnion;
+            int chOpt = RTGetOpt(&GetState, &ValueUnion);
+            switch (chOpt)
+            {
+                case 0:
+                    fContinue = false;
+                    break;
+
+                case 'h':
+                    RTPrintf("Usage: to be written\nOption dump:\n");
+                    for (unsigned i = 0; i < RT_ELEMENTS(s_aOptions); i++)
+                        RTPrintf(" -%c,%s\n", s_aOptions[i].iShort, s_aOptions[i].pszLong);
+                    fContinue = false;
+                    break;
+
+                case 'V':
+                    RTPrintf("%sr%d\n", RTBldCfgVersion(), RTBldCfgRevision());
+                    fContinue = false;
+                    break;
+
+                default:
+                    rcExit = RTGetOptPrintError(chOpt, &ValueUnion);
+                    fContinue = false;
+                    break;
+            }
+        } while (fContinue);
+
+        if (rcExit == RTEXITCODE_SUCCESS)
+            rcExit = rtFuzzCmdClientRun(&This);
+    }
+    else
+        rcExit = RTMsgErrorExit(RTEXITCODE_SYNTAX, "RTGetOptInit: %Rrc", rc);
+    return rcExit;
+}
+
diff --git a/src/VBox/Runtime/common/fuzz/fuzzmastercmd.cpp b/src/VBox/Runtime/common/fuzz/fuzzmastercmd.cpp
new file mode 100644
index 00000000..b73ac07d
--- /dev/null
+++ b/src/VBox/Runtime/common/fuzz/fuzzmastercmd.cpp
@@ -0,0 +1,1351 @@
+/* $Id: fuzzmastercmd.cpp $ */
+/** @file
+ * IPRT - Fuzzing framework API, master command.
+ */
+
+/*
+ * Copyright (C) 2018-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/fuzz.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/base64.h>
+#include <iprt/buildconfig.h>
+#include <iprt/ctype.h>
+#include <iprt/err.h>
+#include <iprt/file.h>
+#include <iprt/getopt.h>
+#include <iprt/json.h>
+#include <iprt/list.h>
+#include <iprt/mem.h>
+#include <iprt/message.h>
+#include <iprt/path.h>
+#include <iprt/process.h>
+#include <iprt/stream.h>
+#include <iprt/string.h>
+#include <iprt/tcp.h>
+#include <iprt/thread.h>
+#include <iprt/vfs.h>
+#include <iprt/zip.h>
+
+
+/**
+ * A running fuzzer state.
+ */
+typedef struct RTFUZZRUN
+{
+    /** List node. */
+    RTLISTNODE                  NdFuzzed;
+    /** Identifier. */
+    char                        *pszId;
+    /** Number of processes. */
+    uint32_t                    cProcs;
+    /** The fuzzing observer state handle. */
+    RTFUZZOBS                   hFuzzObs;
+    /** Flag whether fuzzing was started. */
+    bool                        fStarted;
+} RTFUZZRUN;
+/** Pointer to a running fuzzer state. */
+typedef RTFUZZRUN *PRTFUZZRUN;
+
+
+/**
+ * Fuzzing master command state.
+ */
+typedef struct RTFUZZCMDMASTER
+{
+    /** List of running fuzzers. */
+    RTLISTANCHOR                LstFuzzed;
+    /** The port to listen on. */
+    uint16_t                    uPort;
+    /** The TCP server for requests. */
+    PRTTCPSERVER                hTcpSrv;
+    /** The root temp directory. */
+    const char                  *pszTmpDir;
+    /** The root results directory. */
+    const char                  *pszResultsDir;
+    /** Flag whether to shutdown. */
+    bool                        fShutdown;
+    /** The response message. */
+    char                        *pszResponse;
+} RTFUZZCMDMASTER;
+/** Pointer to a fuzzing master command state. */
+typedef RTFUZZCMDMASTER *PRTFUZZCMDMASTER;
+
+
+/**
+ * Wrapper around RTErrInfoSetV / RTMsgErrorV.
+ *
+ * @returns @a rc
+ * @param   pErrInfo            Extended error info.
+ * @param   rc                  The return code.
+ * @param   pszFormat           The message format.
+ * @param   ...                 The message format arguments.
+ */
+static int rtFuzzCmdMasterErrorRc(PRTERRINFO pErrInfo, int rc, const char *pszFormat, ...)
+{
+    va_list va;
+    va_start(va, pszFormat);
+    if (pErrInfo)
+        RTErrInfoSetV(pErrInfo, rc, pszFormat, va);
+    else
+        RTMsgErrorV(pszFormat, va);
+    va_end(va);
+    return rc;
+}
+
+
+/**
+ * Returns a running fuzzer state by the given ID.
+ *
+ * @returns Pointer to the running fuzzer state or NULL if not found.
+ * @param   pThis               The fuzzing master command state.
+ * @param   pszId               The ID to look for.
+ */
+static PRTFUZZRUN rtFuzzCmdMasterGetFuzzerById(PRTFUZZCMDMASTER pThis, const char *pszId)
+{
+    PRTFUZZRUN pIt = NULL;
+    RTListForEach(&pThis->LstFuzzed, pIt, RTFUZZRUN, NdFuzzed)
+    {
+        if (!RTStrCmp(pIt->pszId, pszId))
+            return pIt;
+    }
+
+    return NULL;
+}
+
+
+#if 0 /* unused */
+/**
+ * Processes and returns the value of the given config item in the JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   ppszStr             Where to store the pointer to the string on success.
+ * @param   pszCfgItem          The config item to resolve.
+ * @param   hJsonCfg            The JSON object containing the item.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessCfgString(char **ppszStr, const char *pszCfgItem, RTJSONVAL hJsonCfg, PRTERRINFO pErrInfo)
+{
+    int rc = RTJsonValueQueryStringByName(hJsonCfg, pszCfgItem, ppszStr);
+    if (RT_FAILURE(rc))
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query string value of \"%s\"", pszCfgItem);
+
+    return rc;
+}
+
+
+/**
+ * Processes and returns the value of the given config item in the JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   pfVal               Where to store the config value on success.
+ * @param   pszCfgItem          The config item to resolve.
+ * @param   hJsonCfg            The JSON object containing the item.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessCfgBool(bool *pfVal, const char *pszCfgItem, RTJSONVAL hJsonCfg, PRTERRINFO pErrInfo)
+{
+    int rc = RTJsonValueQueryBooleanByName(hJsonCfg, pszCfgItem, pfVal);
+    if (RT_FAILURE(rc))
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query boolean value of \"%s\"", pszCfgItem);
+
+    return rc;
+}
+
+
+/**
+ * Processes and returns the value of the given config item in the JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   pfVal               Where to store the config value on success.
