Add a snapshot of flutter/engine/src/build to our sdk

build/util/lastchange.py

Index: build/util/lastchange.py
diff --git a/build/util/lastchange.py b/build/util/lastchange.py
new file mode 100755
index 0000000000000000000000000000000000000000..3f3ee4af47117c5d00143713217a27964eb226c6
--- /dev/null
+++ b/build/util/lastchange.py
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+#!/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.
+
+"""
+lastchange.py -- Chromium revision fetching utility.
+"""
+
+import re
+import optparse
+import os
+import subprocess
+import sys
+
+_GIT_SVN_ID_REGEX = re.compile(r'.*git-svn-id:\s*([^@]*)@([0-9]+)', re.DOTALL)
+
+class VersionInfo(object):
+  def __init__(self, url, revision):
+    self.url = url
+    self.revision = revision
+
+
+def FetchSVNRevision(directory, svn_url_regex):
+  """
+  Fetch the Subversion branch and revision for a given directory.
+
+  Errors are swallowed.
+
+  Returns:
+    A VersionInfo object or None on error.
+  """
+  try:
+    proc = subprocess.Popen(['svn', 'info'],
+                            stdout=subprocess.PIPE,
+                            stderr=subprocess.PIPE,
+                            cwd=directory,
+                            shell=(sys.platform=='win32'))
+  except OSError:
+    # command is apparently either not installed or not executable.
+    return None
+  if not proc:
+    return None
+
+  attrs = {}
+  for line in proc.stdout:
+    line = line.strip()
+    if not line:
+      continue
+    key, val = line.split(': ', 1)
+    attrs[key] = val
+
+  try:
+    match = svn_url_regex.search(attrs['URL'])
+    if match:
+      url = match.group(2)
+    else:
+      url = ''
+    revision = attrs['Revision']
+  except KeyError:
+    return None
+
+  return VersionInfo(url, revision)
+
+
+def RunGitCommand(directory, command):
+  """
+  Launches git subcommand.
+
+  Errors are swallowed.
+
+  Returns:
+    A process object or None.
+  """
+  command = ['git'] + command
+  # Force shell usage under cygwin. This is a workaround for
+  # mysterious loss of cwd while invoking cygwin's git.
+  # We can't just pass shell=True to Popen, as under win32 this will
+  # cause CMD to be used, while we explicitly want a cygwin shell.
+  if sys.platform == 'cygwin':
+    command = ['sh', '-c', ' '.join(command)]
+  try:
+    proc = subprocess.Popen(command,
+                            stdout=subprocess.PIPE,
+                            stderr=subprocess.PIPE,
+                            cwd=directory,
+                            shell=(sys.platform=='win32'))
+    return proc
+  except OSError:
+    return None
+
+
+def FetchGitRevision(directory):
+  """
+  Fetch the Git hash for a given directory.
+
+  Errors are swallowed.
+
+  Returns:
+    A VersionInfo object or None on error.
+  """
+  hsh = ''
+  proc = RunGitCommand(directory, ['rev-parse', 'HEAD'])
+  if proc:
+    output = proc.communicate()[0].strip()
+    if proc.returncode == 0 and output:
+      hsh = output
+  if not hsh:
+    return None
+  pos = ''
+  proc = RunGitCommand(directory, ['cat-file', 'commit', 'HEAD'])
+  if proc:
+    output = proc.communicate()[0]
+    if proc.returncode == 0 and output:
+      for line in reversed(output.splitlines()):
+        if line.startswith('Cr-Commit-Position:'):
+          pos = line.rsplit()[-1].strip()
+          break
+  if not pos:
+    return VersionInfo('git', hsh)
+  return VersionInfo('git', '%s-%s' % (hsh, pos))
+
+
+def FetchGitSVNURLAndRevision(directory, svn_url_regex, go_deeper):
+  """
+  Fetch the Subversion URL and revision through Git.
+
+  Errors are swallowed.
+
+  Returns:
+    A tuple containing the Subversion URL and revision.
+  """
+  git_args = ['log', '-1', '--format=%b']
+  if go_deeper:
+    git_args.append('--grep=git-svn-id')
+  proc = RunGitCommand(directory, git_args)
+  if proc:
+    output = proc.communicate()[0].strip()
+    if proc.returncode == 0 and output:
+      # Extract the latest SVN revision and the SVN URL.
+      # The target line is the last "git-svn-id: ..." line like this:
+      # git-svn-id: svn://svn.chromium.org/chrome/trunk/src@85528 0039d316....
+      match = _GIT_SVN_ID_REGEX.search(output)
+      if match:
+        revision = match.group(2)
+        url_match = svn_url_regex.search(match.group(1))
+        if url_match:
+          url = url_match.group(2)
+        else:
+          url = ''
+        return url, revision
+  return None, None
+
+
+def FetchGitSVNRevision(directory, svn_url_regex, go_deeper):
+  """
+  Fetch the Git-SVN identifier for the local tree.
+
+  Errors are swallowed.
