Adding upstream version 7.0.6-dfsg.upstream/7.0.6-dfsgupstream

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

1 files changed, 460 insertions, 0 deletions

diff --git a/include/iprt/sg.h b/include/iprt/sg.h
new file mode 100644
index 00000000..b0831d95
--- /dev/null
+++ b/include/iprt/sg.h
@@ -0,0 +1,460 @@
+/** @file
+ * IPRT - S/G buffer handling.
+ */
+
+/*
+ * Copyright (C) 2010-2022 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+#ifndef IPRT_INCLUDED_sg_h
+#define IPRT_INCLUDED_sg_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+
+RT_C_DECLS_BEGIN
+
+/** @defgroup grp_rt_sgbuf  RTSgBuf - Scatter / Gather Buffers
+ * @ingroup grp_rt
+ * @{
+ */
+
+/** Pointer to a const S/G entry. */
+typedef const struct RTSGBUF *PCRTSGBUF;
+
+/**
+ * Callback for RTSgBufCopyToFn() called on every segment of the given S/G buffer.
+ *
+ * @returns Number of bytes copied for this segment, a value smaller than cbSrc will stop the copy operation.
+ * @param   pSgBuf          The S/G buffer for reference.
+ * @param   pvSrc           Where to copy from.
+ * @param   cbSrc           The number of bytes in the source buffer.
+ * @param   pvUser          Opaque user data passed in RTSgBufCopyToFn().
+ */
+typedef DECLCALLBACKTYPE(size_t, FNRTSGBUFCOPYTO, (PCRTSGBUF pSgBuf, const void *pvSrc, size_t cbSrc, void *pvUser));
+/** Pointer to a FNRTSGBUFCOPYTO. */
+typedef FNRTSGBUFCOPYTO *PFNRTSGBUFCOPYTO;
+
+/**
+ * Callback for RTSgBufCopyFromFn() called on every segment of the given S/G buffer.
+ *
+ * @returns Number of bytes copied for this segment, a value smaller than cbDst will stop the copy operation.
+ * @param   pSgBuf          The S/G buffer for reference.
+ * @param   pvDst           Where to copy to.
+ * @param   cbDst           The number of bytes in the destination buffer.
+ * @param   pvUser          Opaque user data passed in RTSgBufCopyFromFn().
+ */
+typedef DECLCALLBACKTYPE(size_t, FNRTSGBUFCOPYFROM, (PCRTSGBUF pSgBuf, void *pvDst, size_t cbDst, void *pvUser));
+/** Pointer to a FNRTSGBUFCOPYFROM. */
+typedef FNRTSGBUFCOPYFROM *PFNRTSGBUFCOPYFROM;
+
+/**
+ * A S/G entry.
+ */
+typedef struct RTSGSEG
+{
+    /** Pointer to the segment buffer. */
+    void   *pvSeg;
+    /** Size of the segment buffer. */
+    size_t  cbSeg;
+} RTSGSEG;
+/** Pointer to a S/G entry. */
+typedef RTSGSEG *PRTSGSEG;
+/** Pointer to a const S/G entry. */
+typedef const RTSGSEG *PCRTSGSEG;
+/** Pointer to a S/G entry pointer. */
+typedef PRTSGSEG *PPRTSGSEG;
+
+/**
+ * A S/G buffer.
+ *
+ * The members should be treated as private.
+ *
+ * @warning There is a lot of code, especially in the VFS area of IPRT, that
+ *          totally ignores the idxSeg, pvSegCur and cbSegLeft members!  So,
+ *          it is not recommended to pass buffers that aren't fully reset or
+ *          where cbSegLeft is shorter than what paSegs describes.
