fileio-sg-at-posix.cpp@ 77635

Last change on this file since 77635 was 77635, checked in by vboxsync, 6 years ago
IPRT: Adding RTFileSgRead and RTFileSgWrite (for FsPerf). [build fixes] bugref:9172
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1	/* $Id: fileio-sg-at-posix.cpp 77635 2019-03-10 14:51:26Z vboxsync $ */
2	/** @file
3	* IPRT - File I/O, RTFileSgReadAt & RTFileSgWriteAt, posixy.
4	*/
5
6	/*
7	* Copyright (C) 2006-2019 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*
17	* The contents of this file may alternatively be used under the terms
18	* of the Common Development and Distribution License Version 1.0
19	* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20	* VirtualBox OSE distribution, in which case the provisions of the
21	* CDDL are applicable instead of those of the GPL.
22	*
23	* You may elect to license modified versions of this file under the
24	* terms and conditions of either the GPL or the CDDL or both.
25	*/
26
27
28	/*********************************************************************************************************************************
29	* Header Files *
30	*********************************************************************************************************************************/
31	/*
32	* Determin whether we've got preadv and pwritev.
33	*/
34	#include <iprt/cdefs.h>
35	#ifdef RT_OS_LINUX
36	/* Linux has these since glibc 2.10 and Linux 2.6.30: */
37	# include <features.h>
38	# ifdef __GLIBC_PREREQ
39	# if __GLIBC_PREREQ(2,10)
40	# define HAVE_PREADV_AND_PWRITEV 1
41	#else
42	# endif
43	# endif
44
45	#elif defined(RT_OS_FREEBSD)
46	/* FreeBSD has these since 6.0: */
47	# include <osreldate.h>
48	# ifdef __FreeBSD_version
49	# if __FreeBSD_version >= 600000
50	# define HAVE_PREADV_AND_PWRITEV 1
51	# endif
52	# endif
53
54	#endif
55
56	#ifndef HAVE_PREADV_AND_PWRITEV
57
58	# include "../../generic/fileio-sg-at-generic.cpp"
59
60	#else /* HAVE_PREADV_AND_PWRITEV - rest of the file */
61
62	# include <errno.h>
63	# include <sys/types.h>
64	# include <sys/uio.h>
65	# include <unistd.h>
66	# include <limits.h>
67	# if defined(RT_OS_DARWIN) \|\| defined(RT_OS_FREEBSD) \|\| defined(RT_OS_NETBSD) \|\| defined(RT_OS_OPENBSD)
68	# include <sys/syslimits.h>
69	# endif
70
71	# include "internal/iprt.h"
72	# include <iprt/file.h>
73
74	# include <iprt/assert.h>
75	# include <iprt/err.h>
76	# include <iprt/log.h>
77
78	# ifndef UIO_MAXIOV
79	# ifdef IOV_MAX
80	# define UIO_MAXIOV IOV_MAX
81	# else
82	# error "UIO_MAXIOV and IOV_MAX are undefined"
83	# endif
84	# endif
85
86
87	/* These assumptions simplifies things a lot here. */
88	AssertCompileMembersSameSizeAndOffset(struct iovec, iov_base, RTSGSEG, pvSeg);
89	AssertCompileMembersSameSizeAndOffset(struct iovec, iov_len, RTSGSEG, cbSeg);
90
91
92	RTDECL(int) RTFileSgReadAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToRead, size_t *pcbRead)
93	{
94	/*
95	* Make sure we set pcbRead.
96	*/
97	if (pcbRead)
98	*pcbRead = 0;
99
100	/*
101	* Special case: Zero read == seek.
102	*/
103	if (cbToRead == 0)
104	return RTFileSeek(hFile, off, RTFILE_SEEK_BEGIN, NULL);
105
106	/*
107	* We can use the segment array directly if we're at the start of the
108	* current S/G segment and cbToRead matches the remainder exactly.
109	*/
110	size_t cbTotalRead = 0;
111
112	size_t const cbSgBufLeft = RTSgBufCalcLengthLeft(pSgBuf);
113	AssertMsgReturn(cbSgBufLeft >= cbToRead, ("%#zx vs %#zx\n", cbSgBufLeft, cbToRead), VERR_INVALID_PARAMETER);
114
115	if (cbToRead == cbSgBufLeft)
116	while (RTSgBufIsAtStartOfSegment(pSgBuf))
117	{
118	size_t const cSegsLeft = pSgBuf->cSegs - pSgBuf->idxSeg;
119	ssize_t cbThisRead = preadv(RTFileToNative(hFile), (const struct iovec *)&pSgBuf->paSegs[pSgBuf->idxSeg],
120	RT_MIN(cSegsLeft, UIO_MAXIOV), off);
121	if (cbThisRead >= 0)
122	{
123	AssertStmt((size_t)cbThisRead <= cbToRead, cbThisRead = cbToRead);
124
125	RTSgBufAdvance(pSgBuf, cbThisRead);
126	cbTotalRead += cbThisRead;
127	cbToRead -= cbThisRead;
128	if (cbToRead == 0)
129	{
130	if (pcbRead)
131	*pcbRead = cbTotalRead;
132	return VINF_SUCCESS;
133	}
134
135	if ( pcbRead
