string/_strerror.c

   1 /* Copyright (C) 1991,93,95,96,97,98,2000,2002,2006,2011
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <libintl.h>
  21 #include <stdbool.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/param.h>
  26 #include <stdio-common/_itoa.h>
  27
  28 /* It is critical here that we always use the `dcgettext' function for
  29    the message translation.  Since <libintl.h> only defines the macro
  30    `dgettext' to use `dcgettext' for optimizing programs this is not
  31    always guaranteed.  */
  32 #ifndef dgettext
  33 # include <locale.h>            /* We need LC_MESSAGES.  */
  34 # define dgettext(domainname, msgid) dcgettext (domainname, msgid, LC_MESSAGES)
  35 #endif
  36
  37 /* Return a string describing the errno code in ERRNUM.  */
  38 char *
  39 __strerror_r (int errnum, char *buf, size_t buflen)
  40 {
  41   if (__builtin_expect (errnum < 0 || errnum >= _sys_nerr_internal
  42                         || _sys_errlist_internal[errnum] == NULL, 0))
  43     {
  44       /* Buffer we use to print the number in.  For a maximum size for
  45          `int' of 8 bytes we never need more than 20 digits.  */
  46       char numbuf[21];
  47       const char *unk = _("Unknown error ");
  48       size_t unklen = strlen (unk);
  49       char *p, *q;
  50       bool negative = errnum < 0;
  51
  52       numbuf[20] = '\0';
  53       p = _itoa_word (abs (errnum), &numbuf[20], 10, 0);
  54
  55       /* Now construct the result while taking care for the destination
  56          buffer size.  */
  57       q = __mempcpy (buf, unk, MIN (unklen, buflen));
  58       if (negative && unklen < buflen)
  59         {
  60           *q++ = '-';
  61           ++unklen;
  62         }
  63       if (unklen < buflen)
  64         memcpy (q, p, MIN ((size_t) (&numbuf[21] - p), buflen - unklen));
  65
  66       /* Terminate the string in any case.  */
  67       if (buflen > 0)
  68         buf[buflen - 1] = '\0';
  69
  70       return buf;
  71     }
  72
  73   return (char *) _(_sys_errlist_internal[errnum]);
  74 }
  75 weak_alias (__strerror_r, strerror_r)
  76 libc_hidden_def (__strerror_r)