| 1 | /* $Id: fileio-sg-at-posix.cpp 77632 2019-03-10 13:33:52Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - File I/O, RTFileSgReadAt & RTFileSgWriteAt, posixy.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2006-2019 Oracle Corporation
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| 8 | *
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| 9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | * available from http://www.virtualbox.org. This file is free software;
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| 11 | * you can redistribute it and/or modify it under the terms of the GNU
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| 12 | * General Public License (GPL) as published by the Free Software
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| 13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | *
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| 17 | * The contents of this file may alternatively be used under the terms
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| 18 | * of the Common Development and Distribution License Version 1.0
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| 19 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | * VirtualBox OSE distribution, in which case the provisions of the
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| 21 | * CDDL are applicable instead of those of the GPL.
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| 22 | *
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| 23 | * You may elect to license modified versions of this file under the
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| 24 | * terms and conditions of either the GPL or the CDDL or both.
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| 25 | */
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| 26 |
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| 27 |
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| 28 | /*********************************************************************************************************************************
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| 29 | * Header Files *
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| 30 | *********************************************************************************************************************************/
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| 31 | /*
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| 32 | * Determin whether we've got preadv and pwritev.
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| 33 | */
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| 34 | #include <iprt/cdefs.h>
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| 35 | #ifdef RT_OS_LINUX
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| 36 | /* Linux has these since glibc 2.10 and Linux 2.6.30: */
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| 37 | # include <features.h>
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| 38 | # ifdef __GLIBC_PREREQ
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| 39 | # if __GLIBC_PREREQ(2,10)
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| 40 | # define HAVE_PREADV_AND_PWRITEV 1
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| 41 | #else
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| 42 | # endif
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| 43 | # endif
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| 44 |
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| 45 | #elif defined(RT_OS_FREEBSD)
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| 46 | /* FreeBSD has these since 6.0: */
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| 47 | # include <osreldate.h>
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| 48 | # ifdef __FreeBSD_version
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| 49 | # if __FreeBSD_version >= 600000
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| 50 | # define HAVE_PREADV_AND_PWRITEV 1
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| 51 | # endif
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| 52 | # endif
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| 53 |
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| 54 | #endif
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| 55 |
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| 56 | #ifndef HAVE_PREADV_AND_PWRITEV
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| 57 |
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| 58 | # include "../../generic/fileio-sg-generic.cpp"
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| 59 |
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| 60 | #else /* HAVE_PREADV_AND_PWRITEV - rest of the file */
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| 61 |
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| 62 | # include <errno.h>
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| 63 | # include <sys/types.h>
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| 64 | # include <sys/uio.h>
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| 65 | # include <unistd.h>
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| 66 |
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| 67 | # include "internal/iprt.h"
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| 68 | # include <iprt/file.h>
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| 69 |
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| 70 | # include <iprt/assert.h>
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| 71 | # include <iprt/err.h>
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| 72 | # include <iprt/log.h>
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| 73 |
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| 74 | # ifndef UIO_MAXIOV
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| 75 | # error "UIO_MAXIOV is undefined"
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| 76 | # endif
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| 77 |
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| 78 |
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| 79 | /* These assumptions simplifies things a lot here. */
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| 80 | AssertCompileMembersSameSizeAndOffset(struct iovec, iov_base, RTSGSEG, pvSeg);
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| 81 | AssertCompileMembersSameSizeAndOffset(struct iovec, iov_len, RTSGSEG, cbSeg);
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| 82 |
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| 83 |
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| 84 | RTDECL(int) RTFileSgReadAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToRead, size_t *pcbRead)
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| 85 | {
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| 86 | /*
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| 87 | * Make sure we set pcbRead.
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| 88 | */
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| 89 | if (pcbRead)
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| 90 | *pcbRead = 0;
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| 91 |
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| 92 | /*
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| 93 | * Special case: Zero read == seek.
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| 94 | */
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| 95 | if (cbToRead == 0)
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| 96 | return RTFileSeek(hFile, off, RTFILE_SEEK_BEGIN, NULL);
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| 97 |
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| 98 | /*
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| 99 | * We can use the segment array directly if we're at the start of the
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| 100 | * current S/G segment and cbToRead matches the remainder exactly.