+ * @param   pszCfgItem          The config item to resolve.
+ * @param   hJsonCfg            The JSON object containing the item.
+ * @param   fDef                Default value if the item wasn't found.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessCfgBoolDef(bool *pfVal, const char *pszCfgItem, RTJSONVAL hJsonCfg, bool fDef, PRTERRINFO pErrInfo)
+{
+    int rc = RTJsonValueQueryBooleanByName(hJsonCfg, pszCfgItem, pfVal);
+    if (rc == VERR_NOT_FOUND)
+    {
+        *pfVal = fDef;
+        rc = VINF_SUCCESS;
+    }
+    else if (RT_FAILURE(rc))
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query boolean value of \"%s\"", pszCfgItem);
+
+    return rc;
+}
+#endif
+
+
+/**
+ * Processes and returns the value of the given config item in the JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   pcbVal              Where to store the config value on success.
+ * @param   pszCfgItem          The config item to resolve.
+ * @param   hJsonCfg            The JSON object containing the item.
+ * @param   cbDef               Default value if the item wasn't found.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessCfgSizeDef(size_t *pcbVal, const char *pszCfgItem, RTJSONVAL hJsonCfg, size_t cbDef, PRTERRINFO pErrInfo)
+{
+    *pcbVal = cbDef; /* Make GCC 6.3.0 happy. */
+
+    int64_t i64Val = 0;
+    int rc = RTJsonValueQueryIntegerByName(hJsonCfg, pszCfgItem, &i64Val);
+    if (rc == VERR_NOT_FOUND)
+        rc = VINF_SUCCESS;
+    else if (RT_FAILURE(rc))
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query size_t value of \"%s\"", pszCfgItem);
+    else if (i64Val < 0 || (size_t)i64Val != (uint64_t)i64Val)
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_OUT_OF_RANGE, "JSON request malformed: Integer \"%s\" is out of range", pszCfgItem);
+    else
+        *pcbVal = (size_t)i64Val;
+
+    return rc;
+}
+
+
+/**
+ * Processes and returns the value of the given config item in the JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   pcbVal              Where to store the config value on success.
+ * @param   pszCfgItem          The config item to resolve.
+ * @param   hJsonCfg            The JSON object containing the item.
+ * @param   cbDef               Default value if the item wasn't found.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessCfgU32Def(uint32_t *pu32Val, const char *pszCfgItem, RTJSONVAL hJsonCfg, uint32_t u32Def, PRTERRINFO pErrInfo)
+{
+    int64_t i64Val = 0;
+    int rc = RTJsonValueQueryIntegerByName(hJsonCfg, pszCfgItem, &i64Val);
+    if (rc == VERR_NOT_FOUND)
+    {
+        *pu32Val = u32Def;
+        rc = VINF_SUCCESS;
+    }
+    else if (RT_FAILURE(rc))
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query uint32_t value of \"%s\"", pszCfgItem);
+    else if (i64Val < 0 || (uint32_t)i64Val != (uint64_t)i64Val)
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_OUT_OF_RANGE, "JSON request malformed: Integer \"%s\" is out of range", pszCfgItem);
+    else
+        *pu32Val = (uint32_t)i64Val;
+
+    return rc;
+}
+
+
+/**
+ * Returns the configured input channel for the binary under test.
+ *
+ * @returns Selected input channel or RTFUZZOBSINPUTCHAN_INVALID if an error occurred.
+ * @param   pszCfgItem          The config item to resolve.
+ * @param   hJsonCfg            The JSON object containing the item.
+ * @param   enmChanDef          Default value if the item wasn't found.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static RTFUZZOBSINPUTCHAN rtFuzzCmdMasterFuzzRunProcessCfgGetInputChan(const char *pszCfgItem, RTJSONVAL hJsonCfg, RTFUZZOBSINPUTCHAN enmChanDef, PRTERRINFO pErrInfo)
+{
+    RTFUZZOBSINPUTCHAN enmInputChan = RTFUZZOBSINPUTCHAN_INVALID;
+
+    RTJSONVAL hJsonVal;
+    int rc = RTJsonValueQueryByName(hJsonCfg, pszCfgItem, &hJsonVal);
+    if (rc == VERR_NOT_FOUND)
+        enmInputChan = enmChanDef;
+    else if (RT_SUCCESS(rc))
+    {
+        const char *pszBinary = RTJsonValueGetString(hJsonVal);
+        if (pszBinary)
+        {
+            if (!RTStrCmp(pszBinary, "File"))
+                enmInputChan = RTFUZZOBSINPUTCHAN_FILE;
+            else if (!RTStrCmp(pszBinary, "Stdin"))
+                enmInputChan = RTFUZZOBSINPUTCHAN_STDIN;
+            else if (!RTStrCmp(pszBinary, "FuzzingAware"))
+                enmInputChan = RTFUZZOBSINPUTCHAN_FUZZING_AWARE_CLIENT;
+            else
+                rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_PARAMETER, "JSON request malformed: \"%s\" for \"%s\" is not known", pszCfgItem, pszBinary);
+        }
+        else
+            rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "JSON request malformed: \"%s\" is not a string", pszCfgItem);
+
+        RTJsonValueRelease(hJsonVal);
+    }
+    else
+        rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query \"%s\"", pszCfgItem);
+
+    return enmInputChan;
+}
+
+
+/**
+ * Processes binary related configs for the given fuzzing run.
+ *
+ * @returns IPRT status code.
+ * @param   pFuzzRun            The fuzzing run.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessBinaryCfg(PRTFUZZRUN pFuzzRun, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    RTJSONVAL hJsonVal;
+    int rc = RTJsonValueQueryByName(hJsonRoot, "BinaryPath", &hJsonVal);
+    if (RT_SUCCESS(rc))
+    {
+        const char *pszBinary = RTJsonValueGetString(hJsonVal);
+        if (RT_LIKELY(pszBinary))
+        {
+            RTFUZZOBSINPUTCHAN enmInputChan = rtFuzzCmdMasterFuzzRunProcessCfgGetInputChan("InputChannel", hJsonRoot, RTFUZZOBSINPUTCHAN_STDIN, pErrInfo);
+            if (enmInputChan != RTFUZZOBSINPUTCHAN_INVALID)
+            {
+                rc = RTFuzzObsSetTestBinary(pFuzzRun->hFuzzObs, pszBinary, enmInputChan);
+                if (RT_FAILURE(rc))
+                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Failed to add the binary path for the fuzzing run");
+            }
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "JSON request malformed: \"BinaryPath\" is not a string");
+        RTJsonValueRelease(hJsonVal);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to query value of \"BinaryPath\"");
+
+    return rc;
+}
+
+
+/**
+ * Processes argument related configs for the given fuzzing run.
