From: Karel Zak <kzak@redhat.com>
Date: Tue, 24 Jan 2023 17:35:21 +0000 (+0100)
Subject: libmount: don't require return argument in get-like functions
X-Git-Tag: v2.39-rc1~116
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6729c112f73d04232db8a976b335e5eab2bd519e;p=thirdparty%2Futil-linux.git

libmount: don't require return argument in get-like functions

Fixes: https://github.com/util-linux/util-linux/issues/2039
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libmount/src/monitor.c b/libmount/src/monitor.c
index dada02ed39..f99751e71e 100644
--- a/libmount/src/monitor.c
+++ b/libmount/src/monitor.c
@@ -171,14 +171,16 @@ static int monitor_next_entry(struct libmnt_monitor *mn,
 
 	assert(mn);
 	assert(itr);
-	assert(me);
 
-	*me = NULL;
+	if (me)
+		*me = NULL;
 
 	if (!itr->head)
 		MNT_ITER_INIT(itr, &mn->ents);
 	if (itr->p != itr->head) {
-		MNT_ITER_ITERATE(itr, *me, struct monitor_entry, ents);
+		if (me)
+			*me = MNT_ITER_GET_ENTRY(itr, struct monitor_entry, ents);
+		MNT_ITER_ITERATE(itr);
 		rc = 0;
 	}
 
diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index 964b896735..438ccfa7ef 100644
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -174,9 +174,11 @@ struct libmnt_iter {
 		(itr)->head = (list); \
 	} while(0)
 
-#define MNT_ITER_ITERATE(itr, res, restype, member) \
+#define MNT_ITER_GET_ENTRY(itr, restype, member) \
+		list_entry((itr)->p, restype, member)
+
+#define MNT_ITER_ITERATE(itr) \
 	do { \
-		res = list_entry((itr)->p, restype, member); \
 		(itr)->p = IS_ITER_FORWARD(itr) ? \
 				(itr)->p->next : (itr)->p->prev; \
 	} while(0)
diff --git a/libmount/src/optlist.c b/libmount/src/optlist.c
index a226028ee8..d0243d9039 100644
--- a/libmount/src/optlist.c
+++ b/libmount/src/optlist.c
@@ -232,14 +232,17 @@ int mnt_optlist_next_opt(struct libmnt_optlist *ls,
 {
 	int rc = 1;
 
-	if (!ls || !itr || !opt)
+	if (!ls || !itr)
 		return -EINVAL;
-	*opt = NULL;
+	if (opt)
+		*opt = NULL;
 
 	if (!itr->head)
 		MNT_ITER_INIT(itr, &ls->opts);
 	if (itr->p != itr->head) {
-		MNT_ITER_ITERATE(itr, *opt, struct libmnt_opt, opts);
+		if (opt)
+			*opt = MNT_ITER_GET_ENTRY(itr, struct libmnt_opt, opts);
+		MNT_ITER_ITERATE(itr);
 		rc = 0;
 	}
 
diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index 0133ff6185..a7da09481c 100644
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -590,7 +590,7 @@ static inline struct libmnt_fs *get_parent_fs(struct libmnt_table *tb, struct li
 /**
  * mnt_table_get_root_fs:
  * @tb: mountinfo file (/proc/self/mountinfo)
- * @root: returns pointer to the root filesystem (/)
+ * @root: NULL or returns pointer to the root filesystem (/)
  *
  * The function uses the parent ID from the mountinfo file to determine the
  * root filesystem (the filesystem with the smallest ID with parent ID missing
@@ -609,37 +609,38 @@ static inline struct libmnt_fs *get_parent_fs(struct libmnt_table *tb, struct li
 int mnt_table_get_root_fs(struct libmnt_table *tb, struct libmnt_fs **root)
 {
 	struct libmnt_iter itr;
-	struct libmnt_fs *fs;
+	struct libmnt_fs *fs, *root_fs = NULL;
 	int root_id = 0;
 
-	if (!tb || !root || !is_mountinfo(tb))
+	if (!tb || !is_mountinfo(tb))
 		return -EINVAL;
 
 	DBG(TAB, ul_debugobj(tb, "lookup root fs"));
 
-	*root = NULL;
-
 	/* get smallest possible ID from the table */
 	mnt_reset_iter(&itr, MNT_ITER_FORWARD);
-	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+	while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
 		int id = mnt_fs_get_parent_id(fs);
 
