1 files changed, 298 insertions, 0 deletions
diff --git a/src/VBox/Runtime/r3/posix/fileio-sg-at-posix.cpp b/src/VBox/Runtime/r3/posix/fileio-sg-at-posix.cpp
new file mode 100644
index 00000000..5fdea41a
--- /dev/null
+++ b/src/VBox/Runtime/r3/posix/fileio-sg-at-posix.cpp
@@ -0,0 +1,298 @@
+/* $Id: fileio-sg-at-posix.cpp $ */
+/** @file
+ * IPRT - File I/O, RTFileSgReadAt & RTFileSgWriteAt, posixy.
+ */
+
+/*
+ * Copyright (C) 2006-2023 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
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+/*
+ * Determin whether we've got preadv and pwritev.
+ */
+#include <iprt/cdefs.h>
+#ifdef RT_OS_LINUX
+/* Linux has these since glibc 2.10 and Linux 2.6.30: */
+# include <features.h>
+# ifdef __GLIBC_PREREQ
+#  if __GLIBC_PREREQ(2,10)
+#   define HAVE_PREADV_AND_PWRITEV 1
+#else
+#  endif
+# endif
+
+#elif defined(RT_OS_FREEBSD)
+/* FreeBSD has these since 6.0: */
+# include <osreldate.h>
+# ifdef __FreeBSD_version
+#  if __FreeBSD_version >= 600000
+#   define HAVE_PREADV_AND_PWRITEV 1
+#  endif
+# endif
+
+#endif
+
+#ifndef HAVE_PREADV_AND_PWRITEV
+
+# include "../../generic/fileio-sg-at-generic.cpp"
+
+#else /* HAVE_PREADV_AND_PWRITEV - rest of the file */
+
+# include <errno.h>
+# include <sys/types.h>
+# include <sys/uio.h>
+# include <unistd.h>
+# include <limits.h>
+# if defined(RT_OS_DARWIN) || defined(RT_OS_FREEBSD) || defined(RT_OS_NETBSD) || defined(RT_OS_OPENBSD)
+#  include <sys/syslimits.h>
+# endif
+
+# include "internal/iprt.h"
+# include <iprt/file.h>
+
+# include <iprt/assert.h>
+# include <iprt/err.h>
+# include <iprt/log.h>
+
+# ifndef UIO_MAXIOV
+#  ifdef IOV_MAX
+#   define UIO_MAXIOV IOV_MAX
+#  else
+#   error "UIO_MAXIOV and IOV_MAX are undefined"
+#  endif
+# endif
+
+
+/* These assumptions simplifies things a lot here. */
+AssertCompileMembersSameSizeAndOffset(struct iovec, iov_base, RTSGSEG, pvSeg);
+AssertCompileMembersSameSizeAndOffset(struct iovec, iov_len,  RTSGSEG, cbSeg);
+
+
+RTDECL(int)  RTFileSgReadAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToRead, size_t *pcbRead)
+{
+    /*
+     * Make sure we set pcbRead.
+     */
+    if (pcbRead)
+        *pcbRead = 0;
+
+    /*
+     * Special case: Zero read == seek.
+     */
+    if (cbToRead == 0)
+        return RTFileSeek(hFile, off, RTFILE_SEEK_BEGIN, NULL);
+
+    /*
+     * We can use the segment array directly if we're at the start of the
+     * current S/G segment and cbToRead matches the remainder exactly.
+     */
+    size_t cbTotalRead = 0;
+
+    size_t const cbSgBufLeft = RTSgBufCalcLengthLeft(pSgBuf);
+    AssertMsgReturn(cbSgBufLeft >= cbToRead, ("%#zx vs %#zx\n", cbSgBufLeft, cbToRead), VERR_INVALID_PARAMETER);
+
+    if (cbToRead == cbSgBufLeft)
+        while (RTSgBufIsAtStartOfSegment(pSgBuf))
+        {
+            size_t const cSegsLeft  = pSgBuf->cSegs - pSgBuf->idxSeg;
+            ssize_t      cbThisRead = preadv(RTFileToNative(hFile), (const struct iovec *)&pSgBuf->paSegs[pSgBuf->idxSeg],
+                                             RT_MIN(cSegsLeft, UIO_MAXIOV), off);
+            if (cbThisRead >= 0)
+            {
+                AssertStmt((size_t)cbThisRead <= cbToRead, cbThisRead = cbToRead);
+
+                RTSgBufAdvance(pSgBuf, cbThisRead);
+                cbTotalRead += cbThisRead;
+                cbToRead    -= cbThisRead;
+                if (cbToRead == 0)
+                {
+                    if (pcbRead)
+                        *pcbRead = cbTotalRead;
+                    return VINF_SUCCESS;
+                }
+
+                if (   pcbRead
+                    && (   cSegsLeft <= UIO_MAXIOV
+                        || cbThisRead == 0 /* typically EOF */ ))
+                {
+                    *pcbRead = cbTotalRead;
+                    return VINF_SUCCESS;
+                }
+                if (cbThisRead == 0)
+                    return VERR_EOF;
+
+                off += cbThisRead;
+            }
+            else if (cbTotalRead > 0 && pcbRead)
+            {
+                *pcbRead = cbTotalRead;
+                return VINF_SUCCESS;
+            }
+            else
+                return RTErrConvertFromErrno(errno);
+        }
+
+    /*
+     * Unaligned start or not reading the whole buffer.  For reasons of
+     * simplicity, we work the input segment by segment like the generic code.