+ *
+ * @returns IPRT status code.
+ * @param   pFuzzRun            The fuzzing run.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessArgCfg(PRTFUZZRUN pFuzzRun, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    RTJSONVAL hJsonValArgArray;
+    int rc = RTJsonValueQueryByName(hJsonRoot, "Arguments", &hJsonValArgArray);
+    if (RT_SUCCESS(rc))
+    {
+        unsigned cArgs = 0;
+        rc = RTJsonValueQueryArraySize(hJsonValArgArray, &cArgs);
+        if (RT_SUCCESS(rc))
+        {
+            if (cArgs > 0)
+            {
+                const char **papszArgs = (const char **)RTMemAllocZ(cArgs * sizeof(const char *));
+                RTJSONVAL *pahJsonVal = (RTJSONVAL *)RTMemAllocZ(cArgs * sizeof(RTJSONVAL));
+                if (RT_LIKELY(papszArgs && pahJsonVal))
+                {
+                    unsigned idx = 0;
+
+                    for (idx = 0; idx < cArgs && RT_SUCCESS(rc); idx++)
+                    {
+                        rc = RTJsonValueQueryByIndex(hJsonValArgArray, idx, &pahJsonVal[idx]);
+                        if (RT_SUCCESS(rc))
+                        {
+                            papszArgs[idx] = RTJsonValueGetString(pahJsonVal[idx]);
+                            if (RT_UNLIKELY(!papszArgs[idx]))
+                                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "Argument %u is not a string", idx);
+                        }
+                    }
+
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = RTFuzzObsSetTestBinaryArgs(pFuzzRun->hFuzzObs, papszArgs, cArgs);
+                        if (RT_FAILURE(rc))
+                            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Failed to set arguments for the fuzzing run");
+                    }
+
+                    /* Release queried values. */
+                    while (idx > 0)
+                    {
+                        RTJsonValueRelease(pahJsonVal[idx - 1]);
+                        idx--;
+                    }
+                }
+                else
+                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_NO_MEMORY, "Out of memory allocating memory for the argument vector");
+
+                if (papszArgs)
+                    RTMemFree(papszArgs);
+                if (pahJsonVal)
+                    RTMemFree(pahJsonVal);
+            }
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: \"Arguments\" is not an array");
+        RTJsonValueRelease(hJsonValArgArray);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes the given seed and adds it to the input corpus.
+ *
+ * @returns IPRT status code.
+ * @param   hFuzzCtx            The fuzzing context handle.
+ * @param   pszCompression      Compression used for the seed.
+ * @param   pszSeed             The seed as a base64 encoded string.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessSeed(RTFUZZCTX hFuzzCtx, const char *pszCompression, const char *pszSeed, PRTERRINFO pErrInfo)
+{
+    int rc = VINF_SUCCESS;
+    ssize_t cbSeedDecoded = RTBase64DecodedSize(pszSeed, NULL);
+    if (cbSeedDecoded > 0)
+    {
+        uint8_t *pbSeedDecoded = (uint8_t *)RTMemAllocZ(cbSeedDecoded);
+        if (RT_LIKELY(pbSeedDecoded))
+        {
+            rc = RTBase64Decode(pszSeed, pbSeedDecoded, cbSeedDecoded, NULL, NULL);
+            if (RT_SUCCESS(rc))
+            {
+                /* Decompress if applicable. */
+                if (!RTStrICmp(pszCompression, "None"))
+                    rc = RTFuzzCtxCorpusInputAdd(hFuzzCtx, pbSeedDecoded, cbSeedDecoded);
+                else
+                {
+                    RTVFSIOSTREAM hVfsIosSeed;
+                    rc = RTVfsIoStrmFromBuffer(RTFILE_O_READ, pbSeedDecoded, cbSeedDecoded, &hVfsIosSeed);
+                    if (RT_SUCCESS(rc))
+                    {
+                        RTVFSIOSTREAM hVfsDecomp = NIL_RTVFSIOSTREAM;
+
+                        if (!RTStrICmp(pszCompression, "Gzip"))
+                            rc = RTZipGzipDecompressIoStream(hVfsIosSeed, RTZIPGZIPDECOMP_F_ALLOW_ZLIB_HDR, &hVfsDecomp);
+                        else
+                            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "Request error: Compression \"%s\" is not known", pszCompression);
+
+                        if (RT_SUCCESS(rc))
+                        {
+                            RTVFSFILE hVfsFile;
+                            rc = RTVfsMemFileCreate(hVfsDecomp, 2 * _1M, &hVfsFile);
+                            if (RT_SUCCESS(rc))
+                            {
+                                rc = RTVfsFileSeek(hVfsFile, 0, RTFILE_SEEK_BEGIN, NULL);
+                                if (RT_SUCCESS(rc))
+                                {
+                                    /* The VFS file contains the buffer for the seed now. */
+                                    rc = RTFuzzCtxCorpusInputAddFromVfsFile(hFuzzCtx, hVfsFile);
+                                    if (RT_FAILURE(rc))
+                                        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to add input seed");
+                                    RTVfsFileRelease(hVfsFile);
+                                }
+                                else
+                                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "Request error: Failed to seek to the beginning of the seed");
+                            }
+                            else
+                                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "Request error: Failed to decompress input seed");
+
+                            RTVfsIoStrmRelease(hVfsDecomp);
+                        }
+
+                        RTVfsIoStrmRelease(hVfsIosSeed);
+                    }
+                    else
+                        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to create I/O stream from seed buffer");
+                }
+            }
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to decode the seed string");
+
+            RTMemFree(pbSeedDecoded);
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_NO_MEMORY, "Request error: Failed to allocate %zd bytes of memory for the seed", cbSeedDecoded);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "JSON request malformed: Couldn't find \"Seed\" doesn't contain a base64 encoded value");
+
+    return rc;
+}
+
+
+/**
+ * Processes a signle input seed for the given fuzzing run.
+ *
+ * @returns IPRT status code.
+ * @param   pFuzzRun            The fuzzing run.