+ */
+typedef struct RTSGBUF
+{
+    /** Pointer to the scatter/gather array. */
+    PCRTSGSEG paSegs;
+    /** Number of segments. */
+    unsigned  cSegs;
+
+    /** Current segment we are in. */
+    unsigned  idxSeg;
+    /** Pointer to current byte within the current segment. */
+    void     *pvSegCur;
+    /** Number of bytes left in the current segment. */
+    size_t    cbSegLeft;
+} RTSGBUF;
+/** Pointer to a S/G entry. */
+typedef RTSGBUF *PRTSGBUF;
+/** Pointer to a S/G entry pointer. */
+typedef PRTSGBUF *PPRTSGBUF;
+
+
+/**
+ * Sums up the length of all the segments.
+ *
+ * @returns The complete segment length.
+ * @param   pSgBuf      The S/G buffer to check out.
+ */
+DECLINLINE(size_t) RTSgBufCalcTotalLength(PCRTSGBUF pSgBuf)
+{
+    size_t   cb = 0;
+    unsigned i  = pSgBuf->cSegs;
+    while (i-- > 0)
+        cb += pSgBuf->paSegs[i].cbSeg;
+    return cb;
+}
+
+/**
+ * Sums up the number of bytes left from the current position.
+ *
+ * @returns Number of bytes left.
+ * @param   pSgBuf      The S/G buffer to check out.
+ */
+DECLINLINE(size_t) RTSgBufCalcLengthLeft(PCRTSGBUF pSgBuf)
+{
+    size_t   cb = pSgBuf->cbSegLeft;
+    unsigned i  = pSgBuf->cSegs;
+    while (i-- > pSgBuf->idxSeg + 1)
+        cb += pSgBuf->paSegs[i].cbSeg;
+    return cb;
+}
+
+/**
+ * Checks if the current buffer position is at the start of the first segment.
+ *
+ * @returns true / false.
+ * @param   pSgBuf      The S/G buffer to check out.
+ */
+DECLINLINE(bool) RTSgBufIsAtStart(PCRTSGBUF pSgBuf)
+{
+    return pSgBuf->idxSeg == 0
+        && (   pSgBuf->cSegs == 0
+            || pSgBuf->pvSegCur == pSgBuf->paSegs[0].pvSeg);
+}
+
+/**
+ * Checks if the current buffer position is at the end of all the segments.
+ *
+ * @returns true / false.
+ * @param   pSgBuf      The S/G buffer to check out.
+ */
+DECLINLINE(bool) RTSgBufIsAtEnd(PCRTSGBUF pSgBuf)
+{
+    return pSgBuf->idxSeg > pSgBuf->cSegs
+        || (   pSgBuf->idxSeg == pSgBuf->cSegs
+            && pSgBuf->cbSegLeft == 0);
+}
+
+/**
+ * Checks if the current buffer position is at the start of the current segment.
+ *
+ * @returns true / false.
+ * @param   pSgBuf      The S/G buffer to check out.
+ */
+DECLINLINE(bool) RTSgBufIsAtStartOfSegment(PCRTSGBUF pSgBuf)
+{
+    return pSgBuf->idxSeg < pSgBuf->cSegs
+        && pSgBuf->paSegs[pSgBuf->idxSeg].pvSeg == pSgBuf->pvSegCur;
+}
+
+/**
+ * Initialize a S/G buffer structure.
+ *
+ * @returns nothing.
+ * @param   pSgBuf    Pointer to the S/G buffer to initialize.
+ * @param   paSegs    Pointer to the start of the segment array.
+ * @param   cSegs     Number of segments in the array.
+ *
+ * @note paSegs and cSegs can be NULL and 0 respectively to indicate an empty
+ *       S/G buffer.  Operations on the S/G buffer will not do anything in this
+ *       case.
+ */
+RTDECL(void) RTSgBufInit(PRTSGBUF pSgBuf, PCRTSGSEG paSegs, size_t cSegs);
+
+/**
+ * Resets the internal buffer position of the S/G buffer to the beginning.
+ *
+ * @returns nothing.
+ * @param   pSgBuf    The S/G buffer to reset.
+ */
+RTDECL(void) RTSgBufReset(PRTSGBUF pSgBuf);
+
+/**
+ * Clones a given S/G buffer.
