[NaCl SDK] Remove create_nmf dependency on NACL_SDK_ROOT env var

create_nmf should determine the root of the SDK relative
to its own location.

The exception to this is when its run as part of the
chrome build, when it is not yet installed.  In this
case we pass --no-default-libpath and --objdump to
create_nmf to remove any use of the SDK root.

This is the second attempt at landing this change.
The first one was reverted:
https://codereview.chromium.org/737653003

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_nacl_sdk;tryserver.chromium.mac:mac_nacl_sdk
BUG=none

Review URL: https://codereview.chromium.org/1066823003

Cr-Commit-Position: refs/heads/master@{#325511}

2 files changed, 24 insertions, 35 deletions

diff --git a/native_client_sdk/src/tools/create_nmf.py b/native_client_sdk/src/tools/create_nmf.py
index de72408..dc7e552 100755
--- a/native_client_sdk/src/tools/create_nmf.py
+++ b/native_client_sdk/src/tools/create_nmf.py
@@ -466,15 +466,16 @@ def ParseExtraFiles(encoded_list, err):
 
 
 def GetSDKRoot():
-  """Determine current NACL_SDK_ROOT, either via the environment variable
-  itself, or by attempting to derive it from the location of this script.
+  """Returns the root directory of the NaCl SDK.
   """
-  sdk_root = os.environ.get('NACL_SDK_ROOT')
-  if not sdk_root:
-    sdk_root = os.path.dirname(SCRIPT_DIR)
-    if not os.path.exists(os.path.join(sdk_root, 'toolchain')):
-      return None
-
+  # This script should be installed in NACL_SDK_ROOT/tools. Assert that
+  # the 'toolchain' folder exists within this directory in case, for
+  # example, this script is moved to a different location.
+  # During the Chrome build this script is sometimes run outside of
+  # of an SDK but in these cases it should always be run with --objdump=
+  # and --no-default-libpath which avoids the need to call this function.
+  sdk_root = os.path.dirname(SCRIPT_DIR)
+  assert(os.path.exists(os.path.join(sdk_root, 'toolchain')))
   return sdk_root
 
 
@@ -482,12 +483,8 @@ def FindObjdumpExecutable():
   """Derive path to objdump executable to use for determining shared
   object dependencies.
   """
-  sdk_root = GetSDKRoot()
-  if not sdk_root:
-    return None
-
   osname = getos.GetPlatform()
-  toolchain = os.path.join(sdk_root, 'toolchain', '%s_x86_glibc' % osname)
+  toolchain = os.path.join(GetSDKRoot(), 'toolchain', '%s_x86_glibc' % osname)
   objdump = os.path.join(toolchain, 'bin', 'x86_64-nacl-objdump')
   if osname == 'win':
     objdump += '.exe'
@@ -508,10 +505,6 @@ def GetDefaultLibPath(config):
   """
   assert(config in ('Debug', 'Release'))
   sdk_root = GetSDKRoot()
-  if not sdk_root:
-    # TOOD(sbc): output a warning here?  We would also need to suppress
-    # the warning when run from the chromium build.
-    return []
 
   osname = getos.GetPlatform()
   libpath = [
@@ -580,8 +573,8 @@ def main(args):
                       help='Rename FOO as BAR',
                       action='append', default=[], metavar='FOO,BAR')
   parser.add_argument('-x', '--extra-files',
-                      help=('Add extra key:file tuple to the "files"' +
-                            ' section of the .nmf'),
+                      help='Add extra key:file tuple to the "files"'
+                           ' section of the .nmf',
                       action='append', default=[], metavar='FILE')
   parser.add_argument('-O', '--pnacl-optlevel',
                       help='Set the optimization level to N in PNaCl manifests',
@@ -669,7 +662,7 @@ def main(args):
                  pnacl_debug_optlevel=pnacl_debug_optlevel,
                  nmf_root=nmf_root)
 
-  if not options.output:
+  if options.output is None:
     sys.stdout.write(nmf.GetJson())
   else:
     with open(options.output, 'w') as output:
diff --git a/native_client_sdk/src/tools/tests/create_nmf_test.py b/native_client_sdk/src/tools/tests/create_nmf_test.py
index 86a89a2..d71bee9 100755
--- a/native_client_sdk/src/tools/tests/create_nmf_test.py
+++ b/native_client_sdk/src/tools/tests/create_nmf_test.py
@@ -14,17 +14,19 @@ import unittest
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
 TOOLS_DIR = os.path.dirname(SCRIPT_DIR)
 DATA_DIR = os.path.join(TOOLS_DIR, 'lib', 'tests', 'data')
+BUILD_TOOLS_DIR = os.path.join(os.path.dirname(TOOLS_DIR), 'build_tools')
 CHROME_SRC = os.path.dirname(os.path.dirname(os.path.dirname(TOOLS_DIR)))
 MOCK_DIR = os.path.join(CHROME_SRC, 'third_party', 'pymock')
 
 # For the mock library
 sys.path.append(MOCK_DIR)
 sys.path.append(TOOLS_DIR)
+sys.path.append(BUILD_TOOLS_DIR)
 
 import build_paths
 import create_nmf
 import getos
-import mock
+from mock import patch, Mock
 
 TOOLCHAIN_OUT = os.path.join(build_paths.OUT_DIR, 'sdk_tests', 'toolchain')
 NACL_X86_GLIBC_TOOLCHAIN = os.path.join(TOOLCHAIN_OUT,
@@ -61,24 +63,18 @@ class TestPosixRelPath(unittest.TestCase):
 
 
 class TestDefaultLibpath(unittest.TestCase):
-  def testWithoutNaClSDKRoot(self):
-    """GetDefaultLibPath wihtout NACL_SDK_ROOT set
-
-    In the absence of NACL_SDK_ROOT GetDefaultLibPath should
-    return the empty list."""
-    with mock.patch.dict('os.environ', clear=True):
-      paths = create_nmf.GetDefaultLibPath('Debug')
-    self.assertEqual(paths, [])
-
-  def testHonorNaClSDKRoot(self):
-    with mock.patch.dict('os.environ', {'NACL_SDK_ROOT': '/dummy/path'}):
-      paths = create_nmf.GetDefaultLibPath('Debug')
+  def setUp(self):
+    patcher = patch('create_nmf.GetSDKRoot', Mock(return_value='/dummy/path'))
+    patcher.start()
+    self.addCleanup(patcher.stop)
+
+  def testUsesSDKRoot(self):
+    paths = create_nmf.GetDefaultLibPath('Debug')
     for path in paths:
       self.assertTrue(path.startswith('/dummy/path'))
 
   def testIncludesNaClPorts(self):
-    with mock.patch.dict('os.environ', {'NACL_SDK_ROOT': '/dummy/path'}):
-      paths = create_nmf.GetDefaultLibPath('Debug')
+    paths = create_nmf.GetDefaultLibPath('Debug')
     self.assertTrue(any(os.path.join('ports', 'lib') in p for p in paths),
                     "naclports libpath missing: %s" % str(paths))