+ * @param   hJsonSeed           The seed node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessInputSeedSingle(PRTFUZZRUN pFuzzRun, RTJSONVAL hJsonSeed, PRTERRINFO pErrInfo)
+{
+    RTFUZZCTX hFuzzCtx;
+    int rc = RTFuzzObsQueryCtx(pFuzzRun->hFuzzObs, &hFuzzCtx);
+    if (RT_SUCCESS(rc))
+    {
+        RTJSONVAL hJsonValComp;
+        rc = RTJsonValueQueryByName(hJsonSeed, "Compression", &hJsonValComp);
+        if (RT_SUCCESS(rc))
+        {
+            const char *pszCompression = RTJsonValueGetString(hJsonValComp);
+            if (RT_LIKELY(pszCompression))
+            {
+                RTJSONVAL hJsonValSeed;
+                rc = RTJsonValueQueryByName(hJsonSeed, "Seed", &hJsonValSeed);
+                if (RT_SUCCESS(rc))
+                {
+                    const char *pszSeed = RTJsonValueGetString(hJsonValSeed);
+                    if (RT_LIKELY(pszSeed))
+                        rc = rtFuzzCmdMasterFuzzRunProcessSeed(hFuzzCtx, pszCompression, pszSeed, pErrInfo);
+                    else
+                        rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "JSON request malformed: \"Seed\" value is not a string");
+
+                    RTJsonValueRelease(hJsonValSeed);
+                }
+                else
+                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Couldn't find \"Seed\" value");
+            }
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_INVALID_STATE, "JSON request malformed: \"Compression\" value is not a string");
+
+            RTJsonValueRelease(hJsonValComp);
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Couldn't find \"Compression\" value");
+
+        RTFuzzCtxRelease(hFuzzCtx);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Failed to query fuzzing context from observer");
+
+    return rc;
+}
+
+
+/**
+ * Processes input seed related configs for the given fuzzing run.
+ *
+ * @returns IPRT status code.
+ * @param   pFuzzRun            The fuzzing run.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessInputSeeds(PRTFUZZRUN pFuzzRun, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    RTJSONVAL hJsonValSeedArray;
+    int rc = RTJsonValueQueryByName(hJsonRoot, "InputSeeds", &hJsonValSeedArray);
+    if (RT_SUCCESS(rc))
+    {
+        RTJSONIT hIt;
+        rc = RTJsonIteratorBegin(hJsonValSeedArray, &hIt);
+        if (RT_SUCCESS(rc))
+        {
+            RTJSONVAL hJsonInpSeed;
+            while (   RT_SUCCESS(rc)
+                   && RTJsonIteratorQueryValue(hIt, &hJsonInpSeed, NULL) != VERR_JSON_ITERATOR_END)
+            {
+                rc = rtFuzzCmdMasterFuzzRunProcessInputSeedSingle(pFuzzRun, hJsonInpSeed, pErrInfo);
+                RTJsonValueRelease(hJsonInpSeed);
+                if (RT_FAILURE(rc))
+                    break;
+                rc = RTJsonIteratorNext(hIt);
+            }
+
+            if (rc == VERR_JSON_ITERATOR_END)
+                rc = VINF_SUCCESS;
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Failed to create array iterator");
+
+        RTJsonValueRelease(hJsonValSeedArray);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes miscellaneous config items.
+ *
+ * @returns IPRT status code.
+ * @param   pFuzzRun            The fuzzing run.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterFuzzRunProcessMiscCfg(PRTFUZZRUN pFuzzRun, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    size_t cbTmp;
+    int rc = rtFuzzCmdMasterFuzzRunProcessCfgSizeDef(&cbTmp, "InputSeedMax", hJsonRoot, 0, pErrInfo);
+    if (RT_SUCCESS(rc))
+    {
+        RTFUZZCTX hFuzzCtx;
+        rc = RTFuzzObsQueryCtx(pFuzzRun->hFuzzObs, &hFuzzCtx);
+        AssertRC(rc);
+
+        rc = RTFuzzCtxCfgSetInputSeedMaximum(hFuzzCtx, cbTmp);
+        if (RT_FAILURE(rc))
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to set maximum input seed size to %zu", cbTmp);
+    }
+
+    if (RT_SUCCESS(rc))
+        rc = rtFuzzCmdMasterFuzzRunProcessCfgU32Def(&pFuzzRun->cProcs, "FuzzingProcs", hJsonRoot, 0, pErrInfo);
+
+    return rc;
+}
+
+
+/**
+ * Creates a new fuzzing run with the given ID.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   pszId               The ID to use.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterCreateFuzzRunWithId(PRTFUZZCMDMASTER pThis, const char *pszId, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    int rc = VINF_SUCCESS;
+    PRTFUZZRUN pFuzzRun = (PRTFUZZRUN)RTMemAllocZ(sizeof(*pFuzzRun));
+    if (RT_LIKELY(pFuzzRun))
+    {
+        pFuzzRun->pszId = RTStrDup(pszId);
+        if (RT_LIKELY(pFuzzRun->pszId))
+        {
+            rc = RTFuzzObsCreate(&pFuzzRun->hFuzzObs);
+            if (RT_SUCCESS(rc))
+            {
+                rc = rtFuzzCmdMasterFuzzRunProcessBinaryCfg(pFuzzRun, hJsonRoot, pErrInfo);
+                if (RT_SUCCESS(rc))
+                    rc = rtFuzzCmdMasterFuzzRunProcessArgCfg(pFuzzRun, hJsonRoot, pErrInfo);
+                if (RT_SUCCESS(rc))
+                    rc = rtFuzzCmdMasterFuzzRunProcessInputSeeds(pFuzzRun, hJsonRoot, pErrInfo);
+                if (RT_SUCCESS(rc))
+                    rc = rtFuzzCmdMasterFuzzRunProcessMiscCfg(pFuzzRun, hJsonRoot, pErrInfo);
+                if (RT_SUCCESS(rc))
+                {
+                    /* Create temp directories. */
+                    char szTmpDir[RTPATH_MAX];
+                    rc = RTPathJoin(&szTmpDir[0], sizeof(szTmpDir), pThis->pszTmpDir, pFuzzRun->pszId);
+                    AssertRC(rc);
+                    rc = RTDirCreate(szTmpDir, 0700,   RTDIRCREATE_FLAGS_NOT_CONTENT_INDEXED_SET
+                                                     | RTDIRCREATE_FLAGS_NOT_CONTENT_INDEXED_NOT_CRITICAL);
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = RTFuzzObsSetTmpDirectory(pFuzzRun->hFuzzObs, szTmpDir);
+                        if (RT_SUCCESS(rc))
+                        {
+                            rc = RTPathJoin(&szTmpDir[0], sizeof(szTmpDir), pThis->pszResultsDir, pFuzzRun->pszId);
+                            AssertRC(rc);
+                            rc = RTDirCreate(szTmpDir, 0700,   RTDIRCREATE_FLAGS_NOT_CONTENT_INDEXED_SET
+                                                             | RTDIRCREATE_FLAGS_NOT_CONTENT_INDEXED_NOT_CRITICAL);
+                            if (RT_SUCCESS(rc))
+                            {
+                                rc = RTFuzzObsSetResultDirectory(pFuzzRun->hFuzzObs, szTmpDir);
+                                if (RT_SUCCESS(rc))
+                                {
+                                    /* Start fuzzing. */
+                                    RTListAppend(&pThis->LstFuzzed, &pFuzzRun->NdFuzzed);
+                                    rc = RTFuzzObsExecStart(pFuzzRun->hFuzzObs, pFuzzRun->cProcs);
+                                    if (RT_SUCCESS(rc))
+                                        pFuzzRun->fStarted = true;
+                                    else
+                                        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to start fuzzing with %Rrc", rc);
+                                }
+                                else
+                                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to set results directory to %s", szTmpDir);
+                            }
+                            else
+                                rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to create results directory %s", szTmpDir);
+                        }
+                        else
+                            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to set temporary directory to %s", szTmpDir);
+                    }
+                    else
+                        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to create temporary directory %s", szTmpDir);
+                }
+            }
+        }
+        else
+            rc = VERR_NO_STR_MEMORY;
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_NO_MEMORY, "Request error: Out of memory allocating the fuzzer state");
+
+    return rc;
+}
+
+
+/**
+ * Resolves the fuzzing run from the given ID config item and the given JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pszIdItem           The JSON item which contains the ID of the fuzzing run.
