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/* closeout.c - close standard output
Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006 Free
Software Foundation, Inc.
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.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "closeout.h"
#include <stdio.h>
#include <stdbool.h>
#include <errno.h>
#include "gettext.h"
#define _(msgid) gettext (msgid)
#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;
/* Set the file name to be reported in the event an error is detected
by close_stdout. */
void
close_stdout_set_file_name (const char *file)
{
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.
It's important to detect such failures and exit nonzero because many
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 none_pending = (__fpending (stdout) == 0);
bool prev_fail = (ferror (stdout) != 0);
bool fclose_fail = (fclose (stdout) != 0);
if (prev_fail || fclose_fail)
{
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);
else
error (exit_failure, e, "%s", write_error);
}
}
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