sysdeps/posix/libc_fatal.c

   1 /* Catastrophic failure reports.  Generic POSIX.1 version.
   2    Copyright (C) 1993-2017 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 (enum __libc_message_action action, 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   /* Don't call __libc_secure_getenv if we aren't doing backtrace, which
  79      may access the corrupted stack.  */
  80   if ((action & do_backtrace))
  81     {
  82       /* Open a descriptor for /dev/tty unless the user explicitly
  83          requests errors on standard error.  */
  84       const char *on_2 = __libc_secure_getenv ("LIBC_FATAL_STDERR_");
  85       if (on_2 == NULL || *on_2 == '\0')
  86         fd = __open_nocancel (_PATH_TTY, O_RDWR | O_NOCTTY | O_NDELAY);
  87     }
  88
  89   if (fd == -1)
  90     fd = STDERR_FILENO;
  91
  92   struct str_list *list = NULL;
  93   int nlist = 0;
  94
  95   const char *cp = fmt;
  96   while (*cp != '\0')
  97     {
  98       /* Find the next "%s" or the end of the string.  */
  99       const char *next = cp;
 100       while (next[0] != '%' || next[1] != 's')
 101         {
 102           next = __strchrnul (next + 1, '%');
 103
 104           if (next[0] == '\0')
 105             break;
 106         }
 107
 108       /* Determine what to print.  */
 109       const char *str;
 110       size_t len;
 111       if (cp[0] == '%' && cp[1] == 's')
 112         {
 113           str = va_arg (ap, const char *);
 114           len = strlen (str);
 115           cp += 2;
 116         }
 117       else
 118         {
 119           str = cp;
 120           len = next - cp;
 121           cp = next;
 122         }
 123
 124       struct str_list *newp = alloca (sizeof (struct str_list));
 125       newp->str = str;
 126       newp->len = len;
 127       newp->next = list;
 128       list = newp;
 129       ++nlist;
 130     }
 131
 132   bool written = false;
 133   if (nlist > 0)
 134     {
 135       struct iovec *iov = alloca (nlist * sizeof (struct iovec));
 136       ssize_t total = 0;
 137
 138       for (int cnt = nlist - 1; cnt >= 0; --cnt)
 139         {
 140           iov[cnt].iov_base = (char *) list->str;
 141           iov[cnt].iov_len = list->len;
 142           total += list->len;
 143           list = list->next;
 144         }
 145
 146       written = WRITEV_FOR_FATAL (fd, iov, nlist, total);
 147
 148       if ((action & do_abort))
 149         {
 150           total = ((total + 1 + GLRO(dl_pagesize) - 1)
 151                    & ~(GLRO(dl_pagesize) - 1));
 152           struct abort_msg_s *buf = __mmap (NULL, total,
 153                                             PROT_READ | PROT_WRITE,
 154                                             MAP_ANON | MAP_PRIVATE, -1, 0);
 155           if (__glibc_likely (buf != MAP_FAILED))
 156             {
 157               buf->size = total;
 158               char *wp = buf->msg;
 159               for (int cnt = 0; cnt < nlist; ++cnt)
 160                 wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
 161               *wp = '\0';
 162
 163               /* We have to free the old buffer since the application might
 164                  catch the SIGABRT signal.  */
 165               struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
 166                                                              buf);
 167               if (old != NULL)
 168                 __munmap (old, old->size);
 169             }
 170         }
 171     }
 172
 173   va_end (ap);
 174
 175   if ((action & do_abort))
 176     {
 177       if ((action & do_backtrace))
 178         BEFORE_ABORT (do_abort, written, fd);
 179
 180       /* Kill the application.  */
 181       abort ();
 182     }
 183 }
 184
 185
 186 void
 187 __libc_fatal (const char *message)
 188 {
 189   /* The loop is added only to keep gcc happy.  */
 190   while (1)
 191     __libc_message (do_abort | do_backtrace, "%s", message);
 192 }
 193 libc_hidden_def (__libc_fatal)