contrib/texinfo-4/lib/xexit.c

   1 /* xexit.c -- exit with attention to return values and closing stdout.
   2    $Id: xexit.c,v 1.5 2004/04/11 17:56:46 karl Exp $
   3
   4    Copyright (C) 1999, 2003, 2004 Free Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License along
  17    with this program; if not, write to the Free Software Foundation, Inc.,
  18    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #include "system.h"
  21
  22 /* SunOS 4.1.1 gets STDC_HEADERS defined, but it doesn't provide
  23    EXIT_FAILURE.  So far no system has defined one of EXIT_FAILURE and
  24    EXIT_SUCCESS without the other.  */
  25 #ifdef EXIT_SUCCESS
  26  /* The following test is to work around the gross typo in
  27     systems like Sony NEWS-OS Release 4.0C, whereby EXIT_FAILURE
  28     is defined to 0, not 1.  */
  29 # if !EXIT_FAILURE
  30 #  undef EXIT_FAILURE
  31 #  define EXIT_FAILURE 1
  32 # endif
  33 #else /* not EXIT_SUCCESS */
  34 # ifdef VMS /* these values suppress some messages; from gnuplot */
  35 #   define EXIT_SUCCESS 1
  36 #   define EXIT_FAILURE 0x10000002
  37 # else /* not VMS */
  38 #  define EXIT_SUCCESS 0
  39 #  define EXIT_FAILURE 1
  40 # endif /* not VMS */
  41 #endif /* not EXIT_SUCCESS */
  42
  43
  44 /* Flush stdout first, exit if failure (therefore, xexit should be
  45    called to exit every program, not just `return' from main).
  46    Otherwise, if EXIT_STATUS is zero, exit successfully, else
  47    unsuccessfully.  */
  48
  49 void
  50 xexit (int exit_status)
  51 {
  52   if (ferror (stdout))
  53     {
  54       fputs (_("ferror on stdout\n"), stderr);
  55       exit_status = 1;
  56     }
  57   else if (fflush (stdout) != 0)
  58     {
  59       fputs (_("fflush error on stdout\n"), stderr);
  60       exit_status = 1;
  61     }
  62
  63   exit_status = exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
  64
  65   exit (exit_status);
  66 }
  67
  68
  69 /* Why do we care about stdout you may ask?  Here's why, from Jim
  70    Meyering in the lib/closeout.c file.  */
  71
  72 /* If a program writes *anything* to stdout, that program should close
  73    stdout and make sure that the close succeeds.  Otherwise, suppose that
  74    you go to the extreme of checking the return status of every function
  75    that does an explicit write to stdout.  The last printf can succeed in
  76    writing to the internal stream buffer, and yet the fclose(stdout) could
  77    still fail (due e.g., to a disk full error) when it tries to write
  78    out that buffered data.  Thus, you would be left with an incomplete
  79    output file and the offending program would exit successfully.
  80
  81    Besides, it's wasteful to check the return value from every call
  82    that writes to stdout -- just let the internal stream state record
  83    the failure.  That's what the ferror test is checking below.
  84
  85    It's important to detect such failures and exit nonzero because many
  86    tools (most notably `make' and other build-management systems) depend
  87    on being able to detect failure in other tools via their exit status.  */