[PATCH 2/3] erofs-utils: lib: add match_base_prefix() helper

[Jingbo Xu]

Since the introduction of long xattr name prefix, match_prefix() will
search among the long xattr name prefixes first and return the matched
prefix, while erofs_getxattr() expects a base prefix even when the
queried xattr name matches a long prefix.

Thus introduce match_base_prefix() helper to do this.

Signed-off-by: Jingbo Xu <jefflexu at linux.alibaba.com>
---
 lib/xattr.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/lib/xattr.c b/lib/xattr.c
index 2548750..4091fe6 100644
--- a/lib/xattr.c
+++ b/lib/xattr.c
@@ -137,27 +137,34 @@ static struct xattr_item *get_xattritem(u8 prefix, char *kvbuf,
 	return item;
 }
 
-static bool match_prefix(const char *key, u8 *index, u16 *len)
+static bool match_base_prefix(const char *key, u8 *index, u16 *len)
 {
 	struct xattr_prefix *p;
-	struct ea_type_node *tnode;
 
-	list_for_each_entry(tnode, &ea_name_prefixes, list) {
-		p = &tnode->type;
+	for (p = xattr_types; p < xattr_types + ARRAY_SIZE(xattr_types); ++p) {
 		if (p->prefix && !strncmp(p->prefix, key, p->prefix_len)) {
 			*len = p->prefix_len;
-			*index = tnode->index;
+			*index = p - xattr_types;
 			return true;
 		}
 	}
-	for (p = xattr_types; p < xattr_types + ARRAY_SIZE(xattr_types); ++p) {
+	return false;
+}
+
+static bool match_prefix(const char *key, u8 *index, u16 *len)
+{
+	struct xattr_prefix *p;
+	struct ea_type_node *tnode;
+
+	list_for_each_entry(tnode, &ea_name_prefixes, list) {
+		p = &tnode->type;
 		if (p->prefix && !strncmp(p->prefix, key, p->prefix_len)) {
 			*len = p->prefix_len;
-			*index = p - xattr_types;
+			*index = tnode->index;
 			return true;
 		}
 	}
-	return false;
+	return match_base_prefix(key, index, len);
 }
 
 static struct xattr_item *parse_one_xattr(const char *path, const char *key,
@@ -1198,7 +1205,7 @@ int erofs_getxattr(struct erofs_inode *vi, const char *name, char *buffer,
 	if (ret)
 		return ret;
 
-	if (!match_prefix(name, &prefix, &prefixlen))
+	if (!match_base_prefix(name, &prefix, &prefixlen))
 		return -ENODATA;
 
 	it.it.sbi = vi->sbi;
-- 
2.19.1.6.gb485710b