* nscd/connections.c (send_ro_fd): Also transfer file size.

	* nscd/nscd_helper.c (get_mapping): If nscd also transfers the
	file size don't call fstat.

ChangeLog

@@ -1,5 +1,9 @@
 2007-08-28  Ulrich Drepper  <drepper@redhat.com>
 
+	* nscd/connections.c (send_ro_fd): Also transfer file size.
+	* nscd/nscd_helper.c (get_mapping): If nscd also transfers the
+	file size don't call fstat.
+
 	* nscd/nscd_helper.c (get_mapping): Avoid the pread call, just go
 	ahead and map the file.  This should always be correct and we can
 	catch problems later.

nscd/connections.c

@@ -907,17 +907,22 @@ send_ro_fd (struct database_dyn *db, char *key, int fd)
     return;
 
   /* We need to send some data along with the descriptor.  */
-  struct iovec iov[1];
+  uint64_t mapsize = (db->head->data_size
+		      + roundup (db->head->module * sizeof (ref_t), ALIGN)
+		      + sizeof (struct database_pers_head));
+  struct iovec iov[2];
   iov[0].iov_base = key;
   iov[0].iov_len = strlen (key) + 1;
+  iov[1].iov_base = &mapsize;
+  iov[1].iov_len = sizeof (mapsize);
 
   /* Prepare the control message to transfer the descriptor.  */
   union
   {
     struct cmsghdr hdr;
     char bytes[CMSG_SPACE (sizeof (int))];
   } buf;
-  struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 1,
+  struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 2,
 			.msg_control = buf.bytes,
 			.msg_controllen = sizeof (buf) };
   struct cmsghdr *cmsg = CMSG_FIRSTHDR (&msg);

nscd/nscd_helper.c

@@ -238,16 +238,19 @@ get_mapping (request_type type, const char *key,
 
   /* Room for the data sent along with the file descriptor.  We expect
      the key name back.  */
-  struct iovec iov[1];
+  uint64_t mapsize;
+  struct iovec iov[2];
   iov[0].iov_base = resdata;
   iov[0].iov_len = keylen;
+  iov[1].iov_base = &mapsize;
+  iov[1].iov_len = sizeof (mapsize);
 
   union
   {
     struct cmsghdr hdr;
     char bytes[CMSG_SPACE (sizeof (int))];
   } buf;
-  struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 1,
+  struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 2,
 			.msg_control = buf.bytes,
 			.msg_controllen = sizeof (buf) };
   struct cmsghdr *cmsg = CMSG_FIRSTHDR (&msg);
@@ -268,10 +271,7 @@ get_mapping (request_type type, const char *key,
 # ifndef MSG_CMSG_CLOEXEC
 #  define MSG_CMSG_CLOEXEC 0
 # endif
-  if (__builtin_expect (TEMP_FAILURE_RETRY (__recvmsg (sock, &msg,
-						       MSG_CMSG_CLOEXEC))
-			!= keylen, 0))
-    goto out_close2;
+  ssize_t n = TEMP_FAILURE_RETRY (__recvmsg (sock, &msg, MSG_CMSG_CLOEXEC));
 
   if (__builtin_expect (CMSG_FIRSTHDR (&msg) == NULL
 			|| (CMSG_FIRSTHDR (&msg)->cmsg_len
@@ -280,14 +280,25 @@ get_mapping (request_type type, const char *key,
 
   mapfd = *(int *) CMSG_DATA (cmsg);
 
-  struct stat64 st;
-  if (__builtin_expect (strcmp (resdata, key) != 0, 0)
-      || __builtin_expect (fstat64 (mapfd, &st) != 0, 0)
-      || __builtin_expect (st.st_size < sizeof (struct database_pers_head), 0))
+  if (__builtin_expect (n != keylen && n != keylen + sizeof (mapsize), 0))
+    goto out_close;
+
+  if (__builtin_expect (strcmp (resdata, key) != 0, 0))
     goto out_close;
 
+  if (__builtin_expect (n == keylen, 0))
+    {
+      struct stat64 st;
+      if (__builtin_expect (fstat64 (mapfd, &st) != 0, 0)
+	  || __builtin_expect (st.st_size < sizeof (struct database_pers_head),
+			       0))
+	goto out_close;
+
+      mapsize = st.st_size;
+    }
+
   /* The file is large enough, map it now.  */
-  void *mapping = __mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, mapfd, 0);
+  void *mapping = __mmap (NULL, mapsize, PROT_READ, MAP_SHARED, mapfd, 0);
   if (__builtin_expect (mapping != MAP_FAILED, 1))
     {
       /* Check whether the database is correct and up-to-date.  */
@@ -302,15 +313,15 @@ get_mapping (request_type type, const char *key,
 				   < time (NULL)), 0))
 	{
 	out_unmap:
-	  __munmap (mapping, st.st_size);
+	  __munmap (mapping, mapsize);
 	  goto out_close;
 	}
 
       size_t size = (sizeof (*head) + roundup (head->module * sizeof (ref_t),
 					       ALIGN)
 		     + head->data_size);
 
-      if (__builtin_expect (st.st_size < size, 0))
+      if (__builtin_expect (mapsize < size, 0))
 	goto out_unmap;
 
       /* Allocate a record for the mapping.  */