--- /dev/null
+/* Close standard input, rewinding seekable stdin if necessary.
+
+ Copyright (C) 2007 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 "closein.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 "closeout.h"
+#include "error.h"
+#include "exitfail.h"
+#include "freadahead.h"
+#include "quotearg.h"
+
+static const char *file_name;
+
+/* Set the file name to be reported in the event an error is detected
+ on stdin by close_stdin. See also close_stdout_set_file_name, if
+ an error is detected when closing stdout. */
+void
+close_stdin_set_file_name (const char *file)
+{
+ file_name = file;
+}
+
+/* Close standard input, rewinding any unused input if stdin is
+ seekable. On error, issue a diagnostic and _exit with status
+ 'exit_failure'. Then call close_stdout.
+
+ Most programs can get by with close_stdout. close_stdin is only
+ needed when a program wants to guarantee that partially read input
+ from seekable stdin is not consumed, for any subsequent clients.
+ For example, POSIX requires that these two commands behave alike:
+
+ (sed -ne 1q; cat) < file
+ tail -n 1 file
+
+ Since close_stdin 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_stdin
+ 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 stdin, 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
+ on being able to detect failure in other tools via their exit status. */
+
+void
+close_stdin (void)
+{
+ bool fail = false;
+
+ /* 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) == 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);
+ else
+ error (0, errno, "%s", close_error);
+ }
+
+ close_stdout ();
+
+ if (fail)
+ _exit (exit_failure);
+}
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