sysfs.cpp@ 31453

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1	/* $Id: sysfs.cpp 28800 2010-04-27 08:22:32Z vboxsync $ */
2	/** @file
3	* IPRT - Linux sysfs access.
4	*/
5
6	/*
7	* Copyright (C) 2006-2008 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	#define LOG_GROUP RTLOGGROUP_SYSTEM
32	#include <iprt/linux/sysfs.h>
33	#include <iprt/assert.h>
34	#include <iprt/dir.h>
35	#include <iprt/err.h>
36	#include <iprt/fs.h>
37	#include <iprt/param.h>
38	#include <iprt/path.h>
39	#include <iprt/string.h>
40
41	#include <unistd.h>
42	#include <stdio.h>
43	#include <sys/sysctl.h>
44	#include <sys/stat.h>
45	#include <sys/fcntl.h>
46	#include <errno.h>
47
48	/** @todo r=bird: This whole API should be rewritten to use IPRT status codes.
49	* using errno was a mistake and only results in horrible code. */
50
51
52	/**
53	* Constructs the path of a sysfs file from the format paramaters passed,
54	* prepending a prefix if the path is relative.
55	*
56	* @returns The number of characters returned, or -1 and errno set to ERANGE on
57	* failure.
58	*
59	* @param pszPrefix The prefix to prepend if the path is relative. Must end
60	* in '/'.
61	* @param pszBuf Where to write the path. Must be at least
62	* sizeof(@a pszPrefix) characters long
63	* @param cchBuf The size of the buffer pointed to by @a pszBuf.
64	* @param pszFormat The name format, either absolute or relative to the
65	* prefix specified by @a pszPrefix.
66	* @param va The format args.
67	*/
68	static ssize_t rtLinuxConstructPathV(char *pszBuf, size_t cchBuf,
69	const char *pszPrefix,
70	const char *pszFormat, va_list va)
71	{
72	size_t cchPrefix = strlen(pszPrefix);
73	AssertReturnStmt(pszPrefix[cchPrefix - 1] == '/', errno = ERANGE, -1);
74	AssertReturnStmt(cchBuf > cchPrefix + 1, errno = ERANGE, -1);
75
76	/** @todo While RTStrPrintfV prevents overflows, it doesn't make it easy to
77	* check for truncations. RTPath should provide some formatters and
78	* joiners which can take over this rather common task that is
79	* performed here. */
80	size_t cch = RTStrPrintfV(pszBuf, cchBuf, pszFormat, va);
81	if (*pszBuf != '/')
82	{
83	AssertReturnStmt(cchBuf >= cch + cchPrefix + 1, errno = ERANGE, -1);
84	memmove(pszBuf + cchPrefix, pszBuf, cch + 1);
85	memcpy(pszBuf, pszPrefix, cchPrefix);
86	cch += cchPrefix;
87	}
88	return cch;
89	}
90
91
92	/**
93	* Constructs the path of a sysfs file from the format paramaters passed,
94	* prepending a prefix if the path is relative.
95	*
96	* @returns The number of characters returned, or -1 and errno set to ERANGE on
97	* failure.
98	*
99	* @param pszPrefix The prefix to prepend if the path is relative. Must end
100	* in '/'.
101	* @param pszBuf Where to write the path. Must be at least
102	* sizeof(@a pszPrefix) characters long
103	* @param cchBuf The size of the buffer pointed to by @a pszBuf.
104	* @param pszFormat The name format, either absolute or relative to "/sys/".
105	* @param ... The format args.
106	*/
107	static ssize_t rtLinuxConstructPath(char *pszBuf, size_t cchBuf,
108	const char *pszPrefix,
109	const char *pszFormat, ...)
110	{
111	va_list va;
112	va_start(va, pszFormat);
113	int rc = rtLinuxConstructPathV(pszBuf, cchBuf, pszPrefix, pszFormat, va);
114	va_end(va);
115	return rc;
116	}
117
118
119	/**
120	* Constructs the path of a sysfs file from the format paramaters passed,
121	* prepending "/sys/" if the path is relative.
