lib/closeout.c

   1 /* closeout.c - close standard output
   2    Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 #if HAVE_CONFIG_H
  19 # include <config.h>
  20 #endif
  21
  22 #include "closeout.h"
  23
  24 #include <stdio.h>
  25
  26 #include <errno.h>
  27 #ifndef errno
  28 extern int errno;
  29 #endif
  30
  31 #include "gettext.h"
  32 #define _(msgid) gettext (msgid)
  33
  34 #include "error.h"
  35 #include "exitfail.h"
  36 #include "quotearg.h"
  37 #include "unlocked-io.h"
  38 #include "__fpending.h"
  39
  40 static const char *file_name;
  41
  42 /* Set the file name to be reported in the event an error is detected
  43    by close_stdout.  */
  44 void
  45 close_stdout_set_file_name (const char *file)
  46 {
  47   file_name = file;
  48 }
  49
  50 /* Close standard output, exiting with status 'exit_failure' on failure.
  51    If a program writes *anything* to stdout, that program should `fflush'
  52    stdout and make sure that it succeeds before exiting.  Otherwise,
  53    suppose that you go to the extreme of checking the return status
  54    of every function that does an explicit write to stdout.  The last
  55    printf can succeed in writing to the internal stream buffer, and yet
  56    the fclose(stdout) could still fail (due e.g., to a disk full error)
  57    when it tries to write out that buffered data.  Thus, you would be
  58    left with an incomplete output file and the offending program would
  59    exit successfully.
  60
  61    FIXME: note the fflush suggested above is implicit in the fclose
  62    we actually do below.  Consider doing only the fflush and/or using
  63    setvbuf to inhibit buffering.
  64
  65    Besides, it's wasteful to check the return value from every call
  66    that writes to stdout -- just let the internal stream state record
  67    the failure.  That's what the ferror test is checking below.
  68
  69    It's important to detect such failures and exit nonzero because many
  70    tools (most notably `make' and other build-management systems) depend
  71    on being able to detect failure in other tools via their exit status.  */
  72
  73 void
  74 close_stdout (void)
  75 {
  76   int e = ferror (stdout) ? 0 : -1;
  77
  78   /* If the stream's error bit is clear and there is nothing to flush,
  79      then return right away.  */
  80   if (e && __fpending (stdout) == 0)
  81     return;
  82
  83   if (fclose (stdout) != 0)
  84     e = errno;
  85
  86   if (0 <= e)
  87     {
  88       char const *write_error = _("write error");
  89       if (file_name)
  90         error (exit_failure, e, "%s: %s", quotearg_colon (file_name),
  91                write_error);
  92       else
  93         error (exit_failure, e, "%s", write_error);
  94     }
  95 }