libmount: allow to overwrite mtab/fstab paths

Signed-off-by: Karel Zak <kzak@redhat.com>

7 files changed, 140 insertions, 62 deletions

diff --git a/shlibs/mount/src/context.c b/shlibs/mount/src/context.c
index 863003926..21a5d8a1d 100644
--- a/shlibs/mount/src/context.c
+++ b/shlibs/mount/src/context.c
@@ -547,7 +547,7 @@ int mnt_context_get_fstab(mnt_context *cxt, mnt_tab **tb)
 		if (!cxt->fstab)
 			return -ENOMEM;
 		cxt->flags &= ~MNT_FL_EXTERN_FSTAB;
-		rc = mnt_tab_parse_fstab(cxt->fstab);
+		rc = mnt_tab_parse_fstab(cxt->fstab, NULL);
 		if (rc)
 			return rc;
 	}
@@ -585,7 +585,7 @@ int mnt_context_get_mtab(mnt_context *cxt, mnt_tab **tb)
 		cxt->mtab = mnt_new_tab();
 		if (!cxt->mtab)
 			return -ENOMEM;
-		rc = mnt_tab_parse_mtab(cxt->mtab);
+		rc = mnt_tab_parse_mtab(cxt->mtab, NULL);
 		if (rc)
 			return rc;
 	}
diff --git a/shlibs/mount/src/lock.c b/shlibs/mount/src/lock.c
index 5e18ba250..9149c7b90 100644
--- a/shlibs/mount/src/lock.c
+++ b/shlibs/mount/src/lock.c
@@ -231,7 +231,6 @@ void mnt_unlock_file(mnt_lock *ml)
 	if (!ml)
 		return;
 
-	DBG(LOCKS, mnt_debug_h(ml, "(%d) unlocking/cleaning", getpid()));
 
 	if (ml->locked == 0 && ml->lockfile && ml->linkfile)
 	{
@@ -247,6 +246,10 @@ void mnt_unlock_file(mnt_lock *ml)
 		    lo.st_dev == li.st_dev && lo.st_ino == li.st_ino)
 			ml->locked = 1;
 	}
+
+	DBG(LOCKS, mnt_debug_h(ml, "(%d) %s", getpid(),
+			ml->locked ? "unlocking" : "cleaning"));
+
 	if (ml->linkfile)
 		unlink(ml->linkfile);
 	if (ml->lockfile_fd >= 0)
@@ -468,7 +471,6 @@ void increment_data(const char *filename, int verbose, int loopno)
 
 void clean_lock(void)
 {
-	fprintf(stderr, "%d: cleaning\n", getpid());
 	if (!lock)
 		return;
 	mnt_unlock_file(lock);
@@ -508,8 +510,9 @@ int test_lock(struct mtest *ts, int argc, char *argv[])
 	if (!datafile || !loops)
 		return -EINVAL;
 
-	fprintf(stderr, "%d: start: synctime=%u, verbose=%d, datafile=%s, loops=%d\n",
-		 getpid(), (int) synctime, verbose, datafile, loops);
+	if (verbose)
+		fprintf(stderr, "%d: start: synctime=%u, datafile=%s, loops=%d\n",
+			 getpid(), (int) synctime, datafile, loops);
 
 	atexit(clean_lock);
 
diff --git a/shlibs/mount/src/mount.h.in b/shlibs/mount/src/mount.h.in
index a1143ee27..01ba5a6d6 100644
--- a/shlibs/mount/src/mount.h.in
+++ b/shlibs/mount/src/mount.h.in
@@ -132,6 +132,8 @@ extern int mnt_fstype_is_pseudofs(const char *type);
 extern int mnt_match_fstype(const char *type, const char *pattern);
 extern int mnt_match_options(const char *optstr, const char *pattern);
 extern const char *mnt_get_writable_mtab_path(void);
+extern const char *mnt_get_fstab_path(void);
+extern const char *mnt_get_mtab_path(void);
 
