Make gclient_utils.GetBuildtoolsPath() work in a build-spec checkout

gclient_utils.py

Index: gclient_utils.py
diff --git a/gclient_utils.py b/gclient_utils.py
index 21c44c36a786bc5f9e6b84a3ccef0b9b2f5cc84a..e8d6f72f0549ba185a39a2b0010859dde600605c 100644
--- a/gclient_utils.py
+++ b/gclient_utils.py
@@ -683,7 +683,8 @@ def GetPrimarySolutionPath():
     return None
 
   # Some projects' top directory is not named 'src'.
-  source_dir_name = GetGClientPrimarySolutionName(gclient_root) or 'src'
+  solution_dict = _GetGClientPrimarySolution(gclient_root)
+  source_dir_name = solution_dict.get('name', 'src')
   return os.path.join(gclient_root, source_dir_name)
 
 
@@ -697,13 +698,22 @@ def GetBuildtoolsPath():
   if override is not None:
     return override
 
+  # Attempt to find buildtools/ by reading the DEPS file.
+  gclient_root = FindGclientRoot(os.getcwd())
+  if gclient_root:
+    solution_dict = _GetGClientPrimarySolution(gclient_root)
+    deps_dict = _ReadDepsFileForSolution(gclient_root, solution_dict) or {}
+    for sub_path in deps_dict.get('deps', {}):
+      if sub_path.endswith('/buildtools'):
+        return os.path.join(gclient_root, sub_path)
+
+  # Fall-back to heuristics.
   primary_solution = GetPrimarySolutionPath()
   if not primary_solution:
     return None
   buildtools_path = os.path.join(primary_solution, 'buildtools')
   if not os.path.exists(buildtools_path):
     # Buildtools may be in the gclient root.
-    gclient_root = FindGclientRoot(os.getcwd())
     buildtools_path = os.path.join(gclient_root, 'buildtools')
   return buildtools_path
 
@@ -732,15 +742,33 @@ def GetExeSuffix():
   return ''
 
 
-def GetGClientPrimarySolutionName(gclient_root_dir_path):
-  """Returns the name of the primary solution in the .gclient file specified."""
-  gclient_config_file = os.path.join(gclient_root_dir_path, '.gclient')
+def _ReadDepsFileForSolution(gclient_root, solution_dict):
+  """Reads the DEPS file for the given solution.
+
+  This stubs out Var(), as it's not currently required.
+  """
+  env = {}
+  if 'name' in solution_dict:
+    deps_file = solution_dict.get('deps_file', 'DEPS')
+    deps_path = os.path.join(gclient_root, solution_dict['name'], deps_file)
+    global_scope = {
+        '__builtins__': {'None': None},
+        'Var': lambda x: '',
+        'deps_os': {},
+    }
+    execfile(deps_path, global_scope, env)
+  return env
+
+
+def _GetGClientPrimarySolution(gclient_root):
+  """Returns the dict for the primary solution in the given gclient path."""
+  gclient_config_file = os.path.join(gclient_root, '.gclient')
   env = {}
   execfile(gclient_config_file, env)
   solutions = env.get('solutions', [])
   if solutions:
-    return solutions[0].get('name')
-  return None
+    return solutions[0]
+  return {}
 
 
 def GetGClientRootAndEntries(path=None):