122	*
123	* @returns The number of characters returned, or -1 and errno set to ERANGE on
124	* failure.
125	*
126	* @param pszBuf Where to write the path. Must be at least
127	* sizeof("/sys/") characters long
128	* @param cchBuf The size of the buffer pointed to by @a pszBuf.
129	* @param pszFormat The name format, either absolute or relative to "/sys/".
130	* @param va The format args.
131	*/
132	static ssize_t rtLinuxSysFsConstructPath(char pszBuf, size_t cchBuf, const char pszFormat, va_list va)
133	{
134	return rtLinuxConstructPathV(pszBuf, cchBuf, "/sys/", pszFormat, va);
135	}
136
137
138	RTDECL(bool) RTLinuxSysFsExistsV(const char *pszFormat, va_list va)
139	{
140	int iSavedErrno = errno;
141
142	/*
143	* Construct the filename and call stat.
144	*/
145	bool fRet = false;
146	char szFilename[RTPATH_MAX];
147	ssize_t rc = rtLinuxSysFsConstructPath(szFilename, sizeof(szFilename), pszFormat, va);
148	if (rc != -1)
149	{
150	struct stat st;
151	fRet = stat(szFilename, &st) == 0;
152	}
153
154	errno = iSavedErrno;
155	return fRet;
156	}
157
158
159	RTDECL(bool) RTLinuxSysFsExists(const char *pszFormat, ...)
160	{
161	va_list va;
162	va_start(va, pszFormat);
163	bool fRet = RTLinuxSysFsExistsV(pszFormat, va);
164	va_end(va);
165	return fRet;
166	}
167
168
169	RTDECL(int) RTLinuxSysFsOpenV(const char *pszFormat, va_list va)
170	{
171	/*
172	* Construct the filename and call open.
173	*/
174	char szFilename[RTPATH_MAX];
175	ssize_t rc = rtLinuxSysFsConstructPath(szFilename, sizeof(szFilename), pszFormat, va);
176	if (rc != -1)
177	rc = open(szFilename, O_RDONLY, 0);
178	return rc;
179	}
180
181
182	RTDECL(int) RTLinuxSysFsOpen(const char *pszFormat, ...)
183	{
184	va_list va;
185	va_start(va, pszFormat);
186	int fd = RTLinuxSysFsOpenV(pszFormat, va);
187	va_end(va);
188	return fd;
189	}
190
191
192	RTDECL(void) RTLinuxSysFsClose(int fd)
193	{
194	int iSavedErrno = errno;
195	close(fd);
196	errno = iSavedErrno;
197	}
198
199
200	RTDECL(ssize_t) RTLinuxSysFsReadStr(int fd, char *pszBuf, size_t cchBuf)
201	{
202	Assert(cchBuf > 1);
203	ssize_t cchRead = read(fd, pszBuf, cchBuf - 1);
204	pszBuf[cchRead >= 0 ? cchRead : 0] = '\0';
205	return cchRead;
206	}
207
208
209	RTDECL(int) RTLinuxSysFsReadFile(int fd, void pvBuf, size_t cbBuf, size_t pcbRead)
210	{
211	int rc;
212	ssize_t cbRead = read(fd, pvBuf, cbBuf);
213	if (cbRead >= 0)
214	{
215	if (pcbRead)
216	*pcbRead = cbRead;
217	if ((size_t)cbRead < cbBuf)
218	rc = VINF_SUCCESS;
219	else
220	{
221	/* Check for EOF */
222	char ch;
223	off_t off = lseek(fd, 0, SEEK_CUR);
224	ssize_t cbRead2 = read(fd, &ch, 1);
225	if (cbRead2 == 0)
226	rc = VINF_SUCCESS;
227	else if (cbRead2 > 0)
228	{
229	lseek(fd, off, SEEK_SET);
