+++ /dev/null
-/* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
- * - added Native Language Support
- * Sun Mar 21 1999 - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
- * - fixed strerr(errno) in gettext calls
- *
- * 2006-06-08 Amit Gud <agud@redhat.com>
- * - Moved code to nfs-utils/support/nfs from util-linux/mount.
- */
-
-#include <errno.h>
-#include <stdio.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-#include <sys/stat.h>
-#include <mntent.h>
-
-#include "fstab.h"
-#include "xcommon.h"
-#include "nfs_mntent.h"
-#include "nfs_paths.h"
-#include "nls.h"
-
-#define LOCK_TIMEOUT 10
-#define streq(s, t) (strcmp ((s), (t)) == 0)
-#define PROC_MOUNTS "/proc/mounts"
-
-extern int verbose;
-
-/* Information about mtab. ------------------------------------*/
-static int have_mtab_info = 0;
-static int var_mtab_does_not_exist = 0;
-static int var_mtab_is_a_symlink = 0;
-
-static void
-get_mtab_info(void) {
- struct stat mtab_stat;
-
- if (!have_mtab_info) {
- if (lstat(MOUNTED, &mtab_stat))
- var_mtab_does_not_exist = 1;
- else if (S_ISLNK(mtab_stat.st_mode))
- var_mtab_is_a_symlink = 1;
- have_mtab_info = 1;
- }
-}
-
-int
-mtab_does_not_exist(void) {
- get_mtab_info();
- return var_mtab_does_not_exist;
-}
-
-static int
-mtab_is_a_symlink(void) {
- get_mtab_info();
- return var_mtab_is_a_symlink;
-}
-
-int
-mtab_is_writable() {
- int fd;
-
- /* Should we write to /etc/mtab upon an update?
- Probably not if it is a symlink to /proc/mounts, since that
- would create a file /proc/mounts in case the proc filesystem
- is not mounted. */
- if (mtab_is_a_symlink())
- return 0;
-
- fd = open(MOUNTED, O_RDWR | O_CREAT, 0644);
- if (fd >= 0) {
- close(fd);
- return 1;
- } else
- return 0;
-}
-
-/* Contents of mtab and fstab ---------------------------------*/
-
-struct mntentchn mounttable;
-static int got_mtab = 0;
-struct mntentchn fstab;
-static int got_fstab = 0;
-
-static void read_mounttable(void);
-static void read_fstab(void);
-
-static struct mntentchn *
-mtab_head(void) {
- if (!got_mtab)
- read_mounttable();
- return &mounttable;
-}
-
-static struct mntentchn *
-fstab_head(void)
-{
- if (!got_fstab)
- read_fstab();
- return &fstab;
-}
-
-#if 0
-static void
-my_free(const void *s) {
- if (s)
- free((void *) s);
-}
-
-static void
-discard_mntentchn(struct mntentchn *mc0) {
- struct mntentchn *mc, *mc1;
-
- for (mc = mc0->nxt; mc && mc != mc0; mc = mc1) {
- mc1 = mc->nxt;
- my_free(mc->m.mnt_fsname);
- my_free(mc->m.mnt_dir);
- my_free(mc->m.mnt_type);
- my_free(mc->m.mnt_opts);
- free(mc);
- }
-}
-#endif
-
-static void
-read_mntentchn(mntFILE *mfp, const char *fnam, struct mntentchn *mc0) {
- struct mntentchn *mc = mc0;
- struct mntent *mnt;
-
- while ((mnt = nfs_getmntent(mfp)) != NULL) {
- if (!streq(mnt->mnt_type, MNTTYPE_IGNORE)) {
- mc->nxt = (struct mntentchn *) xmalloc(sizeof(*mc));
- mc->nxt->prev = mc;
- mc = mc->nxt;
- mc->m = *mnt;
- mc->nxt = mc0;
- }
- }
- mc0->prev = mc;
- if (ferror(mfp->mntent_fp)) {
- int errsv = errno;
- nfs_error(_("warning: error reading %s: %s"),
- fnam, strerror (errsv));
- mc0->nxt = mc0->prev = NULL;
- }
- nfs_endmntent(mfp);
-}
-
-/*
- * Read /etc/mtab. If that fails, try /proc/mounts.
- * This produces a linked list. The list head mounttable is a dummy.
- * Return 0 on success.
