libmount: add functions get mtab/utab paths

diff --git a/shlibs/mount/src/utils.c b/shlibs/mount/src/utils.c
index 09457345c3b76861ab2fc7bea5c148407f9c22e0..f2c1bf25b5d6d949bfea832bfb12cb76370fd4e8 100644 (file)
--- a/shlibs/mount/src/utils.c
+++ b/shlibs/mount/src/utils.c
@@ -407,13 +407,15 @@ done:
 /*
  * Returns 1 if /etc/mtab is a reqular file.
  */
-int mnt_has_regular_mtab(void)
+int mnt_has_regular_mtab(const char **mtab)
 {
        struct stat st;
+       const char *x = mnt_get_mtab_path();
 
-       if (lstat(_PATH_MOUNTED, &st) == 0 && S_ISREG(st.st_mode))
-               return 1;
-       return 0;
+       if (mtab)
+               *mtab = x;
+
+       return (lstat(x, &st) == 0 && S_ISREG(st.st_mode));
 }
 
 /**
@@ -430,13 +432,8 @@ const char *mnt_get_fstab_path(void)
 /**
  * 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.
+ * This function returns *default* location of the mtab file. The result does
+ * not have to be writable. See also mnt_get_writable_mtab_path().
  *
  * Returns: path to /etc/mtab or $LIBMOUNT_MTAB.
  */
@@ -447,52 +444,64 @@ const char *mnt_get_mtab_path(void)
 }
 
 /**
- * mnt_get_writable_mtab_path:
+ * mnt_get_utab_path:
  *
- * 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).
+ * This function returns *default* location of the utab file.
  *
- * 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: path to /dev/.mount/utab or $LIBMOUNT_UTAB.
+ */
+const char *mnt_get_utab_path(void)
+{
+       const char *p = mnt_getenv_safe("LIBMOUNT_UTAB");
+       return p ? : MNT_PATH_UTAB;
+}
+
+/**
+ * mnt_get_writable_mtab_path:
  *
  * 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;
+       struct stat st;
        const char *path = mnt_get_mtab_path();
 
-       mtab = !lstat(path, &mst);
-       info = !stat(MNT_PATH_RUNDIR, &ist);
-
-       errno = 0;
-
-       /* A) mtab is symlink, /var/run/mount is available */
-       if (mtab && S_ISLNK(mst.st_mode) && info) {
-               int fd = open(MNT_PATH_MOUNTINFO, O_RDWR | O_CREAT, 0644);
-               if (fd >= 0) {
-                       close(fd);
-                       return MNT_PATH_MOUNTINFO;
-               }
-               return NULL;    /* probably EACCES */
-       }
-
-       /* B) classis system with /etc/mtab or $LIBMOUNT_MTAB */
-       if (mtab && S_ISREG(mst.st_mode)) {
+       if (lstat(path, &st) && S_ISREG(st.st_mode)) {
                int fd = open(path, O_RDWR, 0644);
                if (fd >= 0) {
                        close(fd);
                        return path;
                }
-               return NULL;    /* probably EACCES */
        }
 
        return NULL;
 }
 
+/* returns file descriptor or -errno, @name returns uniques filename
+ */
+int mnt_open_uniq_filename(const char *filename, char **name, int flags)
+{
+       int rc, fd;
+       char *n;
+
+       assert(filename);
+
+       if (name)
+               *name = NULL;
+
+       rc = asprintf(&n, "%s.XXXXXX", filename);
+       if (rc <= 0)
+               return -errno;
+
+       fd = mkostemp(n, flags | O_EXCL);
+       if (fd >= 0 && name)
+               *name = n;
+       else
+               free(n);
+
+       return fd < 0 ? -errno : fd;
+}
 
 /* returns basename and keeps dirname in the @path, if @path is "/" (root)
  * then returns empty string */