rb_backtrace.patch

diff --git a/eval.c b/eval.c
index 11264f7..e2f9687 100644
--- a/eval.c
+++ b/eval.c
@@ -29,6 +29,7 @@
 #endif
 
 #include <stdio.h>
+#include <time.h>
 
 #include "st.h"
 #include "dln.h"
@@ -748,6 +749,8 @@ extern int ruby_nerrs;
 VALUE rb_eLocalJumpError;
 VALUE rb_eSysStackError;
 
+static FILE *rb_backtrace_file;
+
 extern VALUE ruby_top_self;
 
 struct FRAME *ruby_frame;
@@ -1627,6 +1630,28 @@ ruby_cleanup(ex)
 
     return ex;
 }
+static void
+ruby_set_parameters()
+{
+    char *backtrace_file = NULL;
+
+    rb_backtrace_file = stderr;
+
+    backtrace_file = getenv("RUBY_BACKTRACE_FILE");
+    if (backtrace_file != NULL) {
+      char *filename;
+      asprintf(&filename, "%s.%ld", backtrace_file, (long int)(getpid()));
+      FILE *file = fopen(filename, "w");
+      if (file != NULL) {
+        rb_backtrace_file = file;
+      }
+      else {
+        fprintf(stderr, "can't open backtrace file: %s, using stderr\n", backtrace_file);
+        rb_backtrace_file = stderr;
+      }
+      free(filename);
+    }
+}
 
 static int
 ruby_exec_internal()
@@ -1649,6 +1674,7 @@ void
 ruby_stop(ex)
     int ex;
 {
+    fclose(rb_backtrace_file);
     exit(ruby_cleanup(ex));
 }
 
@@ -1658,6 +1684,7 @@ ruby_exec()
     volatile NODE *tmp;
 
     Init_stack((void*)&tmp);
+    ruby_set_parameters();
     return ruby_exec_internal();
 }
 
@@ -6420,6 +6447,19 @@ rb_f_caller(argc, argv)
     return backtrace(lev);
 }
 
+static void
+ruby_print_time(FILE *fp)
+{
+   struct tm *tmp;
+   time_t t;
+
+   t = time(NULL);
+   tmp = localtime(&t);
+   fprintf(fp, "-- %02d.%02d.%04d %02d:%02d:%02d\n",
+     tmp->tm_mday, tmp->tm_mon+1, tmp->tm_year+1900,
+     tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
+}
+
 void
 rb_backtrace()
 {
@@ -6427,9 +6467,11 @@ rb_backtrace()
     VALUE ary;
 
     ary = backtrace(-1);
+    ruby_print_time(rb_backtrace_file);
     for (i=0; i<RARRAY(ary)->len; i++) {
-	printf("\tfrom %s\n", RSTRING(RARRAY(ary)->ptr[i])->ptr);
+	    fprintf(rb_backtrace_file, "\tfrom %s\n", RSTRING(RARRAY(ary)->ptr[i])->ptr);
     }
+    fflush(rb_backtrace_file);
 }
 
 static VALUE