+ * @param   ppFuzzRun           Where to store the pointer to the fuzzing run on success.
+ */
+static int rtFuzzCmdMasterQueryFuzzRunFromJson(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, const char *pszIdItem, PRTERRINFO pErrInfo,
+                                               PRTFUZZRUN *ppFuzzRun)
+{
+    RTJSONVAL hJsonValId;
+    int rc = RTJsonValueQueryByName(hJsonRoot, pszIdItem, &hJsonValId);
+    if (RT_SUCCESS(rc))
+    {
+        const char *pszId = RTJsonValueGetString(hJsonValId);
+        if (pszId)
+        {
+            PRTFUZZRUN pFuzzRun = rtFuzzCmdMasterGetFuzzerById(pThis, pszId);
+            if (pFuzzRun)
+                *ppFuzzRun = pFuzzRun;
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_NOT_FOUND, "Request error: The ID \"%s\" wasn't found", pszId);
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_JSON_VALUE_INVALID_TYPE, "JSON request malformed: \"Id\" is not a string value");
+
+        RTJsonValueRelease(hJsonValId);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Couldn't find \"Id\" value");
+    return rc;
+}
+
+
+/**
+ * Processes the "StartFuzzing" request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonRoot           The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReqStart(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    RTJSONVAL hJsonValId;
+    int rc = RTJsonValueQueryByName(hJsonRoot, "Id", &hJsonValId);
+    if (RT_SUCCESS(rc))
+    {
+        const char *pszId = RTJsonValueGetString(hJsonValId);
+        if (pszId)
+        {
+            PRTFUZZRUN pFuzzRun = rtFuzzCmdMasterGetFuzzerById(pThis, pszId);
+            if (!pFuzzRun)
+                rc = rtFuzzCmdMasterCreateFuzzRunWithId(pThis, pszId, hJsonRoot, pErrInfo);
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_ALREADY_EXISTS, "Request error: The ID \"%s\" is already registered", pszId);
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_JSON_VALUE_INVALID_TYPE, "JSON request malformed: \"Id\" is not a string value");
+
+        RTJsonValueRelease(hJsonValId);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Couldn't find \"Id\" value");
+    return rc;
+}
+
+
+/**
+ * Processes the "StopFuzzing" request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonValRoot        The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReqStop(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    PRTFUZZRUN pFuzzRun;
+    int rc = rtFuzzCmdMasterQueryFuzzRunFromJson(pThis, hJsonRoot, "Id", pErrInfo, &pFuzzRun);
+    if (RT_SUCCESS(rc))
+    {
+        RTListNodeRemove(&pFuzzRun->NdFuzzed);
+        RTFuzzObsExecStop(pFuzzRun->hFuzzObs);
+        RTFuzzObsDestroy(pFuzzRun->hFuzzObs);
+        RTStrFree(pFuzzRun->pszId);
+        RTMemFree(pFuzzRun);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes the "SuspendFuzzing" request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonValRoot        The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReqSuspend(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    PRTFUZZRUN pFuzzRun;
+    int rc = rtFuzzCmdMasterQueryFuzzRunFromJson(pThis, hJsonRoot, "Id", pErrInfo, &pFuzzRun);
+    if (RT_SUCCESS(rc))
+    {
+        if (pFuzzRun->fStarted)
+        {
+            rc = RTFuzzObsExecStop(pFuzzRun->hFuzzObs);
+            if (RT_SUCCESS(rc))
+                pFuzzRun->fStarted = false;
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Suspending the fuzzing process failed");
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes the "ResumeFuzzing" request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonValRoot        The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReqResume(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    PRTFUZZRUN pFuzzRun;
+    int rc = rtFuzzCmdMasterQueryFuzzRunFromJson(pThis, hJsonRoot, "Id", pErrInfo, &pFuzzRun);
+    if (RT_SUCCESS(rc))
+    {
+        if (!pFuzzRun->fStarted)
+        {
+            rc = rtFuzzCmdMasterFuzzRunProcessCfgU32Def(&pFuzzRun->cProcs, "FuzzingProcs", hJsonRoot, pFuzzRun->cProcs, pErrInfo);
+            if (RT_SUCCESS(rc))
+            {
+                rc = RTFuzzObsExecStart(pFuzzRun->hFuzzObs, pFuzzRun->cProcs);
+                if (RT_SUCCESS(rc))
+                    pFuzzRun->fStarted = true;
+                else
+                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Resuming the fuzzing process failed");
+            }
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes the "SaveFuzzingState" request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonValRoot        The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReqSaveState(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    PRTFUZZRUN pFuzzRun;
+    int rc = rtFuzzCmdMasterQueryFuzzRunFromJson(pThis, hJsonRoot, "Id", pErrInfo, &pFuzzRun);
+    if (RT_SUCCESS(rc))
+    {
+        /* Suspend fuzzing, save and resume if not stopped. */
+        if (pFuzzRun->fStarted)
+        {
+            rc = RTFuzzObsExecStop(pFuzzRun->hFuzzObs);
+            if (RT_FAILURE(rc))
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Suspending the fuzzing process failed");
+        }
+
+        if (RT_SUCCESS(rc))
+        {
+            RTFUZZCTX hFuzzCtx;
+            rc = RTFuzzObsQueryCtx(pFuzzRun->hFuzzObs, &hFuzzCtx);
+            AssertRC(rc);
+
+            void *pvState = NULL;
+            size_t cbState = 0;
+            rc = RTFuzzCtxStateExport(hFuzzCtx, &pvState, &cbState);
+            if (RT_SUCCESS(rc))
+            {
+                /* Encode to base64. */
+                size_t cbStateStr = RTBase64EncodedLength(cbState) + 1;
+                char *pszState = (char *)RTMemAllocZ(cbStateStr);
+                if (pszState)
+                {
+                    rc = RTBase64Encode(pvState, cbState, pszState, cbStateStr, &cbStateStr);
