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 #if HAVE_STDLIB_H
  23 # include <stdlib.h>
  24 #endif
  25 #ifndef EXIT_FAILURE
  26 # define EXIT_FAILURE 1
  27 #endif
  28
  29 #include <stdio.h>
  30
  31 #include <errno.h>
  32 #ifndef errno
  33 extern int errno;
  34 #endif
  35
  36 #include "gettext.h"
  37 #define _(msgid) gettext (msgid)
  38
  39 #include "closeout.h"
  40 #include "error.h"
  41 #include "quotearg.h"
  42 #include "unlocked-io.h"
  43 #include "__fpending.h"
  44
  45 static int default_exit_status = EXIT_FAILURE;
  46 static const char *file_name;
  47
  48 /* Set the value to be used for the exit status when close_stdout is called.
  49    This is useful when it is not convenient to call close_stdout_status,
  50    e.g., when close_stdout is called via atexit.  */
  51 void
  52 close_stdout_set_status (int status)
  53 {
  54   default_exit_status = status;
  55 }
  56
  57 /* Set the file name to be reported in the event an error is detected
  58    by close_stdout_status.  */
  59 void
  60 close_stdout_set_file_name (const char *file)
  61 {
  62   file_name = file;
  63 }
  64
  65 /* Close standard output, exiting with status STATUS on failure.
  66    If a program writes *anything* to stdout, that program should `fflush'
  67    stdout and make sure that it succeeds before exiting.  Otherwise,
  68    suppose that you go to the extreme of checking the return status
  69    of every function that does an explicit write to stdout.  The last
  70    printf can succeed in writing to the internal stream buffer, and yet
  71    the fclose(stdout) could still fail (due e.g., to a disk full error)
  72    when it tries to write out that buffered data.  Thus, you would be
  73    left with an incomplete output file and the offending program would
  74    exit successfully.
  75
  76    FIXME: note the fflush suggested above is implicit in the fclose
  77    we actually do below.  Consider doing only the fflush and/or using
  78    setvbuf to inhibit buffering.
  79
  80    Besides, it's wasteful to check the return value from every call
  81    that writes to stdout -- just let the internal stream state record
  82    the failure.  That's what the ferror test is checking below.
  83
  84    It's important to detect such failures and exit nonzero because many
  85    tools (most notably `make' and other build-management systems) depend
  86    on being able to detect failure in other tools via their exit status.  */
  87
  88 void
  89 close_stdout_status (int status)
  90 {
  91   int e = ferror (stdout) ? 0 : -1;
  92
  93   /* If the stream's error bit is clear and there is nothing to flush,
  94      then return right away.  */
  95   if (e && __fpending (stdout) == 0)
  96     return;
  97
  98   if (fclose (stdout) != 0)
  99     e = errno;
 100
 101   if (0 <= e)
 102     {
 103       char const *write_error = _("write error");
 104       if (file_name)
 105         error (status, e, "%s: %s", quotearg_colon (file_name), write_error);
 106       else
 107         error (status, e, "%s", write_error);
 108     }
 109 }
 110
 111 /* Close standard output, exiting with status EXIT_FAILURE on failure.  */
 112 void
 113 close_stdout (void)
 114 {
 115   close_stdout_status (default_exit_status);
 116 }