libmount: export mnt_guess_system_root() by API

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

libmount/docs/libmount-sections.txt

@@ -398,6 +398,7 @@ mnt_get_fstab_path
 mnt_get_mountpoint
 mnt_get_mtab_path
 mnt_get_swaps_path
+mnt_guess_system_root
 mnt_has_regular_mtab
 mnt_mangle
 mnt_match_fstype

libmount/src/libmount.h.in

@@ -326,6 +326,8 @@ extern const char *mnt_get_mtab_path(void);
 extern int mnt_has_regular_mtab(const char **mtab, int *writable);
 extern char *mnt_get_mountpoint(const char *path)
 			__ul_attribute__((warn_unused_result));
+extern int mnt_guess_system_root(dev_t devno, struct libmnt_cache *cache, char **path)
+			__ul_attribute__((nonnull(3)));
 
 /* cache.c */
 extern struct libmnt_cache *mnt_new_cache(void)

libmount/src/libmount.sym

@@ -341,3 +341,7 @@ MOUNT_2.33 {
 	mnt_context_switch_origin_ns;
 	mnt_context_switch_target_ns;
 } MOUNT_2.30;
+
+MOUNT_2.34 {
+	mnt_guess_system_root;
+} MOUNT_2.33;

libmount/src/mountP.h

@@ -120,7 +120,6 @@ extern int mnt_get_filesystems(char ***filesystems, const char *pattern);
 extern void mnt_free_filesystems(char **filesystems);
 
 extern char *mnt_get_kernel_cmdline_option(const char *name);
-extern int mnt_guess_system_root(dev_t devno, struct libmnt_cache *cache, char **path);
 extern int mnt_stat_mountpoint(const char *target, struct stat *st);
 
 /* tab.c */

libmount/src/utils.c

@@ -1037,7 +1037,12 @@ char *mnt_get_kernel_cmdline_option(const char *name)
 	return res;
 }
 
-/*
+/**
+ * mnt_guess_system_root:
+ * @devno: device number or zero
+ * @cache: paths cache or NULL
+ * @path: returns allocated path
+ *
  * Converts @devno to the real device name if devno major number is greater
  * than zero, otherwise use root= kernel cmdline option to get device name.
  *