Make get_xattr_names() even safer at fetching the list of attr names.

diff --git a/xattrs.c b/xattrs.c
index 61d4f60..9eca6bd 100644 (file)
--- a/xattrs.c
+++ b/xattrs.c
@@ -111,6 +111,7 @@ static int rsync_xal_compare_names(const void *x1, const void *x2)
 static ssize_t get_xattr_names(const char *fname)
 {
        ssize_t list_len;
+       double arg;
 
        if (!namebuf) {
                namebuf_len = 1024;
@@ -119,39 +120,36 @@ static ssize_t get_xattr_names(const char *fname)
                        out_of_memory("get_xattr_names");
        }
 
-       /* The length returned includes all the '\0' terminators. */
-       list_len = sys_llistxattr(fname, namebuf, namebuf_len);
-       if (list_len > (ssize_t)namebuf_len) {
-               list_len = -1;
-               errno = ERANGE;
-       }
-       if (list_len >= 0)
-               return list_len;
-       if (errno == ENOTSUP)
-               return 0;
-       if (errno == ERANGE) {
-               list_len = sys_llistxattr(fname, NULL, 0);
-               if (list_len < 0) {
+       while (1) {
+               /* The length returned includes all the '\0' terminators. */
+               list_len = sys_llistxattr(fname, namebuf, namebuf_len);
+               if (list_len >= 0) {
+                       if ((size_t)list_len <= namebuf_len)
+                               break;
+               } else if (errno == ENOTSUP)
+                       return 0;
+               else if (errno != ERANGE) {
+                       arg = (double)namebuf_len;
+                 got_error:
                        rsyserr(FERROR_XFER, errno,
-                               "get_xattr_names: llistxattr(\"%s\",0) failed",
-                               fname);
+                               "get_xattr_names: llistxattr(\"%s\",%.0f) failed",
+                               fname, arg);
                        return -1;
                }
+               list_len = sys_llistxattr(fname, NULL, 0);
+               if (list_len < 0) {
+                       arg = 0;
+                       goto got_error;
+               }
                if (namebuf_len)
                        free(namebuf);
                namebuf_len = list_len + 1024;
                namebuf = new_array(char, namebuf_len);
                if (!namebuf)
                        out_of_memory("get_xattr_names");
-               list_len = sys_llistxattr(fname, namebuf, namebuf_len);
-               if (list_len >= 0)
-                       return list_len;
        }
 
-       rsyserr(FERROR_XFER, errno,
-               "get_xattr_names: llistxattr(\"%s\",%ld) failed",
-               fname, (long)namebuf_len);
-       return -1;
+       return list_len;
 }
 
 /* On entry, the *len_ptr parameter contains the size of the extra space we