+                    if (RT_SUCCESS(rc))
+                    {
+                        /* Strip all new lines from the srting. */
+                        size_t offStr = 0;
+                        while (offStr < cbStateStr)
+                        {
+#if defined(RT_OS_WINDOWS) || defined(RT_OS_OS2)
+                            char *pszEol = strchr(&pszState[offStr], '\r');
+#else
+                            char *pszEol = strchr(&pszState[offStr], '\n');
+#endif
+                            if (pszEol)
+                            {
+                                offStr += pszEol - &pszState[offStr];
+                                memmove(pszEol, &pszEol[RTBASE64_EOL_SIZE], cbStateStr - offStr - RTBASE64_EOL_SIZE);
+                                cbStateStr -= RTBASE64_EOL_SIZE;
+                            }
+                            else
+                                break;
+                        }
+
+                        const char s_szState[] = "{ \"State\": %s }";
+                        pThis->pszResponse = RTStrAPrintf2(s_szState, pszState);
+                        if (RT_UNLIKELY(!pThis->pszResponse))
+                            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_BUFFER_OVERFLOW, "Request error: Response data buffer overflow", rc);
+                    }
+                    else
+                        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to encode the state as a base64 string");
+                    RTMemFree(pszState);
+                }
+                else
+                    rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_NO_STR_MEMORY, "Request error: Failed to allocate a state string for the response");
+                RTMemFree(pvState);
+            }
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Exporting the state failed");
+        }
+
+        if (pFuzzRun->fStarted)
+        {
+            int rc2 = RTFuzzObsExecStart(pFuzzRun->hFuzzObs, pFuzzRun->cProcs);
+            if (RT_FAILURE(rc2))
+                rtFuzzCmdMasterErrorRc(pErrInfo, rc2, "Request error: Resuming the fuzzing process failed");
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes the "QueryStats" request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonValRoot        The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReqQueryStats(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    PRTFUZZRUN pFuzzRun;
+    int rc = rtFuzzCmdMasterQueryFuzzRunFromJson(pThis, hJsonRoot, "Id", pErrInfo, &pFuzzRun);
+    if (RT_SUCCESS(rc))
+    {
+        RTFUZZOBSSTATS Stats;
+        rc = RTFuzzObsQueryStats(pFuzzRun->hFuzzObs, &Stats);
+        if (RT_SUCCESS(rc))
+        {
+            const char s_szStats[] = "{ \"FuzzedInputsPerSec\": %u\n"
+                                     "  \"FuzzedInputs\":       %u\n"
+                                     "  \"FuzzedInputsHang\":   %u\n"
+                                     "  \"FuzzedInputsCrash\":   %u\n}";
+            pThis->pszResponse = RTStrAPrintf2(s_szStats, Stats.cFuzzedInputsPerSec,
+                                               Stats.cFuzzedInputs, Stats.cFuzzedInputsHang, Stats.cFuzzedInputsCrash);
+            if (RT_UNLIKELY(!pThis->pszResponse))
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_BUFFER_OVERFLOW, "Request error: Response data buffer overflow", rc);
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "Request error: Failed to query fuzzing statistics with %Rrc", rc);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Processes a JSON request.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   hJsonValRoot        The root node of the JSON request.
+ * @param   pErrInfo            Where to store the error information on failure, optional.
+ */
+static int rtFuzzCmdMasterProcessJsonReq(PRTFUZZCMDMASTER pThis, RTJSONVAL hJsonRoot, PRTERRINFO pErrInfo)
+{
+    RTJSONVAL hJsonValReq;
+    int rc = RTJsonValueQueryByName(hJsonRoot, "Request", &hJsonValReq);
+    if (RT_SUCCESS(rc))
+    {
+        const char *pszReq = RTJsonValueGetString(hJsonValReq);
+        if (pszReq)
+        {
+            if (!RTStrCmp(pszReq, "StartFuzzing"))
+                rc = rtFuzzCmdMasterProcessJsonReqStart(pThis, hJsonRoot, pErrInfo);
+            else if (!RTStrCmp(pszReq, "StopFuzzing"))
+                rc = rtFuzzCmdMasterProcessJsonReqStop(pThis, hJsonRoot, pErrInfo);
+            else if (!RTStrCmp(pszReq, "SuspendFuzzing"))
+                rc = rtFuzzCmdMasterProcessJsonReqSuspend(pThis, hJsonRoot, pErrInfo);
+            else if (!RTStrCmp(pszReq, "ResumeFuzzing"))
+                rc = rtFuzzCmdMasterProcessJsonReqResume(pThis, hJsonRoot, pErrInfo);
+            else if (!RTStrCmp(pszReq, "SaveFuzzingState"))
+                rc = rtFuzzCmdMasterProcessJsonReqSaveState(pThis, hJsonRoot, pErrInfo);
+            else if (!RTStrCmp(pszReq, "QueryStats"))
+                rc = rtFuzzCmdMasterProcessJsonReqQueryStats(pThis, hJsonRoot, pErrInfo);
+            else if (!RTStrCmp(pszReq, "Shutdown"))
+                pThis->fShutdown = true;
+            else
+                rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_JSON_VALUE_INVALID_TYPE, "JSON request malformed: \"Request\" contains unknown value \"%s\"", pszReq);
+        }
+        else
+            rc = rtFuzzCmdMasterErrorRc(pErrInfo, VERR_JSON_VALUE_INVALID_TYPE, "JSON request malformed: \"Request\" is not a string value");
+
+        RTJsonValueRelease(hJsonValReq);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(pErrInfo, rc, "JSON request malformed: Couldn't find \"Request\" value");
+
+    return rc;
+}
+
+
+/**
+ * Loads a fuzzing configuration for immediate startup from the given file.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   pszFuzzCfg          The fuzzing config to load.
