android: Convert java_deobfuscate.py to Java

build/android/stacktrace/java/org/chromium/build/FlushingReTrace.java

Index: build/android/stacktrace/java/org/chromium/build/FlushingReTrace.java
diff --git a/build/android/stacktrace/java/org/chromium/build/FlushingReTrace.java b/build/android/stacktrace/java/org/chromium/build/FlushingReTrace.java
new file mode 100644
index 0000000000000000000000000000000000000000..1402511ac8f1aa3a5b386c0c8b577a51239113d8
--- /dev/null
+++ b/build/android/stacktrace/java/org/chromium/build/FlushingReTrace.java
@@ -0,0 +1,60 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.build;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.LineNumberReader;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+
+import proguard.retrace.ReTrace;
+
+/**
+ * A wrapper around ReTrace that:
+ *  1. Hardcodes a more useful line regular expression
+ *  2. Disables output buffering
+ */
+public class FlushingReTrace {
+    // This regex is based on the one from:
+    // http://proguard.sourceforge.net/manual/retrace/usage.html.
+    // But with the "at" part changed to "(?::|\bat)", to account for lines like:
+    //     06-22 13:58:02.895  4674  4674 E THREAD_STATE:     bLA.a(PG:173)
+    // Normal stack trace lines look like:
+    // java.lang.RuntimeException: Intentional Java Crash
+    //     at org.chromium.chrome.browser.tab.Tab.handleJavaCrash(Tab.java:682)
+    //     at org.chromium.chrome.browser.tab.Tab.loadUrl(Tab.java:644)
+    private static final String LINE_PARSE_REGEX =
+            "(?:.*?(?::|\\bat)\\s+%c\\.%m\\s*\\(%s(?::%l)?\\)\\s*)|(?:(?:.*?[:\"]\\s+)?%c(?::.*)?)";
+
+    public static void main(String[] args) {
+        if (args.length != 1) {

[jbudorick, 2017/06/28 16:11:38]

I'm surprised that the java standard library doesn't have some sort of
command-line parser.

[agrieve, 2017/06/29 01:59:20]

:( indeed.

+            System.err.println("Usage: retrace Foo.apk.map < foo.log > bar.log");
+            System.exit(1);
+        }
+
+        File mappingFile = new File(args[0]);
+        try {
+            LineNumberReader reader = new LineNumberReader(
+                    new BufferedReader(new InputStreamReader(System.in, "UTF-8")));
+
+            // Enabling autoFlush is the main difference from ReTrace.main().
+            boolean autoFlush = true;
+            PrintWriter writer =
+                    new PrintWriter(new OutputStreamWriter(System.out, "UTF-8"), autoFlush);
+
+            boolean verbose = false;
+            new ReTrace(LINE_PARSE_REGEX, verbose, mappingFile).retrace(reader, writer);
+        } catch (IOException ex) {
+            // Print a verbose stack trace.
+            ex.printStackTrace();
+            System.exit(1);
+        }
+
+        System.exit(0);

[Yaron, 2017/06/28 15:55:25]

unnecessary?

[agrieve, 2017/06/29 01:59:20]

It's necessary if there are any non-daemon threads still running. I have no idea
if this is the case, and ReTrace's main() has this exit(), so best to keep it in
I think.

+    }
+}