libmount: add low-level API for umount

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

4 files changed, 117 insertions, 19 deletions

diff --git a/shlibs/mount/docs/libmount-sections.txt b/shlibs/mount/docs/libmount-sections.txt
index d351aab53..ce744f3a2 100644
--- a/shlibs/mount/docs/libmount-sections.txt
+++ b/shlibs/mount/docs/libmount-sections.txt
@@ -185,6 +185,8 @@ mnt_context_enable_loopdel
 mnt_context_enable_rdonly_umount
 mnt_context_enable_sloppy
 mnt_context_enable_verbose
+mnt_context_finalize_mount
+mnt_context_finalize_umount
 mnt_context_get_cache
 mnt_context_get_fs
 mnt_context_get_fstab
@@ -197,6 +199,9 @@ mnt_context_get_status
 mnt_context_get_target
 mnt_context_get_user_mflags
 mnt_context_is_restricted
+mnt_context_mount
+mnt_context_prepare_mount
+mnt_context_prepare_umount
 mnt_context_set_cache
 mnt_context_set_fs
 mnt_context_set_fstab
@@ -211,12 +216,9 @@ mnt_context_set_source
 mnt_context_set_target
 mnt_context_set_user_mflags
 mnt_context_strerror
-mnt_context_mount
+mnt_context_umount
 mnt_free_context
 mnt_new_context
 mnt_reset_context
-mnt_context_prepare_mount
-mnt_context_do_mount
-mnt_context_finalize_mount
 </SECTION>
 
diff --git a/shlibs/mount/src/context_umount.c b/shlibs/mount/src/context_umount.c
index 7f71ef2be..d38e5de6e 100644
--- a/shlibs/mount/src/context_umount.c
+++ b/shlibs/mount/src/context_umount.c
@@ -443,27 +443,31 @@ static int do_umount(struct libmnt_context *cxt)
 }
 
 /**
- * mnt_context_do_umount:
+ * mnt_context_prepare_umount:
  * @cxt: mount context
  *
- * Umount filesystem by umount(2) or fork()+exec(/sbin/umount.type).
- *
- * See also mnt_context_disable_helpers().
+ * Prepare context for umounting, unnecessary for mnt_context_umount().
  *
  * Returns: 0 on success, and negative number in case of error.
  */
-int mnt_context_do_umount(struct libmnt_context *cxt)
+int mnt_context_prepare_umount(struct libmnt_context *cxt)
 {
 	int rc;
 
+	assert(cxt);
+	assert(cxt->fs);
+	assert(cxt->helper_exec_status == 1);
+	assert(cxt->syscall_status == 1);
+
 	if (!cxt || !cxt->fs || (cxt->fs->flags & MNT_FS_SWAP))
 		return -EINVAL;
 	if (!mnt_fs_get_source(cxt->fs) && !mnt_fs_get_target(cxt->fs))
 		return -EINVAL;
+	if (cxt->flags & MNT_FL_PREPARED)
+		return 0;
 
 	free(cxt->helper);	/* be paranoid */
 	cxt->helper = NULL;
-
 	cxt->action = MNT_ACT_UMOUNT;
 
 	rc = lookup_umount_fs(cxt);
@@ -475,20 +479,41 @@ int mnt_context_do_umount(struct libmnt_context *cxt)
 	       rc = mnt_context_prepare_target(cxt);
 	if (!rc && !cxt->helper)
 		rc = mnt_context_prepare_helper(cxt, "umount", NULL);
-
-	/* TODO : evaluate fstype pattern */
-
 /* TODO
 	if ((cxt->flags & MNT_FL_LOOPDEL) &&
 	    (!mnt_is_loopdev(src) || mnt_loopdev_is_autoclear(src)))
 		cxt->flags &= ~MNT_FL_LOOPDEL;
 */
-	if (!rc)
-		rc = mnt_context_prepare_update(cxt);
 	if (rc) {
-		DBG(CXT, mnt_debug_h(cxt, "prepared umount failed"));
+		DBG(CXT, mnt_debug_h(cxt, "umount: preparing failed"));
 		return rc;
 	}
+	cxt->flags |= MNT_FL_PREPARED;
+	return rc;
+}
+
+/**
+ * mnt_context_do_umount:
+ * @cxt: mount context
+ *
+ * Umount filesystem by umount(2) or fork()+exec(/sbin/umount.type).
+ * Unnecessary for mnt_context_umount().
+ *
+ * See also mnt_context_disable_helpers().
+ *
+ * Returns: 0 on success, and negative number in case of error.
+ */
+int mnt_context_do_umount(struct libmnt_context *cxt)
+{
+	int rc;
+
+	assert(cxt);
+	assert(cxt->fs);
+	assert(cxt->helper_exec_status == 1);
+	assert(cxt->syscall_status == 1);
+	assert((cxt->flags & MNT_FL_PREPARED));
+	assert((cxt->action == MNT_ACT_UMOUNT));
+	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
 
 	rc = do_umount(cxt);
 	if (rc)
@@ -503,7 +528,7 @@ int mnt_context_do_umount(struct libmnt_context *cxt)
 	if ((cxt->flags & MNT_FL_RDONLY_UMOUNT) &&
 	    (cxt->mountflags & (MS_RDONLY | MS_REMOUNT))) {
 		/*
-		 * remount --> read-only mount
+		 * fix options, remount --> read-only mount
 		 */
 		const char *o = mnt_fs_get_vfs_options(cxt->fs);
 		char *n = o ? strdup(o) : NULL;
@@ -522,5 +547,67 @@ int mnt_context_do_umount(struct libmnt_context *cxt)
 					       cxt->mountflags, NULL, cxt->fs);
 	}
 