230	rc = VERR_BUFFER_OVERFLOW;
231	}
232	else
233	rc = RTErrConvertFromErrno(errno);
234	}
235	}
236	else
237	rc = RTErrConvertFromErrno(errno);
238	return rc;
239	}
240
241
242	RTDECL(int64_t) RTLinuxSysFsReadIntFileV(unsigned uBase, const char *pszFormat, va_list va)
243	{
244	int fd = RTLinuxSysFsOpenV(pszFormat, va);
245	if (fd == -1)
246	return -1;
247
248	int64_t i64Ret = -1;
249	char szNum[128];
250	ssize_t cchNum = RTLinuxSysFsReadStr(fd, szNum, sizeof(szNum));
251	if (cchNum > 0)
252	{
253	int rc = RTStrToInt64Ex(szNum, NULL, uBase, &i64Ret);
254	if (RT_FAILURE(rc))
255	{
256	i64Ret = -1;
257	errno = -ETXTBSY; /* just something that won't happen at read / open. */
258	}
259	}
260	else if (cchNum == 0)
261	errno = -ETXTBSY; /* just something that won't happen at read / open. */
262
263	RTLinuxSysFsClose(fd);
264	return i64Ret;
265	}
266
267
268	RTDECL(int64_t) RTLinuxSysFsReadIntFile(unsigned uBase, const char *pszFormat, ...)
269	{
270	va_list va;
271	va_start(va, pszFormat);
272	int64_t i64Ret = RTLinuxSysFsReadIntFileV(uBase, pszFormat, va);
273	va_end(va);
274	return i64Ret;
275	}
276
277
278	RTDECL(dev_t) RTLinuxSysFsReadDevNumFileV(const char *pszFormat, va_list va)
279	{
280	int fd = RTLinuxSysFsOpenV(pszFormat, va);
281	if (fd == -1)
282	return 0;
283
284	dev_t DevNum = 0;
285	char szNum[128];
286	ssize_t cchNum = RTLinuxSysFsReadStr(fd, szNum, sizeof(szNum));
287	if (cchNum > 0)
288	{
289	uint32_t u32Maj = 0;
290	uint32_t u32Min = 0;
291	char *pszNext = NULL;
292	int rc = RTStrToUInt32Ex(szNum, &pszNext, 10, &u32Maj);
293	if (RT_FAILURE(rc) \|\| (rc != VWRN_TRAILING_CHARS) \|\| (*pszNext != ':'))
294	errno = EINVAL;
295	else
296	{
297	rc = RTStrToUInt32Ex(pszNext + 1, NULL, 10, &u32Min);
298	if ( rc != VINF_SUCCESS
299	&& rc != VWRN_TRAILING_CHARS
300	&& rc != VWRN_TRAILING_SPACES)
301	errno = EINVAL;
302	else
303	{
304	errno = 0;
305	DevNum = makedev(u32Maj, u32Min);
306	}
307	}
308	}
309	else if (cchNum == 0)
310	errno = EINVAL;
311
312	RTLinuxSysFsClose(fd);
313	return DevNum;
314	}
315
316
317	RTDECL(dev_t) RTLinuxSysFsReadDevNumFile(const char *pszFormat, ...)
318	{
319	va_list va;
320	va_start(va, pszFormat);
321	dev_t DevNum = RTLinuxSysFsReadDevNumFileV(pszFormat, va);
322	va_end(va);
323	return DevNum;
324	}
325
326
327	RTDECL(ssize_t) RTLinuxSysFsReadStrFileV(char pszBuf, size_t cchBuf, const char pszFormat, va_list va)
328	{
329	int fd = RTLinuxSysFsOpenV(pszFormat, va);
330	if (fd == -1)
331	return -1;
332
333	ssize_t cchRet = RTLinuxSysFsReadStr(fd, pszBuf, cchBuf);
334	RTLinuxSysFsClose(fd);
335	if (cchRet > 0)
336	{
337	char pchNewLine = (char )memchr(pszBuf, '\n', cchRet);
338	if (pchNewLine)
339	*pchNewLine = '\0';
340	}
341	return cchRet;
