libmount: allows to swap source and target

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

1 files changed, 144 insertions, 24 deletions

diff --git a/shlibs/mount/src/context.c b/shlibs/mount/src/context.c
index 07a72c2d3..1d3c76a75 100644
--- a/shlibs/mount/src/context.c
+++ b/shlibs/mount/src/context.c
@@ -57,7 +57,6 @@ void mnt_free_context(mnt_context *cxt)
 
 	free(cxt->fstype_pattern);
 	free(cxt->optstr_pattern);
-	free(cxt->spec);
 	free(cxt->helper);
 	free(cxt->orig_user);
 
@@ -113,11 +112,9 @@ int mnt_reset_context(mnt_context *cxt)
 	cxt->fs = NULL;
 	cxt->mtab = NULL;
 
-	free(cxt->spec);
 	free(cxt->helper);
 	free(cxt->orig_user);
 
-	cxt->spec = NULL;
 	cxt->helper = NULL;
 
 	cxt->mountflags = 0;
@@ -333,27 +330,6 @@ int mnt_context_enable_loopdel(mnt_context *cxt, int enable)
 }
 
 /**
- * mnt_context_set_spec:
- * @cxt: mount context
- * @spec: unresolved source (device, label, uuid, ...) or target (mountpoint)
- *
- * Returns: 0 on success, negative number in case of error.
- */
-int mnt_context_set_spec(mnt_context *cxt, const char *spec)
-{
-	char *p;
-
-	if (!cxt)
-		return -EINVAL;
-	p = strdup(spec);
-	if (!p)
-		return -ENOMEM;
-	free(cxt->spec);
-	cxt->spec = p;
-	return 0;
-}
-
-/**
  * mnt_context_set_fs:
  * @cxt: mount context
  * @fs: filesystem description
@@ -960,3 +936,147 @@ int mnt_context_prepare_update(mnt_context *cxt, int act)
 	return rc;
 }
 
+static int is_remount(mnt_context *cxt)
+{
+	unsigned long fl = 0;
+
+	if (cxt->mountflags & MS_REMOUNT)
+		return 1;
+	if (!mnt_context_get_mountflags(cxt, &fl) && (fl & MS_REMOUNT))
+		return 1;
+	return 0;
+}
+
+static int apply_tab(mnt_context *cxt, mnt_tab *tb)
+{
+	mnt_fs *fs = NULL;
+	const char *src = NULL, *tgt = NULL;
+	int rc;
+
+	if (!cxt->fs)
+		return -EINVAL;
+
+	src = mnt_fs_get_source(cxt->fs);
+	tgt = mnt_fs_get_target(cxt->fs);
+
+	if (tgt && src)
+		;	/* TODO: search pair for MNT_OPTSMODE_FORCE */
+	else {
+		if (src)
+			fs = mnt_tab_find_source(tb, src, MNT_ITER_FORWARD);
+		else if (tgt)
+			fs = mnt_tab_find_target(tb, tgt, MNT_ITER_FORWARD);
+
+		if (!fs) {
+			/* swap source and target (if @src is not LABEL/UUID),
+			 * for example in
+			 *
+			 *	mount /foo/bar
+			 *
+			 * the path could be a mountpoint as well as source (for
+			 * example bind mount, symlink to device, ...).
+			 */
+			if (src && !mnt_fs_get_tag(cxt->fs, NULL, NULL))
+				fs = mnt_tab_find_target(tb, src,
+							MNT_ITER_FORWARD);
+			if (!fs && tgt)
+				fs = mnt_tab_find_source(tb, tgt,
+							MNT_ITER_FORWARD);
+		}
+	}
+
+	if (!fs)
+		return -EINVAL;
+
+	DBG(CXT, mnt_debug_h(cxt, "apply entry:"));
+	DBG(CXT, mnt_fs_print_debug(fs, stderr));
+
+	/* copy from fstab to our FS description
+	 */
+	rc = mnt_fs_set_source(cxt->fs, mnt_fs_get_source(fs));
+	if (!rc)
+		rc = mnt_fs_set_target(cxt->fs, mnt_fs_get_target(fs));
+
+	if (!rc && !mnt_fs_get_fstype(cxt->fs))
+		rc = mnt_fs_set_fstype(cxt->fs, mnt_fs_get_fstype(fs));
+
+	if (!rc && cxt->optsmode != MNT_OPTSMODE_IGNORE)
+		rc = mnt_fs_prepend_optstr(cxt->fs, mnt_fs_get_optstr(fs));
+
+	if (!rc)
+		cxt->flags |= MNT_FL_FSTAB_APPLIED;
+
+	return rc;
+}
+
+int mnt_context_apply_fstab(mnt_context *cxt)
+{
+	int rc;
+	mnt_cache *cache;
+	const char *src = NULL, *tgt = NULL;
+
+	if (!cxt || !cxt->fs)
+		return -EINVAL;
+
+	if (cxt->flags & MNT_FL_FSTAB_APPLIED)
+		return 0;
+
+	if (cxt->fs) {
+		src = mnt_fs_get_source(cxt->fs);
+		tgt = mnt_fs_get_target(cxt->fs);
+	}
+
+	/* fstab is not required if source and target are specified */
+	if (src && tgt && !(cxt->optsmode == MNT_OPTSMODE_FORCE ||
+			    cxt->optsmode == MNT_OPTSMODE_MTABFORCE))
+		return 0;
+
+	DBG(CXT, mnt_debug_h(cxt,
+		"trying to apply fstab (src=%s, target=%s)", src, tgt));
+
+	/* initialize fstab */
+	if (!cxt->fstab) {
+		cxt->fstab = mnt_new_tab();
+		if (!cxt->fstab)
+			goto errnomem;
+		cxt->flags &= ~MNT_FL_EXTERN_FSTAB;
+		rc = mnt_tab_parse_fstab(cxt->fstab);
+		if (rc)
+			goto err;
+	}
+
+	cache = mnt_context_get_cache(cxt);	/* NULL if MNT_FL_NOCANONICALIZE is enabled */
+
+	/*  never touch an external fstab */
+	if (!(cxt->flags & MNT_FL_EXTERN_FSTAB))
+		mnt_tab_set_cache(cxt->fstab, cache);
+
+	/* let's initialize cxt->fs */
+	mnt_context_get_fs(cxt);
+
+	/* try fstab */
+	rc = apply_tab(cxt, cxt->fstab);
+
+	/* try mtab */
+	if (rc || (cxt->optsmode == MNT_OPTSMODE_MTABFORCE && is_remount(cxt))) {
+
+		cxt->mtab = mnt_new_tab();
+		if (!cxt->mtab)
+			goto errnomem;
+		rc = mnt_tab_parse_mtab(cxt->mtab);
+		if (rc)
+			goto err;
+
+		mnt_tab_set_cache(cxt->mtab, cache);
+		rc = apply_tab(cxt, cxt->mtab);
+		if (rc)
+			goto err;
+	}
+	return 0;
+
+errnomem:
+	rc = ENOMEM;
+err:
+	DBG(CXT, mnt_debug_h(cxt, "failed to found entry in fstab/mtab"));
+	return rc;
+}