+ */
+static int rtFuzzCmdMasterFuzzCfgLoadFromFile(PRTFUZZCMDMASTER pThis, const char *pszFuzzCfg)
+{
+    RTJSONVAL hJsonRoot;
+    int rc = RTJsonParseFromFile(&hJsonRoot, pszFuzzCfg, NULL);
+    if (RT_SUCCESS(rc))
+    {
+        rc = rtFuzzCmdMasterProcessJsonReqStart(pThis, hJsonRoot, NULL);
+        RTJsonValueRelease(hJsonRoot);
+    }
+    else
+        rc = rtFuzzCmdMasterErrorRc(NULL, rc, "JSON request malformed: Couldn't load file \"%s\"", pszFuzzCfg);
+
+    return rc;
+}
+
+
+/**
+ * Destroys all running fuzzers for the given master state.
+ *
+ * @returns nothing.
+ * @param   pThis               The fuzzing master command state.
+ */
+static void rtFuzzCmdMasterDestroy(PRTFUZZCMDMASTER pThis)
+{
+    RT_NOREF(pThis);
+}
+
+
+/**
+ * Sends an ACK response to the client.
+ *
+ * @returns nothing.
+ * @param   hSocket             The socket handle to send the ACK to.
+ * @param   pszResponse         Additional response data.
+ */
+static void rtFuzzCmdMasterTcpSendAck(RTSOCKET hSocket, const char *pszResponse)
+{
+    const char s_szSucc[] = "{ \"Status\": \"ACK\" }\n";
+    const char s_szSuccResp[] = "{ \"Status\": \"ACK\"\n  \"Response\":\n";
+    const char s_szSuccRespClose[] = "\n }\n";
+    if (pszResponse)
+    {
+        RTSGSEG aSegs[3];
+        RTSGBUF SgBuf;
+        aSegs[0].pvSeg = (void *)s_szSuccResp;
+        aSegs[0].cbSeg = sizeof(s_szSuccResp) - 1;
+        aSegs[1].pvSeg = (void *)pszResponse;
+        aSegs[1].cbSeg = strlen(pszResponse);
+        aSegs[2].pvSeg = (void *)s_szSuccRespClose;
+        aSegs[2].cbSeg = sizeof(s_szSuccRespClose) - 1;
+
+        RTSgBufInit(&SgBuf, &aSegs[0], RT_ELEMENTS(aSegs));
+        RTTcpSgWrite(hSocket, &SgBuf);
+    }
+    else
+        RTTcpWrite(hSocket, s_szSucc, sizeof(s_szSucc));
+}
+
+
+/**
+ * Sends an NACK response to the client.
+ *
+ * @returns nothing.
+ * @param   hSocket             The socket handle to send the ACK to.
+ * @param   pErrInfo            Optional error information to send along.
+ */
+static void rtFuzzCmdMasterTcpSendNAck(RTSOCKET hSocket, PRTERRINFO pErrInfo)
+{
+    const char s_szFail[] = "{ \"Status\": \"NACK\" }\n";
+    const char s_szFailInfo[] = "{ \"Status\": \"NACK\"\n \"Information\": \"%s\" }\n";
+
+    if (pErrInfo)
+    {
+        char szTmp[_1K];
+        ssize_t cchResp = RTStrPrintf2(szTmp, sizeof(szTmp), s_szFailInfo, pErrInfo->pszMsg);
+        if (cchResp > 0)
+            RTTcpWrite(hSocket, szTmp, cchResp);
+        else
+            RTTcpWrite(hSocket, s_szFail, strlen(s_szFail));
+    }
+    else
+        RTTcpWrite(hSocket, s_szFail, strlen(s_szFail));
+}
+
+
+/**
+ * TCP server serving callback for a single connection.
+ *
+ * @returns IPRT status code.
+ * @param   hSocket             The socket handle of the connection.
+ * @param   pvUser              Opaque user data.
+ */
+static DECLCALLBACK(int) rtFuzzCmdMasterTcpServe(RTSOCKET hSocket, void *pvUser)
+{
+    PRTFUZZCMDMASTER pThis = (PRTFUZZCMDMASTER)pvUser;
+    size_t cbReqMax = _32K;
+    size_t cbReq = 0;
+    uint8_t *pbReq = (uint8_t *)RTMemAllocZ(cbReqMax);
+
+    if (RT_LIKELY(pbReq))
+    {
+        uint8_t *pbCur = pbReq;
+
+        for (;;)
+        {
+            size_t cbThisRead = cbReqMax - cbReq;
+            int rc = RTTcpRead(hSocket, pbCur, cbThisRead, &cbThisRead);
+            if (RT_SUCCESS(rc))
+            {
+                cbReq += cbThisRead;
+
+                /* Check for a zero terminator marking the end of the request. */
+                uint8_t *pbEnd = (uint8_t *)memchr(pbCur, 0, cbThisRead);
+                if (pbEnd)
+                {
+                    /* Adjust request size, data coming after the zero terminiator is ignored right now. */
+                    cbReq -= cbThisRead - (pbEnd - pbCur) + 1;
+
+                    RTJSONVAL hJsonReq;
+                    RTERRINFOSTATIC ErrInfo;
+                    RTErrInfoInitStatic(&ErrInfo);
+
+                    rc = RTJsonParseFromBuf(&hJsonReq, pbReq, cbReq, &ErrInfo.Core);
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = rtFuzzCmdMasterProcessJsonReq(pThis, hJsonReq, &ErrInfo.Core);
+                        if (RT_SUCCESS(rc))
+                            rtFuzzCmdMasterTcpSendAck(hSocket, pThis->pszResponse);
+                        else
+                            rtFuzzCmdMasterTcpSendNAck(hSocket, &ErrInfo.Core);
+                        RTJsonValueRelease(hJsonReq);
+                    }
+                    else
+                        rtFuzzCmdMasterTcpSendNAck(hSocket, &ErrInfo.Core);
+
+                    if (pThis->pszResponse)
+                    {
+                        RTStrFree(pThis->pszResponse);
+                        pThis->pszResponse = NULL;
+                    }
+                    break;
+                }
+                else if (cbReq == cbReqMax)
+                {
+                    /* Try to increase the buffer. */
+                    uint8_t *pbReqNew = (uint8_t *)RTMemRealloc(pbReq, cbReqMax + _32K);
+                    if (RT_LIKELY(pbReqNew))
+                    {
+                        cbReqMax += _32K;
+                        pbReq = pbReqNew;
+                        pbCur = pbReq + cbReq;
+                    }
+                    else
+                        rtFuzzCmdMasterTcpSendNAck(hSocket, NULL);
+                }
+                else
+                    pbCur += cbThisRead;
+            }
+            else
+                break;
+        }
+    }
+    else
+        rtFuzzCmdMasterTcpSendNAck(hSocket, NULL);
+
+    if (pbReq)
+        RTMemFree(pbReq);
+
+    return pThis->fShutdown ? VERR_TCP_SERVER_STOP : VINF_SUCCESS;
+}
+
+
+/**
+ * Mainloop for the fuzzing master.
