diff options
Diffstat (limited to 'src/utils/lib/ismounted.c')
| -rw-r--r-- | src/utils/lib/ismounted.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/src/utils/lib/ismounted.c b/src/utils/lib/ismounted.c new file mode 100644 index 0000000..9a20b23 --- /dev/null +++ b/src/utils/lib/ismounted.c @@ -0,0 +1,396 @@ +/* + * 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> +#ifdef HAVE_MNTENT_H +#include <mntent.h> +#endif +#include <string.h> +#include <sys/stat.h> +#include <ctype.h> +#include <sys/param.h> + +#ifndef __linux__ +# ifdef HAVE_SYS_UCRED_H +# include <sys/ucred.h> +# endif +# ifdef HAVE_SYS_MOUNT_H +# include <sys/mount.h> +# endif +#endif + +#include "pathnames.h" +#include "strutils.h" +#include "ismounted.h" +#include "c.h" +#ifdef __linux__ +# include "loopdev.h" +#endif + + + +#ifdef HAVE_MNTENT_H +/* + * 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, char *mtpt, int mtlen) +{ + struct mntent *mnt; + struct stat st_buf; + int retval = 0; + dev_t file_dev=0, file_rdev=0; + ino_t file_ino=0; + FILE *f; + int fd; + + *mount_flags = 0; + 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 ((mnt = getmntent (f)) != NULL) { + if (mnt->mnt_fsname[0] != '/') + continue; + if (strcmp(file, mnt->mnt_fsname) == 0) + break; + if (stat(mnt->mnt_fsname, &st_buf) != 0) + continue; + + if (S_ISBLK(st_buf.st_mode)) { +#ifndef __GNU__ + if (file_rdev && file_rdev == st_buf.st_rdev) + break; +#ifdef __linux__ + /* maybe the file is loopdev backing file */ + if (file_dev + && major(st_buf.st_rdev) == LOOPDEV_MAJOR + && loopdev_is_used(mnt->mnt_fsname, file, 0, 0, 0)) + break; +#endif /* __linux__ */ +#endif /* __GNU__ */ + } else { + if (file_dev && ((file_dev == st_buf.st_dev) && + (file_ino == st_buf.st_ino))) + break; + } + } + + if (mnt == NULL) { +#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; + if (mtpt) + xstrncpy(mtpt, "/", mtlen); + goto is_root; + } +#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->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->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->mnt_dir); +#endif /* DEBUG */ + goto errout; + } +#endif /* __GNU__ */ + *mount_flags = MF_MOUNTED; + +#ifdef MNTOPT_RO + /* Check to see if the ro option is set */ + if (hasmntopt(mnt, MNTOPT_RO)) + *mount_flags |= MF_READONLY; +#endif + + if (mtpt) + xstrncpy(mtpt, mnt->mnt_dir, mtlen); + /* + * Check to see if we're referring to the root filesystem. + * If so, do a manual check to see if we can open /etc/mtab + * read/write, since if the root is mounted read/only, the + * contents of /etc/mtab may not be accurate. + */ + if (!strcmp(mnt->mnt_dir, "/")) { +is_root: +#define TEST_FILE "/.ismount-test-file" + *mount_flags |= MF_ISROOT; + fd = open(TEST_FILE, O_RDWR|O_CREAT|O_CLOEXEC, 0600); + if (fd < 0) { + if (errno == EROFS) + *mount_flags |= MF_READONLY; + } else + close(fd); + (void) unlink(TEST_FILE); + } + retval = 0; +errout: + endmntent (f); + return retval; +} + +static int check_mntent(const char *file, int *mount_flags, + char *mtpt, int mtlen) +{ + int retval; + +#ifdef DEBUG + retval = check_mntent_file("/tmp/mtab", file, mount_flags, + mtpt, mtlen); + if (retval == 0) + return 0; +#endif /* DEBUG */ +#ifdef __linux__ + retval = check_mntent_file("/proc/mounts", file, mount_flags, + mtpt, mtlen); + if (retval == 0 && (*mount_flags != 0)) + return 0; + if (access("/proc/mounts", R_OK) == 0) { + *mount_flags = 0; + return retval; + } +#endif /* __linux__ */ +#if defined(MOUNTED) || defined(_PATH_MOUNTED) +#ifndef MOUNTED +#define MOUNTED _PATH_MOUNTED +#endif /* MOUNTED */ + retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen); + return retval; +#else + *mount_flags = 0; + return 0; +#endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */ +} + +#else +#if defined(HAVE_GETMNTINFO) + +static int check_getmntinfo(const char *file, int *mount_flags, + char *mtpt, int mtlen) +{ + struct statfs *mp; + int len, n; + const char *s1; + char *s2; + + n = getmntinfo(&mp, MNT_NOWAIT); + if (n == 0) + return errno; + + len = sizeof(_PATH_DEV) - 1; + s1 = file; + if (strncmp(_PATH_DEV, s1, len) == 0) + s1 += len; + + *mount_flags = 0; + while (--n >= 0) { + s2 = mp->f_mntfromname; + if (strncmp(_PATH_DEV, s2, len) == 0) { + s2 += len - 1; + *s2 = 'r'; + } + if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) { + *mount_flags = MF_MOUNTED; + break; + } + ++mp; + } + if (mtpt) + xstrncpy(mtpt, mp->f_mntonname, mtlen); + return 0; +} +#endif /* HAVE_GETMNTINFO */ +#endif /* HAVE_MNTENT_H */ + +/* + * Check to see if we're dealing with the swap device. + */ +static int is_swap_device(const char *file) +{ + FILE *f; + char buf[1024], *cp; + dev_t file_dev; + struct stat st_buf; + int ret = 0; + + file_dev = 0; +#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ + if ((stat(file, &st_buf) == 0) && + S_ISBLK(st_buf.st_mode)) + file_dev = st_buf.st_rdev; +#endif /* __GNU__ */ + + if (!(f = fopen("/proc/swaps", "r" UL_CLOEXECSTR))) + return 0; + /* Skip the first line */ + if (!fgets(buf, sizeof(buf), f)) + goto leave; + if (*buf && strncmp(buf, "Filename\t", 9) != 0) + /* Linux <=2.6.19 contained a bug in the /proc/swaps + * code where the header would not be displayed + */ + goto valid_first_line; + + while (fgets(buf, sizeof(buf), f)) { +valid_first_line: + if ((cp = strchr(buf, ' ')) != NULL) + *cp = 0; + if ((cp = strchr(buf, '\t')) != NULL) + *cp = 0; + if (strcmp(buf, file) == 0) { + ret++; + break; + } +#ifndef __GNU__ + if (file_dev && (stat(buf, &st_buf) == 0) && + S_ISBLK(st_buf.st_mode) && + file_dev == st_buf.st_rdev) { + ret++; + break; + } +#endif /* __GNU__ */ + } + +leave: + fclose(f); + return ret; +} + + +/* + * check_mount_point() fills determines if the device is mounted or otherwise + * busy, and fills in mount_flags with one or more of the following flags: + * MF_MOUNTED, MF_ISROOT, MF_READONLY, MF_SWAP, and MF_BUSY. If mtpt is + * non-NULL, the directory where the device is mounted is copied to where mtpt + * is pointing, up to mtlen characters. + */ +#ifdef __TURBOC__ + #pragma argsused +#endif +int check_mount_point(const char *device, int *mount_flags, + char *mtpt, int mtlen) +{ + int retval = 0; + + if (is_swap_device(device)) { + *mount_flags = MF_MOUNTED | MF_SWAP; + if (mtpt && mtlen) + xstrncpy(mtpt, "[SWAP]", mtlen); + } else { +#ifdef HAVE_MNTENT_H + retval = check_mntent(device, mount_flags, mtpt, mtlen); +#else +#ifdef HAVE_GETMNTINFO + retval = check_getmntinfo(device, mount_flags, mtpt, mtlen); +#else +#ifdef __GNUC__ + #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!" +#endif + *mount_flags = 0; +#endif /* HAVE_GETMNTINFO */ +#endif /* HAVE_MNTENT_H */ + } + if (retval) + return retval; + +#ifdef __linux__ /* This only works on Linux 2.6+ systems */ + { + struct stat st_buf; + int fd; + if ((stat(device, &st_buf) != 0) || + !S_ISBLK(st_buf.st_mode)) + return 0; + fd = open(device, O_RDONLY|O_EXCL|O_CLOEXEC); + if (fd < 0) { + if (errno == EBUSY) + *mount_flags |= MF_BUSY; + } else + close(fd); + } +#endif + + return 0; +} + +int is_mounted(const char *file) +{ + int retval; + int mount_flags = 0; + + retval = check_mount_point(file, &mount_flags, NULL, 0); + if (retval) + return 0; + return mount_flags & MF_MOUNTED; +} + +#ifdef TEST_PROGRAM_ISMOUNTED +int main(int argc, char **argv) +{ + int flags = 0; + char devname[PATH_MAX]; + + if (argc < 2) { + fprintf(stderr, "Usage: %s device\n", argv[0]); + return EXIT_FAILURE; + } + + if (check_mount_point(argv[1], &flags, devname, sizeof(devname)) == 0 && + (flags & MF_MOUNTED)) { + if (flags & MF_SWAP) + printf("used swap device\n"); + else + printf("mounted on %s\n", devname); + return EXIT_SUCCESS; + } + + printf("not mounted\n"); + return EXIT_FAILURE; +} +#endif /* DEBUG */ |