+  """
+  url, revision = FetchGitSVNURLAndRevision(directory, svn_url_regex, go_deeper)
+  if url and revision:
+    return VersionInfo(url, revision)
+  return None
+
+
+def FetchVersionInfo(default_lastchange, directory=None,
+                     directory_regex_prior_to_src_url='chrome|blink|svn',
+                     go_deeper=False):
+  """
+  Returns the last change (in the form of a branch, revision tuple),
+  from some appropriate revision control system.
+  """
+  svn_url_regex = re.compile(
+      r'.*/(' + directory_regex_prior_to_src_url + r')(/.*)')
+
+  version_info = (FetchSVNRevision(directory, svn_url_regex) or
+                  FetchGitSVNRevision(directory, svn_url_regex, go_deeper) or
+                  FetchGitRevision(directory))
+  if not version_info:
+    if default_lastchange and os.path.exists(default_lastchange):
+      revision = open(default_lastchange, 'r').read().strip()
+      version_info = VersionInfo(None, revision)
+    else:
+      version_info = VersionInfo(None, None)
+  return version_info
+
+def GetHeaderGuard(path):
+  """
+  Returns the header #define guard for the given file path.
+  This treats everything after the last instance of "src/" as being a
+  relevant part of the guard. If there is no "src/", then the entire path
+  is used.
+  """
+  src_index = path.rfind('src/')
+  if src_index != -1:
+    guard = path[src_index + 4:]
+  else:
+    guard = path
+  guard = guard.upper()
+  return guard.replace('/', '_').replace('.', '_').replace('\\', '_') + '_'
+
+def GetHeaderContents(path, define, version):
+  """
+  Returns what the contents of the header file should be that indicate the given
+  revision. Note that the #define is specified as a string, even though it's
+  currently always a SVN revision number, in case we need to move to git hashes.
+  """
+  header_guard = GetHeaderGuard(path)
+
+  header_contents = """/* Generated by lastchange.py, do not edit.*/
+
+#ifndef %(header_guard)s
+#define %(header_guard)s
+
+#define %(define)s "%(version)s"
+
+#endif  // %(header_guard)s
+"""
+  header_contents = header_contents % { 'header_guard': header_guard,
+                                        'define': define,
+                                        'version': version }
+  return header_contents
+
+def WriteIfChanged(file_name, contents):
+  """
+  Writes the specified contents to the specified file_name
+  iff the contents are different than the current contents.
+  """
+  try:
+    old_contents = open(file_name, 'r').read()
+  except EnvironmentError:
+    pass
+  else:
+    if contents == old_contents:
+      return
+    os.unlink(file_name)
+  open(file_name, 'w').write(contents)
+
+
+def main(argv=None):
+  if argv is None:
+    argv = sys.argv
+
+  parser = optparse.OptionParser(usage="lastchange.py [options]")
+  parser.add_option("-d", "--default-lastchange", metavar="FILE",
+                    help="Default last change input FILE.")
+  parser.add_option("-m", "--version-macro",
+                    help="Name of C #define when using --header. Defaults to " +
+                    "LAST_CHANGE.",
+                    default="LAST_CHANGE")
+  parser.add_option("-o", "--output", metavar="FILE",
+                    help="Write last change to FILE. " +
+                    "Can be combined with --header to write both files.")
+  parser.add_option("", "--header", metavar="FILE",
+                    help="Write last change to FILE as a C/C++ header. " +
+                    "Can be combined with --output to write both files.")
+  parser.add_option("--revision-only", action='store_true',
+                    help="Just print the SVN revision number. Overrides any " +
+                    "file-output-related options.")
+  parser.add_option("-s", "--source-dir", metavar="DIR",
+                    help="Use repository in the given directory.")
+  parser.add_option("--git-svn-go-deeper", action='store_true',
+                    help="In a Git-SVN repo, dig down to the last committed " +
+                    "SVN change (historic behaviour).")
+  opts, args = parser.parse_args(argv[1:])
+
+  out_file = opts.output
+  header = opts.header
+
+  while len(args) and out_file is None:
+    if out_file is None:
+      out_file = args.pop(0)
+  if args:
+    sys.stderr.write('Unexpected arguments: %r\n\n' % args)
+    parser.print_help()
+    sys.exit(2)
+
+  if opts.source_dir:
+    src_dir = opts.source_dir
+  else:
+    src_dir = os.path.dirname(os.path.abspath(__file__))
+
+  version_info = FetchVersionInfo(opts.default_lastchange,
+                                  directory=src_dir,
+                                  go_deeper=opts.git_svn_go_deeper)
+
+  if version_info.revision == None:
+    version_info.revision = '0'
+
+  if opts.revision_only:
+    print version_info.revision
+  else:
+    contents = "LASTCHANGE=%s\n" % version_info.revision
+    if not out_file and not opts.header:
+      sys.stdout.write(contents)
+    else:
+      if out_file:
+        WriteIfChanged(out_file, contents)
+      if header:
+        WriteIfChanged(header,
+                       GetHeaderContents(header, opts.version_macro,
+                                         version_info.revision))
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())