stdio-common/perror.c

   1 /* Copyright (C) 1991-1993,1997,1998,2000-2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <wchar.h>
  24 #ifdef USE_IN_LIBIO
  25 # include "libioP.h"
  26 #endif
  27
  28 static void
  29 perror_internal (FILE *fp, const char *s, int errnum)
  30 {
  31   char buf[1024];
  32   const char *colon;
  33   const char *errstring;
  34
  35   if (s == NULL || *s == '\0')
  36     s = colon = "";
  37   else
  38     colon = ": ";
  39
  40   errstring = __strerror_r (errnum, buf, sizeof buf);
  41
  42 #ifdef USE_IN_LIBIO
  43   if (_IO_fwide (fp, 0) > 0)
  44     (void) __fwprintf (fp, L"%s%s%s\n", s, colon, errstring);
  45   else
  46 #endif
  47     (void) fprintf (fp, "%s%s%s\n", s, colon, errstring);
  48 }
  49
  50
  51 /* Print a line on stderr consisting of the text in S, a colon, a space,
  52    a message describing the meaning of the contents of `errno' and a newline.
  53    If S is NULL or "", the colon and space are omitted.  */
  54 void
  55 perror (const char *s)
  56 {
  57   int errnum = errno;
  58 #ifdef USE_IN_LIBIO
  59   FILE *fp;
  60   int fd = -1;
  61
  62
  63   /* The standard says that 'perror' must not change the orientation
  64      of the stream.  What is supposed to happen when the stream isn't
  65      oriented yet?  In this case we'll create a new stream which is
  66      using the same underlying file descriptor.  */
  67   if (__builtin_expect (_IO_fwide (stderr, 0) != 0, 1)
  68       || (fd = fileno (stderr)) == -1
  69       || (fd = __dup (fd)) == -1
  70       || (fp = fdopen (fd, "w+")) == NULL)
  71     {
  72       if (__builtin_expect (fd != -1, 0))
  73         __close (fd);
  74
  75       /* Use standard error as is.  */
  76       perror_internal (stderr, s, errnum);
  77     }
  78   else
  79     {
  80       /* We don't have to do any special hacks regarding the file
  81          position.  Since the stderr stream wasn't used so far we just
  82          write to the descriptor.  */
  83       perror_internal (fp, s, errnum);
  84       /* Close the stream.  */
  85       fclose (fp);
  86
  87       ((_IO_FILE *) stderr)->_offset = _IO_pos_BAD;
  88     }
  89 #else
  90   perror_internal (stderr, s, errnum);
  91 #endif
  92 }
  93 libc_hidden_def (perror)