- */
-static void
-read_mounttable() {
- mntFILE *mfp;
- const char *fnam;
- struct mntentchn *mc = &mounttable;
-
- got_mtab = 1;
- mc->nxt = mc->prev = NULL;
-
- fnam = MOUNTED;
- mfp = nfs_setmntent (fnam, "r");
- if (mfp == NULL || mfp->mntent_fp == NULL) {
- int errsv = errno;
- fnam = PROC_MOUNTS;
- mfp = nfs_setmntent (fnam, "r");
- if (mfp == NULL || mfp->mntent_fp == NULL) {
- nfs_error(_("warning: can't open %s: %s"),
- MOUNTED, strerror (errsv));
- return;
- }
- if (verbose)
- printf (_("mount: could not open %s - "
- "using %s instead\n"),
- MOUNTED, PROC_MOUNTS);
- }
- read_mntentchn(mfp, fnam, mc);
-}
-
-static void
-read_fstab()
-{
- mntFILE *mfp = NULL;
- const char *fnam;
- struct mntentchn *mc = &fstab;
-
- got_fstab = 1;
- mc->nxt = mc->prev = NULL;
-
- fnam = _PATH_FSTAB;
- mfp = nfs_setmntent (fnam, "r");
- if (mfp == NULL || mfp->mntent_fp == NULL) {
- int errsv = errno;
- nfs_error(_("warning: can't open %s: %s"),
- _PATH_FSTAB, strerror (errsv));
- return;
- }
- read_mntentchn(mfp, fnam, mc);
-}
-
-/*
- * Given the directory name NAME, and the place MCPREV we found it last time,
- * try to find more occurrences.
- */
-struct mntentchn *
-getmntdirbackward (const char *name, struct mntentchn *mcprev) {
- struct mntentchn *mc, *mc0;
-
- mc0 = mtab_head();
- if (!mcprev)
- mcprev = mc0;
- for (mc = mcprev->prev; mc && mc != mc0; mc = mc->prev)
- if (streq(mc->m.mnt_dir, name))
- return mc;
- return NULL;
-}
-
-/*
- * Given the device name NAME, and the place MCPREV we found it last time,
- * try to find more occurrences.
- */
-struct mntentchn *
-getmntdevbackward (const char *name, struct mntentchn *mcprev) {
- struct mntentchn *mc, *mc0;
-
- mc0 = mtab_head();
- if (!mcprev)
- mcprev = mc0;
- for (mc = mcprev->prev; mc && mc != mc0; mc = mc->prev)
- if (streq(mc->m.mnt_fsname, name))
- return mc;
- return NULL;
-}
-
-/* Find the dir FILE in fstab. */
-struct mntentchn *
-getfsfile (const char *file)
-{
- struct mntentchn *mc, *mc0;
-
- mc0 = fstab_head();
- for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt)
- if (streq(mc->m.mnt_dir, file))
- return mc;
- return NULL;
-}
-
-/* Find the device SPEC in fstab. */
-struct mntentchn *
-getfsspec (const char *spec)
-{
- struct mntentchn *mc, *mc0;
-
- mc0 = fstab_head();
- for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt)
- if (streq(mc->m.mnt_fsname, spec))
- return mc;
- return NULL;
-}
-
-/* Updating mtab ----------------------------------------------*/
-
-/* Flag for already existing lock file. */
-static int we_created_lockfile = 0;
-static int lockfile_fd = -1;
-
-/* Flag to indicate that signals have been set up. */
-static int signals_have_been_setup = 0;
-
-/* Ensure that the lock is released if we are interrupted. */
-extern char *strsignal(int sig); /* not always in <string.h> */
-
-static void
-handler (int sig) {
- die(EX_USER, "%s", strsignal(sig));
-}
-
-static void
-setlkw_timeout (int sig) {
- /* nothing, fcntl will fail anyway */
-}
-
-/* Remove lock file. */
-void
-unlock_mtab (void) {
- if (we_created_lockfile) {
- close(lockfile_fd);
- lockfile_fd = -1;
- unlink (MOUNTED_LOCK);
- we_created_lockfile = 0;
- }
-}
-
-/* Create the lock file.
- The lock file will be removed if we catch a signal or when we exit. */
-/* The old code here used flock on a lock file /etc/mtab~ and deleted
- this lock file afterwards. However, as rgooch remarks, that has a
- race: a second mount may be waiting on the lock and proceed as
- soon as the lock file is deleted by the first mount, and immediately
- afterwards a third mount comes, creates a new /etc/mtab~, applies
- flock to that, and also proceeds, so that the second and third mount
- now both are scribbling in /etc/mtab.
