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-rw-r--r--lib/ismounted.c396
1 files changed, 396 insertions, 0 deletions
diff --git a/lib/ismounted.c b/lib/ismounted.c
new file mode 100644
index 0000000..31be71a
--- /dev/null
+++ b/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 && n >= 0)
+ 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() 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|O_NONBLOCK);
+ 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 */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 09:51:21 +0000