Download arm sysroot as part of gclient hooks

build/linux/install-arm-sysroot.py

+#!/usr/bin/env python
+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Script to install arm choot image for cross building of arm chrome on linux.
+# This script can be run manually but is more often run as part of gclient
+# hooks. When run from hooks this script should be a no-op on non-linux
+# platforms.
+
+# The sysroot image could be constructed from scratch based on the current
+# state or precise/arm but for consistency we currently use a pre-built root
+# image which was originally designed for building trusted NaCl code. The image
+# will normally need to be rebuilt every time chrome's build dependancies are
+# changed.
+
+import os
+import shutil
+import subprocess
+import sys
+
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+url_prefix = 'https://commondatastorage.googleapis.com/nativeclient-archive2/toolchain'
+revision = 8002

[iannucci, 2012/12/07 23:50:08]

nit: upcase for globals

[Sam Clegg, 2012/12/07 23:57:36]

Done.

+
+def main(args):
+  if '--linux-only' in args:
+    # This argument is passed when run from the gclient hooks.
+    # In this case we return early on non-linux platforms
+    # or if GYP_DEFINES doesn't include target_arch=arm
+    if not sys.platform.startswith('linux'):
+      return 0
+
+    if "target_arch=arm" not in os.environ.get('GYP_DEFINES', ''):
+      return 0
+
+  src_root = os.path.dirname(os.path.dirname(SCRIPT_DIR))
+  sysroot = os.path.join(src_root, 'arm-sysroot')
+  url = "%s/%s/naclsdk_linux_arm-trusted.tgz" % (url_prefix, revision)
+
+  stamp = os.path.join(sysroot, ".stamp")
+  if os.path.exists(stamp):
+    with open(stamp) as s:
+      if s.read() == url:
+        print "ARM root image already up-to-date: %s" % sysroot
+        return 0
+
+  print "Installing ARM root image: %s" % sysroot
+  if os.path.isdir(sysroot):

[iannucci, 2012/12/07 23:50:08]

Nit: this would fail if sysroot is something other than a dir... unlikely, I
know, but this will fail on the mkdir if sysroot it was a symlink. Not really
sure how this would ever happen though.

[Sam Clegg, 2012/12/07 23:57:36]

Hmm. Interesting failure cases here.  os.path.isdir() and os.path.isfile()
actually return True for links that point to files and dirs respectively.

The problem is that shutil.rmtree() won't remove a symlinked tree :)

My conclusion is that if you have arm-sysroot symlinked to somewhere else you
probably don't want this script delete it or messing with it so its probably
better to let it fail and have the user diagnose their strange situation.

Failing silently, or following the link and removing that tree both seem wrong
to me.

Does that make sense?

+    shutil.rmtree(sysroot)
+  os.mkdir(sysroot)
+  tarball = os.path.join(sysroot, 'naclsdk_linux_arm-trusted.tgz')
+  subprocess.check_call(['curl', '-L', url, '-o', tarball])
+  subprocess.check_call(['tar', 'xf', tarball, '-C', sysroot])
+  os.remove(tarball)
+
+  with open(stamp, 'w') as s:
+    s.write(url)
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv[1:]))