-	return rc ? : mnt_context_update_tabs(cxt);
+	return rc;
+}
+
+/**
+ * mnt_context_finalize_umount:
+ * @cxt: context
+ *
+ * Mtab update, etc. Unnecessary for mnt_context_umount(), but should be called
+ * after mnt_context_do_umount(). See also mnt_context_set_syscall_status().
+ *
+ * Returns: negative number on error, 0 on success.
+ */
+int mnt_context_finalize_umount(struct libmnt_context *cxt)
+{
+	int rc;
+
+	assert(cxt);
+	assert(cxt->fs);
+	assert((cxt->flags & MNT_FL_PREPARED));
+	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
+
+	rc = mnt_context_prepare_update(cxt);
+	if (!rc)
+		rc = mnt_context_update_tabs(cxt);;
+	return rc;
+}
+
+
+/**
+ * mnt_context_umount:
+ * @cxt: umount context
+ *
+ * High-level, umounts filesystem by umount(2) or fork()+exec(/sbin/umount.type).
+ *
+ * This is similar to:
+ *
+ *	mnt_context_prepare_umount(cxt);
+ *	mnt_context_do_umount(cxt);
+ *	mnt_context_finalize_umount(cxt);
+ *
+ * See also mnt_context_disable_helpers().
+ *
+ * Returns: 0 on success, and negative number in case of error. WARNING: error
+ *          does not mean that umount(2) syscall or mount.type helper wasn't
+ *          sucessfully called. Check mnt_context_get_status() after error!
+ */
+int mnt_context_umount(struct libmnt_context *cxt)
+{
+	int rc;
+
+	assert(cxt);
+	assert(cxt->fs);
+	assert(cxt->helper_exec_status == 1);
+	assert(cxt->syscall_status == 1);
+
+	rc = mnt_context_prepare_umount(cxt);
+	if (!rc)
+		rc = mnt_context_prepare_update(cxt);
+	if (!rc)
+		rc = mnt_context_do_umount(cxt);
+	if (!rc)
+		rc = mnt_context_update_tabs(cxt);
+	return rc;
 }
diff --git a/shlibs/mount/src/libmount.h.in b/shlibs/mount/src/libmount.h.in
index 9870ba792..81fa1df33 100644
--- a/shlibs/mount/src/libmount.h.in
+++ b/shlibs/mount/src/libmount.h.in
@@ -417,10 +417,16 @@ extern int mnt_context_strerror(struct libmnt_context *cxt, char *buf,
 				size_t bufsiz);
 
 extern int mnt_context_mount(struct libmnt_context *cxt);
+extern int mnt_context_umount(struct libmnt_context *cxt);
 
 extern int mnt_context_prepare_mount(struct libmnt_context *cxt);
 extern int mnt_context_do_mount(struct libmnt_context *cxt);
 extern int mnt_context_finalize_mount(struct libmnt_context *cxt);
+
+extern int mnt_context_prepare_umount(struct libmnt_context *cxt);
+extern int mnt_context_do_umount(struct libmnt_context *cxt);
+extern int mnt_context_finalize_umount(struct libmnt_context *cxt);
+
 extern int mnt_context_set_syscall_status(struct libmnt_context *cxt, int status);
 
 extern int mnt_context_do_umount(struct libmnt_context *cxt);
diff --git a/shlibs/mount/src/libmount.sym b/shlibs/mount/src/libmount.sym
index 47488b512..78f4f7e2f 100644
--- a/shlibs/mount/src/libmount.sym
+++ b/shlibs/mount/src/libmount.sym
@@ -23,6 +23,7 @@ global:
 	mnt_context_enable_sloppy;
 	mnt_context_enable_verbose;
 	mnt_context_finalize_mount;
+	mnt_context_finalize_umount;
 	mnt_context_get_cache;
 	mnt_context_get_fs;
 	mnt_context_get_fstab;
@@ -44,8 +45,10 @@ global:
 	mnt_context_is_restricted;
 	mnt_context_is_sloppy;
 	mnt_context_is_verbose;
+	mnt_context_mount;
 	mnt_context_mounthelper_setopt;
 	mnt_context_prepare_mount;
+	mnt_context_prepare_umount;
 	mnt_context_set_cache;
 	mnt_context_set_fs;
 	mnt_context_set_fstab;
@@ -61,6 +64,7 @@ global:
 	mnt_context_set_target;
 	mnt_context_set_user_mflags;
 	mnt_context_strerror;
+	mnt_context_umount;
 	mnt_copy_fs;
 	mnt_free_cache;
 	mnt_free_context;
@@ -133,7 +137,6 @@ global:
 	mnt_mangle;
 	mnt_match_fstype;
 	mnt_match_options;
-	mnt_context_mount;
 	mnt_new_cache;
 	mnt_new_context;
 	mnt_new_fs;