 /* cache.c */
 extern mnt_cache *mnt_new_cache(void);
@@ -251,8 +253,8 @@ extern int mnt_fs_print_debug(mnt_fs *ent, FILE *file);
 extern mnt_tab *mnt_new_tab_from_file(const char *filename);
 extern int mnt_tab_parse_stream(mnt_tab *tb, FILE *f, const char *filename);
 extern int mnt_tab_parse_file(mnt_tab *tb, const char *filename);
-extern int mnt_tab_parse_fstab(mnt_tab *tb);
-extern int mnt_tab_parse_mtab(mnt_tab *tb);
+extern int mnt_tab_parse_fstab(mnt_tab *tb, const char *filename);
+extern int mnt_tab_parse_mtab(mnt_tab *tb, const char *filename);
 extern int mnt_tab_set_parser_errcb(mnt_tab *tb,
                 int (*cb)(mnt_tab *tb, const char *filename, int line));
 
diff --git a/shlibs/mount/src/mount.sym b/shlibs/mount/src/mount.sym
index f97d0048b..2db74df34 100644
--- a/shlibs/mount/src/mount.sym
+++ b/shlibs/mount/src/mount.sym
@@ -55,6 +55,8 @@ global:
 	mnt_get_builtin_optmap;
 	mnt_get_library_version;
 	mnt_get_writable_mtab_path;
+	mnt_get_fstab_path;
+	mnt_get_mtab_path;
 	mnt_init_debug;
 	mnt_iter_get_direction;
 	mnt_lock_file;
diff --git a/shlibs/mount/src/tab_parse.c b/shlibs/mount/src/tab_parse.c
index 224fcb68f..5ac51ab87 100644
--- a/shlibs/mount/src/tab_parse.c
+++ b/shlibs/mount/src/tab_parse.c
@@ -437,6 +437,7 @@ int mnt_tab_set_parser_errcb(mnt_tab *tb,
 /**
  * mnt_tab_parse_fstab:
  * @tb: table
+ * @filename: overwrites default (/etc/fstab or $LIBMOUNT_FSTAB) or NULL
  *
  * This function parses /etc/fstab or /etc/fstab.d and appends new lines to the
  * @tab. If the system contains classic fstab file and also fstab.d directory
@@ -452,28 +453,30 @@ int mnt_tab_set_parser_errcb(mnt_tab *tb,
  * Returns: 0 on success (least one record has been successfully parsed) or
  *          negative number in case of error.
  */
-int mnt_tab_parse_fstab(mnt_tab *tb)
+int mnt_tab_parse_fstab(mnt_tab *tb, const char *filename)
 {
 	int num, n = 0, i;
 	DIR *dir = NULL;
 	FILE *f;
 	struct dirent **namelist = NULL;
-	const char *env;
 
 	assert(tb);
 	if (!tb)
 		return -EINVAL;
 
 	num = mnt_tab_get_nents(tb);
-	env = mnt_getenv_safe("LIBMOUNT_FSTAB");
 
-	f = fopen(env ? : _PATH_MNTTAB, "r");
+	if (!filename)
+		filename = mnt_get_fstab_path();
+
+	f = fopen(filename, "r");
 	if (f) {
-		mnt_tab_parse_stream(tb, f, _PATH_MNTTAB);
+		mnt_tab_parse_stream(tb, f, filename);
 		fclose(f);
 
-		if (env)
-			goto done;	/* ignore /etc/fstab.d if $LIBMOUNT_FSTAB defined */
+		if (strcmp(filename, _PATH_MNTTAB))
+			/* /etc/fstab.d sould be used together with /etc/fstab only */
+			goto done;
 	}
 
 	/* TODO: it would be nice to have a scandir() implementaion that
@@ -581,46 +584,66 @@ static mnt_fs *mnt_tab_merge_userspace_fs(mnt_tab *tb, mnt_fs *uf)
 /**
  * mnt_tab_parse_mtab:
  * @tb: table
+ * @filename: overwrites default (/etc/mtab or $LIBMOUNT_MTAB) or NULL
  *
  * This function parses /etc/mtab or {/proc/self,/var/run/mount}/mountinfo or
  * /proc/mounts. Note that the /var/run/mount/mountinfo file is optional and
  * contains userspace specific mount options only.
  *
+ * Note that /var/run/mount/mountinfo is ignored if /etc/mtab is writable or
+ * $LIBMOUNT_MTAB or @filename does not end with "mountinfo" postfix.
+ *
  * See also mnt_tab_set_parser_errcb().
  *
  * Returns: 0 on success or negative number in case of error.
  */
-int mnt_tab_parse_mtab(mnt_tab *tb)
+int mnt_tab_parse_mtab(mnt_tab *tb, const char *filename)
 {
 	int rc;
-	mnt_tab *u_tb;
-	mnt_fs *u_fs;
-	mnt_iter itr;
-	const char *env = mnt_getenv_safe("LIBMOUNT_MTAB");
 
