[PATCH 2/2] erofs-utils: mkfs: skip xattrs where getxattr() returns ENODATA

[Gao Xiang]

For example, unprivileged users may not have access to the `trusted.*`
namespace.

It also dumps unidentified xattrs with index 0, which the kernel/FUSE
implementations will ignore.

Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
---
 lib/xattr.c | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/lib/xattr.c b/lib/xattr.c
index b382ee4..091c88c 100644
--- a/lib/xattr.c
+++ b/lib/xattr.c
@@ -165,6 +165,8 @@ bool erofs_xattr_prefix_matches(const char *key, unsigned 
int *index,
 {
        struct xattr_prefix *p;
 
+       *index = 0;
+       *len = 0;
        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;
@@ -219,13 +221,9 @@ static struct xattr_item *get_xattritem(char *kvbuf, 
unsigned int len[2])
        if (!item)
                return ERR_PTR(-ENOMEM);
 
-       if (!erofs_xattr_prefix_matches(kvbuf, &item->base_index,
-                                       &item->prefix_len)) {
-               free(item);
-               return ERR_PTR(-ENODATA);
-       }
+       (void)erofs_xattr_prefix_matches(kvbuf, &item->base_index,
+                                        &item->prefix_len);
        DBG_BUGON(len[0] < item->prefix_len);
-
        INIT_HLIST_NODE(&item->node);
        item->count = 1;
        item->kvbuf = kvbuf;
@@ -292,12 +290,7 @@ static struct xattr_item *parse_one_xattr(const char 
*path, const char *key,
        item = get_xattritem(kvbuf, len);
        if (!IS_ERR(item))
                return item;
-       if (item == ERR_PTR(-ENODATA)) {
-               erofs_warn("skipped unidentified xattr: %s", key);
-               ret = 0;
-       } else {
-               ret = PTR_ERR(item);
-       }
+       ret = PTR_ERR(item);
 out:
        free(kvbuf);
        return ERR_PTR(ret);
@@ -443,13 +436,16 @@ static int read_xattrs_from_file(const char *path, mode_t 
mode,
                        continue;
 
                item = parse_one_xattr(path, key, keylen);
+               /* skip inaccessible xattrs */
+               if (item == ERR_PTR(-ENODATA) || !item) {
+                       erofs_warn("skipped inaccessible xattr %s in %s",
+                                  key, path);
+                       continue;
+               }
                if (IS_ERR(item)) {
                        ret = PTR_ERR(item);
                        goto err;
                }
-               /* skip unidentified xattrs */
-               if (!item)
-                       continue;
 
                ret = erofs_xattr_add(ixattrs, item);
                if (ret < 0)
@@ -1430,7 +1426,6 @@ int erofs_getxattr(struct erofs_inode *vi, const char 
*name, char *buffer,
 
        if (!erofs_xattr_prefix_matches(name, &prefix, &prefixlen))
                return -ENODATA;
-
        it.it.sbi = vi->sbi;
        it.index = prefix;
        it.name = name + prefixlen;
-- 
2.43.5