+ *
+ * @returns nothing.
+ * @param   pSgBufNew    The new S/G buffer to clone to.
+ * @param   pSgBufOld    The source S/G buffer to clone from.
+ *
+ * @note This is only a shallow copy. Both S/G buffers will point to the
+ *       same segment array.
+ */
+RTDECL(void) RTSgBufClone(PRTSGBUF pSgBufNew, PCRTSGBUF pSgBufOld);
+
+/**
+ * Returns the next segment in the S/G buffer or NULL if no segments left.
+ *
+ * @returns Pointer to the next segment in the S/G buffer.
+ * @param   pSgBuf      The S/G buffer.
+ * @param   cbDesired   The max number of bytes to get.
+ * @param   pcbSeg      Where to store the size of the returned segment, this is
+ *                      equal or smaller than @a cbDesired.
+ *
+ * @note    Use RTSgBufAdvance() to advance after read/writing into the buffer.
+ */
+DECLINLINE(void *) RTSgBufGetCurrentSegment(PRTSGBUF pSgBuf, size_t cbDesired, size_t *pcbSeg)
+{
+    if (!RTSgBufIsAtEnd(pSgBuf))
+    {
+        *pcbSeg = RT_MIN(cbDesired, pSgBuf->cbSegLeft);
+        return pSgBuf->pvSegCur;
+    }
+    *pcbSeg = 0;
+    return NULL;
+}
+
+/**
+ * Returns the next segment in the S/G buffer or NULL if no segment is left.
+ *
+ * @returns Pointer to the next segment in the S/G buffer.
+ * @param   pSgBuf       The S/G buffer.
+ * @param   pcbSeg       Where to store the size of the returned segment.
+ *                       Holds the number of bytes requested initially or 0 to
+ *                       indicate that the size doesn't matter.
+ *                       This may contain fewer bytes on success if the current segment
+ *                       is smaller than the amount of bytes requested.
+ *
+ * @note This operation advances the internal buffer pointer of both S/G buffers.
+ */
+RTDECL(void *) RTSgBufGetNextSegment(PRTSGBUF pSgBuf, size_t *pcbSeg);
+
+/**
+ * Copy data between two S/G buffers.
+ *
+ * @returns The number of bytes copied.
+ * @param   pSgBufDst    The destination S/G buffer.
+ * @param   pSgBufSrc    The source S/G buffer.
+ * @param   cbCopy       Number of bytes to copy.
+ *
+ * @note This operation advances the internal buffer pointer of both S/G buffers.
+ */
+RTDECL(size_t) RTSgBufCopy(PRTSGBUF pSgBufDst, PRTSGBUF pSgBufSrc, size_t cbCopy);
+
+/**
+ * Compares the content of two S/G buffers.
+ *
+ * @returns Whatever memcmp returns.
+ * @param   pSgBuf1      First S/G buffer.
+ * @param   pSgBuf2      Second S/G buffer.
+ * @param   cbCmp        How many bytes to compare.
+ *
+ * @note This operation doesn't change the internal position of the S/G buffers.
+ */
+RTDECL(int) RTSgBufCmp(PCRTSGBUF pSgBuf1, PCRTSGBUF pSgBuf2, size_t cbCmp);
+
+/**
+ * Compares the content of two S/G buffers - advanced version.
+ *
+ * @returns Whatever memcmp returns.
+ * @param   pSgBuf1      First S/G buffer.
+ * @param   pSgBuf2      Second S/G buffer.
+ * @param   cbCmp        How many bytes to compare.
+ * @param   poffDiff     Where to store the offset of the first different byte
+ *                       in the buffer starting from the position of the S/G
+ *                       buffer before this call.
+ * @param   fAdvance     Flag whether the internal buffer position should be advanced.
+ *
+ */
+RTDECL(int) RTSgBufCmpEx(PRTSGBUF pSgBuf1, PRTSGBUF pSgBuf2, size_t cbCmp, size_t *poffDiff, bool fAdvance);
+
+/**
+ * Fills an S/G buf with a constant byte.
