string/strsignal.c

   1 /* Copyright (C) 1991-2017 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 <libc-lock.h>
  24
  25 static __libc_key_t key;
  26
  27 /* If nonzero the key allocation failed and we should better use a
  28    static buffer than fail.  */
  29 #define BUFFERSIZ       100
  30 static char local_buf[BUFFERSIZ];
  31 static char *static_buf;
  32
  33 /* Destructor for the thread-specific data.  */
  34 static void init (void);
  35 static void free_key_mem (void *mem);
  36 static char *getbuffer (void);
  37
  38
  39 /* Return a string describing the meaning of the signal number SIGNUM.  */
  40 char *
  41 strsignal (int signum)
  42 {
  43   __libc_once_define (static, once);
  44   const char *desc;
  45
  46   /* If we have not yet initialized the buffer do it now.  */
  47   __libc_once (once, init);
  48
  49   if (
  50 #ifdef SIGRTMIN
  51       (signum >= SIGRTMIN && signum <= SIGRTMAX) ||
  52 #endif
  53       signum < 0 || signum >= NSIG
  54       || (desc = _sys_siglist[signum]) == NULL)
  55     {
  56       char *buffer = getbuffer ();
  57       int len;
  58 #ifdef SIGRTMIN
  59       if (signum >= SIGRTMIN && signum <= SIGRTMAX)
  60         len = __snprintf (buffer, BUFFERSIZ - 1, _("Real-time signal %d"),
  61                           signum - SIGRTMIN);
  62       else
  63 #endif
  64         len = __snprintf (buffer, BUFFERSIZ - 1, _("Unknown signal %d"),
  65                           signum);
  66       if (len >= BUFFERSIZ)
  67         buffer = NULL;
  68       else
  69         buffer[len] = '\0';
  70
  71       return buffer;
  72     }
  73
  74   return (char *) _(desc);
  75 }
  76
  77
  78 /* Initialize buffer.  */
  79 static void
  80 init (void)
  81 {
  82   if (__libc_key_create (&key, free_key_mem))
  83     /* Creating the key failed.  This means something really went
  84        wrong.  In any case use a static buffer which is better than
  85        nothing.  */
  86     static_buf = local_buf;
  87 }
  88
  89
  90 /* Free the thread specific data, this is done if a thread terminates.  */
  91 static void
  92 free_key_mem (void *mem)
  93 {
  94   free (mem);
  95   __libc_setspecific (key, NULL);
  96 }
  97
  98
  99 /* Return the buffer to be used.  */
 100 static char *
 101 getbuffer (void)
 102 {
 103   char *result;
 104
 105   if (static_buf != NULL)
 106     result = static_buf;
 107   else
 108     {
 109       /* We don't use the static buffer and so we have a key.  Use it
 110          to get the thread-specific buffer.  */
 111       result = __libc_getspecific (key);
 112       if (result == NULL)
 113         {
 114           /* No buffer allocated so far.  */
 115           result = malloc (BUFFERSIZ);
 116           if (result == NULL)
 117             /* No more memory available.  We use the static buffer.  */
 118             result = local_buf;
 119           else
 120             __libc_setspecific (key, result);
 121         }
 122     }
 123
 124   return result;
 125 }