+ *
+ * @returns Process exit code.
+ * @param   pThis               The fuzzing master command state.
+ * @param   pszLoadCfg          Initial config to load.
+ */
+static RTEXITCODE rtFuzzCmdMasterRun(PRTFUZZCMDMASTER pThis, const char *pszLoadCfg)
+{
+    if (pszLoadCfg)
+    {
+        int rc = rtFuzzCmdMasterFuzzCfgLoadFromFile(pThis, pszLoadCfg);
+        if (RT_FAILURE(rc))
+            return RTEXITCODE_FAILURE;
+    }
+
+    /* Start up the control server. */
+    int rc = RTTcpServerCreateEx(NULL, pThis->uPort, &pThis->hTcpSrv);
+    if (RT_SUCCESS(rc))
+    {
+        do
+        {
+            rc = RTTcpServerListen(pThis->hTcpSrv, rtFuzzCmdMasterTcpServe, pThis);
+        } while (rc != VERR_TCP_SERVER_STOP);
+    }
+
+    RTTcpServerDestroy(pThis->hTcpSrv);
+    rtFuzzCmdMasterDestroy(pThis);
+    return RTEXITCODE_SUCCESS;
+}
+
+
+RTR3DECL(RTEXITCODE) RTFuzzCmdMaster(unsigned cArgs, char **papszArgs)
+{
+    /*
+     * Parse the command line.
+     */
+    static const RTGETOPTDEF s_aOptions[] =
+    {
+        { "--fuzz-config",                     'c', RTGETOPT_REQ_STRING  },
+        { "--temp-dir",                        't', RTGETOPT_REQ_STRING  },
+        { "--results-dir",                     'r', RTGETOPT_REQ_STRING  },
+        { "--listen-port",                     'p', RTGETOPT_REQ_UINT16  },
+        { "--daemonize",                       'd', RTGETOPT_REQ_NOTHING },
+        { "--daemonized",                      'Z', RTGETOPT_REQ_NOTHING },
+        { "--help",                            'h', RTGETOPT_REQ_NOTHING },
+        { "--version",                         'V', RTGETOPT_REQ_NOTHING },
+    };
+
+    RTEXITCODE rcExit = RTEXITCODE_SUCCESS;
+    RTGETOPTSTATE GetState;
+    int rc = RTGetOptInit(&GetState, cArgs, papszArgs, s_aOptions, RT_ELEMENTS(s_aOptions), 1,
+                          RTGETOPTINIT_FLAGS_OPTS_FIRST);
+    if (RT_SUCCESS(rc))
+    {
+        /* Option variables:  */
+        bool fDaemonize = false;
+        bool fDaemonized = false;
+        const char *pszLoadCfg = NULL;
+        RTFUZZCMDMASTER This;
+
+        RTListInit(&This.LstFuzzed);
+        This.hTcpSrv       = NIL_RTTCPSERVER;
+        This.uPort         = 4242;
+        This.pszTmpDir     = NULL;
+        This.pszResultsDir = NULL;
+        This.fShutdown     = false;
+        This.pszResponse   = NULL;
+
+        /* Argument parsing loop. */
+        bool fContinue = true;
+        do
+        {
+            RTGETOPTUNION ValueUnion;
+            int chOpt = RTGetOpt(&GetState, &ValueUnion);
+            switch (chOpt)
+            {
+                case 0:
+                    fContinue = false;
+                    break;
+
+                case 'c':
+                    pszLoadCfg = ValueUnion.psz;
+                    break;
+
+                case 'p':
+                    This.uPort = ValueUnion.u16;
+                    break;
+
+                case 't':
+                    This.pszTmpDir = ValueUnion.psz;
+                    break;
+
+                case 'r':
+                    This.pszResultsDir = ValueUnion.psz;
+                    break;
+
+                case 'd':
+                    fDaemonize = true;
+                    break;
+
+                case 'Z':
+                    fDaemonized = true;
+                    fDaemonize = false;
+                    break;
+
+                case 'h':
+                    RTPrintf("Usage: to be written\nOption dump:\n");
+                    for (unsigned i = 0; i < RT_ELEMENTS(s_aOptions); i++)
+                        RTPrintf(" -%c,%s\n", s_aOptions[i].iShort, s_aOptions[i].pszLong);
+                    fContinue = false;
+                    break;
+
+                case 'V':
+                    RTPrintf("%sr%d\n", RTBldCfgVersion(), RTBldCfgRevision());
+                    fContinue = false;
+                    break;
+
+                default:
+                    rcExit = RTGetOptPrintError(chOpt, &ValueUnion);
+                    fContinue = false;
+                    break;
+            }
+        } while (fContinue);
+
+        if (rcExit == RTEXITCODE_SUCCESS)
+        {
+            /*
+             * Daemonize ourselves if asked to.
+             */
+            if (fDaemonize)
+            {
+                rc = RTProcDaemonize(papszArgs, "--daemonized");
+                if (RT_FAILURE(rc))
+                    return RTMsgErrorExit(RTEXITCODE_FAILURE, "RTProcDaemonize: %Rrc\n", rc);
+            }
+            else
+                rcExit = rtFuzzCmdMasterRun(&This, pszLoadCfg);
+        }
+    }
+    else
+        rcExit = RTMsgErrorExit(RTEXITCODE_SYNTAX, "RTGetOptInit: %Rrc", rc);
+    return rcExit;
+}
+