342	}
343
344
345	RTDECL(ssize_t) RTLinuxSysFsReadStrFile(char pszBuf, size_t cchBuf, const char pszFormat, ...)
346	{
347	va_list va;
348	va_start(va, pszFormat);
349	ssize_t cchRet = RTLinuxSysFsReadStrFileV(pszBuf, cchBuf, pszFormat, va);
350	va_end(va);
351	return cchRet;
352	}
353
354
355	RTDECL(ssize_t) RTLinuxSysFsGetLinkDestV(char pszBuf, size_t cchBuf, const char pszFormat, va_list va)
356	{
357	AssertReturnStmt(cchBuf >= 2, errno = EINVAL, -1);
358
359	/*
360	* Construct the filename and read the link.
361	*/
362	char szFilename[RTPATH_MAX];
363	int rc = rtLinuxSysFsConstructPath(szFilename, sizeof(szFilename), pszFormat, va);
364	if (rc == -1)
365	return -1;
366
367	char szLink[RTPATH_MAX];
368	rc = readlink(szFilename, szLink, sizeof(szLink));
369	if (rc == -1)
370	return -1;
371	if ((size_t)rc > sizeof(szLink) - 1)
372	{
373	errno = ERANGE;
374	return -1;
375	}
376	szLink[rc] = '\0'; /* readlink fun. */
377
378	/*
379	* Extract the file name component and copy it into the return buffer.
380	*/
381	size_t cchName;
382	const char *pszName = RTPathFilename(szLink);
383	if (pszName)
384	{
385	cchName = strlen(pszName); /* = &szLink[rc] - pszName; */
386	if (cchName >= cchBuf)
387	{
388	errno = ERANGE;
389	return -1;
390	}
391	memcpy(pszBuf, pszName, cchName + 1);
392	}
393	else
394	{
395	*pszBuf = '\0';
396	cchName = 0;
397	}
398	return cchName;
399	}
400
401
402	RTDECL(ssize_t) RTLinuxSysFsGetLinkDest(char pszBuf, size_t cchBuf, const char pszFormat, ...)
403	{
404	va_list va;
405	va_start(va, pszFormat);
406	int rc = RTLinuxSysFsGetLinkDestV(pszBuf, cchBuf, pszFormat, va);
407	va_end(va);
408	return rc;
409	}
410
411
412	static ssize_t rtLinuxFindDevicePathRecursive(dev_t DevNum, RTFMODE fMode, const char *pszBasePath,
413	char *pszBuf, size_t cchBuf)
414	{
415	/*
416	* Check assumptions made by the code below.
417	*/
418	size_t const cchBasePath = strlen(pszBasePath);
419	AssertReturnStmt(cchBasePath < RTPATH_MAX - 10U, errno = ENAMETOOLONG, -1);
420
421	ssize_t rcRet;
422	PRTDIR pDir;
423	int rc = RTDirOpen(&pDir, pszBasePath);
424	if (RT_SUCCESS(rc))
425	{
426	char szPath[RTPATH_MAX]; /** @todo 4K per recursion - can easily be optimized away by passing it along pszBasePath
427	and only remember the length. */
428	memcpy(szPath, pszBasePath, cchBasePath + 1);
429
430	for (;;)
431	{
432	RTDIRENTRYEX Entry;
433	rc = RTDirReadEx(pDir, &Entry, NULL, RTFSOBJATTRADD_UNIX, RTPATH_F_ON_LINK);
434	if (RT_FAILURE(rc))
435	{
436	errno = rc == VERR_NO_MORE_FILES
437	? ENOENT
438	: rc == VERR_BUFFER_OVERFLOW
439	? EOVERFLOW
440	: EIO;
441	rcRet = -1;
442	break;
443	}
444	if (RTFS_IS_SYMLINK(Entry.Info.Attr.fMode))
445	continue;
446
447	/* Do the matching. */
448	if ( Entry.Info.Attr.u.Unix.Device == DevNum
449	&& (Entry.Info.Attr.fMode & RTFS_TYPE_MASK) == fMode)
450	{
451	rcRet = rtLinuxConstructPath(pszBuf, cchBuf, pszBasePath, "%s", Entry.szName);
452	break;
453	}
454
455	/* Recurse into subdirectories. */
456	if (!RTFS_IS_DIRECTORY(Entry.Info.Attr.fMode))
457	continue;
458	if (Entry.szName[0] == '.')