+ *
+ * @returns The number of actually filled bytes.
+ *          Can be less than than cbSet if the end of the S/G buffer was reached.
+ * @param   pSgBuf       The S/G buffer.
+ * @param   ubFill       The byte to fill the buffer with.
+ * @param   cbSet        How many bytes to set.
+ *
+ * @note This operation advances the internal buffer pointer of the S/G buffer.
+ */
+RTDECL(size_t) RTSgBufSet(PRTSGBUF pSgBuf, uint8_t ubFill, size_t cbSet);
+
+/**
+ * Copies data from an S/G buffer into a given non scattered buffer.
+ *
+ * @returns Number of bytes copied.
+ * @param   pSgBuf       The S/G buffer to copy from.
+ * @param   pvBuf        Buffer to copy the data into.
+ * @param   cbCopy       How many bytes to copy.
+ *
+ * @note This operation advances the internal buffer pointer of the S/G buffer.
+ */
+RTDECL(size_t) RTSgBufCopyToBuf(PRTSGBUF pSgBuf, void *pvBuf, size_t cbCopy);
+
+/**
+ * Copies data from a non scattered buffer into an S/G buffer.
+ *
+ * @returns Number of bytes copied.
+ * @param   pSgBuf       The S/G buffer to copy to.
+ * @param   pvBuf        Buffer to copy the data from.
+ * @param   cbCopy       How many bytes to copy.
+ *
+ * @note This operation advances the internal buffer pointer of the S/G buffer.
+ */
+RTDECL(size_t) RTSgBufCopyFromBuf(PRTSGBUF pSgBuf, const void *pvBuf, size_t cbCopy);
+
+/**
+ * Copies data from the given S/G buffer to a destination handled by the given callback.
+ *
+ * @returns Number of bytes copied.
+ * @param   pSgBuf       The S/G buffer to copy from.
+ * @param   cbCopy       How many bytes to copy.
+ * @param   pfnCopyTo    The callback to call on every S/G buffer segment until the operation finished.
+ * @param   pvUser       Opaque user data to pass in the given callback.
+ *
+ * @note This operation advances the internal buffer pointer of the S/G buffer.
+ */
+RTDECL(size_t) RTSgBufCopyToFn(PRTSGBUF pSgBuf, size_t cbCopy, PFNRTSGBUFCOPYTO pfnCopyTo, void *pvUser);
+
+/**
+ * Copies data to the given S/G buffer from a destination handled by the given callback.
+ *
+ * @returns Number of bytes copied.
+ * @param   pSgBuf       The S/G buffer to copy to.
+ * @param   cbCopy       How many bytes to copy.
+ * @param   pfnCopyFrom  The callback to call on every S/G buffer segment until the operation finished.
+ * @param   pvUser       Opaque user data to pass in the given callback.
+ *
+ * @note This operation advances the internal buffer pointer of the S/G buffer.
+ */
+RTDECL(size_t) RTSgBufCopyFromFn(PRTSGBUF pSgBuf, size_t cbCopy, PFNRTSGBUFCOPYFROM pfnCopyFrom, void *pvUser);
+
+/**
+ * Advances the internal buffer pointer.
+ *
+ * @returns Number of bytes the pointer was moved forward.
+ * @param   pSgBuf      The S/G buffer.
+ * @param   cbAdvance   Number of bytes to move forward.
+ */
+RTDECL(size_t) RTSgBufAdvance(PRTSGBUF pSgBuf, size_t cbAdvance);
+
+/**
+ * Constructs a new segment array starting from the current position
+ * and describing the given number of bytes.
+ *
+ * @returns Number of bytes the array describes.
+ * @param   pSgBuf      The S/G buffer.
+ * @param   paSeg       The uninitialized segment array.
+ *                      If NULL pcSeg will contain the number of segments needed
+ *                      to describe the requested amount of data.
