sysdeps/unix/sysv/linux/libc_fatal.c

   1 /* Copyright (C) 1993-2012 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 <atomic.h>
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <ldsodefs.h>
  22 #include <paths.h>
  23 #include <stdarg.h>
  24 #include <stdbool.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <sysdep.h>
  29 #include <unistd.h>
  30 #include <sys/mman.h>
  31 #include <sys/syslog.h>
  32 #include <execinfo.h>
  33
  34 /* Abort with an error message.  */
  35 #include <not-cancel.h>
  36
  37 #ifdef FATAL_PREPARE_INCLUDE
  38 #include FATAL_PREPARE_INCLUDE
  39 #endif
  40
  41 struct str_list
  42 {
  43   const char *str;
  44   size_t len;
  45   struct str_list *next;
  46 };
  47
  48
  49 /* Abort with an error message.  */
  50 void
  51 __libc_message (int do_abort, const char *fmt, ...)
  52 {
  53   va_list ap;
  54   va_list ap_copy;
  55   int fd = -1;
  56
  57   va_start (ap, fmt);
  58   va_copy (ap_copy, ap);
  59
  60 #ifdef FATAL_PREPARE
  61   FATAL_PREPARE;
  62 #endif
  63
  64   /* Open a descriptor for /dev/tty unless the user explicitly
  65      requests errors on standard error.  */
  66   const char *on_2 = __libc_secure_getenv ("LIBC_FATAL_STDERR_");
  67   if (on_2 == NULL || *on_2 == '\0')
  68     fd = open_not_cancel_2 (_PATH_TTY, O_RDWR | O_NOCTTY | O_NDELAY);
  69
  70   if (fd == -1)
  71     fd = STDERR_FILENO;
  72
  73   struct str_list *list = NULL;
  74   int nlist = 0;
  75
  76   const char *cp = fmt;
  77   while (*cp != '\0')
  78     {
  79       /* Find the next "%s" or the end of the string.  */
  80       const char *next = cp;
  81       while (next[0] != '%' || next[1] != 's')
  82         {
  83           next = __strchrnul (next + 1, '%');
  84
  85           if (next[0] == '\0')
  86             break;
  87         }
  88
  89       /* Determine what to print.  */
  90       const char *str;
  91       size_t len;
  92       if (cp[0] == '%' && cp[1] == 's')
  93         {
  94           str = va_arg (ap, const char *);
  95           len = strlen (str);
  96           cp += 2;
  97         }
  98       else
  99         {
 100           str = cp;
 101           len = next - cp;
 102           cp = next;
 103         }
 104
 105       struct str_list *newp = alloca (sizeof (struct str_list));
 106       newp->str = str;
 107       newp->len = len;
 108       newp->next = list;
 109       list = newp;
 110       ++nlist;
 111     }
 112
 113   bool written = false;
 114   if (nlist > 0)
 115     {
 116       struct iovec *iov = alloca (nlist * sizeof (struct iovec));
 117       ssize_t total = 0;
 118
 119       for (int cnt = nlist - 1; cnt >= 0; --cnt)
 120         {
 121           iov[cnt].iov_base = (void *) list->str;
 122           iov[cnt].iov_len = list->len;
 123           total += list->len;
 124           list = list->next;
 125         }
 126
 127       INTERNAL_SYSCALL_DECL (err);
 128       ssize_t cnt;
 129       do
 130         cnt = INTERNAL_SYSCALL (writev, err, 3, fd, iov, nlist);
 131       while (INTERNAL_SYSCALL_ERROR_P (cnt, err)
 132              && INTERNAL_SYSCALL_ERRNO (cnt, err) == EINTR);
 133
 134       if (cnt == total)
 135         written = true;
 136
 137       if (do_abort)
 138         {
 139           total = ((total + 1 + GLRO(dl_pagesize) - 1)
 140                    & ~(GLRO(dl_pagesize) - 1));
 141           struct abort_msg_s *buf = __mmap (NULL, total,
 142                                             PROT_READ | PROT_WRITE,
 143                                             MAP_ANON | MAP_PRIVATE, -1, 0);
 144           if (__builtin_expect (buf != MAP_FAILED, 1))
 145             {
 146               buf->size = total;
 147               char *wp = buf->msg;
 148               for (int cnt = 0; cnt < nlist; ++cnt)
 149                 wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
 150               *wp = '\0';
 151
 152               /* We have to free the old buffer since the application might
 153                  catch the SIGABRT signal.  */
 154               struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
 155                                                              buf);
 156               if (old != NULL)
 157                 __munmap (old, old->size);
 158             }
 159         }
 160     }
 161
 162   va_end (ap);
 163
 164   /* If we  had no success writing the message, use syslog.  */
 165   if (! written)
 166     vsyslog (LOG_ERR, fmt, ap_copy);
 167
 168   va_end (ap_copy);
 169
 170   if (do_abort)
 171     {
 172       if (do_abort > 1 && written)
 173         {
 174           void *addrs[64];
 175 #define naddrs (sizeof (addrs) / sizeof (addrs[0]))
 176           int n = __backtrace (addrs, naddrs);
 177           if (n > 2)
 178             {
 179 #define strnsize(str) str, strlen (str)
 180 #define writestr(str) write_not_cancel (fd, str)
 181               writestr (strnsize ("======= Backtrace: =========\n"));
 182               __backtrace_symbols_fd (addrs + 1, n - 1, fd);
 183
 184               writestr (strnsize ("======= Memory map: ========\n"));
 185               int fd2 = open_not_cancel_2 ("/proc/self/maps", O_RDONLY);
 186               char buf[1024];
 187               ssize_t n2;
 188               while ((n2 = read_not_cancel (fd2, buf, sizeof (buf))) > 0)
 189                 if (write_not_cancel (fd, buf, n2) != n2)
 190                   break;
 191               close_not_cancel_no_status (fd2);
 192             }
 193         }
 194
 195       /* Terminate the process.  */
 196       abort ();
 197     }
 198 }
 199
 200
 201 void
 202 __libc_fatal (message)
 203      const char *message;
 204 {
 205   /* The loop is added only to keep gcc happy.  */
 206   while (1)
 207     __libc_message (1, "%s", message);
 208 }
 209 libc_hidden_def (__libc_fatal)