Make sure that get_xattr_data() never tries to malloc 0 bytes.

[rsync/rsync.git] / xattrs.c

diff --git a/xattrs.c b/xattrs.c
index e65f652..23b5faa 100644 (file)
--- a/xattrs.c
+++ b/xattrs.c
@@ -161,8 +161,11 @@ static char *get_xattr_data(const char *fname, const char *name, size_t *len_ptr
                            int no_missing_error)
 {
        size_t datum_len = sys_lgetxattr(fname, name, NULL, 0);
+       size_t extra_len = *len_ptr;
        char *ptr;
 
+       *len_ptr = datum_len;
+
        if (datum_len == (size_t)-1) {
                if (errno == ENOTSUP || no_missing_error)
                        return NULL;
@@ -172,12 +175,12 @@ static char *get_xattr_data(const char *fname, const char *name, size_t *len_ptr
                return NULL;
        }
 
-       if (datum_len + *len_ptr < datum_len /* checks for overflow */
-        || !(ptr = new_array(char, datum_len + *len_ptr)))
+       if (!datum_len && !extra_len)
+               extra_len = 1; /* request non-zero amount of memory */
+       if (datum_len + extra_len < datum_len /* checks for overflow */
+        || !(ptr = new_array(char, datum_len + extra_len)))
                out_of_memory("get_xattr_data");
 
-       *len_ptr = datum_len;
-
        if (datum_len) {
                size_t len = sys_lgetxattr(fname, name, ptr, datum_len);
                if (len != datum_len) {
@@ -804,6 +807,7 @@ int set_xattr(const char *fname, const struct file_struct *file,
 char *get_xattr_acl(const char *fname, int is_access_acl, size_t *len_p)
 {
        const char *name = is_access_acl ? XACC_ACL_ATTR : XDEF_ACL_ATTR;
+       *len_p = 0; /* no extra data alloc needed from get_xattr_data() */
        return get_xattr_data(fname, name, len_p, 1);
 }