void update_mtab(const char *dir, struct mntent *instead)
{
struct mntent *mnt;
struct mntent *next;
struct mntent remnt;
int added = 0;
mntFILE *mfp, *mftmp;
if (mtab_does_not_exist() || mtab_is_a_symlink())
return;
lock_mtab();
mfp = my_setmntent(MOUNTED, "r");
if (mfp == NULL || mfp->mntent_fp == NULL) {
error("cannot open %s (%s) - mtab not updated", MOUNTED, strerror(errno));
goto leave;
}
mftmp = my_setmntent(MOUNTED_TEMP, "w");
if (mftmp == NULL || mftmp->mntent_fp == NULL) {
error("can't open %s (%s) - mtab not updated", MOUNTED_TEMP, strerror(errno));
goto leave;
}
while ((mnt = my_getmntent(mfp))) {
if (streq(mnt->mnt_dir, dir)) {
added++;
if (instead) { /* a remount */
remnt = *instead;
next = &remnt;
remnt.mnt_fsname = mnt->mnt_fsname;
remnt.mnt_type = mnt->mnt_type;
if (instead->mnt_fsname && !streq(mnt->mnt_fsname, instead->mnt_fsname))
printf("mount: warning: cannot change " "mounted device with a remount\n");
else if (instead->mnt_type && !streq(instead->mnt_type, "unknown")
&& !streq(mnt->mnt_type, instead->mnt_type))
printf("mount: warning: cannot change " "filesystem type with a remount\n");
} else
next = NULL;
} else
next = mnt;
if (next && my_addmntent(mftmp, next) == 1)
die(EX_FILEIO, "error writing %s: %s", MOUNTED_TEMP, strerror(errno));
}
if (instead && !added && my_addmntent(mftmp, instead) == 1)
die(EX_FILEIO, "error writing %s: %s", MOUNTED_TEMP, strerror(errno));
my_endmntent(mfp);
if (fchmod(fileno(mftmp->mntent_fp), S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) < 0)
fprintf(stderr, "error changing mode of %s: %s\n", MOUNTED_TEMP, strerror(errno));
my_endmntent(mftmp);
if (rename(MOUNTED_TEMP, MOUNTED) < 0)
fprintf(stderr, "can't rename %s to %s: %s\n", MOUNTED_TEMP, MOUNTED, strerror(errno));
leave:
unlock_mtab();
}
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;
}
static FILE *
open_locked_mtab(const char *mnttabname, char *mode, char *fs)
{
FILE *mfp = NULL;
if (mnt_file) {
dlog("Forced close on %s in read_mtab", mnttabname);
endmntent(mnt_file);
mnt_file = NULL;
}
if (!mtab_is_a_symlink() &&
!lock_mtab()) {
plog(XLOG_ERROR, "Couldn't lock mtab");
return 0;
}
mfp = setmntent((char *)mnttabname, mode);
if (!mfp) {
plog(XLOG_ERROR, "setmntent(\"%s\", \"%s\"): %m", mnttabname, mode);
return 0;
}
return mfp;
}
void
update_mtab (const char *dir, struct my_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_a_symlink())
return;
lock_mtab();
/* having locked mtab, read it again */
mc0 = mc = &mtabhead;
mc->nxt = mc->prev = NULL;
mfp = my_setmntent(fnam, "r");
if (mfp == NULL || mfp->mntent_fp == NULL) {
int errsv = errno;
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 = my_setmntent (MOUNTED_TEMP, "w");
if (mftmp == NULL || mftmp->mntent_fp == NULL) {
int errsv = errno;
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 (my_addmntent(mftmp, &(mc->m)) == 1) {
int errsv = errno;
die (EX_FILEIO, _("error writing %s: %s"),
MOUNTED_TEMP, strerror (errsv));
}
}
discard_mntentchn(mc0);
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));
}
my_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)
if (chown (MOUNTED_TEMP, sbuf.st_uid, sbuf.st_gid) < 0) {
int errsv = errno;
fprintf(stderr, _("error changing ownership of %s: %s\n"),
MOUNTED_TEMP, strerror (errsv));
}
}
/* 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();
}
