(append_file): Open the file before statting it, to avoid a race.

Complain about file shrinkage only when we reach EOF.

diff --git a/src/update.c b/src/update.c
index ea4dccf9a48efb75c88e0a566cac38e39e6054c9..5982b9ffe313976a51ed5f993144b31f9198e033 100644 (file)
--- a/src/update.c
+++ b/src/update.c
@@ -45,52 +45,51 @@ char *output_start;
 static void
 append_file (char *path)
 {
-  int handle;
+  int handle = open (path, O_RDONLY | O_BINARY);
   struct stat stat_data;
-  off_t bytes_left;
 
-  if (stat (path, &stat_data) != 0
-      || (handle = open (path, O_RDONLY | O_BINARY), handle < 0))
+  if (handle < 0)
     {
       ERROR ((0, errno, _("Cannot open file %s"), path));
       return;
     }
 
-  bytes_left = stat_data.st_size;
-
-  while (bytes_left > 0)
+  if (fstat (handle, &stat_data) != 0)
+    ERROR ((0, errno, "%s", path));
+  else
     {
-      union block *start = find_next_block ();
-      size_t buffer_size = available_space_after (start);
-      ssize_t status;
-
-      if (bytes_left < buffer_size)
-       {
-         buffer_size = bytes_left;
-         status = buffer_size % BLOCKSIZE;
-         if (status)
-           memset (start->buffer + bytes_left, 0,
-                   (size_t) (BLOCKSIZE - status));
-       }
+      off_t bytes_left = stat_data.st_size;
 
-      status = safe_read (handle, start->buffer, buffer_size);
-      if (status < 0)
+      while (bytes_left > 0)
        {
+         union block *start = find_next_block ();
+         size_t buffer_size = available_space_after (start);
+         ssize_t status;
          char buf[UINTMAX_STRSIZE_BOUND];
-         FATAL_ERROR ((0, errno,
-                       _("Read error at byte %s reading %lu bytes in file %s"),
-                       STRINGIFY_BIGINT (stat_data.st_size - bytes_left, buf),
-                       (unsigned long) buffer_size, path));
-       }
-      bytes_left -= status;
 
-      set_next_block_after (start + (status - 1) / BLOCKSIZE);
+         if (bytes_left < buffer_size)
+           {
+             buffer_size = bytes_left;
+             status = buffer_size % BLOCKSIZE;
+             if (status)
+               memset (start->buffer + bytes_left, 0,
+                       (size_t) (BLOCKSIZE - status));
+           }
 
-      if (status != buffer_size)
-       {
-         char buf[UINTMAX_STRSIZE_BOUND];
-         FATAL_ERROR ((0, 0, _("%s: File shrunk by %s bytes, (yark!)"),
-                       path, STRINGIFY_BIGINT (bytes_left, buf)));
+         status = safe_read (handle, start->buffer, buffer_size);
+         if (status < 0)
+           FATAL_ERROR ((0, errno,
+                         _("Read error at byte %s reading %lu bytes in file %s"),
+                         STRINGIFY_BIGINT (stat_data.st_size - bytes_left,
+                                           buf),
+                         (unsigned long) buffer_size, path));
+         if (status == 0)
+           FATAL_ERROR ((0, 0, _("%s: File shrunk by %s bytes, (yark!)"),
+                         path, STRINGIFY_BIGINT (bytes_left, buf)));
+
+         bytes_left -= status;
+
+         set_next_block_after (start + (status - 1) / BLOCKSIZE);
        }
     }