sysfs.cpp revision 0d7011109d3d6a3608cd2e3e2d4f80bf537501b9
/* $Id$ */
/** @file
* IPRT - Linux sysfs access.
*/
/*
* Copyright (C) 2006-2008 Sun Microsystems, Inc.
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE 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.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 USA or visit http://www.sun.com if you need
* additional information or have any questions.
*/
/*******************************************************************************
* Header Files *
*******************************************************************************/
#define LOG_GROUP RTLOGGROUP_SYSTEM
#include <iprt/linux/sysfs.h>
#include <iprt/assert.h>
#include <iprt/param.h>
#include <iprt/path.h>
#include <iprt/string.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/sysctl.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <errno.h>
/**
* Constructs the path of a sysfs file from the format paramaters passed,
* prepending "/sys/" if the path is relative.
*
* @returns The number of characters returned, or -1 and errno set to ERANGE on
* failure.
*
* @param pszBuf Where to write the path. Must be at least
* sizeof("/sys/") characters long
* @param cchBuf The size of the buffer pointed to by @a pszBuf.
* @param pszFormat The name format, either absolute or relative to "/sys/".
* @param va The format args.
*/
static ssize_t rtLinuxSysFsConstructPath(char *pszBuf, size_t cchBuf, const char *pszFormat, va_list va)
{
static const char s_szPrefix[] = "/sys/";
AssertReturnStmt(cchBuf > sizeof(s_szPrefix), errno = ERANGE, -1);
size_t cch = RTStrPrintfV(pszBuf, cchBuf, pszFormat, va);
if (*pszBuf != '/')
{
AssertReturnStmt(cchBuf >= cch + sizeof(s_szPrefix), errno = ERANGE, -1);
memmove(pszBuf + sizeof(s_szPrefix) - 1, pszBuf, cch + 1);
memcpy(pszBuf, s_szPrefix, sizeof(s_szPrefix) - 1);
cch += sizeof(s_szPrefix) - 1;
}
return cch;
}
RTDECL(bool) RTLinuxSysFsExistsV(const char *pszFormat, va_list va)
{
int iSavedErrno = errno;
/*
* Construct the filename and call stat.
*/
bool fRet = false;
char szFilename[RTPATH_MAX];
ssize_t rc = rtLinuxSysFsConstructPath(szFilename, sizeof(szFilename), pszFormat, va);
if (rc != -1)
{
struct stat st;
fRet = stat(szFilename, &st) == 0;
}
errno = iSavedErrno;
return fRet;
}
RTDECL(bool) RTLinuxSysFsExists(const char *pszFormat, ...)
{
va_list va;
va_start(va, pszFormat);
bool fRet = RTLinuxSysFsExistsV(pszFormat, va);
va_end(va);
return fRet;
}
RTDECL(int) RTLinuxSysFsOpenV(const char *pszFormat, va_list va)
{
/*
* Construct the filename and call open.
*/
char szFilename[RTPATH_MAX];
ssize_t rc = rtLinuxSysFsConstructPath(szFilename, sizeof(szFilename), pszFormat, va);
if (rc != -1)
rc = open(szFilename, O_RDONLY, 0);
return rc;
}
RTDECL(int) RTLinuxSysFsOpen(const char *pszFormat, ...)
{
va_list va;
va_start(va, pszFormat);
int fd = RTLinuxSysFsOpenV(pszFormat, va);
va_end(va);
return fd;
}
RTDECL(void) RTLinuxSysFsClose(int fd)
{
int iSavedErrno = errno;
close(fd);
errno = iSavedErrno;
}
RTDECL(ssize_t) RTLinuxSysFsReadStr(int fd, char *pszBuf, size_t cchBuf)
{
Assert(cchBuf > 1);
ssize_t cchRead = read(fd, pszBuf, cchBuf - 1);
pszBuf[cchRead >= 0 ? cchRead : 0] = '\0';
return cchRead;
}
RTDECL(int64_t) RTLinuxSysFsReadIntFileV(unsigned uBase, const char *pszFormat, va_list va)
{
int fd = RTLinuxSysFsOpenV(pszFormat, va);
if (fd == -1)
return -1;
int64_t i64Ret = -1;
char szNum[128];
ssize_t cchNum = RTLinuxSysFsReadStr(fd, szNum, sizeof(szNum));
if (cchNum > 0)
{
int rc = RTStrToInt64Ex(szNum, NULL, uBase, &i64Ret);
if (RT_FAILURE(rc))
{
i64Ret = -1;
errno = -ETXTBSY; /* just something that won't happen at read / open. */
}
}
else if (cchNum == 0)
errno = -ETXTBSY; /* just something that won't happen at read / open. */
RTLinuxSysFsClose(fd);
return i64Ret;
}
RTDECL(int64_t) RTLinuxSysFsReadIntFile(unsigned uBase, const char *pszFormat, ...)
{
va_list va;
va_start(va, pszFormat);
int64_t i64Ret = RTLinuxSysFsReadIntFileV(uBase, pszFormat, va);
va_end(va);
return i64Ret;
}
RTDECL(ssize_t) RTLinuxSysFsReadStrFileV(char *pszBuf, size_t cchBuf, const char *pszFormat, va_list va)
{
int fd = RTLinuxSysFsOpenV(pszFormat, va);
if (fd == -1)
return -1;
ssize_t cchRet = RTLinuxSysFsReadStr(fd, pszBuf, cchBuf);
RTLinuxSysFsClose(fd);
if (cchRet > 0)
{
char *pchNewLine = (char *)memchr(pszBuf, '\n', cchRet);
if (pchNewLine)
*pchNewLine = '\0';
}
return cchRet;
}
RTDECL(ssize_t) RTLinuxSysFsReadStrFile(char *pszBuf, size_t cchBuf, const char *pszFormat, ...)
{
va_list va;
va_start(va, pszFormat);
ssize_t cchRet = RTLinuxSysFsReadStrFileV(pszBuf, cchBuf, pszFormat, va);
va_end(va);
return cchRet;
}
RTDECL(ssize_t) RTLinuxSysFsGetLinkDestV(char *pszBuf, size_t cchBuf, const char *pszFormat, va_list va)
{
AssertReturnStmt(cchBuf >= 2, errno = EINVAL, -1);
/*
* Construct the filename and read the link.
*/
char szFilename[RTPATH_MAX];
int rc = rtLinuxSysFsConstructPath(szFilename, sizeof(szFilename), pszFormat, va);
if (rc == -1)
return -1;
char szLink[RTPATH_MAX];
rc = readlink(szFilename, szLink, sizeof(szLink));
if (rc == -1)
return -1;
if ((size_t)rc > sizeof(szLink) - 1)
{
errno = ERANGE;
return -1;
}
szLink[rc] = '\0'; /* readlink fun. */
/*
* Extract the file name component and copy it into the return buffer.
*/
size_t cchName;
const char *pszName = RTPathFilename(szLink);
if (pszName)
{
cchName = strlen(pszName);
if (cchName >= cchBuf)
{
errno = ERANGE;
return -1;
}
memcpy(pszBuf, pszName, cchName);
}
else
{
*pszBuf = '\0';
cchName = 0;
}
return cchName;
}
RTDECL(ssize_t) RTLinuxSysFsGetLinkDest(char *pszBuf, size_t cchBuf, const char *pszFormat, ...)
{
va_list va;
va_start(va, pszFormat);
int rc = RTLinuxSysFsGetLinkDestV(pszBuf, cchBuf, pszFormat, va);
va_end(va);
return rc;
}