[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Bug-gnulib] *now*, close_stdout always does
From: |
Jim Meyering |
Subject: |
Re: [Bug-gnulib] *now*, close_stdout always does |
Date: |
Sun, 14 Nov 2004 01:41:14 +0100 |
Jim Meyering <address@hidden> wrote:
> I wrote:
>> That makes it clear to me that close_stdout must always close
>> standard output.
Well, almost always.
Not when it's already closed at start-up.
Does anyone know how portable the use of EBADF is, below?
Without this change, ``mkdir D >&-'' (and many other tools
that needn't generate output) would fail unnecessarily.
I've just committed this in coreutils, along with some tests.
I'll update gnulib tomorrow.
2004-11-14 Jim Meyering <address@hidden>
* closeout.c (close_stdout): Don't fail just because stdout was
closed initially, since some programs don't write to stdout in the
normal course of operation (other than --version and --help), and
we don't want this function to make e.g. `cp 1 2 >&-' fail.
But do fail if it was closed and someone has tried to write to it.
E.g., printf 'foo' >&-
Index: lib/closeout.c
===================================================================
RCS file: /fetish/cu/lib/closeout.c,v
retrieving revision 1.16
retrieving revision 1.17
diff -u -p -u -r1.16 -r1.17
--- lib/closeout.c 6 Nov 2004 22:37:23 -0000 1.16
+++ lib/closeout.c 14 Nov 2004 00:20:01 -0000 1.17
@@ -24,6 +24,7 @@
#include "closeout.h"
#include <stdio.h>
+#include <stdbool.h>
#include <errno.h>
#include "gettext.h"
@@ -32,6 +33,7 @@
#include "error.h"
#include "exitfail.h"
#include "quotearg.h"
+#include "__fpending.h"
#if USE_UNLOCKED_IO
# include "unlocked-io.h"
@@ -71,14 +73,25 @@ close_stdout_set_file_name (const char *
void
close_stdout (void)
{
- int e = ferror (stdout) ? 0 : -1;
+ bool prev_fail = ferror (stdout);
+ bool none_pending = (0 == __fpending (stdout));
+ bool fclose_fail = fclose (stdout);
- if (fclose (stdout) != 0)
- e = errno;
-
- if (0 <= e)
+ if (prev_fail || fclose_fail)
{
- char const *write_error = _("write error");
+ int e = fclose_fail ? errno : 0;
+ char const *write_error;
+
+ /* If ferror returned zero, no data remains to be flushed, and we'd
+ otherwise fail with EBADF due to a failed fclose, then assume that
+ it's ok to ignore the fclose failure. That can happen when a
+ program like cp is invoked like this `cp a b >&-' (i.e., with
+ stdout closed) and doesn't generate any output (hence no previous
+ error and nothing to be flushed). */
+ if (e == EBADF && !prev_fail && none_pending)
+ return;
+
+ write_error = _("write error");
if (file_name)
error (exit_failure, e, "%s: %s", quotearg_colon (file_name),
write_error);