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author | Claudio Fontana <sick_soul@users.sourceforge.net> | 2005-11-01 09:38:51 +0000 |
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committer | Claudio Fontana <sick_soul@users.sourceforge.net> | 2005-11-01 09:38:51 +0000 |
commit | c43b80e61df1aeb6d7872d89baa35a28dd05bd40 (patch) | |
tree | 22fb26c4916c45c898c7ddd5ff07cfd73523b152 /lib/closeout.c | |
parent | c12afffc3d06c2acfc5fab3aa4746d1096f4950a (diff) | |
download | idutils-c43b80e61df1aeb6d7872d89baa35a28dd05bd40.tar.gz idutils-c43b80e61df1aeb6d7872d89baa35a28dd05bd40.tar.bz2 idutils-c43b80e61df1aeb6d7872d89baa35a28dd05bd40.zip |
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Diffstat (limited to 'lib/closeout.c')
-rw-r--r-- | lib/closeout.c | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/lib/closeout.c b/lib/closeout.c new file mode 100644 index 0000000..5d0509d --- /dev/null +++ b/lib/closeout.c @@ -0,0 +1,101 @@ +/* closeout.c - close standard output + + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 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 prev_fail = ferror (stdout); + bool none_pending = (0 == __fpending (stdout)); + bool fclose_fail = fclose (stdout); + + 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); + } +} |