-		if (!*root || id < root_id) {
-			*root = fs;
+		if (!root_fs || id < root_id) {
+			root_fs = fs;
 			root_id = id;
 		}
 	}
 
 	/* go to the root node by "parent_id -> id" relation */
-	while (*root) {
-		struct libmnt_fs *x = get_parent_fs(tb, *root);
-		if (!x || x == *root)
+	while (root_fs) {
+		struct libmnt_fs *x = get_parent_fs(tb, root_fs);
+		if (!x || x == root_fs)
 			break;
 		DBG(TAB, ul_debugobj(tb, " messy mountinfo, walk to %s", mnt_fs_get_target(x)));
-		*root = x;
+		root_fs = x;
 	}
 
-	return *root ? 0 : -EINVAL;
+	if (root)
+		*root = root_fs;
+
+	return root_fs ? 0 : -EINVAL;
 }
 
 /**
@@ -647,7 +648,7 @@ int mnt_table_get_root_fs(struct libmnt_table *tb, struct libmnt_fs **root)
  * @tb: mountinfo file (/proc/self/mountinfo)
  * @itr: iterator
  * @parent: parental FS
- * @chld: returns the next child filesystem
+ * @chld: NULL or returns the next child filesystem
  *
  * Note that filesystems are returned in the order of mounting (according to
  * IDs in /proc/self/mountinfo).
@@ -657,7 +658,7 @@ int mnt_table_get_root_fs(struct libmnt_table *tb, struct libmnt_fs **root)
 int mnt_table_next_child_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
 			struct libmnt_fs *parent, struct libmnt_fs **chld)
 {
-	struct libmnt_fs *fs;
+	struct libmnt_fs *fs, *chfs = NULL;
 	int parent_id, lastchld_id = 0, chld_id = 0;
 
 	if (!tb || !itr || !parent || !is_mountinfo(tb))
@@ -665,19 +666,17 @@ int mnt_table_next_child_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
 
 	DBG(TAB, ul_debugobj(tb, "lookup next child of '%s'",
 				mnt_fs_get_target(parent)));
-
 	parent_id = mnt_fs_get_id(parent);
 
 	/* get ID of the previously returned child */
 	if (itr->head && itr->p != itr->head) {
-		MNT_ITER_ITERATE(itr, fs, struct libmnt_fs, ents);
+		fs = MNT_ITER_GET_ENTRY(itr, struct libmnt_fs, ents);
+		MNT_ITER_ITERATE(itr);
 		lastchld_id = mnt_fs_get_id(fs);
 	}
 
-	*chld = NULL;
-
 	mnt_reset_iter(itr, MNT_ITER_FORWARD);
-	while(mnt_table_next_fs(tb, itr, &fs) == 0) {
+	while (mnt_table_next_fs(tb, itr, &fs) == 0) {
 		int id;
 
 		if (mnt_fs_get_parent_id(fs) != parent_id)
@@ -691,17 +690,19 @@ int mnt_table_next_child_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
 			continue;
 
 		if ((!lastchld_id || id > lastchld_id) &&
-		    (!*chld || id < chld_id)) {
-			*chld = fs;
+		    (!chfs || id < chld_id)) {
+			chfs = fs;
 			chld_id = id;
 		}
 	}
 
-	if (!*chld)
+	if (chld)
+		*chld = chfs;
+	if (!chfs)
 		return 1;	/* end of iterator */
 
-	/* set the iterator to the @chld for the next call */
-	mnt_table_set_iter(tb, itr, *chld);
+	/* set the iterator to the @chfs for the next call */
+	mnt_table_set_iter(tb, itr, chfs);
 
 	return 0;
 }
@@ -765,7 +766,7 @@ int mnt_table_over_fs(struct libmnt_table *tb, struct libmnt_fs *parent,
  * mnt_table_next_fs:
  * @tb: tab pointer
  * @itr: iterator
- * @fs: returns the next tab entry
+ * @fs: NULL or returns the next tab entry
  *
  * Returns: 0 on success, negative number in case of error or 1 at the end of list.
  *
@@ -785,14 +786,17 @@ int mnt_table_next_fs(struct libmnt_table *tb, struct libmnt_iter *itr, struct l
 {
 	int rc = 1;
 
