/* Close standard input, rewinding seekable stdin if necessary.
- Copyright (C) 2007 Free Software Foundation, Inc.
+ Copyright (C) 2007, 2009-2013 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/>. */
#include <config.h>
#include "closein.h"
-#include "closeout.h"
#include <errno.h>
#include <stdbool.h>
#define _(msgid) gettext (msgid)
#include "close-stream.h"
+#include "closeout.h"
#include "error.h"
#include "exitfail.h"
+#include "freadahead.h"
#include "quotearg.h"
static const char *file_name;
For example, POSIX requires that these two commands behave alike:
(sed -ne 1q; cat) < file
- tail -n 1 file
+ tail -n +2 file
Since close_stdin is commonly registered via 'atexit', POSIX
and the C standard both say that it should not call 'exit',
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_stdin (void)
{
bool fail = false;
- if (fflush (stdin) != 0 || close_stream (stdin) != 0)
+
+ /* There is no need to flush stdin if we can determine quickly that stdin's
+ input buffer is empty; in this case we know that if stdin is seekable,
+ (fseeko (stdin, 0, SEEK_CUR), ftello (stdin))
+ == lseek (0, 0, SEEK_CUR). */
+ if (freadahead (stdin) > 0)
{
+ /* Only attempt flush if stdin is seekable, as fflush is entitled to
+ fail on non-seekable streams. */
+ if (fseeko (stdin, 0, SEEK_CUR) == 0 && fflush (stdin) != 0)
+ fail = true;
+ }
+ if (close_stream (stdin) != 0)
+ fail = true;
+ if (fail)
+ {
+ /* Report failure, but defer exit until after closing stdout,
+ since the failure report should still be flushed. */
char const *close_error = _("error closing file");
if (file_name)
- error (0, errno, "%s: %s", quotearg_colon (file_name),
- close_error);
+ error (0, errno, "%s: %s", quotearg_colon (file_name),
+ close_error);
else
- error (0, errno, "%s", close_error);
-
- /* Defer failure until after closing stdout, since the output
- can still usefully be flushed. */
- fail = true;
+ error (0, errno, "%s", close_error);
}
close_stdout ();