[fuchsia] Determine llvm-symbolizer path from test host architecture

and Linux distro.

This supports running tests on x64 Ubuntu and on arm64 Ubuntu 16.04
and arm64 Ubuntu 18.04.

Bug: 1131647
Change-Id: Ie75adcb775bc32601fb4001720e960b17607edee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517991
Commit-Queue: Stephen Roe <steveroe@google.com>
Reviewed-by: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#829884}

build/fuchsia/symbolizer.py

@@ -4,19 +4,48 @@
 
 import logging
 import os
+import re
 import subprocess
 
 from common import SDK_ROOT
 from common import GetHostArchFromPlatform
 from common import GetHostToolPathFromPlatform
 
-# TODO(crbug.com/1131647): Change 'llvm-3.8' to 'llvm' after docker image is
-# updated.
-ARM64_DOCKER_LLVM_SYMBOLIZER_PATH = os.path.join('/', 'usr', 'lib', 'llvm-3.8',
+# Paths to the llvm-symbolizer executable in different test hosts.
+X64_LLVM_SYMBOLIZER_PATH = os.path.join(SDK_ROOT, os.pardir, os.pardir,
+                                        'llvm-build', 'Release+Asserts', 'bin',
+                                        'llvm-symbolizer')
+ARM64_XENIAL_LLVM_SYMBOLIZER_PATH = os.path.join('/', 'usr', 'lib', 'llvm-3.8',
                                                  'bin', 'llvm-symbolizer')
+ARM64_BIONIC_LLVM_SYMBOLIZER_PATH = os.path.join('/', 'usr', 'lib', 'llvm-6.0',
+                                                 'bin', 'llvm-symbolizer')
+
+
+def _GetLLVMSymbolizerPath():
+  """Determines the path to the LLVM symbolizer executable based on test host
+  architecture and Ubuntu distro."""
+
+  if GetHostArchFromPlatform() == 'x64':
+    return X64_LLVM_SYMBOLIZER_PATH
+
+  # Get distro codename from /etc/os-release.
+  with open(os.path.join('/', 'etc', 'os-release')) as os_release_file:
+    os_release_text = os_release_file.read()
+  version_codename_re = r'^VERSION_CODENAME=(?P<codename>[\w.-]+)$'
+  match = re.search(version_codename_re, os_release_text, re.MULTILINE)
+  codename = match.group('codename') if match else None
+
+  if codename == 'xenial':
+    return ARM64_XENIAL_LLVM_SYMBOLIZER_PATH
+  elif codename == 'bionic':
+    return ARM64_BIONIC_LLVM_SYMBOLIZER_PATH
+  else:
+    raise Exception('Unknown Ubuntu release "%s"' % codename)
+
 
 def BuildIdsPaths(package_paths):
-  """Generate build ids paths for symbolizer processes."""
+  """Generates build ids paths for symbolizer processes."""
+
   build_ids_paths = map(
       lambda package_path: os.path.join(
           os.path.dirname(package_path), 'ids.txt'),
@@ -33,15 +62,8 @@ def RunSymbolizer(input_file, output_file, build_ids_files):
                   unstripped binaries on the filesystem.
   Returns a Popen object for the started process."""
 
-  if (GetHostArchFromPlatform() == 'arm64' and
-      os.path.isfile(ARM64_DOCKER_LLVM_SYMBOLIZER_PATH)):
-    llvm_symbolizer_path = ARM64_DOCKER_LLVM_SYMBOLIZER_PATH
-  else:
-    llvm_symbolizer_path = os.path.join(SDK_ROOT, os.pardir, os.pardir,
-                                        'llvm-build', 'Release+Asserts', 'bin',
-                                        'llvm-symbolizer')
-
   symbolizer = GetHostToolPathFromPlatform('symbolize')
+  llvm_symbolizer_path = _GetLLVMSymbolizerPath()
   symbolizer_cmd = [symbolizer,
                     '-ids-rel', '-llvm-symbolizer', llvm_symbolizer_path,
                     '-build-id-dir', os.path.join(SDK_ROOT, '.build-id')]