- The new code uses a link() instead of a creat(), where we proceed
- only if it was us that created the lock, and hence we always have
- to delete the lock afterwards. Now the use of flock() is in principle
- superfluous, but avoids an arbitrary sleep(). */
-
-/* Where does the link point to? Obvious choices are mtab and mtab~~.
- HJLu points out that the latter leads to races. Right now we use
- mtab~.<pid> instead. Use 20 as upper bound for the length of %d. */
-#define MOUNTLOCK_LINKTARGET MOUNTED_LOCK "%d"
-#define MOUNTLOCK_LINKTARGET_LTH (sizeof(MOUNTED_LOCK)+20)
-
-void
-lock_mtab (void) {
- int tries = 100000, i;
- char linktargetfile[MOUNTLOCK_LINKTARGET_LTH];
-
- at_die = unlock_mtab;
-
- if (!signals_have_been_setup) {
- int sig = 0;
- struct sigaction sa;
-
- sa.sa_handler = handler;
- sa.sa_flags = 0;
- sigfillset (&sa.sa_mask);
-
- while (sigismember (&sa.sa_mask, ++sig) != -1
- && sig != SIGCHLD) {
- if (sig == SIGALRM)
- sa.sa_handler = setlkw_timeout;
- else
- sa.sa_handler = handler;
- sigaction (sig, &sa, (struct sigaction *) 0);
- }
- signals_have_been_setup = 1;
- }
-
- sprintf(linktargetfile, MOUNTLOCK_LINKTARGET, getpid ());
-
- i = open (linktargetfile, O_WRONLY|O_CREAT, 0);
- if (i < 0) {
- int errsv = errno;
- /* linktargetfile does not exist (as a file)
- and we cannot create it. Read-only filesystem?
- Too many files open in the system?
- Filesystem full? */
- die (EX_FILEIO, _("can't create lock file %s: %s "
- "(use -n flag to override)"),
- linktargetfile, strerror (errsv));
- }
- close(i);
-
- /* Repeat until it was us who made the link */
- while (!we_created_lockfile) {
- struct flock flock;
- int errsv, j;
-
- j = link(linktargetfile, MOUNTED_LOCK);
- errsv = errno;
-
- if (j == 0)
- we_created_lockfile = 1;
-
- if (j < 0 && errsv != EEXIST) {
- (void) unlink(linktargetfile);
- die (EX_FILEIO, _("can't link lock file %s: %s "
- "(use -n flag to override)"),
- MOUNTED_LOCK, strerror (errsv));
- }
-
- lockfile_fd = open (MOUNTED_LOCK, O_WRONLY);
-
- if (lockfile_fd < 0) {
- int errsv = errno;
- /* Strange... Maybe the file was just deleted? */
- if (errno == ENOENT && tries-- > 0) {
- if (tries % 200 == 0)
- usleep(30);
- continue;
- }
- (void) unlink(linktargetfile);
- die (EX_FILEIO, _("can't open lock file %s: %s "
- "(use -n flag to override)"),
- MOUNTED_LOCK, strerror (errsv));
- }
-
- flock.l_type = F_WRLCK;
- flock.l_whence = SEEK_SET;
- flock.l_start = 0;
- flock.l_len = 0;
-
- if (j == 0) {
- /* We made the link. Now claim the lock. */
- if (fcntl (lockfile_fd, F_SETLK, &flock) == -1) {
- if (verbose) {
- int errsv = errno;
- printf(_("Can't lock lock file %s: %s\n"),
- MOUNTED_LOCK, strerror (errsv));
- }
- /* proceed anyway */
- }
- (void) unlink(linktargetfile);
- } else {
- static int tries = 0;
-
- /* Someone else made the link. Wait. */
- alarm(LOCK_TIMEOUT);
- if (fcntl (lockfile_fd, F_SETLKW, &flock) == -1) {
- int errsv = errno;
- (void) unlink(linktargetfile);
- die (EX_FILEIO, _("can't lock lock file %s: %s"),
- MOUNTED_LOCK, (errno == EINTR) ?
