mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-11-28 07:45:00 +00:00
79 lines
3.0 KiB
C
79 lines
3.0 KiB
C
/* Close a stream, with nicer error checking than fclose's.
|
|
|
|
Copyright (C) 1998-2002, 2004, 2006-2013 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 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
|
|
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, see <http://www.gnu.org/licenses/>. */
|
|
|
|
#include <config.h>
|
|
|
|
#include "close-stream.h"
|
|
|
|
#include <errno.h>
|
|
#include <stdbool.h>
|
|
|
|
#include "fpending.h"
|
|
|
|
#if USE_UNLOCKED_IO
|
|
# include "unlocked-io.h"
|
|
#endif
|
|
|
|
/* Close STREAM. Return 0 if successful, EOF (setting errno)
|
|
otherwise. A failure might set errno to 0 if the error number
|
|
cannot be determined.
|
|
|
|
A failure with errno set to EPIPE may or may not indicate an error
|
|
situation worth signaling to the user. See the documentation of the
|
|
close_stdout_set_ignore_EPIPE function for details.
|
|
|
|
If a program writes *anything* to STREAM, that program should close
|
|
STREAM 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 STREAM. The last
|
|
printf can succeed in writing to the internal stream buffer, and yet
|
|
the fclose(STREAM) 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 STREAM -- just let the internal stream state record
|
|
the failure. That's what the ferror test is checking below. */
|
|
|
|
int
|
|
close_stream (FILE *stream)
|
|
{
|
|
const bool some_pending = (__fpending (stream) != 0);
|
|
const bool prev_fail = (ferror (stream) != 0);
|
|
const bool fclose_fail = (fclose (stream) != 0);
|
|
|
|
/* Return an error indication if there was a previous failure or if
|
|
fclose failed, with one exception: ignore an fclose failure if
|
|
there was no previous error, no data remains to be flushed, and
|
|
fclose failed with EBADF. That can happen when a program like cp
|
|
is invoked like this 'cp a b >&-' (i.e., with standard output
|
|
closed) and doesn't generate any output (hence no previous error
|
|
and nothing to be flushed). */
|
|
|
|
if (prev_fail || (fclose_fail && (some_pending || errno != EBADF)))
|
|
{
|
|
if (! fclose_fail)
|
|
errno = 0;
|
|
return EOF;
|
|
}
|
|
|
|
return 0;
|
|
}
|