sysdeps/unix/sysv/linux/libc_fatal.c

   1 /* Copyright (C) 1993-1995,1997,2000,2002-2005,2009,2011
   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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <atomic.h>
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <ldsodefs.h>
  23 #include <paths.h>
  24 #include <stdarg.h>
  25 #include <stdbool.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <sysdep.h>
  30 #include <unistd.h>
  31 #include <sys/mman.h>
  32 #include <sys/syslog.h>
  33 #include <execinfo.h>
  34
  35 /* Abort with an error message.  */
  36 #include <not-cancel.h>
  37
  38 #ifdef FATAL_PREPARE_INCLUDE
  39 #include FATAL_PREPARE_INCLUDE
  40 #endif
  41
  42 struct str_list
  43 {
  44   const char *str;
  45   size_t len;
  46   struct str_list *next;
  47 };
  48
  49
  50 /* Abort with an error message.  */
  51 void
  52 __libc_message (int do_abort, const char *fmt, ...)
  53 {
  54   va_list ap;
  55   va_list ap_copy;
  56   int fd = -1;
  57
  58   va_start (ap, fmt);
  59   va_copy (ap_copy, ap);
  60
  61 #ifdef FATAL_PREPARE
  62   FATAL_PREPARE;
  63 #endif
  64
  65   /* Open a descriptor for /dev/tty unless the user explicitly
  66      requests errors on standard error.  */
  67   const char *on_2 = __secure_getenv ("LIBC_FATAL_STDERR_");
  68   if (on_2 == NULL || *on_2 == '\0')
  69     fd = open_not_cancel_2 (_PATH_TTY, O_RDWR | O_NOCTTY | O_NDELAY);
  70
  71   if (fd == -1)
  72     fd = STDERR_FILENO;
  73
  74   struct str_list *list = NULL;
  75   int nlist = 0;
  76
  77   const char *cp = fmt;
  78   while (*cp != '\0')
  79     {
  80       /* Find the next "%s" or the end of the string.  */
  81       const char *next = cp;
  82       while (next[0] != '%' || next[1] != 's')
  83         {
  84           next = __strchrnul (next + 1, '%');
  85
  86           if (next[0] == '\0')
  87             break;
  88         }
  89
  90       /* Determine what to print.  */
  91       const char *str;
  92       size_t len;
  93       if (cp[0] == '%' && cp[1] == 's')
  94         {
  95           str = va_arg (ap, const char *);
  96           len = strlen (str);
  97           cp += 2;
  98         }
  99       else
 100         {
 101           str = cp;
 102           len = next - cp;
 103           cp = next;
 104         }
 105
 106       struct str_list *newp = alloca (sizeof (struct str_list));
 107       newp->str = str;
 108       newp->len = len;
 109       newp->next = list;
 110       list = newp;
 111       ++nlist;
 112     }
 113
 114   bool written = false;
 115   if (nlist > 0)
 116     {
 117       struct iovec *iov = alloca (nlist * sizeof (struct iovec));
 118       ssize_t total = 0;
 119
 120       for (int cnt = nlist - 1; cnt >= 0; --cnt)
 121         {
 122           iov[cnt].iov_base = (void *) list->str;
 123           iov[cnt].iov_len = list->len;
 124           total += list->len;
 125           list = list->next;
 126         }
 127
 128       INTERNAL_SYSCALL_DECL (err);
 129       ssize_t cnt;
 130       do
 131         cnt = INTERNAL_SYSCALL (writev, err, 3, fd, iov, nlist);
 132       while (INTERNAL_SYSCALL_ERROR_P (cnt, err)
 133              && INTERNAL_SYSCALL_ERRNO (cnt, err) == EINTR);
 134
 135       if (cnt == total)
 136         written = true;
 137
 138       if (do_abort)
 139         {
 140           total = ((total + 1 + GLRO(dl_pagesize) - 1)
 141                    & ~(GLRO(dl_pagesize) - 1));
 142           struct abort_msg_s *buf = __mmap (NULL, total,
 143                                             PROT_READ | PROT_WRITE,
 144                                             MAP_ANON | MAP_PRIVATE, -1, 0);
 145           if (__builtin_expect (buf != MAP_FAILED, 1))
 146             {
 147               buf->size = total;
 148               char *wp = buf->msg;
 149               for (int cnt = 0; cnt < nlist; ++cnt)
 150                 wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
 151               *wp = '\0';
 152
 153               /* We have to free the old buffer since the application might
 154                  catch the SIGABRT signal.  */
 155               struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
 156                                                              buf);
 157               if (old != NULL)
 158                 __munmap (old, old->size);
 159             }
 160         }
 161     }
 162
 163   va_end (ap);
 164
 165   /* If we  had no success writing the message, use syslog.  */
 166   if (! written)
 167     vsyslog (LOG_ERR, fmt, ap_copy);
 168
 169   va_end (ap_copy);
 170
 171   if (do_abort)
 172     {
 173       if (do_abort > 1 && written)
 174         {
 175           void *addrs[64];
 176 #define naddrs (sizeof (addrs) / sizeof (addrs[0]))
 177           int n = __backtrace (addrs, naddrs);
 178           if (n > 2)
 179             {
 180 #define strnsize(str) str, strlen (str)
 181 #define writestr(str) write_not_cancel (fd, str)
 182               writestr (strnsize ("======= Backtrace: =========\n"));
 183               __backtrace_symbols_fd (addrs + 1, n - 1, fd);
 184
 185               writestr (strnsize ("======= Memory map: ========\n"));
 186               int fd2 = open_not_cancel_2 ("/proc/self/maps", O_RDONLY);
 187               char buf[1024];
 188               ssize_t n2;
 189               while ((n2 = read_not_cancel (fd2, buf, sizeof (buf))) > 0)
 190                 if (write_not_cancel (fd, buf, n2) != n2)
 191                   break;
 192               close_not_cancel_no_status (fd2);
 193             }
 194         }
 195
 196       /* Terminate the process.  */
 197       abort ();
 198     }
 199 }
 200
 201
 202 void
 203 __libc_fatal (message)
 204      const char *message;
 205 {
 206   /* The loop is added only to keep gcc happy.  */
 207   while (1)
 208     __libc_message (1, "%s", message);
 209 }
 210 libc_hidden_def (__libc_fatal)