459	continue;
460
461	szPath[cchBasePath] = '\0';
462	rc = RTPathAppend(szPath, sizeof(szPath) - 1, Entry.szName); /* -1: for slash */
463	if (RT_FAILURE(rc))
464	{
465	errno = ENAMETOOLONG;
466	rcRet = -1;
467	break;
468	}
469	strcat(&szPath[cchBasePath], "/");
470	rcRet = rtLinuxFindDevicePathRecursive(DevNum, fMode, szPath, pszBuf, cchBuf);
471	if (rcRet >= 0 \|\| errno != ENOENT)
472	break;
473	}
474	RTDirClose(pDir);
475	}
476	else
477	{
478	rcRet = -1;
479	errno = RTErrConvertToErrno(rc);
480	}
481	return rcRet;
482	}
483
484
485	RTDECL(ssize_t) RTLinuxFindDevicePathV(dev_t DevNum, RTFMODE fMode, char *pszBuf, size_t cchBuf,
486	const char *pszSuggestion, va_list va)
487	{
488	AssertReturnStmt(cchBuf >= 2, errno = EINVAL, -1);
489	AssertReturnStmt( fMode == RTFS_TYPE_DEV_CHAR
490	\|\| fMode == RTFS_TYPE_DEV_BLOCK,
491	errno = EINVAL, -1);
492
493	if (pszSuggestion)
494	{
495	/*
496	* Construct the filename and read the link.
497	*/
498	char szFilename[RTPATH_MAX];
499	int rc = rtLinuxConstructPathV(szFilename, sizeof(szFilename), "/dev/", pszSuggestion, va);
500	if (rc == -1)
501	return -1;
502
503	/*
504	* Check whether the caller's suggestion was right.
505	*/
506	RTFSOBJINFO Info;
507	rc = RTPathQueryInfo(szFilename, &Info, RTFSOBJATTRADD_UNIX);
508	if ( RT_SUCCESS(rc)
509	&& Info.Attr.u.Unix.Device == DevNum
510	&& (Info.Attr.fMode & RTFS_TYPE_MASK) == fMode)
511	{
512	size_t cchPath = strlen(szFilename);
513	if (cchPath >= cchBuf)
514	{
515	errno = EOVERFLOW;
516	return -1;
517	}
518	memcpy(pszBuf, szFilename, cchPath + 1);
519	return cchPath;
520	}
521
522	/* The suggestion was wrong, fall back on the brute force attack. */
523	}
524
525	return rtLinuxFindDevicePathRecursive(DevNum, fMode, "/dev/", pszBuf, cchBuf);
526	}
527
528
529	RTDECL(ssize_t) RTLinuxFindDevicePath(dev_t DevNum, RTFMODE fMode, char *pszBuf, size_t cchBuf,
530	const char *pszSuggestion, ...)
531	{
532	va_list va;
533	va_start(va, pszSuggestion);
534	int rc = RTLinuxFindDevicePathV(DevNum, fMode, pszBuf, cchBuf, pszSuggestion, va);
535	va_end(va);
536	return rc;
537	}
538

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