libmount: support MS_RDONLY on write-protected devices

This feature is supported by mount(8) only. It seems better move
this code to libmount. The results is more simple mount(8) and the
feature is accessible for all libmount users.

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

1 files changed, 46 insertions, 1 deletions

diff --git a/libmount/src/context.c b/libmount/src/context.c
index e731749b4..6a7c7d351 100644
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -172,6 +172,7 @@ int mnt_reset_context(struct libmnt_context *cxt)
 	cxt->flags |= (fl & MNT_FL_FORCE);
 	cxt->flags |= (fl & MNT_FL_NOCANONICALIZE);
 	cxt->flags |= (fl & MNT_FL_RDONLY_UMOUNT);
+	cxt->flags |= (fl & MNT_FL_RWONLY_MOUNT);
 	cxt->flags |= (fl & MNT_FL_NOSWAPMATCH);
 	cxt->flags |= (fl & MNT_FL_TABPATHS_CHECKED);
 	return 0;
@@ -478,6 +479,48 @@ int mnt_context_is_rdonly_umount(struct libmnt_context *cxt)
 }
 
 /**
+ * mnt_context_enable_rwonly_mount:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Force read-write mount; if enabled libmount will never try MS_RDONLY
+ * after failed mount(2) EROFS. (See mount(8) man page, option -w).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_rwonly_mount(struct libmnt_context *cxt, int enable)
+{
+	return set_flag(cxt, MNT_FL_RWONLY_MOUNT, enable);
+}
+
+/**
+ * mnt_context_is_rwonly_mount
+ * @cxt: mount context
+ *
+ * See also mnt_context_enable_rwonly_mount() and mount(8) man page,
+ * option -w.
+ *
+ * Returns: 1 if only read-write mount is allowed.
+ */
+int mnt_context_is_rwonly_mount(struct libmnt_context *cxt)
+{
+	return cxt->flags & MNT_FL_RWONLY_MOUNT ? 1 : 0;
+}
+
+/**
+ * mnt_context_forced_rdonly:
+ * @cxt: mount context
+ *
+ * See also mnt_context_enable_rwonly_mount().
+ *
+ * Returns: 1 if mounted read-only on write-protected device.
+ */
+int mnt_context_forced_rdonly(struct libmnt_context *cxt)
+{
+	return cxt->flags & MNT_FL_FORCED_RDONLY ? 1 : 0;
+}
+
+/**
  * mnt_context_disable_helpers:
  * @cxt: mount context
  * @disable: TRUE or FALSE
@@ -2002,8 +2045,10 @@ int mnt_context_apply_fstab(struct libmnt_context *cxt)
 	if (!cxt || !cxt->fs)
 		return -EINVAL;
 
-	if (mnt_context_tab_applied(cxt))	/* already applied */
+	if (mnt_context_tab_applied(cxt)) {	/* already applied */
+		DBG(CXT, ul_debugobj(cxt, "fstab already applied -- skip"));
 		return 0;
+	}
 
 	if (mnt_context_is_restricted(cxt)) {
 		DBG(CXT, ul_debugobj(cxt, "force fstab usage for non-root users!"));