libvtv/vtv_utils.cc

   1 /* Copyright (C) 2012-2013
   2    Free Software Foundation
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 /* This file is part of the vtable verication runtime library (see
  26    comments in vtv_rts.cc for more information about vtable
  27    verification).  This file contains log file utilities.  */
  28
  29 #include <sys/types.h>
  30 #include <sys/stat.h>
  31 #include <fcntl.h>
  32 #include <stdarg.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #if defined (__CYGWIN__) || defined (__MINGW32__)
  37 #include <windows.h>
  38 #else
  39 #include <execinfo.h>
  40 #endif
  41
  42 #include <unistd.h>
  43 #include <errno.h>
  44
  45 #include "vtv_utils.h"
  46
  47 #ifndef HAVE_SECURE_GETENV
  48 #  ifdef HAVE___SECURE_GETENV
  49 #    define secure_getenv __secure_getenv
  50 #  else
  51 #    define secure_getenv getenv
  52 #  endif
  53 #endif
  54
  55 static int vtv_failures_log_fd = -1;
  56
  57 /* This function takes the NAME of a log file to open, attempts to
  58    open it in the logs_dir directory, and returns the resulting file
  59    descriptor.
  60
  61    This function first checks to see if the user has specifed (via
  62    the environment variable VTV_LOGS_DIR) a directory to use for the
  63    vtable verification logs.  If that fails, the function will open
  64    the logs in the current directory.
  65 */
  66
  67 int
  68 __vtv_open_log (const char *name)
  69 {
  70   char log_name[1024];
  71   char log_dir[512];
  72 #if defined (__CYGWIN__) || defined (__MINGW32__)
  73   pid_t process_id = GetCurrentProcessId ();
  74 #else
  75   uid_t user_id = getuid ();
  76   pid_t process_id = getpid ();
  77 #endif
  78   char *logs_prefix;
  79   bool logs_dir_specified = false;
  80   int fd = -1;
  81
  82   logs_prefix = secure_getenv ("VTV_LOGS_DIR");
  83   if (logs_prefix && strlen (logs_prefix) > 0)
  84     {
  85       logs_dir_specified = true;
  86 #ifdef __MINGW32__
  87       mkdir (logs_prefix);
  88 #else
  89       mkdir (logs_prefix, S_IRWXU);
  90 #endif
  91
  92       snprintf (log_dir, sizeof (log_dir), "%s/vtv_logs", logs_prefix);
  93
  94 #ifdef __MINGW32__
  95       mkdir (log_dir);
  96 #else
  97       mkdir (log_dir, S_IRWXU);
  98 #endif
  99 #if defined (__CYGWIN__) || defined (__MINGW32__)
 100       snprintf (log_name, sizeof (log_name), "%s_%d_%s", log_dir,
 101                 (unsigned) process_id, name);
 102       fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT, S_IRWXU);
 103 #else
 104       snprintf (log_name, sizeof (log_name), "%s/%d_%d_%s", log_dir,
 105                 (unsigned) user_id, (unsigned) process_id, name);
 106       fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW,
 107                  S_IRWXU);
 108 #endif
 109     }
 110   else
 111     fd = dup (2);
 112
 113   if (fd == -1)
 114     __vtv_add_to_log (2, "Cannot open log file %s %s\n", name,
 115                     strerror (errno));
 116   return fd;
 117 }
 118
 119 /* This function takes a file descriptor (FD) and a string (STR) and
 120    tries to write the string to the file.  */
 121
 122 static int
 123 vtv_log_write (int fd, const char *str)
 124 {
 125   if (write (fd, str, strlen (str)) != -1)
 126     return 0;
 127
 128   if (fd != 2) /* Make sure we dont get in a loop.  */
 129     __vtv_add_to_log (2, "Error writing to log: %s\n", strerror (errno));
 130   return -1;
 131 }
 132
 133
 134 /* This function takes a file decriptor (LOG_FILE) and an output
 135  format string (FORMAT), followed by zero or more print format
 136  arguments (the same as fprintf, for example).  It gets the current
 137  process ID and PPID, pre-pends them to the formatted message, and
 138  writes write it out to the log file referenced by LOG_FILE via calles
 139  to vtv_log_write.  */
 140
 141 int
 142 __vtv_add_to_log (int log_file, const char * format, ...)
 143 {
 144   /* We dont want to dynamically allocate this buffer. This should be
 145      more than enough in most cases. It if isn't we are careful not to
 146      do a buffer overflow.  */
 147   char output[1024];
 148
 149   va_list ap;
 150   va_start (ap, format);
 151
 152 #if defined (__CYGWIN__) || defined (__MINGW32__)
 153   snprintf (output, sizeof (output), "VTV: PID=%ld ", GetCurrentProcessId ());
 154 #else
 155   snprintf (output, sizeof (output), "VTV: PID=%d PPID=%d ", getpid (),
 156             getppid ());
 157 #endif
 158   vtv_log_write (log_file, output);
 159   vsnprintf (output, sizeof (output), format, ap);
 160   vtv_log_write (log_file, output);
 161   va_end (ap);
 162
 163   return 0;
 164 }
 165
 166 /* Open error logging file, if not already open, and write vtable
 167    verification failure messages (LOG_MSG) to the log file.  Also
 168    generate a backtrace in the log file, if GENERATE_BACKTRACE is
 169    set.  */
 170
 171 void
 172 __vtv_log_verification_failure (const char *log_msg, bool generate_backtrace)
 173 {
 174   if (vtv_failures_log_fd == -1)
 175     vtv_failures_log_fd = __vtv_open_log ("vtable_verification_failures.log");
 176
 177   if (vtv_failures_log_fd == -1)
 178     return;
 179
 180   __vtv_add_to_log (vtv_failures_log_fd, "%s", log_msg);
 181
 182 #if !defined (__CYGWIN__) && !defined (__MINGW32__)
 183   if (generate_backtrace)
 184     {
 185 #define STACK_DEPTH 20
 186       void *callers[STACK_DEPTH];
 187       int actual_depth = backtrace (callers, STACK_DEPTH);
 188       backtrace_symbols_fd (callers, actual_depth, vtv_failures_log_fd);
 189     }
 190 #endif
 191 }