-	if ((env && !endswith(env, "mountinfo")) || mnt_has_regular_mtab()) {
-		rc = mnt_tab_parse_file(tb, env ? : _PATH_MOUNTED);
+	if (!filename)
+		filename = mnt_get_writable_mtab_path();
+
+	/*
+	 * Regular mtab file
+	 */
+	if (filename && !endswith(filename, "mountinfo")) {
+		rc = mnt_tab_parse_file(tb, filename);
 		if (!rc)
-			return 0;		/* system with regular mtab */
+			return 0;
+		filename = NULL;
 	}
 
-	/* read kernel information from /proc/self/mountinfo */
+	/*
+	 * useless /etc/mtab or /var/run/mount/mountinfo is supported
+	 * -- read kernel information from /proc/self/mountinfo
+	 */
 	rc = mnt_tab_parse_file(tb, _PATH_PROC_MOUNTINFO);
 	if (rc)
 		/* hmm, old kernel? ...try /proc/mounts */
 		return mnt_tab_parse_file(tb, _PATH_PROC_MOUNTS);
 
-	/* try to read userspace specific information from /var/run/mount */
-	u_tb = mnt_new_tab_from_file(env ? : MNT_PATH_MOUNTINFO);
-	if (!u_tb)
-		return 0;	/* private mountinfo does not exist */
+	/*
+	 * try to read userspace specific information from
+	 * /var/run/mount/mountinfo
+	 */
+	if (filename) {
+		mnt_tab *u_tb = mnt_new_tab_from_file(filename);
+
+		assert(endswith(filename, "mountinfo"));
 
-	mnt_reset_iter(&itr, MNT_ITER_BACKWARD);
+		if (u_tb) {
+			mnt_fs *u_fs;
+			mnt_iter itr;
 
-	/*  merge userspace options into mountinfo from kernel */
-	while(mnt_tab_next_fs(u_tb, &itr, &u_fs) == 0)
-		mnt_tab_merge_userspace_fs(tb, u_fs);
+			mnt_reset_iter(&itr, MNT_ITER_BACKWARD);
 
-	mnt_free_tab(u_tb);
+			/*  merge userspace options into mountinfo from kernel */
+			while(mnt_tab_next_fs(u_tb, &itr, &u_fs) == 0)
+				mnt_tab_merge_userspace_fs(tb, u_fs);
+
+			mnt_free_tab(u_tb);
+		}
+	}
 	return 0;
 }
diff --git a/shlibs/mount/src/tab_update.c b/shlibs/mount/src/tab_update.c
index 830225277..946cdc090 100644
--- a/shlibs/mount/src/tab_update.c
+++ b/shlibs/mount/src/tab_update.c
@@ -27,6 +27,12 @@
  *   /var/run/mount/mountinfo file (the file format compatible to
  *   /proc/self/mountinfo)
  *
+ * Note that mnt_update_* interface does not manage mount options. It's callers
+ * responsibility set the right mount options (for example merge options from
+ * mtab with command line on MS_REMOUNT).
+ *
+ * The small exception is the /var/run/mount/mountinfo file where are store
+ * userspace mount options only. This is done by mnt_prepare_update().
  *
  * The mtab is always updated in two steps. The first step is to prepare a new
  * update entry -- mnt_prepare_update(), this step has to be done before
@@ -126,11 +132,11 @@ int mnt_update_set_filename(mnt_update *upd, const char *filename)
 
 	assert(upd);
 	if (!upd)
-		return -1;
+		return -EINVAL;
 	if (filename) {
 		p = strdup(filename);
 		if (!p)
-			return -1;
+			return -ENOMEM;
 	}
 	free(upd->filename);
 	upd->filename = p;
@@ -164,7 +170,7 @@ int mnt_update_set_action(mnt_update *upd, int action)
 {
 	assert(upd);
 	if (!upd)
-		return -1;
+		return -EINVAL;
 	upd->action = action;
 	return 0;
 }
@@ -184,7 +190,7 @@ int mnt_update_set_format(mnt_update *upd, int format)
 {
 	assert(upd);
 	if (!upd)
-		return -1;
+		return -EINVAL;
 	upd->format = format;
 	return 0;
 }
@@ -219,11 +225,11 @@ int mnt_update_set_fs(mnt_update *upd, const mnt_fs *fs)
 
