sysdeps/posix/libc_fatal.c

   1 /* Catastrophic failure reports.  Generic POSIX.1 version.
   2    Copyright (C) 1993-2015 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/uio.h>
  33 #include <not-cancel.h>
  34
  35 #ifdef FATAL_PREPARE_INCLUDE
  36 #include FATAL_PREPARE_INCLUDE
  37 #endif
  38
  39 #ifndef WRITEV_FOR_FATAL
  40 # define WRITEV_FOR_FATAL       writev_for_fatal
  41 static bool
  42 writev_for_fatal (int fd, const struct iovec *iov, size_t niov, size_t total)
  43 {
  44   return TEMP_FAILURE_RETRY (__writev (fd, iov, niov)) == total;
  45 }
  46 #endif
  47
  48 #ifndef BEFORE_ABORT
  49 # define BEFORE_ABORT           before_abort
  50 static void
  51 before_abort (int do_abort __attribute__ ((unused)),
  52               bool written __attribute__ ((unused)),
  53               int fd __attribute__ ((unused)))
  54 {
  55 }
  56 #endif
  57
  58 struct str_list
  59 {
  60   const char *str;
  61   size_t len;
  62   struct str_list *next;
  63 };
  64
  65 /* Abort with an error message.  */
  66 void
  67 __libc_message (int do_abort, const char *fmt, ...)
  68 {
  69   va_list ap;
  70   int fd = -1;
  71
  72   va_start (ap, fmt);
  73
  74 #ifdef FATAL_PREPARE
  75   FATAL_PREPARE;
  76 #endif
  77
  78   /* Open a descriptor for /dev/tty unless the user explicitly
  79      requests errors on standard error.  */
  80   const char *on_2 = __libc_secure_getenv ("LIBC_FATAL_STDERR_");
  81   if (on_2 == NULL || *on_2 == '\0')
  82     fd = open_not_cancel_2 (_PATH_TTY, O_RDWR | O_NOCTTY | O_NDELAY);
  83
  84   if (fd == -1)
  85     fd = STDERR_FILENO;
  86
  87   struct str_list *list = NULL;
  88   int nlist = 0;
  89
  90   const char *cp = fmt;
  91   while (*cp != '\0')
  92     {
  93       /* Find the next "%s" or the end of the string.  */
  94       const char *next = cp;
  95       while (next[0] != '%' || next[1] != 's')
  96         {
  97           next = __strchrnul (next + 1, '%');
  98
  99           if (next[0] == '\0')
 100             break;
 101         }
 102
 103       /* Determine what to print.  */
 104       const char *str;
 105       size_t len;
 106       if (cp[0] == '%' && cp[1] == 's')
 107         {
 108           str = va_arg (ap, const char *);
 109           len = strlen (str);
 110           cp += 2;
 111         }
 112       else
 113         {
 114           str = cp;
 115           len = next - cp;
 116           cp = next;
 117         }
 118
 119       struct str_list *newp = alloca (sizeof (struct str_list));
 120       newp->str = str;
 121       newp->len = len;
 122       newp->next = list;
 123       list = newp;
 124       ++nlist;
 125     }
 126
 127   bool written = false;
 128   if (nlist > 0)
 129     {
 130       struct iovec *iov = alloca (nlist * sizeof (struct iovec));
 131       ssize_t total = 0;
 132
 133       for (int cnt = nlist - 1; cnt >= 0; --cnt)
 134         {
 135           iov[cnt].iov_base = (char *) list->str;
 136           iov[cnt].iov_len = list->len;
 137           total += list->len;
 138           list = list->next;
 139         }
 140
 141       written = WRITEV_FOR_FATAL (fd, iov, nlist, total);
 142
 143       if (do_abort)
 144         {
 145           total = ((total + 1 + GLRO(dl_pagesize) - 1)
 146                    & ~(GLRO(dl_pagesize) - 1));
 147           struct abort_msg_s *buf = __mmap (NULL, total,
 148                                             PROT_READ | PROT_WRITE,
 149                                             MAP_ANON | MAP_PRIVATE, -1, 0);
 150           if (__glibc_likely (buf != MAP_FAILED))
 151             {
 152               buf->size = total;
 153               char *wp = buf->msg;
 154               for (int cnt = 0; cnt < nlist; ++cnt)
 155                 wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
 156               *wp = '\0';
 157
 158               /* We have to free the old buffer since the application might
 159                  catch the SIGABRT signal.  */
 160               struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
 161                                                              buf);
 162               if (old != NULL)
 163                 __munmap (old, old->size);
 164             }
 165         }
 166     }
 167
 168   va_end (ap);
 169
 170   if (do_abort)
 171     {
 172       BEFORE_ABORT (do_abort, written, fd);
 173
 174       /* Kill the application.  */
 175       abort ();
 176     }
 177 }
 178
 179
 180 void
 181 __libc_fatal (message)
 182      const char *message;
 183 {
 184   /* The loop is added only to keep gcc happy.  */
 185   while (1)
 186     __libc_message (1, "%s", message);
 187 }
 188 libc_hidden_def (__libc_fatal)