From 2a51cb5fd50b6f45616928f729ff9dba90989126 Mon Sep 17 00:00:00 2001
From: Scott Graham <scottmg@chromium.org>
Date: Thu, 11 Jan 2018 14:19:49 -0800
Subject: [PATCH] fuchsia: Fixes for finding GN when in bot configuration

On buildbot, GN isn't in the path, and must be run with a full explicit
path. GN saves this to the build.gn for regeneration purposes, so
extract it out of there.

Additionally, set cwd when calling GN, otherwise, it will be unable to
find the .gn in the root of the source tree.

Bug: crashpad:196
Change-Id: Ia14db175ba0af6dc61b215da6ba5c624bca56886
Reviewed-on: https://chromium-review.googlesource.com/862547
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>
---
 build/run_tests.py | 57 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 47 insertions(+), 10 deletions(-)

diff --git a/build/run_tests.py b/build/run_tests.py
index e180a6cb..b33478cf 100755
--- a/build/run_tests.py
+++ b/build/run_tests.py
@@ -30,19 +30,54 @@ CRASHPAD_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)),
 IS_WINDOWS_HOST = sys.platform.startswith('win')
 
 
+def _FindGNFromBinaryDir(binary_dir):
+  """Attempts to determine the path to a GN binary used to generate the build
+  files in the given binary_dir. This is necessary because `gn` might not be in
+  the path or might be in a non-standard location, particularly on build
+  machines."""
+
+  build_ninja = os.path.join(binary_dir, 'build.ninja')
+  if os.path.isfile(build_ninja):
+    with open(build_ninja, 'rb') as f:
+      # Look for the always-generated regeneration rule of the form:
+      #
+      # rule gn
+      #   command = <gn binary> ... arguments ...
+      #
+      # to extract the gn binary's full path.
+      found_rule_gn = False
+      for line in f:
+        if line.strip() == 'rule gn':
+          found_rule_gn = True
+          continue
+        if found_rule_gn:
+          if len(line) == 0 or line[0] != ' ':
+            return None
+          if line.startswith('  command = '):
+            gn_command_line_parts = line.strip().split(' ')
+            if len(gn_command_line_parts) > 2:
+              return gn_command_line_parts[2]
+
+  return None
+
+
 def _BinaryDirTargetOS(binary_dir):
   """Returns the apparent target OS of binary_dir, or None if none appear to be
   explicitly specified."""
 
-  # Look for a GN “target_os”.
-  popen = subprocess.Popen(
-      ['gn', 'args', binary_dir, '--list=target_os', '--short'],
-      shell=IS_WINDOWS_HOST, stdout=subprocess.PIPE, stderr=open(os.devnull))
-  value = popen.communicate()[0]
-  if popen.returncode == 0:
-    match = re.match('target_os = "(.*)"$', value.decode('utf-8'))
-    if match:
-      return match.group(1)
+  gn_path = _FindGNFromBinaryDir(binary_dir)
+
+  if gn_path:
+    # Look for a GN “target_os”.
+    popen = subprocess.Popen(
+        [gn_path, 'args', binary_dir, '--list=target_os', '--short'],
+        shell=IS_WINDOWS_HOST, stdout=subprocess.PIPE, stderr=open(os.devnull),
+        cwd=CRASHPAD_DIR)
+    value = popen.communicate()[0]
+    if popen.returncode == 0:
+      match = re.match('target_os = "(.*)"$', value.decode('utf-8'))
+      if match:
+        return match.group(1)
 
   # For GYP with Ninja, look for the appearance of “linux-android” in the path
   # to ar. This path is configured by gyp_crashpad_android.py.
@@ -277,8 +312,10 @@ def _GenerateFuchsiaRuntimeDepsFiles(binary_dir, tests):
   targets_file = os.path.abspath(os.path.join(binary_dir, 'targets.txt'))
   with open(targets_file, 'wb') as f:
     f.write('//:' + '\n//:'.join(tests) + '\n')
+  gn_path = _FindGNFromBinaryDir(binary_dir)
   subprocess.check_call(
-      ['gn', 'gen', binary_dir, '--runtime-deps-list-file=' + targets_file])
+      [gn_path, 'gen', binary_dir, '--runtime-deps-list-file=' + targets_file],
+      cwd=CRASHPAD_DIR)
 
 
 def _HandleOutputFromFuchsiaLogListener(process, done_message):