 	assert(upd);
 	if (!upd)
-		return -1;
+		return -EINVAL;
 	if (fs) {
 		x = mnt_copy_fs(fs);
 		if (!x)
-			return -1;
+			return -ENOMEM;
 	}
 
 	mnt_free_fs(upd->fs);
@@ -247,7 +253,7 @@ int mnt_update_set_mountflags(mnt_update *upd, unsigned long flags)
 {
 	assert(upd);
 	if (!upd)
-		return -1;
+		return -EINVAL;
 	upd->mountflags = flags;
 	return 0;
 }
@@ -305,8 +311,8 @@ int mnt_update_set_old_target(mnt_update *upd, const char *target)
 	char *p = NULL;
 
 	if (!upd)
-		return -1;
-	if (p) {
+		return -EINVAL;
+	if (target) {
 		p = strdup(target);
 		if (!p)
 			return -1;
@@ -331,7 +337,7 @@ static int fprintf_mountinfo_fs(FILE *f, mnt_fs *fs)
 	assert(f);
 
 	if (!fs || !f)
-		return -1;
+		return -EINVAL;
 	devno = mnt_fs_get_devno(fs);
 	source = mangle(mnt_fs_get_source(fs));
 	root = mangle(mnt_fs_get_root(fs));
@@ -372,7 +378,7 @@ static int fprintf_mtab_fs(FILE *f, mnt_fs *fs)
 	assert(f);
 
 	if (!fs || !f)
-		return -1;
+		return -EINVAL;
 
 	m1 = mangle(mnt_fs_get_source(fs));
 	m2 = mangle(mnt_fs_get_target(fs));
@@ -408,7 +414,7 @@ static int update_file(const char *filename, int fmt, mnt_tab *tb)
 
 	assert(tb);
 	if (!tb)
-		goto error;
+		return -EINVAL;
 
 	DBG(UPDATE, mnt_debug("%s: update from tab %p", filename, tb));
 
@@ -450,7 +456,7 @@ error:
 	DBG(UPDATE, mnt_debug("%s: update from tab %p failed", filename, tb));
 	if (f)
 		fclose(f);
-	return -1;
+	return errno ? -errno : -1;
 }
 
 static int set_fs_root(mnt_update *upd, mnt_fs *fs)
@@ -602,10 +608,8 @@ int mnt_prepare_update(mnt_update *upd)
 		mnt_fs_get_optstr(upd->fs)));
 
 	if (!upd->filename) {
-		const char *p = mnt_getenv_safe("LIBMOUNT_MTAB");
+		const char *p = mnt_get_writable_mtab_path();
 
-		if (!p)
-			p = mnt_get_writable_mtab_path();
 		if (!p) {
 			if (errno) {
 				rc = -errno;
@@ -631,6 +635,10 @@ int mnt_prepare_update(mnt_update *upd)
 			upd->format = MNT_FMT_MTAB;
 	}
 
+	DBG(UPDATE, mnt_debug_h(upd, "format: %s",
+			upd->format == MNT_FMT_MOUNTINFO ? "mountinfo" :
+			upd->format == MNT_FMT_FSTAB ? "fstab" : "mtab"));
+
 	/* TODO: cannonicalize source and target paths on mnt->fs */
 
 	if (upd->format != MNT_FMT_FSTAB) {
@@ -643,13 +651,13 @@ int mnt_prepare_update(mnt_update *upd)
 
 	/* umount */
 	if (upd->action == MNT_ACT_UMOUNT)
-		return 0;
+		goto done;
 
 	/*
 	 * A) classic /etc/mtab or /etc/fstab update
 	 */
 	if (upd->format != MNT_FMT_MOUNTINFO)
-		return 0;
+		goto done;
 
 	/*
 	 * B) /var/run/mount/mountinfo
@@ -680,6 +688,7 @@ int mnt_prepare_update(mnt_update *upd)
 		u = NULL;
 	}
 