136	&& ( cSegsLeft <= UIO_MAXIOV
137	\|\| cbThisRead == 0 /* typically EOF */ ))
138	{
139	*pcbRead = cbTotalRead;
140	return VINF_SUCCESS;
141	}
142	if (cbThisRead == 0)
143	return VERR_EOF;
144
145	off += cbThisRead;
146	}
147	else if (cbTotalRead > 0 && pcbRead)
148	{
149	*pcbRead = cbTotalRead;
150	return VINF_SUCCESS;
151	}
152	else
153	return RTErrConvertFromErrno(errno);
154	}
155
156	/*
157	* Unaligned start or not reading the whole buffer. For reasons of
158	* simplicity, we work the input segment by segment like the generic code.
159	*/
160	int rc = VINF_SUCCESS;
161	while (cbToRead > 0)
162	{
163	size_t cbSeg;
164	void *pvSeg = RTSgBufGetCurrentSegment(pSgBuf, cbToRead, &cbSeg);
165	size_t cbThisRead = cbSeg;
166	rc = RTFileReadAt(hFile, off, pvSeg, cbSeg, pcbRead ? &cbThisRead : NULL);
167	if (RT_SUCCESS(rc))
168	{
169	RTSgBufAdvance(pSgBuf, cbThisRead);
170	cbTotalRead += cbThisRead;
171	}
172	else
173	break;
174	if ((size_t)cbThisRead < cbSeg)
175	{
176	AssertStmt(pcbRead, rc = VERR_INTERNAL_ERROR_2);
177	break;
178	}
179
180	Assert(cbSeg == cbThisRead);
181	cbToRead -= cbSeg;
182	off += cbSeg;
183	}
184	if (pcbRead)
185	*pcbRead = cbTotalRead;
186	return rc;
187	}
188
189
190	RTDECL(int) RTFileSgWriteAt(RTFILE hFile, RTFOFF off, PRTSGBUF pSgBuf, size_t cbToWrite, size_t *pcbWritten)
191	{
192	/*
193	* Make sure we set pcbWritten.
194	*/
195	if (pcbWritten)
196	*pcbWritten = 0;
197
198	/*
199	* Special case: Zero write == seek.
200	*/
201	if (cbToWrite == 0)
202	return RTFileSeek(hFile, off, RTFILE_SEEK_BEGIN, NULL);
203
204	/*
205	* We can use the segment array directly if we're at the start of the
206	* current S/G segment and cbToWrite matches the remainder exactly.
207	*/
208	size_t cbTotalWritten = 0;
209
210	size_t const cbSgBufLeft = RTSgBufCalcLengthLeft(pSgBuf);
211	AssertMsgReturn(cbSgBufLeft >= cbToWrite, ("%#zx vs %#zx\n", cbSgBufLeft, cbToWrite), VERR_INVALID_PARAMETER);
212
213	if (cbToWrite == cbSgBufLeft)
214	while (RTSgBufIsAtStartOfSegment(pSgBuf))
215	{
216	size_t const cSegsLeft = pSgBuf->cSegs - pSgBuf->idxSeg;
217	ssize_t cbThisWritten = pwritev(RTFileToNative(hFile), (const struct iovec *)&pSgBuf->paSegs[pSgBuf->idxSeg],
218	RT_MIN(cSegsLeft, UIO_MAXIOV), off);
219	if (cbThisWritten >= 0)
220	{
221	AssertStmt((size_t)cbThisWritten <= cbToWrite, cbThisWritten = cbToWrite);
222
223	RTSgBufAdvance(pSgBuf, cbThisWritten);
224	cbTotalWritten += cbThisWritten;
225	cbToWrite -= cbThisWritten;
226	if (cbToWrite == 0)
227	{
228	if (pcbWritten)
229	*pcbWritten = cbTotalWritten;
230	return VINF_SUCCESS;
231	}
232
233	if ( pcbWritten
234	&& ( cSegsLeft <= UIO_MAXIOV
235	\|\| cbThisWritten == 0 /* non-file, full buffer/whatever */ ))
236	{
237	*pcbWritten = cbTotalWritten;
238	return VINF_SUCCESS;
239	}
240	if (cbThisWritten == 0)
241	return VERR_TRY_AGAIN;
242
243	off += cbThisWritten;
244	}
245	else if (cbTotalWritten > 0 && pcbWritten)
246	{
247	*pcbWritten = cbTotalWritten;
248	return VINF_SUCCESS;
249	}
250	else
251	return RTErrConvertFromErrno(errno);
252	}
253
254	/*
255	* Unaligned start or not writing the whole buffer. For reasons of
256	* simplicity, we work the input segment by segment like the generic code.
257	*/
258	int rc = VINF_SUCCESS;
259	while (cbToWrite > 0)
260	{
261	size_t cbSeg;
262	void *pvSeg = RTSgBufGetCurrentSegment(pSgBuf, cbToWrite, &cbSeg);
263	size_t cbThisWritten = cbSeg;
264	rc = RTFileWriteAt(hFile, off, pvSeg, cbSeg, pcbWritten ? &cbThisWritten : NULL);
265	if (RT_SUCCESS(rc))
266	{
267	RTSgBufAdvance(pSgBuf, cbThisWritten);
268	cbTotalWritten += cbThisWritten;
269	}
270	else
271	break;
272	if ((size_t)cbThisWritten < cbSeg)
273	{
274	AssertStmt(pcbWritten, rc = VERR_INTERNAL_ERROR_2);
275	break;
276	}
277
278	Assert(cbSeg == cbThisWritten);
279	cbToWrite -= cbSeg;
280	off += cbSeg;
281	}
282	if (pcbWritten)
283	*pcbWritten = cbTotalWritten;
284	return rc;
285	}
286
287	#endif /* HAVE_PREADV_AND_PWRITEV */
288

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source: vbox/trunk/src/VBox/Runtime/r3/posix/fileio-sg-at-posix.cpp@ 77635

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