libvtv/vtv_utils.cc

   1 /* Copyright (C) 2012-2020 Free Software Foundation, Inc.
   2
   3    This file is part of GCC.
   4
   5    GCC is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3, or (at your option)
   8    any later version.
   9
  10    GCC 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
  13    GNU General Public License for more details.
  14
  15    Under Section 7 of GPL version 3, you are granted additional
  16    permissions described in the GCC Runtime Library Exception, version
  17    3.1, as published by the Free Software Foundation.
  18
  19    You should have received a copy of the GNU General Public License and
  20    a copy of the GCC Runtime Library Exception along with this program;
  21    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22    <http://www.gnu.org/licenses/>.  */
  23
  24 /* This file is part of the vtable verication runtime library (see
  25    comments in vtv_rts.cc for more information about vtable
  26    verification).  This file contains log file utilities.  */
  27
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <fcntl.h>
  31 #include <stdarg.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #if defined (__CYGWIN__) || defined (__MINGW32__)
  36 #include <windows.h>
  37 #else
  38 #include <execinfo.h>
  39 #endif
  40
  41 #include <unistd.h>
  42 #include <errno.h>
  43
  44 #include "vtv_utils.h"
  45
  46 #ifndef HAVE_SECURE_GETENV
  47 #  ifdef HAVE___SECURE_GETENV
  48 #    define secure_getenv __secure_getenv
  49 #  else
  50 #    define secure_getenv getenv
  51 #  endif
  52 #endif
  53
  54 static int vtv_failures_log_fd = -1;
  55
  56 /* This function takes the NAME of a log file to open, attempts to
  57    open it in the logs_dir directory, and returns the resulting file
  58    descriptor.
  59
  60    This function first checks to see if the user has specifed (via
  61    the environment variable VTV_LOGS_DIR) a directory to use for the
  62    vtable verification logs.  If that fails, the function will open
  63    the logs in the current directory.
  64 */
  65
  66 int
  67 __vtv_open_log (const char *name)
  68 {
  69   char log_name[1024];
  70   char log_dir[512];
  71 #if defined (__CYGWIN__) || defined (__MINGW32__)
  72   pid_t process_id = GetCurrentProcessId ();
  73 #else
  74   uid_t user_id = getuid ();
  75   pid_t process_id = getpid ();
  76 #endif
  77   char *logs_prefix;
  78   bool logs_dir_specified = false;
  79   int fd = -1;
  80
  81   logs_prefix = secure_getenv ("VTV_LOGS_DIR");
  82   if (logs_prefix && strlen (logs_prefix) > 0)
  83     {
  84       logs_dir_specified = true;
  85 #ifdef __MINGW32__
  86       mkdir (logs_prefix);
  87 #else
  88       mkdir (logs_prefix, S_IRWXU);
  89 #endif
  90
  91       snprintf (log_dir, sizeof (log_dir), "%s/vtv_logs", logs_prefix);
  92
  93 #ifdef __MINGW32__
  94       mkdir (log_dir);
  95 #else
  96       mkdir (log_dir, S_IRWXU);
  97 #endif
  98 #if defined (__CYGWIN__) || defined (__MINGW32__)
  99       snprintf (log_name, sizeof (log_name), "%s_%d_%s", log_dir,
 100                 (unsigned) process_id, name);
 101       fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT, S_IRWXU);
 102 #else
 103       snprintf (log_name, sizeof (log_name), "%s/%d_%d_%s", log_dir,
 104                 (unsigned) user_id, (unsigned) process_id, name);
 105       fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW,
 106                  S_IRWXU);
 107 #endif
 108     }
 109   else
 110     fd = dup (2);
 111
 112   if (fd == -1)
 113     __vtv_add_to_log (2, "Cannot open log file %s %s\n", name,
 114                     strerror (errno));
 115   return fd;
 116 }
 117
 118 /* This function takes a file descriptor (FD) and a string (STR) and
 119    tries to write the string to the file.  */
 120
 121 static int
 122 vtv_log_write (int fd, const char *str)
 123 {
 124   if (write (fd, str, strlen (str)) != -1)
 125     return 0;
 126
 127   if (fd != 2) /* Make sure we dont get in a loop.  */
 128     __vtv_add_to_log (2, "Error writing to log: %s\n", strerror (errno));
 129   return -1;
 130 }
 131
 132
 133 /* This function takes a file decriptor (LOG_FILE) and an output
 134  format string (FORMAT), followed by zero or more print format
 135  arguments (the same as fprintf, for example).  It gets the current
 136  process ID and PPID, pre-pends them to the formatted message, and
 137  writes write it out to the log file referenced by LOG_FILE via calles
 138  to vtv_log_write.  */
 139
 140 int
 141 __vtv_add_to_log (int log_file, const char * format, ...)
 142 {
 143   /* We dont want to dynamically allocate this buffer. This should be
 144      more than enough in most cases. It if isn't we are careful not to
 145      do a buffer overflow.  */
 146   char output[1024];
 147
 148   va_list ap;
 149   va_start (ap, format);
 150
 151 #if defined (__CYGWIN__) || defined (__MINGW32__)
 152   snprintf (output, sizeof (output), "VTV: PID=%ld ", GetCurrentProcessId ());
 153 #else
 154   snprintf (output, sizeof (output), "VTV: PID=%d PPID=%d ", getpid (),
 155             getppid ());
 156 #endif
 157   vtv_log_write (log_file, output);
 158   vsnprintf (output, sizeof (output), format, ap);
 159   vtv_log_write (log_file, output);
 160   va_end (ap);
 161
 162   return 0;
 163 }
 164
 165 /* Open error logging file, if not already open, and write vtable
 166    verification failure messages (LOG_MSG) to the log file.  Also
 167    generate a backtrace in the log file, if GENERATE_BACKTRACE is
 168    set.  */
 169
 170 void
 171 __vtv_log_verification_failure (const char *log_msg, bool generate_backtrace)
 172 {
 173   if (vtv_failures_log_fd == -1)
 174     vtv_failures_log_fd = __vtv_open_log ("vtable_verification_failures.log");
 175
 176   if (vtv_failures_log_fd == -1)
 177     return;
 178
 179   __vtv_add_to_log (vtv_failures_log_fd, "%s", log_msg);
 180
 181 #if !defined (__CYGWIN__) && !defined (__MINGW32__)
 182   if (generate_backtrace)
 183     {
 184 #define STACK_DEPTH 20
 185       void *callers[STACK_DEPTH];
 186       int actual_depth = backtrace (callers, STACK_DEPTH);
 187       backtrace_symbols_fd (callers, actual_depth, vtv_failures_log_fd);
 188     }
 189 #endif
 190 }