[Android] Symbolize the stack trace in logcat.

Previously the stack trace inside logcat is not symbolized, making it
difficult to debug.

This cl creates a logcat_symbolizer that symbolizes the stack trace in a logcat with
the new stack_symbolizer and replaces the unsymbolized stack trace in logcat
with the symbolized stace trace. The logcat_symbolizer will be called when we record
logcat during test runs.

Bug: 657040
Change-Id: Ie6c762a088a8e32dbb7095eb661d3a8a25918baf
Reviewed-on: https://chromium-review.googlesource.com/592492
Commit-Queue: Zhiling Huang <hzl@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496496}

build/android/pylib/android/logcat_symbolizer.py

+# 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.
+
+import re
+
+from devil.android import logcat_monitor
+
+BACKTRACE_LINE_RE = re.compile(r'#\d+')
+THREADTIME_RE = re.compile(
+    logcat_monitor.LogcatMonitor.THREADTIME_RE_FORMAT % (
+        r' *\S* *', r' *\S* *', r' *\S* *', r' *\S* *', r'.*'))
+
+def SymbolizeLogcat(logcat, dest, symbolizer, abi):
+  """Symbolize stack trace in the logcat.
+
+  Symbolize the logcat and write the symbolized logcat to a new file.
+
+  Args:
+    logcat: Path to logcat file.
+    dest: Path to where to write the symbolized logcat.
+    symbolizer: The stack symbolizer to symbolize stack trace in logcat.
+    abi: The device's product_cpu_abi. Symbolizer needs it to symbolize.
+
+  A sample logcat that needs to be symbolized, after stripping the prefix,
+  such as '08-07 18:39:37.692 28649 28649 E Ion     : ', would be:
+  Build fingerprint: 'google/shamu/shamu:7.1.1/NMF20B/3370:userdebug/dev-keys'
+  Revision: '0'
+  ABI: 'arm'
+  pid: 28936, tid: 28936, name: chromium.chrome  >>> org.chromium.chrome <<<
+  signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
+  Abort message: '[FATAL:debug_urls.cc(151)] Check failed: false.
+  #00 0x63e16c41 /data/app/org.chromium.chrome-1/lib/arm/libchrome.so+0x0006cc4
+  #01 0x63f19be3 /data/app/org.chromium.chrome-1/lib/arm/libchrome.so+0x0016fbe
+  #02 0x63f19737 /data/app/org.chromium.chrome-1/lib/arm/libchrome.so+0x0016f73
+  #03 0x63f18ddf /data/app/org.chromium.chrome-1/lib/arm/libchrome.so+0x0016edd
+  #04 0x63f18b79 /data/app/org.chromium.chrome-1/lib/arm/libchrome.so+0x0016eb7
+  #05 0xab53f319 /system/lib/libart.so+0x000a3319
+  #06
+     r0 00000000  r1 00007108  r2 00000006  r3 00000008
+     r4 ae60258c  r5 00000006  r6 ae602534  r7 0000010c
+     r8 bede5cd0  r9 00000030  sl 00000000  fp 9265a800
+     ip 0000000b  sp bede5c38  lr ac8e5537  pc ac8e7da0  cpsr 600f0010
+
+  backtrace:
+     #00 pc 00049da0  /system/lib/libc.so (tgkill+12)
+     #01 pc 00047533  /system/lib/libc.so (pthread_kill+34)
+     #02 pc 0001d635  /system/lib/libc.so (raise+10)
+     #03 pc 00019181  /system/lib/libc.so (__libc_android_abort+34)
+     #04 pc 00017048  /system/lib/libc.so (abort+4)
+     #05 pc 00948605  /data/app/org.chromium.chrome-1/lib/arm/libchrome.so
+     #06 pc 002c9f73  /data/app/org.chromium.chrome-1/lib/arm/libchrome.so
+     #07 pc 003ccbe1  /data/app/org.chromium.chrome-1/lib/arm/libchrome.so
+     #08 pc 003cc735  /data/app/org.chromium.chrome-1/lib/arm/libchrome.so
+     #09 pc 003cbddf  /data/app/org.chromium.chrome-1/lib/arm/libchrome.so
+     #10 pc 003cbb77  /data/app/org.chromium.chrome-1/lib/arm/libchrome.so
+  """
+
+  with open(logcat) as logcat_file:
+    with open(dest, 'w') as dest_file:
+      # The current stack script will only print out the symbolized stack,
+      # and completely ignore logs other than the crash log that is used for
+      # symbolization, if any exists. Thus the code here extracts the
+      # crash log inside the logcat and pass only the crash log to the script,
+      # because we don't want to lose other information in the logcat that,
+      # if passed to the stack script, will just be ignored by it.
+      # TODO(crbug.com/755225): Rewrite the logic here.
+      outside_of_crash_log = True
+      in_lower_half_crash = False
+      data_to_symbolize = []
+
+      for line in logcat_file:
+        if outside_of_crash_log:
+          # Check whether it is the start of crash log.
+          if 'Build fingerprint: ' in line:
+            outside_of_crash_log = False
+            # Only include necessary information for symbolization.
+            # The logic here that removes date, time, proc_id etc.
+            # should be in sync with _THREADTIME_RE_FORMAT in logcat_monitor.
+            data_to_symbolize.append(
+              re.search(THREADTIME_RE, line).group(7))
+          else:
+            dest_file.write(line)
+        else:
+          # Once we have reached the end of the backtrace section,
+          # we will start symbolizing.
+          if in_lower_half_crash and not bool(BACKTRACE_LINE_RE.search(line)):
+            outside_of_crash_log = True
+            in_lower_half_crash = False
+            symbolized_lines = symbolizer.ExtractAndResolveNativeStackTraces(
+                data_to_symbolize, abi)
+            dest_file.write('\n'.join(symbolized_lines) + '\n' + line)
+            data_to_symbolize = []
+          else:
+            if not in_lower_half_crash and 'backtrace:' in line:
+              in_lower_half_crash = True
+            data_to_symbolize.append(
+                re.search(THREADTIME_RE, line).group(7))