/* * ismounted.c --- Check to see if the filesystem was mounted * * Copyright (C) 1995,1996,1997,1998,1999,2000 Theodore Ts'o. * * %Begin-Header% * This file may be redistributed under the terms of the GNU Public * License. * %End-Header% */ #include #if HAVE_UNISTD_H #include #endif #if HAVE_ERRNO_H #include #endif #include #ifdef HAVE_LINUX_FD_H #include #endif #ifdef HAVE_MNTENT_H #include #endif #ifdef HAVE_GETMNTINFO #include #include #include #endif /* HAVE_GETMNTINFO */ #include #include #include "ext2_fs.h" #include "ext2fs.h" #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 errcode_t check_mntent_file(const char *mtab_file, const char *file, int *mount_flags, char *mtpt, int mtlen) { struct mntent *mnt; struct stat st_mntpnt, st_file; errcode_t retval = 0; FILE *f; int fd; *mount_flags = 0; if ((f = setmntent (mtab_file, "r")) == NULL) return errno; while ((mnt = getmntent (f)) != NULL) if (strcmp(file, mnt->mnt_fsname) == 0) break; if (mnt == 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 (stat("/", &st_mntpnt) == 0 && stat(file, &st_file) == 0) { if (st_mntpnt.st_dev == st_file.st_rdev) { *mount_flags = EXT2_MF_MOUNTED; if (mtpt) strncpy(mtpt, "/", mtlen); goto is_root; } } #endif goto exit; } #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 */ /* Validate the entry in case /etc/mtab is out of date */ /* * We need to be paranoid, because some broken distributions * (read: Slackware) don't initialize /etc/mtab before checking * all of the non-root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_mntpnt) < 0) { retval = errno; if (retval == ENOENT) { #ifdef DEBUG printf("Bogus entry in %s! (%s does not exist)\n", mtab_file, mnt->mnt_dir); #endif retval = 0; } goto exit; } if (stat(file, &st_file) == 0) { if (st_mntpnt.st_dev != st_file.st_rdev) { #ifdef DEBUG printf("Bogus entry in %s! (%s not mounted on %s)\n", mtab_file, file, mnt->mnt_dir); #endif goto exit; } } #endif *mount_flags = EXT2_MF_MOUNTED; /* Check to see if the ro option is set */ if (hasmntopt(mnt, MNTOPT_RO)) *mount_flags |= EXT2_MF_READONLY; if (mtpt) strncpy(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 |= EXT2_MF_ISROOT; fd = open(TEST_FILE, O_RDWR|O_CREAT); if (fd < 0) { if (errno == EROFS) *mount_flags |= EXT2_MF_READONLY; } else close(fd); (void) unlink(TEST_FILE); } retval = 0; exit: endmntent (f); return retval; } static errcode_t check_mntent(const char *file, int *mount_flags, char *mtpt, int mtlen) { errcode_t retval; #ifdef DEBUG retval = check_mntent_file("/tmp/mtab", file, mount_flags, mtpt, mtlen); if (retval == 0) return 0; #endif #ifdef __linux__ retval = check_mntent_file("/proc/mounts", file, mount_flags, mtpt, mtlen); if (retval == 0) return 0; #endif retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen); return retval; } #elif defined(HAVE_GETMNTINFO) static errcode_t 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 = EXT2_MF_MOUNTED; break; } ++mp; } if (mtpt) strncpy(mtpt, mp->f_mntonname, mtlen); return 0; } #endif /* HAVE_GETMNTINFO */ /* * ext2fs_check_mount_point() returns 1 if the device is mounted, 0 * otherwise. 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 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, char *mtpt, int mtlen) { #ifdef HAVE_MNTENT_H return check_mntent(device, mount_flags, mtpt, mtlen); #else #ifdef HAVE_GETMNTINFO return check_getmntinfo(device, mount_flags, mtpt, mtlen); #else #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!" *mount_flags = 0; return 0; #endif /* HAVE_GETMNTINFO */ #endif /* HAVE_MNTENT_H */ } /* * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED, * EXT2_MF_READONLY, and EXT2_MF_ROOT * */ errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags) { return ext2fs_check_mount_point(file, mount_flags, NULL, 0); } #ifdef DEBUG int main(int argc, char **argv) { int retval, mount_flags; if (argc < 2) { fprintf(stderr, "Usage: %s device\n", argv[0]); exit(1); } retval = ext2fs_check_if_mounted(argv[1], &mount_flags); if (retval) { com_err(argv[0], retval, "while calling ext2fs_check_if_mounted"); exit(1); } printf("Device %s reports flags %02x\n", argv[1], mount_flags); if (mount_flags & EXT2_MF_MOUNTED) printf("\t%s is mounted.\n", argv[1]); if (mount_flags & EXT2_MF_READONLY) printf("\t%s is read-only.\n", argv[1]); if (mount_flags & EXT2_MF_ISROOT) printf("\t%s is the root filesystem.\n", argv[1]); exit(0); } #endif