From c3441d156f8beb8cdd76880988132c197ddef2e1 Mon Sep 17 00:00:00 2001
From: dpranke <dpranke@chromium.org>
Date: Tue, 23 Jun 2015 16:01:35 -0700
Subject: [PATCH] Fix errors in MB when run for the first time on a new
 builder.

The first time we run a build on a GN builder, it's possible
that MB will run and the build directory (//out/Release) may not
exist yet; in that case, we need to create the directory before
trying to write the list of runtime_deps that GN will need to read.

R=maruel@chromium.org
BUG=480053

Review URL: https://codereview.chromium.org/1204793002

Cr-Commit-Position: refs/heads/master@{#335793}
---
 tools/mb/mb.py          | 12 ++++++++++++
 tools/mb/mb_unittest.py |  9 +++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/tools/mb/mb.py b/tools/mb/mb.py
index 5b43c61d5fda..35c0e9124fd6 100755
--- a/tools/mb/mb.py
+++ b/tools/mb/mb.py
@@ -13,6 +13,7 @@ from __future__ import print_function
 
 import argparse
 import ast
+import errno
 import json
 import os
 import pipes
@@ -339,6 +340,10 @@ class MetaBuildWrapper(object):
         gn_labels.append(ninja_targets_to_labels[target])
 
       gn_runtime_deps_path = self.ToAbsPath(path, 'runtime_deps')
+
+      # Since GN hasn't run yet, the build directory may not even exist.
+      self.MaybeMakeDirectory(self.ToAbsPath(path))
+
       self.WriteFile(gn_runtime_deps_path, '\n'.join(gn_labels) + '\n')
       cmd.append('--runtime-deps-list-file=%s' % gn_runtime_deps_path)
 
@@ -738,6 +743,13 @@ class MetaBuildWrapper(object):
     # This function largely exists so it can be overridden for testing.
     return os.path.exists(path)
 
+  def MaybeMakeDirectory(self, path):
+    try:
+      os.makedirs(path)
+    except OSError, e:
+      if e.errno != errno.EEXIST:
+        raise
+
   def ReadFile(self, path):
     # This function largely exists so it can be overriden for testing.
     with open(path) as fp:
diff --git a/tools/mb/mb_unittest.py b/tools/mb/mb_unittest.py
index d0326ca06d87..2d6ae62e8e1a 100644
--- a/tools/mb/mb_unittest.py
+++ b/tools/mb/mb_unittest.py
@@ -16,6 +16,7 @@ class FakeMBW(mb.MetaBuildWrapper):
     super(FakeMBW, self).__init__()
     self.files = {}
     self.calls = []
+    self.cmds = []
     self.out = ''
     self.err = ''
     self.platform = 'linux2'
@@ -28,6 +29,9 @@ class FakeMBW(mb.MetaBuildWrapper):
   def Exists(self, path):
     return self.files.get(path) is not None
 
+  def MaybeMakeDirectory(self, path):
+    pass
+
   def ReadFile(self, path):
     return self.files[path]
 
@@ -36,6 +40,8 @@ class FakeMBW(mb.MetaBuildWrapper):
 
   def Call(self, cmd):
     self.calls.append(cmd)
+    if self.cmds:
+      return self.cmds.pop(0)
     return 0, '', ''
 
   def Print(self, *args, **kwargs):
@@ -47,7 +53,7 @@ class FakeMBW(mb.MetaBuildWrapper):
     else:
       self.out += sep.join(args) + end
 
-  def TempFile(self):
+  def TempFile(self, mode='w'):
     return FakeFile(self.files)
 
   def RemoveFile(self, path):
@@ -185,7 +191,6 @@ class UnitTest(unittest.TestCase):
         (1, 'The input matches no targets, configs, or files\n', ''),
         (1, 'The input matches no targets, configs, or files\n', ''),
     ]
-    mbw.Call = lambda cmd: mbw.cmds.pop(0)
 
     self.check(['analyze', '-c', 'gn_debug', '//out/Default',
                 '/tmp/in.json', '/tmp/out.json'], mbw=mbw, ret=0)
-- 
2.11.4.GIT