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| 101 | */
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| 102 | size_t cbTotalRead = 0;
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| 103 |
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| 104 | size_t const cbSgBufLeft = RTSgBufCalcLengthLeft(pSgBuf);
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| 105 | AssertMsgReturn(cbSgBufLeft >= cbToRead, ("%#zx vs %#zx\n", cbSgBufLeft, cbToRead), VERR_INVALID_PARAMETER);
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| 106 |
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| 107 | if (cbToRead == cbSgBufLeft)
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| 108 | while (RTSgBufIsAtStartOfSegment(pSgBuf))
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| 109 | {
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| 110 | size_t const cSegsLeft = pSgBuf->cSegs - pSgBuf->idxSeg;
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| 111 | ssize_t cbThisRead = preadv(RTFileToNative(hFile), (const struct iovec *)&pSgBuf->paSegs[pSgBuf->idxSeg],
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| 112 | RT_MIN(cSegsLeft, UIO_MAXIOV), off);
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| 113 | if (cbThisRead >= 0)
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| 114 | {
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| 115 | AssertStmt((size_t)cbThisRead <= cbToRead, cbThisRead = cbToRead);
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| 116 |
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| 117 | RTSgBufAdvance(pSgBuf, cbThisRead);
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| 118 | cbTotalRead += cbThisRead;
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| 119 | cbToRead -= cbThisRead;
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| 120 | if (cbToRead == 0)
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| 121 | {
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| 122 | if (pcbRead)
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| 123 | *pcbRead = cbTotalRead;
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| 124 | return VINF_SUCCESS;
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| 125 | }
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| 126 |
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| 127 | if ( pcbRead
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| 128 | && ( cSegsLeft <= UIO_MAXIOV
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| 129 | || cbThisRead == 0 /* typically EOF */ ))
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| 130 | {
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| 131 | *pcbRead = cbTotalRead;
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| 132 | return VINF_SUCCESS;
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| 133 | }
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| 134 | if (cbThisRead == 0)
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| 135 | return VERR_EOF;
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| 136 |
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| 137 | off += cbThisRead;
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| 138 | }
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| 139 | else if (cbTotalRead > 0 && pcbRead)
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| 140 | {
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| 141 | *pcbRead = cbTotalRead;
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| 142 | return VINF_SUCCESS;
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| 143 | }
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| 144 | else
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| 145 | return RTErrConvertFromErrno(errno);
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| 146 | }
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| 147 |
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| 148 | /*
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| 149 | * Unaligned start or not reading the whole buffer. For reasons of
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| 150 | * simplicity, we work the input segment by segment like the generic code.
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| 151 | */
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| 152 | int rc = VINF_SUCCESS;
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| 153 | while (cbToRead > 0)
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| 154 | {
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| 155 | size_t cbSeg;
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| 156 | void *pvSeg = RTSgBufGetCurrentSegment(pSgBuf, cbToRead, &cbSeg);
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| 157 | size_t cbThisRead = cbSeg;
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| 158 | rc = RTFileReadAt(hFile, off, pvSeg, cbSeg, pcbRead ? &cbThisRead : NULL);
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| 159 | if (RT_SUCCESS(rc))
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| 160 | {
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| 161 | RTSgBufAdvance(pSgBuf, cbThisRead);
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| 162 | cbTotalRead += cbThisRead;
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| 163 | }
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| 164 | else
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| 165 | break;
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| 166 | if ((size_t)cbThisRead < cbSeg)
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| 167 | {
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| 168 | AssertStmt(pcbRead, rc = VERR_INTERNAL_ERROR_2);
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| 169 | break;
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| 170 | }
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| 171 |
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| 172 | Assert(cbSeg == cbThisRead);
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| 173 | cbToRead -= cbSeg;
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| 174 | off += cbSeg;
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| 175 | }
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| 176 | if (pcbRead)
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| 177 | *pcbRead = cbTotalRead;
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| 178 | return rc;
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| 179 | }
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| 180 |
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| 181 |
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| 182 | RTDECL(int) RTFileSgWriteAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToWrite, size_t *pcbWritten)
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| 183 | {
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| 184 | /*
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| 185 | * Make sure we set pcbWritten.
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| 186 | */
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| 187 | if (pcbWritten)
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| 188 | *pcbWritten = 0;
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| 189 |
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| 190 | /*
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| 191 | * Special case: Zero write == seek.
