Catch compressor execution errors.

* src/misc.c (write_fatal_details): Move to buffer.c
* src/buffer.c (write_fatal_details): Close the archive and wait for
the compressor program to terminate in order to catch eventual execution
errors.
* src/system.c (sys_child_open_for_compress): Ignore SIGPIPE so tar will
not silently terminate when unable to write to the compressor.
* tests/comperr.at: New file.
* tests/Makefile.am: Add comperr.at
* tests/testsuite.at: Include comperr.at

src/buffer.c

@@ -1115,6 +1115,16 @@ close_archive (void)
   bufmap_free (NULL);
 }
 
+void
+write_fatal_details (char const *name, ssize_t status, size_t size)
+{
+  write_error_details (name, status, size);
+  if (rmtclose (archive) != 0)
+    close_error (*archive_name_cursor);
+  sys_wait_for_child (child_pid, false);
+  fatal_exit ();
+}
+
 /* Called to initialize the global volume number.  */
 void
 init_volume_number (void)

src/misc.c

@@ -1113,13 +1113,6 @@ file_removed_diag (const char *name, bool top_level,
     diagfn (name);
 }
 
-void
-write_fatal_details (char const *name, ssize_t status, size_t size)
-{
-  write_error_details (name, status, size);
-  fatal_exit ();
-}
-
 /* Fork, aborting if unsuccessful.  */
 pid_t
 xfork (void)

src/system.c

@@ -330,6 +330,7 @@ sys_child_open_for_compress (void)
   pid_t grandchild_pid;
   pid_t child_pid;
 
+  signal (SIGPIPE, SIG_IGN);
   xpipe (parent_pipe);
   child_pid = xfork ();