lseek should not yield a negative file position

diff --git a/servers/avfs/open.c b/servers/avfs/open.c
index a236107fdff5ab4716ddc79de7b09b4cdefc5171..e3cbf44707154f112e197d02beeba6a978c7a9b6 100644 (file)
--- a/servers/avfs/open.c
+++ b/servers/avfs/open.c
@@ -612,9 +612,11 @@ PUBLIC int do_lseek()
        newpos = sub64ul(pos, -offset);
 
   /* Check for overflow. */
-  if (ex64hi(newpos) != 0)
-       r = EINVAL;
-  else {
+  if (ex64hi(newpos) != 0) {
+       r = EOVERFLOW;
+  } else if ((off_t) ex64lo(newpos) < 0) { /* no negative file size */
+       r = EOVERFLOW;
+  } else {
        rfilp->filp_pos = newpos;
 
        /* insert the new position into the output message */