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| 192 | */
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| 193 | if (cbToWrite == 0)
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| 194 | return RTFileSeek(hFile, off, RTFILE_SEEK_BEGIN, NULL);
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| 195 |
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| 196 | /*
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| 197 | * We can use the segment array directly if we're at the start of the
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| 198 | * current S/G segment and cbToWrite matches the remainder exactly.
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| 199 | */
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| 200 | size_t cbTotalWritten = 0;
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| 201 |
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| 202 | size_t const cbSgBufLeft = RTSgBufCalcLengthLeft(pSgBuf);
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| 203 | AssertMsgReturn(cbSgBufLeft >= cbToWrite, ("%#zx vs %#zx\n", cbSgBufLeft, cbToWrite), VERR_INVALID_PARAMETER);
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| 204 |
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| 205 | if (cbToWrite == cbSgBufLeft)
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| 206 | while (RTSgBufIsAtStartOfSegment(pSgBuf))
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| 207 | {
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| 208 | size_t const cSegsLeft = pSgBuf->cSegs - pSgBuf->idxSeg;
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| 209 | ssize_t cbThisWritten = pwritev(RTFileToNative(hFile), (const struct iovec *)&pSgBuf->paSegs[pSgBuf->idxSeg],
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| 210 | RT_MIN(cSegsLeft, UIO_MAXIOV), off);
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| 211 | if (cbThisWritten >= 0)
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| 212 | {
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| 213 | AssertStmt((size_t)cbThisWritten <= cbToWrite, cbThisWritten = cbToWrite);
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| 214 |
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| 215 | RTSgBufAdvance(pSgBuf, cbThisWritten);
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| 216 | cbTotalWritten += cbThisWritten;
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| 217 | cbToWrite -= cbThisWritten;
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| 218 | if (cbToWrite == 0)
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| 219 | {
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| 220 | if (pcbWritten)
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| 221 | *pcbWritten = cbTotalWritten;
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| 222 | return VINF_SUCCESS;
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| 223 | }
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| 224 |
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| 225 | if ( pcbWritten
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| 226 | && ( cSegsLeft <= UIO_MAXIOV
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| 227 | || cbThisWritten == 0 /* non-file, full buffer/whatever */ ))
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| 228 | {
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| 229 | *pcbWritten = cbTotalWritten;
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| 230 | return VINF_SUCCESS;
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| 231 | }
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| 232 | if (cbThisWritten == 0)
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| 233 | return VERR_TRY_AGAIN;
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| 234 |
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| 235 | off += cbThisWritten;
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| 236 | }
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| 237 | else if (cbTotalWritten > 0 && pcbWritten)
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| 238 | {
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| 239 | *pcbWritten = cbTotalWritten;
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| 240 | return VINF_SUCCESS;
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| 241 | }
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| 242 | else
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| 243 | return RTErrConvertFromErrno(errno);
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| 244 | }
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| 245 |
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| 246 | /*
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| 247 | * Unaligned start or not writing the whole buffer. For reasons of
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| 248 | * simplicity, we work the input segment by segment like the generic code.
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| 249 | */
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| 250 | int rc = VINF_SUCCESS;
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| 251 | while (cbToWrite > 0)
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| 252 | {
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| 253 | size_t cbSeg;
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| 254 | void *pvSeg = RTSgBufGetCurrentSegment(pSgBuf, cbToWrite, &cbSeg);
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| 255 | size_t cbThisWritten = cbSeg;
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| 256 | rc = RTFileWriteAt(hFile, off, pvSeg, cbSeg, pcbWritten ? &cbThisWritten : NULL);
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| 257 | if (RT_SUCCESS(rc))
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| 258 | {
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| 259 | RTSgBufAdvance(pSgBuf, cbThisWritten);
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| 260 | cbTotalWritten += cbThisWritten;
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| 261 | }
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| 262 | else
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| 263 | break;
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| 264 | if ((size_t)cbThisWritten < cbSeg)
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| 265 | {
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| 266 | AssertStmt(pcbWritten, rc = VERR_INTERNAL_ERROR_2);
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| 267 | break;
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| 268 | }
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| 269 |
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| 270 | Assert(cbSeg == cbThisWritten);
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| 271 | cbToWrite -= cbSeg;
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| 272 | off += cbSeg;
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| 273 | }
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| 274 | if (pcbWritten)
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| 275 | *pcbWritten = cbTotalWritten;
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| 276 | return rc;
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| 277 | }
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| 278 |
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| 279 | #endif /* HAVE_PREADV_AND_PWRITEV */
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| 280 |
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