string/strsignal.c

   1 /* Copyright (C) 1991, 1994-2002, 2005 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <signal.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <libintl.h>
  23 #include <bits/libc-lock.h>
  24
  25
  26 /* Defined in siglist.c.  */
  27 extern const char *const _sys_siglist[];
  28 extern const char *const _sys_siglist_internal[] attribute_hidden;
  29 static __libc_key_t key;
  30
  31 /* If nonzero the key allocation failed and we should better use a
  32    static buffer than fail.  */
  33 #define BUFFERSIZ       100
  34 static char local_buf[BUFFERSIZ];
  35 static char *static_buf;
  36
  37 /* Destructor for the thread-specific data.  */
  38 static void init (void);
  39 static void free_key_mem (void *mem);
  40 static char *getbuffer (void);
  41
  42
  43 /* Return a string describing the meaning of the signal number SIGNUM.  */
  44 char *
  45 strsignal (int signum)
  46 {
  47   __libc_once_define (static, once);
  48   const char *desc;
  49
  50   /* If we have not yet initialized the buffer do it now.  */
  51   __libc_once (once, init);
  52
  53   if (
  54 #ifdef SIGRTMIN
  55       (signum >= SIGRTMIN && signum <= SIGRTMAX) ||
  56 #endif
  57       signum < 0 || signum >= NSIG
  58       || (desc = INTUSE(_sys_siglist)[signum]) == NULL)
  59     {
  60       char *buffer = getbuffer ();
  61       int len;
  62 #ifdef SIGRTMIN
  63       if (signum >= SIGRTMIN && signum <= SIGRTMAX)
  64         len = __snprintf (buffer, BUFFERSIZ - 1, _("Real-time signal %d"),
  65                           signum - SIGRTMIN);
  66       else
  67 #endif
  68         len = __snprintf (buffer, BUFFERSIZ - 1, _("Unknown signal %d"),
  69                           signum);
  70       if (len >= BUFFERSIZ)
  71         buffer = NULL;
  72       else
  73         buffer[len] = '\0';
  74
  75       return buffer;
  76     }
  77
  78   return (char *) _(desc);
  79 }
  80
  81
  82 /* Initialize buffer.  */
  83 static void
  84 init (void)
  85 {
  86   if (__libc_key_create (&key, free_key_mem))
  87     /* Creating the key failed.  This means something really went
  88        wrong.  In any case use a static buffer which is better than
  89        nothing.  */
  90     static_buf = local_buf;
  91 }
  92
  93
  94 /* Free the thread specific data, this is done if a thread terminates.  */
  95 static void
  96 free_key_mem (void *mem)
  97 {
  98   free (mem);
  99   __libc_setspecific (key, NULL);
 100 }
 101
 102
 103 /* Return the buffer to be used.  */
 104 static char *
 105 getbuffer (void)
 106 {
 107   char *result;
 108
 109   if (static_buf != NULL)
 110     result = static_buf;
 111   else
 112     {
 113       /* We don't use the static buffer and so we have a key.  Use it
 114          to get the thread-specific buffer.  */
 115       result = __libc_getspecific (key);
 116       if (result == NULL)
 117         {
 118           /* No buffer allocated so far.  */
 119           result = malloc (BUFFERSIZ);
 120           if (result == NULL)
 121             /* No more memory available.  We use the static buffer.  */
 122             result = local_buf;
 123           else
 124             __libc_setspecific (key, result);
 125         }
 126     }
 127
 128   return result;
 129 }