sysdeps/posix/libc_fatal.c

   1 /* Catastrophic failure reports.  Generic POSIX.1 version.
   2    Copyright (C) 1993-2020 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    <https://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 struct str_list
  49 {
  50   const char *str;
  51   size_t len;
  52   struct str_list *next;
  53 };
  54
  55 /* Abort with an error message.  */
  56 void
  57 __libc_message (enum __libc_message_action action, const char *fmt, ...)
  58 {
  59   va_list ap;
  60   int fd = -1;
  61
  62   va_start (ap, fmt);
  63
  64 #ifdef FATAL_PREPARE
  65   FATAL_PREPARE;
  66 #endif
  67
  68   if (fd == -1)
  69     fd = STDERR_FILENO;
  70
  71   struct str_list *list = NULL;
  72   int nlist = 0;
  73
  74   const char *cp = fmt;
  75   while (*cp != '\0')
  76     {
  77       /* Find the next "%s" or the end of the string.  */
  78       const char *next = cp;
  79       while (next[0] != '%' || next[1] != 's')
  80         {
  81           next = __strchrnul (next + 1, '%');
  82
  83           if (next[0] == '\0')
  84             break;
  85         }
  86
  87       /* Determine what to print.  */
  88       const char *str;
  89       size_t len;
  90       if (cp[0] == '%' && cp[1] == 's')
  91         {
  92           str = va_arg (ap, const char *);
  93           len = strlen (str);
  94           cp += 2;
  95         }
  96       else
  97         {
  98           str = cp;
  99           len = next - cp;
 100           cp = next;
 101         }
 102
 103       struct str_list *newp = alloca (sizeof (struct str_list));
 104       newp->str = str;
 105       newp->len = len;
 106       newp->next = list;
 107       list = newp;
 108       ++nlist;
 109     }
 110
 111   if (nlist > 0)
 112     {
 113       struct iovec *iov = alloca (nlist * sizeof (struct iovec));
 114       ssize_t total = 0;
 115
 116       for (int cnt = nlist - 1; cnt >= 0; --cnt)
 117         {
 118           iov[cnt].iov_base = (char *) list->str;
 119           iov[cnt].iov_len = list->len;
 120           total += list->len;
 121           list = list->next;
 122         }
 123
 124       WRITEV_FOR_FATAL (fd, iov, nlist, total);
 125
 126       if ((action & do_abort))
 127         {
 128           total = ((total + 1 + GLRO(dl_pagesize) - 1)
 129                    & ~(GLRO(dl_pagesize) - 1));
 130           struct abort_msg_s *buf = __mmap (NULL, total,
 131                                             PROT_READ | PROT_WRITE,
 132                                             MAP_ANON | MAP_PRIVATE, -1, 0);
 133           if (__glibc_likely (buf != MAP_FAILED))
 134             {
 135               buf->size = total;
 136               char *wp = buf->msg;
 137               for (int cnt = 0; cnt < nlist; ++cnt)
 138                 wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
 139               *wp = '\0';
 140
 141               /* We have to free the old buffer since the application might
 142                  catch the SIGABRT signal.  */
 143               struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
 144                                                              buf);
 145               if (old != NULL)
 146                 __munmap (old, old->size);
 147             }
 148         }
 149     }
 150
 151   va_end (ap);
 152
 153   if ((action & do_abort))
 154     /* Kill the application.  */
 155     abort ();
 156 }
 157
 158
 159 void
 160 __libc_fatal (const char *message)
 161 {
 162   /* The loop is added only to keep gcc happy.  */
 163   while (1)
 164     __libc_message (do_abort, "%s", message);
 165 }
 166 libc_hidden_def (__libc_fatal)