-/* closeout.c - close standard output
+/* Close standard output and standard error, exiting with a diagnostic on error.
- Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 Free Software
- Foundation, Inc.
+ Copyright (C) 1998-2002, 2004, 2006, 2008-2013 Free Software Foundation,
+ Inc.
- This program is free software; you can redistribute it and/or modify
+ This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
#include "closeout.h"
-#include <stdio.h>
-#include <stdbool.h>
#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
#include "gettext.h"
#define _(msgid) gettext (msgid)
+#include "close-stream.h"
#include "error.h"
#include "exitfail.h"
#include "quotearg.h"
-#include "__fpending.h"
-
-#if USE_UNLOCKED_IO
-# include "unlocked-io.h"
-#endif
static const char *file_name;
file_name = file;
}
-/* Close standard output, exiting with status 'exit_failure' on failure.
- If a program writes *anything* to stdout, that program should close
- stdout and make sure that it succeeds before exiting. Otherwise,
- suppose that you go to the extreme of checking the return status
- of every function that does an explicit write to stdout. The last
- printf can succeed in writing to the internal stream buffer, and yet
- the fclose(stdout) could still fail (due e.g., to a disk full error)
- when it tries to write out that buffered data. Thus, you would be
- left with an incomplete output file and the offending program would
- exit successfully. Even calling fflush is not always sufficient,
- since some file systems (NFS and CODA) buffer written/flushed data
- until an actual close call.
-
- Besides, it's wasteful to check the return value from every call
- that writes to stdout -- just let the internal stream state record
- the failure. That's what the ferror test is checking below.
+static bool ignore_EPIPE /* = false */;
+
+/* Specify the reaction to an EPIPE error during the closing of stdout:
+ - If ignore = true, it shall be ignored.
+ - If ignore = false, it shall evoke a diagnostic, along with a nonzero
+ exit status.
+ The default is ignore = false.
+
+ This setting matters only if the SIGPIPE signal is ignored (i.e. its
+ handler set to SIG_IGN) or blocked. Only particular programs need to
+ temporarily ignore SIGPIPE. If SIGPIPE is ignored or blocked because
+ it was ignored or blocked in the parent process when it created the
+ child process, it usually is a bug in the parent process: It is bad
+ practice to have SIGPIPE ignored or blocked while creating a child
+ process.
+
+ EPIPE occurs when writing to a pipe or socket that has no readers now,
+ when SIGPIPE is ignored or blocked.
+
+ The ignore = false setting is suitable for a scenario where it is normally
+ guaranteed that the pipe writer terminates before the pipe reader. In
+ this case, an EPIPE is an indication of a premature termination of the
+ pipe reader and should lead to a diagnostic and a nonzero exit status.
+
+ The ignore = true setting is suitable for a scenario where you don't know
+ ahead of time whether the pipe writer or the pipe reader will terminate
+ first. In this case, an EPIPE is an indication that the pipe writer can
+ stop doing useless write() calls; this is what close_stdout does anyway.
+ EPIPE is part of the normal pipe/socket shutdown protocol in this case,
+ and should not lead to a diagnostic message. */
+
+void
+close_stdout_set_ignore_EPIPE (bool ignore)
+{
+ ignore_EPIPE = ignore;
+}
+
+/* Close standard output. On error, issue a diagnostic and _exit
+ with status 'exit_failure'.
+
+ Also close standard error. On error, _exit with status 'exit_failure'.
+
+ Since close_stdout is commonly registered via 'atexit', POSIX
+ and the C standard both say that it should not call 'exit',
+ because the behavior is undefined if 'exit' is called more than
+ once. So it calls '_exit' instead of 'exit'. If close_stdout
+ is registered via atexit before other functions are registered,
+ the other functions can act before this _exit is invoked.
+
+ Applications that use close_stdout should flush any streams
+ other than stdout and stderr before exiting, since the call to
+ _exit will bypass other buffer flushing. Applications should
+ be flushing and closing other streams anyway, to check for I/O
+ errors. Also, applications should not use tmpfile, since _exit
+ can bypass the removal of these files.
It's important to detect such failures and exit nonzero because many
- tools (most notably `make' and other build-management systems) depend
+ tools (most notably 'make' and other build-management systems) depend
on being able to detect failure in other tools via their exit status. */
void
close_stdout (void)
{
- bool prev_fail = ferror (stdout);
- bool none_pending = (0 == __fpending (stdout));
- bool fclose_fail = fclose (stdout);
-
- if (prev_fail || fclose_fail)
+ if (close_stream (stdout) != 0
+ && !(ignore_EPIPE && errno == EPIPE))
{
- 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");
+ char const *write_error = _("write error");
if (file_name)
- error (exit_failure, e, "%s: %s", quotearg_colon (file_name),
- write_error);
+ error (0, errno, "%s: %s", quotearg_colon (file_name),
+ write_error);
else
- error (exit_failure, e, "%s", write_error);
+ error (0, errno, "%s", write_error);
+
+ _exit (exit_failure);
}
+
+ if (close_stream (stderr) != 0)
+ _exit (exit_failure);
}
projects / gnulib.git / blobdiff