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/*
* ismounted.c --- Check to see if the filesystem was mounted
*
* Copyright (C) 1995,1996,1997,1998,1999,2000,2008 Theodore Ts'o.
*
* This file may be redistributed under the terms of the GNU Public
* License.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <mntent.h>
#include <string.h>
#include <sys/stat.h>
#include <ctype.h>
#include "pathnames.h"
#include "ismounted.h"
/*
* ext2fs_check_if_mounted flags
*/
#define MF_MOUNTED 1
static char *skip_over_blank(char *cp)
{
while (*cp && isspace(*cp))
cp++;
return cp;
}
static char *skip_over_word(char *cp)
{
while (*cp && !isspace(*cp))
cp++;
return cp;
}
static char *parse_word(char **buf)
{
char *word, *next;
word = *buf;
if (*word == 0)
return 0;
word = skip_over_blank(word);
next = skip_over_word(word);
if (*next)
*next++ = 0;
*buf = next;
return word;
}
/*
* Helper function which checks a file in /etc/mtab format to see if a
* filesystem is mounted. Returns an error if the file doesn't exist
* or can't be opened.
*/
static int check_mntent_file(const char *mtab_file, const char *file,
int *mount_flags)
{
struct stat st_buf;
int retval = 0;
dev_t file_dev=0, file_rdev=0;
ino_t file_ino=0;
FILE *f;
char buf[1024], *device = 0, *mnt_dir = 0, *cp;
*mount_flags = 0;
if ((f = fopen(mtab_file, "r")) == NULL)
return errno;
if ((f = setmntent (mtab_file, "r")) == NULL)
return errno;
if (stat(file, &st_buf) == 0) {
if (S_ISBLK(st_buf.st_mode)) {
#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
file_rdev = st_buf.st_rdev;
#endif /* __GNU__ */
} else {
file_dev = st_buf.st_dev;
file_ino = st_buf.st_ino;
}
}
while (1) {
if (!fgets(buf, sizeof(buf), f)) {
device = mnt_dir = 0;
break;
}
buf[sizeof(buf)-1] = 0;
cp = buf;
device = parse_word(&cp);
if (!device || *device == '#')
return 0; /* Ignore blank lines and comments */
mnt_dir = parse_word(&cp);
if (device[0] != '/')
continue;
if (strcmp(file, device) == 0)
break;
if (stat(device, &st_buf) == 0) {
if (S_ISBLK(st_buf.st_mode)) {
#ifndef __GNU__
if (file_rdev && (file_rdev == st_buf.st_rdev))
break;
#endif /* __GNU__ */
} else {
if (file_dev && ((file_dev == st_buf.st_dev) &&
(file_ino == st_buf.st_ino)))
break;
}
}
}
if (mnt_dir == 0) {
#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
/*
* Do an extra check to see if this is the root device. We
* can't trust /etc/mtab, and /proc/mounts will only list
* /dev/root for the root filesystem. Argh. Instead we
* check if the given device has the same major/minor number
* as the device that the root directory is on.
*/
if (file_rdev && (stat("/", &st_buf) == 0) &&
(st_buf.st_dev == file_rdev))
*mount_flags = MF_MOUNTED;
#endif /* __GNU__ */
goto errout;
}
#ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
/* Validate the entry in case /etc/mtab is out of date */
/*
* We need to be paranoid, because some broken distributions
* (read: Slackware) don't initialize /etc/mtab before checking
* all of the non-root filesystems on the disk.
*/
if (stat(mnt_dir, &st_buf) < 0) {
retval = errno;
if (retval == ENOENT) {
#ifdef DEBUG
printf("Bogus entry in %s! (%s does not exist)\n",
mtab_file, mnt_dir);
#endif /* DEBUG */
retval = 0;
}
goto errout;
}
if (file_rdev && (st_buf.st_dev != file_rdev)) {
#ifdef DEBUG
printf("Bogus entry in %s! (%s not mounted on %s)\n",
mtab_file, file, mnt_dir);
#endif /* DEBUG */
goto errout;
}
#endif /* __GNU__ */
*mount_flags = MF_MOUNTED;
retval = 0;
errout:
endmntent (f);
return retval;
}
int is_mounted(const char *file)
{
int retval;
int mount_flags = 0;
#ifdef __linux__
retval = check_mntent_file(_PATH_PROC_MOUNTS, file, &mount_flags);
if (retval)
return 0;
if (mount_flags)
return 1;
#endif /* __linux__ */
retval = check_mntent_file(_PATH_MOUNTED, file, &mount_flags);
if (retval)
return 0;
return mount_flags;
}
#ifdef TEST_PROGRAM
int main(int argc, char **argv)
{
if (argc < 2) {
fprintf(stderr, "Usage: %s device\n", argv[0]);
return EXIT_FAILURE;
}
if (is_mounted(argv[1])) {
printf("mounted\n");
return EXIT_SUCCESS;
}
printf("not mounted\n");
return EXIT_FAILURE;
}
#endif /* DEBUG */
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