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

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

1 files changed, 209 insertions, 0 deletions

diff --git a/include/iprt/once.h b/include/iprt/once.h
new file mode 100644
index 00000000..75a2b2d2
--- /dev/null
+++ b/include/iprt/once.h
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+/** @file
+ * IPRT - Execute Once.
+ */
+
+/*
+ * Copyright (C) 2006-2019 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.
+ */
+
+#ifndef IPRT_INCLUDED_once_h
+#define IPRT_INCLUDED_once_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cdefs.h>
+#include <iprt/types.h>
+#include <iprt/asm.h>
+#include <iprt/errcore.h>
+#include <iprt/list.h>
+
+RT_C_DECLS_BEGIN
+
+/** @defgroup grp_rt_once       RTOnce - Execute Once
+ * @ingroup grp_rt
+ * @{
+ */
+
+/**
+ * Callback that gets executed once.
+ *
+ * @returns IPRT style status code, RTOnce returns this.
+ *
+ * @param   pvUser          The user parameter.
+ */
+typedef DECLCALLBACK(int32_t) FNRTONCE(void *pvUser);
+/** Pointer to a FNRTONCE. */
+typedef FNRTONCE *PFNRTONCE;
+
+/**
+ * Callback that gets executed on IPRT/process termination.
+ *
+ * @param   pvUser          The user parameter.
+ * @param   fLazyCleanUpOk  Indicates whether lazy clean-up is OK (see
+ *                          initterm.h).
+ */
+typedef DECLCALLBACK(void) FNRTONCECLEANUP(void *pvUser, bool fLazyCleanUpOk);
+/** Pointer to a FNRTONCE. */
+typedef FNRTONCECLEANUP *PFNRTONCECLEANUP;
+
+/**
+ * Execute once structure.
+ *
+ * This is typically a global variable that is statically initialized
+ * by RTONCE_INITIALIZER.
+ */
+typedef struct RTONCE
+{
+    /** Event semaphore that the other guys are blocking on. */
+    RTSEMEVENTMULTI volatile    hEventMulti;
+    /** Reference counter for hEventMulti. */
+    int32_t volatile            cEventRefs;
+    /** See RTONCESTATE. */
+    int32_t volatile            iState;
+    /** The return code of pfnOnce. */
+    int32_t volatile            rc;
+
+    /** Pointer to the clean-up function. */
+    PFNRTONCECLEANUP            pfnCleanUp;
+    /** Argument to hand to the clean-up function. */
+    void                       *pvUser;
+    /** Clean-up list entry. */
+    RTLISTNODE                  CleanUpNode;
+} RTONCE;
+/** Pointer to a execute once struct. */
+typedef RTONCE *PRTONCE;
+
+/**
+ * The execute once statemachine.
+ */
+typedef enum RTONCESTATE
+{
+    /** RTOnce() has not been called.
+     *  Next: NO_SEM */
+    RTONCESTATE_UNINITIALIZED = 1,
+    /** RTOnce() is busy, no race.
+     *  Next: CREATING_SEM, DONE */
+    RTONCESTATE_BUSY_NO_SEM,
+    /** More than one RTOnce() caller is busy.
+     *  Next: BUSY_HAVE_SEM, BUSY_SPIN, DONE_CREATING_SEM, DONE */
+    RTONCESTATE_BUSY_CREATING_SEM,
+    /** More than one RTOnce() caller, the first is busy, the others are
+     *  waiting.
+     *  Next: DONE */
+    RTONCESTATE_BUSY_HAVE_SEM,
+    /** More than one RTOnce() caller, the first is busy, the others failed to
+     *  create a semaphore and are spinning.
+     *  Next: DONE */
+    RTONCESTATE_BUSY_SPIN,
+    /** More than one RTOnce() caller, the first has completed, the others
+     *  are busy creating the semaphore.
+     *  Next: DONE_HAVE_SEM */
+    RTONCESTATE_DONE_CREATING_SEM,
+    /** More than one RTOnce() caller, the first is busy grabbing the
+     *  semaphore, while the others are waiting.
+     *  Next: DONE */
+    RTONCESTATE_DONE_HAVE_SEM,
+    /** The execute once stuff has completed. */
+    RTONCESTATE_DONE = 16
+} RTONCESTATE;
+
+/** Static initializer for RTONCE variables. */
+#define RTONCE_INITIALIZER \
+    { NIL_RTSEMEVENTMULTI, 0, RTONCESTATE_UNINITIALIZED, VERR_INTERNAL_ERROR, NULL, NULL, { NULL, NULL } }
+
+
+/**
+ * Serializes execution of the pfnOnce function, making sure it's
+ * executed exactly once and that nobody returns from RTOnce before
+ * it has executed successfully.
+ *
+ * @returns IPRT like status code returned by pfnOnce.
+ *
+ * @param   pOnce           Pointer to the execute once variable.
+ * @param   pfnOnce         The function to executed once.
+ * @param   pfnCleanUp      The function that will be doing the cleaning up.
+ *                          Optional.
+ * @param   pvUser          The user parameter for pfnOnce.
+ */
+RTDECL(int) RTOnceSlow(PRTONCE pOnce, PFNRTONCE pfnOnce, FNRTONCECLEANUP pfnCleanUp, void *pvUser);
+
+/**
+ * Serializes execution of the pfnOnce function, making sure it's
+ * executed exactly once and that nobody returns from RTOnce before
+ * it has executed successfully.
+ *
+ * @returns IPRT like status code returned by pfnOnce.
+ *
+ * @param   pOnce           Pointer to the execute once variable.
+ * @param   pfnOnce         The function to executed once.
+ * @param   pvUser          The user parameter for pfnOnce.
+ */
+DECLINLINE(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser)
+{
+    int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
+    if (RT_LIKELY(   iState == RTONCESTATE_DONE
+                  || iState == RTONCESTATE_DONE_CREATING_SEM
+                  || iState == RTONCESTATE_DONE_HAVE_SEM ))
+        return ASMAtomicUoReadS32(&pOnce->rc);
+    return RTOnceSlow(pOnce, pfnOnce, NULL, pvUser);
+}
+
+/**
+ * Execute pfnOnce once and register a termination clean-up callback.
+ *
+ * Serializes execution of the pfnOnce function, making sure it's
+ * executed exactly once and that nobody returns from RTOnce before
+ * it has executed successfully.
+ *
+ * @returns IPRT like status code returned by pfnOnce.
+ *
+ * @param   pOnce           Pointer to the execute once variable.
+ * @param   pfnOnce         The function to executed once.
+ * @param   pfnCleanUp      The function that will be doing the cleaning up.
+ * @param   pvUser          The user parameter for pfnOnce.
+ */
+DECLINLINE(int) RTOnceEx(PRTONCE pOnce, PFNRTONCE pfnOnce, PFNRTONCECLEANUP pfnCleanUp, void *pvUser)
+{
+    int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
+    if (RT_LIKELY(   iState == RTONCESTATE_DONE
+                  || iState == RTONCESTATE_DONE_CREATING_SEM
+                  || iState == RTONCESTATE_DONE_HAVE_SEM ))
+        return ASMAtomicUoReadS32(&pOnce->rc);
+    return RTOnceSlow(pOnce, pfnOnce, pfnCleanUp, pvUser);
+}
+
+
+/**
+ * Resets an execute once variable.
+ *
+ * The caller is responsible for making sure there are no concurrent accesses to
+ * the execute once variable.
+ *
+ * @param   pOnce           Pointer to the execute once variable.
+ */
+RTDECL(void) RTOnceReset(PRTONCE pOnce);
+
+/** @} */
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_once_h */
+