/*
# Copyright 2014 Ball Aerospace & Technologies Corp.
# All Rights Reserved.
#
# This program is free software; you can modify and/or redistribute it
# under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 3 with
# attribution addendums as found in the LICENSE.txt
*/

#include "ruby.h"
#include "stdio.h"

/* Cosmos module reference */
VALUE mCosmos = Qnil;

/* SegFault class reference */
VALUE cSegFault = Qnil;

#ifdef _WIN32
  #include <windows.h>
#else
  #include <signal.h>
  #include <unistd.h>
  #include <time.h>
  #include <string.h>
  #include <sys/stat.h>

  static void catch_sigsegv(int sig_num) {
    const int FILENAME_LEN = 256;
    char *cosmos_log_dir = NULL;
    time_t rawtime;
    struct tm timeinfo;
    struct tm *timeinfo_ptr;
    struct stat stats;
    char filename[FILENAME_LEN];
    FILE* file = NULL;

    signal(SIGSEGV, SIG_DFL);
    signal(SIGILL, SIG_DFL);

    cosmos_log_dir = getenv("COSMOS_LOGS_DIR");
    // If the COSMOS_LOGS_DIR env var isn't set or if it's too big set to "."
    // NOTE: The filename buffer will be written to by snprintf which appends
    // a null terminator so we have 1 less byte available minus the length
    // of the fixed filename structure
    if ((cosmos_log_dir == NULL) || (strlen(cosmos_log_dir) > (FILENAME_LEN - 1 - strlen("/YYYY_MM_DD_HH_MM_SS_segfault.txt"))))
    {
      cosmos_log_dir = (char*)".";
    }
    // Validate that we can write to this directory
    if (stat(cosmos_log_dir, &stats) == 0)
    {
      if (!((stats.st_mode & W_OK)&& S_ISDIR(stats.st_mode)))
      {
        cosmos_log_dir = (char *)".";
      }
    }
    else
    {
      cosmos_log_dir = (char *)".";
    }

    time(&rawtime);
    timeinfo_ptr = localtime_r(&rawtime, &timeinfo);
    if (timeinfo_ptr == NULL)
    {
      // If localtime returns NULL we set our own and set to 1919 to make it interesting
      strptime("1919-01-01 00:00:00", "%Y-%m-%d %H:%M:%S", &timeinfo);
    }
    snprintf(filename, FILENAME_LEN, "%s/%04u_%02u_%02u_%02u_%02u_%02u_segfault.txt",
            cosmos_log_dir,
            1900 + timeinfo.tm_year,
            1 + timeinfo.tm_mon,
            timeinfo.tm_mday,
            timeinfo.tm_hour,
            timeinfo.tm_min,
            timeinfo.tm_sec);

    // Fortify warns about Path Manipulation here. We explictly allow this to let
    // segfault files be written to a directory of their choosing.
    // The input is validated above for length and to ensure it is a writable directory.
    // If the checks fail the directory is set to the current directory without additional info.
    file = freopen(filename, "a", stderr);
    /* Using file removes a warning */
    if (file) {
      rb_bug("COSMOS caught segfault");
    } else {
      rb_bug("COSMOS caught segfault");
    }
  }
#endif

/* NOTE: Uncomment and rebuilt for testing the handler */
// static VALUE segfault(VALUE self) {
//   char *a = 0;
//   *a = 50;
//   return Qnil;
// }

/*
 * Initialize methods for Platform specific C code
 */
void Init_platform (void) {
#ifdef _WIN32
  volatile VALUE ruby_version = rb_const_get(rb_cObject, rb_intern("RUBY_VERSION"));
  char* rversion = RSTRING_PTR(ruby_version);

#if __x86_64__
  if ((rversion[0] == '2') && (rversion[2] == '0')) {
    LoadLibraryA("exchndl20-x64.dll");
  } else if ((rversion[0] == '2') && (rversion[2] == '1')) {
    LoadLibraryA("exchndl21-x64.dll");
  } else if ((rversion[0] == '2') && (rversion[2] == '2')) {
    LoadLibraryA("exchndl22-x64.dll");
  }
#else
  if ((rversion[0] == '2') && (rversion[2] == '0')) {
    LoadLibraryA("exchndl20.dll");
  } else if ((rversion[0] == '2') && (rversion[2] == '1')) {
    LoadLibraryA("exchndl21.dll");
  } else if ((rversion[0] == '2') && (rversion[2] == '2')) {
    LoadLibraryA("exchndl22.dll");
  }
#endif

#else
  signal(SIGSEGV, catch_sigsegv);
  signal(SIGILL, catch_sigsegv);
#endif

  /* NOTE: Uncomment and rebuilt for testing the handler */
  // mCosmos = rb_define_module("Cosmos");
  // cSegFault = rb_define_class_under(mCosmos, "SegFault", rb_cObject);
  // rb_define_singleton_method(cSegFault, "segfault", segfault, 0);
}