From e5ecb5b549585caea5b8e3becc9e7ac94d159022 Mon Sep 17 00:00:00 2001
From: Joel Dice <joel.dice@gmail.com>
Date: Tue, 15 Mar 2011 17:27:17 -0600
Subject: [PATCH] add optional avian.error.log system property

This property may be used to specify a file name to use for printing
stack traces for unhandled exceptions.  The default is stderr.
---
 src/machine.cpp | 19 ++++++++++---------
 src/machine.h   | 16 ++++++++++++++++
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/src/machine.cpp b/src/machine.cpp
index 1f4e895148..7c1863c8f3 100644
--- a/src/machine.cpp
+++ b/src/machine.cpp
@@ -2258,6 +2258,7 @@ Machine::Machine(System* system, Heap* heap, Finder* bootFinder,
   referenceLock(0),
   shutdownLock(0),
   libraries(0),
+  errorLog(0),
   types(0),
   roots(0),
   finalizers(0),
@@ -3888,19 +3889,19 @@ printTrace(Thread* t, object exception)
 
   for (object e = exception; e; e = throwableCause(t, e)) {
     if (e != exception) {
-      fprintf(stderr, "caused by: ");
+      fprintf(errorLog(t), "caused by: ");
     }
 
-    fprintf(stderr, "%s", &byteArrayBody
+    fprintf(errorLog(t), "%s", &byteArrayBody
             (t, className(t, objectClass(t, e)), 0));
   
     if (throwableMessage(t, e)) {
       object m = throwableMessage(t, e);
       THREAD_RUNTIME_ARRAY(t, char, message, stringLength(t, m) + 1);
       stringChars(t, m, RUNTIME_ARRAY_BODY(message));
-      fprintf(stderr, ": %s\n", RUNTIME_ARRAY_BODY(message));
+      fprintf(errorLog(t), ": %s\n", RUNTIME_ARRAY_BODY(message));
     } else {
-      fprintf(stderr, "\n");
+      fprintf(errorLog(t), "\n");
     }
 
     object trace = throwableTrace(t, e);
@@ -3914,17 +3915,17 @@ printTrace(Thread* t, object exception)
         int line = t->m->processor->lineNumber
           (t, traceElementMethod(t, e), traceElementIp(t, e));
 
-        fprintf(stderr, "  at %s.%s ", class_, method);
+        fprintf(errorLog(t), "  at %s.%s ", class_, method);
 
         switch (line) {
         case NativeLine:
-          fprintf(stderr, "(native)\n");
+          fprintf(errorLog(t), "(native)\n");
           break;
         case UnknownLine:
-          fprintf(stderr, "(unknown line)\n");
+          fprintf(errorLog(t), "(unknown line)\n");
           break;
         default:
-          fprintf(stderr, "(line %d)\n", line);
+          fprintf(errorLog(t), "(line %d)\n", line);
         }
       }
     }
@@ -3934,7 +3935,7 @@ printTrace(Thread* t, object exception)
     }
   }
 
-  fflush(stderr);
+  fflush(errorLog(t));
 }
 
 object
diff --git a/src/machine.h b/src/machine.h
index 4031093138..b784d6072a 100644
--- a/src/machine.h
+++ b/src/machine.h
@@ -1298,6 +1298,7 @@ class Machine {
   System::Monitor* referenceLock;
   System::Monitor* shutdownLock;
   System::Library* libraries;
+  FILE* errorLog;
   object types;
   object roots;
   object finalizers;
@@ -3577,6 +3578,21 @@ methodClone(Thread* t, object method)
      methodCode(t, method));
 }
 
+inline FILE*
+errorLog(Thread* t)
+{
+  if (t->m->errorLog == 0) {
+    const char* path = findProperty(t, "avian.error.log");
+    if (path) {
+      t->m->errorLog = vm::fopen(path, "wb");
+    } else {
+      t->m->errorLog = stderr;
+    }
+  }
+
+  return t->m->errorLog;
+}
+
 } // namespace vm
 
 void