- _("timed out") : strerror (errsv));
- }
- alarm(0);
- /* Limit the number of iterations - maybe there
- still is some old /etc/mtab~ */
- ++tries;
- if (tries % 200 == 0)
- usleep(30);
- if (tries > 100000) {
- (void) unlink(linktargetfile);
- close(lockfile_fd);
- die (EX_FILEIO, _("Cannot create link %s\n"
- "Perhaps there is a stale lock file?\n"),
- MOUNTED_LOCK);
- }
- close(lockfile_fd);
- }
- }
-}
-
-/*
- * Update the mtab.
- * Used by umount with null INSTEAD: remove the last DIR entry.
- * Used by mount upon a remount: update option part,
- * and complain if a wrong device or type was given.
- * [Note that often a remount will be a rw remount of /
- * where there was no entry before, and we'll have to believe
- * the values given in INSTEAD.]
- */
-
-void
-update_mtab (const char *dir, struct mntent *instead)
-{
- mntFILE *mfp, *mftmp;
- const char *fnam = MOUNTED;
- struct mntentchn mtabhead; /* dummy */
- struct mntentchn *mc, *mc0, *absent = NULL;
-
- if (mtab_does_not_exist() || !mtab_is_writable())
- return;
-
- lock_mtab();
-
- /* having locked mtab, read it again */
- mc0 = mc = &mtabhead;
- mc->nxt = mc->prev = NULL;
-
- mfp = nfs_setmntent(fnam, "r");
- if (mfp == NULL || mfp->mntent_fp == NULL) {
- int errsv = errno;
- nfs_error (_("cannot open %s (%s) - mtab not updated"),
- fnam, strerror (errsv));
- goto leave;
- }
-
- read_mntentchn(mfp, fnam, mc);
-
- /* find last occurrence of dir */
- for (mc = mc0->prev; mc && mc != mc0; mc = mc->prev)
- if (streq(mc->m.mnt_dir, dir))
- break;
- if (mc && mc != mc0) {
- if (instead == NULL) {
- /* An umount - remove entry */
- if (mc && mc != mc0) {
- mc->prev->nxt = mc->nxt;
- mc->nxt->prev = mc->prev;
- free(mc);
- }
- } else {
- /* A remount */
- mc->m.mnt_opts = instead->mnt_opts;
- }
- } else if (instead) {
- /* not found, add a new entry */
- absent = xmalloc(sizeof(*absent));
- absent->m = *instead;
- absent->nxt = mc0;
- absent->prev = mc0->prev;
- mc0->prev = absent;
- if (mc0->nxt == NULL)
- mc0->nxt = absent;
- }
-
- /* write chain to mtemp */
- mftmp = nfs_setmntent (MOUNTED_TEMP, "w");
- if (mftmp == NULL || mftmp->mntent_fp == NULL) {
- int errsv = errno;
- nfs_error (_("cannot open %s (%s) - mtab not updated"),
- MOUNTED_TEMP, strerror (errsv));
- goto leave;
- }
-
- for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) {
- if (nfs_addmntent(mftmp, &(mc->m)) == 1) {
- int errsv = errno;
- die (EX_FILEIO, _("error writing %s: %s"),
- MOUNTED_TEMP, strerror (errsv));
- }
- }
-
-#if 0
- /* the chain might have strings copied from 'instead',
- * so we cannot safely free it.
- * And there is no need anyway because we are going to exit
- * shortly. So just don't call discard_mntentchn....
- */
- discard_mntentchn(mc0);
-#endif
- if (fchmod (fileno (mftmp->mntent_fp),
- S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) {
- int errsv = errno;
- fprintf(stderr, _("error changing mode of %s: %s\n"),
- MOUNTED_TEMP, strerror (errsv));
- }
- nfs_endmntent (mftmp);
-
- { /*
- * If mount is setuid and some non-root user mounts sth,
- * then mtab.tmp might get the group of this user. Copy uid/gid
- * from the present mtab before renaming.
- */
- struct stat sbuf;
- if (stat (MOUNTED, &sbuf) == 0)
- chown (MOUNTED_TEMP, sbuf.st_uid, sbuf.st_gid);
- }
-
- /* rename mtemp to mtab */
- if (rename (MOUNTED_TEMP, MOUNTED) < 0) {
- int errsv = errno;
- fprintf(stderr, _("can't rename %s to %s: %s\n"),
- MOUNTED_TEMP, MOUNTED, strerror(errsv));
- }
-
- leave:
- unlock_mtab();
-}
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