1 /* Close standard input, rewinding seekable stdin if necessary.
3 Copyright (C) 2007 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
30 #define _(msgid) gettext (msgid)
32 #include "close-stream.h"
37 static const char *file_name;
39 /* Set the file name to be reported in the event an error is detected
40 on stdin by close_stdin. See also close_stdout_set_file_name, if
41 an error is detected when closing stdout. */
43 close_stdin_set_file_name (const char *file)
48 /* Close standard input, rewinding any unused input if stdin is
49 seekable. On error, issue a diagnostic and _exit with status
50 'exit_failure'. Then call close_stdout.
52 Most programs can get by with close_stdout. close_stdin is only
53 needed when a program wants to guarantee that partially read input
54 from seekable stdin is not consumed, for any subsequent clients.
55 For example, POSIX requires that these two commands behave alike:
57 (sed -ne 1q; cat) < file
60 Since close_stdin is commonly registered via 'atexit', POSIX
61 and the C standard both say that it should not call 'exit',
62 because the behavior is undefined if 'exit' is called more than
63 once. So it calls '_exit' instead of 'exit'. If close_stdin
64 is registered via atexit before other functions are registered,
65 the other functions can act before this _exit is invoked.
67 Applications that use close_stdout should flush any streams other
68 than stdin, stdout, and stderr before exiting, since the call to
69 _exit will bypass other buffer flushing. Applications should be
70 flushing and closing other streams anyway, to check for I/O errors.
71 Also, applications should not use tmpfile, since _exit can bypass
72 the removal of these files.
74 It's important to detect such failures and exit nonzero because many
75 tools (most notably `make' and other build-management systems) depend
76 on being able to detect failure in other tools via their exit status. */
82 if (close_stream (stdin) != 0)
84 char const *close_error = _("error closing file");
86 error (0, errno, "%s: %s", quotearg_colon (file_name),
89 error (0, errno, "%s", close_error);
91 /* Defer failure until after closing stdout, since the output
92 can still usefully be flushed. */