+done:
 	if (!upd->nolock && !upd->lc) {
 		upd->lc = mnt_new_lock(upd->filename, 0);
 		if (!upd->lc) {
@@ -908,15 +917,17 @@ static int update(mnt_update *upd)
 	rc = mnt_prepare_update(upd);
 	if (!rc) {
 		/* setup lock fallback */
+		int rc;
+
 		lock = mnt_update_get_lock(upd);
 		atexit(lock_fallback);
 
-		return mnt_update_file(upd);
+		rc = mnt_update_file(upd);
+		lock = NULL;
+		return rc;
 	}
-	if (rc == 1) {
-		printf("update: update is not reuquired\n");
+	if (rc == 1)
 		return 0;
-	}
 	fprintf(stderr, "update: failed to prepare update\n");
 	return -1;
 }
@@ -966,7 +977,8 @@ int test_add_fstab(struct mtest *ts, int argc, char *argv[])
 		return -1;
 
 	mnt_update_disable_lock(upd, TRUE);		/* lock is unnecessary */
-	mnt_update_set_filename(upd, _PATH_MNTTAB);	/* fstab */
+
+	mnt_update_set_filename(upd, mnt_get_fstab_path());
 	mnt_update_set_format(upd, MNT_FMT_FSTAB);
 
 	rc = update(upd);
diff --git a/shlibs/mount/src/utils.c b/shlibs/mount/src/utils.c
index 3aa8d9b82..09457345c 100644
--- a/shlibs/mount/src/utils.c
+++ b/shlibs/mount/src/utils.c
@@ -417,19 +417,55 @@ int mnt_has_regular_mtab(void)
 }
 
 /**
+ * mnt_get_fstab_path:
+ *
+ * Returns: path to /etc/fstab or $LIBMOUNT_FSTAB.
+ */
+const char *mnt_get_fstab_path(void)
+{
+	const char *p = mnt_getenv_safe("LIBMOUNT_FSTAB");
+	return p ? : _PATH_MNTTAB;
+}
+
+/**
+ * mnt_get_mtab_path:
+ *
+ * This function returns *default* location of the mtab file. The result does not have to
+ * be writable. See also mnt_get_writable_mtab_path().
+ *
+ * It's possible that libmount uses /proc/self/mountinfo together with
+ * /var/run/mount/mountinfo file (or files). The ideal solution is to use
+ * mnt_tab_parse_mtab() that provides abstraction and returns mtab records
+ * independently on the way how things are managed by libmount.
+ *
+ * Returns: path to /etc/mtab or $LIBMOUNT_MTAB.
+ */
+const char *mnt_get_mtab_path(void)
+{
+	const char *p = mnt_getenv_safe("LIBMOUNT_MTAB");
+	return p ? : _PATH_MOUNTED;
+}
+
+/**
  * mnt_get_writable_mtab_path:
  *
- * It's not error if this function return NULL and errno is not set. In case of
+ * It's not error if this function returns NULL and errno is not set. In case of
  * error the errno is set by open(2).
  *
- * Returns: pointer to the static string with path to mtab or NULL.
+ * Note that writable mtab does not have to contains all necessary information.
+ * For example /var/run/mount/mountinfo is used for userspace mount options
+ * only. FS depend information are usually maintaibed by kernel only.
+ *
+ * Returns: pointer to the static string with path to mtab or NULL if writable
+ *          mtab is unsupported.
  */
 const char *mnt_get_writable_mtab_path(void)
 {
 	struct stat mst, ist;
 	int mtab, info;
+	const char *path = mnt_get_mtab_path();
 
-	mtab = !lstat(_PATH_MOUNTED, &mst);
+	mtab = !lstat(path, &mst);
 	info = !stat(MNT_PATH_RUNDIR, &ist);
 
 	errno = 0;
@@ -444,12 +480,12 @@ const char *mnt_get_writable_mtab_path(void)
 		return NULL;	/* probably EACCES */
 	}
 
-	/* B) classis system with /etc/mtab */
+	/* B) classis system with /etc/mtab or $LIBMOUNT_MTAB */
 	if (mtab && S_ISREG(mst.st_mode)) {
-		int fd = open(_PATH_MOUNTED, O_RDWR, 0644);
+		int fd = open(path, O_RDWR, 0644);
 		if (fd >= 0) {
 			close(fd);
-			return _PATH_MOUNTED;
+			return path;
 		}
 		return NULL;    /* probably EACCES */
 	}