-	if (!tb || !itr || !fs)
+	if (!tb || !itr)
 		return -EINVAL;
-	*fs = NULL;
+	if (fs)
+		*fs = NULL;
 
 	if (!itr->head)
 		MNT_ITER_INIT(itr, &tb->ents);
 	if (itr->p != itr->head) {
-		MNT_ITER_ITERATE(itr, *fs, struct libmnt_fs, ents);
+		if (fs)
+			*fs = MNT_ITER_GET_ENTRY(itr, struct libmnt_fs, ents);
+		MNT_ITER_ITERATE(itr);
 		rc = 0;
 	}
 
@@ -802,34 +806,36 @@ int mnt_table_next_fs(struct libmnt_table *tb, struct libmnt_iter *itr, struct l
 /**
  * mnt_table_first_fs:
  * @tb: tab pointer
- * @fs: returns the first tab entry
+ * @fs: NULL or returns the first tab entry
  *
  * Returns: 0 on success, negative number in case of error or 1 at the end of list.
  */
 int mnt_table_first_fs(struct libmnt_table *tb, struct libmnt_fs **fs)
 {
-	if (!tb || !fs)
+	if (!tb)
 		return -EINVAL;
 	if (list_empty(&tb->ents))
 		return 1;
-	*fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
+	if (fs)
+		*fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
 	return 0;
 }
 
 /**
  * mnt_table_last_fs:
  * @tb: tab pointer
- * @fs: returns the last tab entry
+ * @fs: NULL or returns the last tab entry
  *
  * Returns: 0 on success, negative number in case of error or 1 at the end of list.
  */
 int mnt_table_last_fs(struct libmnt_table *tb, struct libmnt_fs **fs)
 {
-	if (!tb || !fs)
+	if (!tb)
 		return -EINVAL;
 	if (list_empty(&tb->ents))
 		return 1;
-	*fs = list_last_entry(&tb->ents, struct libmnt_fs, ents);
+	if (fs)
+		*fs = list_last_entry(&tb->ents, struct libmnt_fs, ents);
 	return 0;
 }
 
@@ -839,7 +845,7 @@ int mnt_table_last_fs(struct libmnt_table *tb, struct libmnt_fs **fs)
  * @itr: iterator
  * @match_func: function returning 1 or 0
  * @userdata: extra data for match_func
- * @fs: returns pointer to the next matching table entry
+ * @fs: NULL or returns pointer to the next matching table entry
  *
  * This function allows searching in @tb.
  *
@@ -849,26 +855,32 @@ int mnt_table_find_next_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
 		int (*match_func)(struct libmnt_fs *, void *), void *userdata,
 		struct libmnt_fs **fs)
 {
-	if (!tb || !itr || !fs || !match_func)
+	struct libmnt_fs *re = NULL;
+	int match = 0;
+
+	if (!tb || !itr || !match_func)
 		return -EINVAL;
 
 	DBG(TAB, ul_debugobj(tb, "lookup next fs"));
 
+	if (fs)
+		*fs = NULL;
 	if (!itr->head)
 		MNT_ITER_INIT(itr, &tb->ents);
 
-	do {
-		if (itr->p != itr->head)
-			MNT_ITER_ITERATE(itr, *fs, struct libmnt_fs, ents);
-		else
-			break;			/* end */
+	while (!match) {
+		if (itr->p != itr->head) {
+			re = MNT_ITER_GET_ENTRY(itr, struct libmnt_fs, ents);
+			MNT_ITER_ITERATE(itr);
+		} else
+			return 1;	/*end */
 
-		if (match_func(*fs, userdata))
-			return 0;
-	} while(1);
+		match = match_func(re, userdata);
+	}
 
-	*fs = NULL;
-	return 1;
+	if (fs)
+		*fs = re;
+	return 0;
 }
 
 static int mnt_table_move_parent(struct libmnt_table *tb, int oldid, int newid)
diff --git a/libmount/src/tab_diff.c b/libmount/src/tab_diff.c
index 81694bc6df..d5fbc4d49c 100644
--- a/libmount/src/tab_diff.c
+++ b/libmount/src/tab_diff.c
@@ -110,7 +110,8 @@ int mnt_tabdiff_next_change(struct libmnt_tabdiff *df, struct libmnt_iter *itr,
 	if (!itr->head)
 		MNT_ITER_INIT(itr, &df->changes);
 	if (itr->p != itr->head) {
-		MNT_ITER_ITERATE(itr, de, struct tabdiff_entry, changes);
+		de = MNT_ITER_GET_ENTRY(itr, struct tabdiff_entry, changes);
+		MNT_ITER_ITERATE(itr);
 		rc = 0;
 	}