+ * @param   pcSeg       The number of segments the given array has.
+ *                      This will hold the actual number of entries needed upon return.
+ * @param   cbData      Number of bytes the new array should describe.
+ *
+ * @note This operation advances the internal buffer pointer of the S/G buffer if paSeg is not NULL.
+ */
+RTDECL(size_t) RTSgBufSegArrayCreate(PRTSGBUF pSgBuf, PRTSGSEG paSeg, unsigned *pcSeg, size_t cbData);
+
+/**
+ * Returns whether the given S/G buffer is zeroed out from the current position
+ * upto the number of bytes to check.
+ *
+ * @returns true if the buffer has only zeros
+ *          false otherwise.
+ * @param   pSgBuf      The S/G buffer.
+ * @param   cbCheck     Number of bytes to check.
+ */
+RTDECL(bool) RTSgBufIsZero(PRTSGBUF pSgBuf, size_t cbCheck);
+
+/**
+ * Maps the given S/G buffer to a segment array of another type (for example to
+ * iovec on POSIX or WSABUF on Windows).
+ *
+ * @param   paMapped    Where to store the pointer to the start of the native
+ *                      array or NULL.  The memory needs to be freed with
+ *                      RTMemTmpFree().
+ * @param   pSgBuf      The S/G buffer to map.
+ * @param   Struct      Struct used as the destination.
+ * @param   pvBufField  Name of the field holding the pointer to a buffer.
+ * @param   TypeBufPtr  Type of the buffer pointer.
+ * @param   cbBufField  Name of the field holding the size of the buffer.
+ * @param   TypeBufSize Type of the field for the buffer size.
+ * @param   cSegsMapped Where to store the number of segments the native array
+ *                      has.
+ *
+ * @note    This operation maps the whole S/G buffer starting at the current
+ *          internal position.  The internal buffer position is unchanged by
+ *          this operation.
+ *
+ * @remark  Usage is a bit ugly but saves a few lines of duplicated code
+ *          somewhere else and makes it possible to keep the S/G buffer members
+ *          private without going through RTSgBufSegArrayCreate() first.
+ */
+#define RTSgBufMapToNative(paMapped, pSgBuf, Struct, pvBufField, TypeBufPtr, cbBufField, TypeBufSize, cSegsMapped) \
+    do \
+    { \
+        AssertCompileMemberSize(Struct, pvBufField, RT_SIZEOFMEMB(RTSGSEG, pvSeg)); \
+        /*AssertCompile(RT_SIZEOFMEMB(Struct, cbBufField) >=  RT_SIZEOFMEMB(RTSGSEG, cbSeg));*/ \
+        (cSegsMapped) = (pSgBuf)->cSegs - (pSgBuf)->idxSeg; \
+        \
+        /* We need room for at least one segment. */ \
+        if ((pSgBuf)->cSegs == (pSgBuf)->idxSeg) \
+            (cSegsMapped)++; \
+        \
+        (paMapped) = (Struct *)RTMemTmpAllocZ((cSegsMapped) * sizeof(Struct)); \
+        if ((paMapped)) \
+        { \
+            /* The first buffer is special because we could be in the middle of a segment. */ \
+            (paMapped)[0].pvBufField = (TypeBufPtr)(pSgBuf)->pvSegCur; \
+            (paMapped)[0].cbBufField = (TypeBufSize)(pSgBuf)->cbSegLeft; \
+            \
+            for (unsigned i = 1; i < (cSegsMapped); i++) \
+            { \
+                (paMapped)[i].pvBufField = (TypeBufPtr)(pSgBuf)->paSegs[(pSgBuf)->idxSeg + i].pvSeg; \
+                (paMapped)[i].cbBufField = (TypeBufSize)(pSgBuf)->paSegs[(pSgBuf)->idxSeg + i].cbSeg; \
+            } \
+        } \
+    } while (0)
+
+RT_C_DECLS_END
+
+/** @} */
+
+#endif /* !IPRT_INCLUDED_sg_h */
+