| 1 | /* $Id: fileio-sg-generic.cpp 77209 2019-02-07 23:46:50Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - File I/O, RTFileSgReadAt & RTFileSgWriteAt, generic.
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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 | #include "internal/iprt.h"
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| 32 | #include <iprt/file.h>
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| 33 |
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| 34 | #include <iprt/errcore.h>
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| 35 |
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| 36 |
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| 37 | /**
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| 38 | * Read bytes from a file at a given offset into a S/G buffer.
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| 39 | * This function may modify the file position.
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| 40 | *
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| 41 | * @returns iprt status code.
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| 42 | * @param hFile Handle to the file.
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| 43 | * @param off Where to read.
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| 44 | * @param pSgBuf Pointer to the S/G buffer to read into.
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| 45 | * @param cbToRead How much to read.
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| 46 | * @param pcbRead How much we actually read.
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| 47 | * If NULL an error will be returned for a partial read.
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| 48 | */
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| 49 | RTDECL(int) RTFileSgReadAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToRead, size_t *pcbRead)
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| 50 | {
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| 51 | int rc = VINF_SUCCESS;
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| 52 | size_t cbRead = 0;
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| 53 | while (cbToRead)
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| 54 | {
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| 55 | size_t cbBuf = cbToRead;
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| 56 | void *pvBuf = RTSgBufGetNextSegment(pSgBuf, &cbBuf);
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| 57 |
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| 58 | size_t cbThisRead = 0;
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| 59 | rc = RTFileReadAt(hFile, off, pvBuf, cbBuf, pcbRead ? &cbThisRead : NULL);
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| 60 | if (RT_SUCCESS(rc))
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| 61 | cbRead += cbThisRead;
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| 62 | else
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| 63 | break;
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| 64 | if ( cbThisRead < cbBuf
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| 65 | && pcbRead)
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| 66 | break;
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| 67 |
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| 68 | cbToRead -= cbBuf;
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| 69 | off += cbBuf;
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| 70 | }
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| 71 |
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| 72 | if (pcbRead)
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| 73 | *pcbRead = cbRead;
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| 74 |
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| 75 | return rc;
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| 76 | }
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| 77 |
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| 78 |
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| 79 | /**
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| 80 | * Write bytes from a S/G buffer to a file at a given offset.
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| 81 | * This function may modify the file position.
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| 82 | *
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| 83 | * @returns iprt status code.
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| 84 | * @param hFile Handle to the file.
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| 85 | * @param off Where to write.
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| 86 | * @param pSgBuf What to write.
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| 87 | * @param cbToWrite How much to write.
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| 88 | * @param pcbWritten How much we actually wrote.
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| 89 | * If NULL an error will be returned for a partial write.
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| 90 | */
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| 91 | RTDECL(int) RTFileSgWriteAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToWrite, size_t *pcbWritten)
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| 92 | {
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| 93 | int rc = VINF_SUCCESS;
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| 94 | size_t cbWritten = 0;
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| 95 | while (cbToWrite)
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| 96 | {
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| 97 | size_t cbBuf = cbToWrite;
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| 98 | void *pvBuf = RTSgBufGetNextSegment(pSgBuf, &cbBuf);
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| 99 |
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| 100 | size_t cbThisWritten = 0;
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| 101 | rc = RTFileWriteAt(hFile, off, pvBuf, cbBuf, pcbWritten ? &cbThisWritten : NULL);
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| 102 | if (RT_SUCCESS(rc))
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| 103 | cbWritten += cbThisWritten;
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| 104 | else
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| 105 | break;
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| 106 | if ( cbThisWritten < cbBuf
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| 107 | && pcbWritten)
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| 108 | break;
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| 109 |
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| 110 | cbToWrite -= cbBuf;
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| 111 | off += cbBuf;
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| 112 | }
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| 113 |
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| 114 | if (pcbWritten)
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| 115 | *pcbWritten = cbWritten;
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| 116 |
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| 117 | return rc;
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| 118 | }
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| 119 |
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