+     */
+    int rc = VINF_SUCCESS;
+    while (cbToRead > 0)
+    {
+        size_t cbSeg;
+        void  *pvSeg = RTSgBufGetCurrentSegment(pSgBuf, cbToRead, &cbSeg);
+        size_t cbThisRead = cbSeg;
+        rc = RTFileReadAt(hFile, off, pvSeg, cbSeg, pcbRead ? &cbThisRead : NULL);
+        if (RT_SUCCESS(rc))
+        {
+            RTSgBufAdvance(pSgBuf, cbThisRead);
+            cbTotalRead += cbThisRead;
+        }
+        else
+            break;
+        if ((size_t)cbThisRead < cbSeg)
+        {
+            AssertStmt(pcbRead, rc = VERR_INTERNAL_ERROR_2);
+            break;
+        }
+
+        Assert(cbSeg == cbThisRead);
+        cbToRead -= cbSeg;
+        off      += cbSeg;
+    }
+    if (pcbRead)
+        *pcbRead = cbTotalRead;
+    return rc;
+}
+
+
+RTDECL(int)  RTFileSgWriteAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToWrite, size_t *pcbWritten)
+{
+    /*
+     * Make sure we set pcbWritten.
+     */
+    if (pcbWritten)
+        *pcbWritten = 0;
+
+    /*
+     * Special case: Zero write == seek.
+     */
+    if (cbToWrite == 0)
+        return RTFileSeek(hFile, off, RTFILE_SEEK_BEGIN, NULL);
+
+    /*
+     * We can use the segment array directly if we're at the start of the
+     * current S/G segment and cbToWrite matches the remainder exactly.
+     */
+    size_t cbTotalWritten = 0;
+
+    size_t const cbSgBufLeft = RTSgBufCalcLengthLeft(pSgBuf);
+    AssertMsgReturn(cbSgBufLeft >= cbToWrite, ("%#zx vs %#zx\n", cbSgBufLeft, cbToWrite), VERR_INVALID_PARAMETER);
+
+    if (cbToWrite == cbSgBufLeft)
+        while (RTSgBufIsAtStartOfSegment(pSgBuf))
+        {
+            size_t const cSegsLeft     = pSgBuf->cSegs - pSgBuf->idxSeg;
+            ssize_t      cbThisWritten = pwritev(RTFileToNative(hFile), (const struct iovec *)&pSgBuf->paSegs[pSgBuf->idxSeg],
+                                                 RT_MIN(cSegsLeft, UIO_MAXIOV), off);
+            if (cbThisWritten >= 0)
+            {
+                AssertStmt((size_t)cbThisWritten <= cbToWrite, cbThisWritten = cbToWrite);
+
+                RTSgBufAdvance(pSgBuf, cbThisWritten);
+                cbTotalWritten += cbThisWritten;
+                cbToWrite      -= cbThisWritten;
+                if (cbToWrite == 0)
+                {
+                    if (pcbWritten)
+                        *pcbWritten = cbTotalWritten;
+                    return VINF_SUCCESS;
+                }
+
+                if (   pcbWritten
+                    && (   cSegsLeft <= UIO_MAXIOV
+                        || cbThisWritten == 0 /* non-file, full buffer/whatever */ ))
+                {
+                    *pcbWritten = cbTotalWritten;
+                    return VINF_SUCCESS;
+                }
+                if (cbThisWritten == 0)
+                    return VERR_TRY_AGAIN;
+
+                off += cbThisWritten;
+            }
+            else if (cbTotalWritten > 0 && pcbWritten)
+            {
+                *pcbWritten = cbTotalWritten;
+                return VINF_SUCCESS;
+            }
+            else
+                return RTErrConvertFromErrno(errno);
+        }
+
+    /*
+     * Unaligned start or not writing the whole buffer.  For reasons of
+     * simplicity, we work the input segment by segment like the generic code.
+     */
+    int rc = VINF_SUCCESS;
+    while (cbToWrite > 0)
+    {
+        size_t cbSeg;
+        void  *pvSeg = RTSgBufGetCurrentSegment(pSgBuf, cbToWrite, &cbSeg);
+        size_t cbThisWritten = cbSeg;
+        rc = RTFileWriteAt(hFile, off, pvSeg, cbSeg, pcbWritten ? &cbThisWritten : NULL);
+        if (RT_SUCCESS(rc))
+        {
+            RTSgBufAdvance(pSgBuf, cbThisWritten);
+            cbTotalWritten += cbThisWritten;
+        }
+        else
+            break;
+        if ((size_t)cbThisWritten < cbSeg)
+        {
+            AssertStmt(pcbWritten, rc = VERR_INTERNAL_ERROR_2);
+            break;
+        }
+
+        Assert(cbSeg == cbThisWritten);
+        cbToWrite -= cbSeg;
+        off       += cbSeg;
+    }
+    if (pcbWritten)
+        *pcbWritten = cbTotalWritten;
+    return rc;
+}
+
+#endif /* HAVE_PREADV_AND_PWRITEV */
+