Add a new gclient-new-workdir script which clones an existing gclient working directory much like g…

gclient-new-workdir.py

Index: gclient-new-workdir.py
diff --git a/gclient-new-workdir.py b/gclient-new-workdir.py
new file mode 100755
index 0000000000000000000000000000000000000000..2e2435de20aa69c0e79dab0f640bf1f6f71d66e0
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+++ b/gclient-new-workdir.py
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+#!/usr/bin/env python
+# Copyright (c) 2013 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.
+#
+# Usage:
+#    gclient-new-workdir.py <repository> <new_workdir> [<branch>]
+#
+
+import os
+import shutil
+import subprocess
+import sys
+
+def parse_options(argv):

[iannucci, 2013/11/04 22:30:43]

style nit: 2 lines between top-level statements

+  if len(argv) != 3:
+    usage()
+    return False, "", ""

[iannucci, 2013/11/04 22:30:43]

I think sys.exit(1) is clearer, instead of passing back an explicit 'success'.

+
+  success = True
+  repository = argv[1]
+  new_workdir = argv[2]
+
+  if not os.path.exists(repository):
+    print("Repository does not exist: " + repository)
+    success = False
+
+  if os.path.exists(new_workdir):
+    print("New workdir already exists: " + new_workdir)
+    success = False
+
+  return success, repository, new_workdir
+
+def main(argv):
+  assert not sys.platform.startswith("win")

[iannucci, 2013/11/04 22:30:43]

nit: I would move this into parse_options, but up to you.

+
+  success, repository, new_workdir = parse_options(argv)
+  if not success:
+    return 1
+
+  gclient = os.path.join(repository, ".gclient")
+  if not os.path.exists(gclient):
+    print("No .gclient file: " + gclient)
+
+  gclient_entries = os.path.join(repository, ".gclient_entries")
+  if not os.path.exists(gclient_entries):
+    print("No .gclient_entries file: " + gclient_entries)
+
+  os.mkdir(new_workdir)
+  os.symlink(gclient, os.path.join(new_workdir, ".gclient"))
+  os.symlink(gclient_entries, os.path.join(new_workdir, ".gclient_entries"))
+
+  for root, dirs, files in os.walk(repository):
+    for name in dirs:
+      if name == ".git":

[iannucci, 2013/11/04 22:30:43]

Why not just:

if '.git' in dirs:
  # do stuff with '.git'

?

+        workdir = root.replace(repository, new_workdir, 1)
+        make_workdir(os.path.join(root, name), os.path.join(workdir, name))

[iannucci, 2013/11/04 22:30:43]

What happens if something breaks half-way through? Is there any appropriate
cleanup we should do?

[atreat, 2013/11/04 22:51:35]

We aren't touching the original workdir.  The only cleanup to do would be to
remove the new workdir, but the script should give an error and then the user
can decide what to do with the new workdir.  This is how git-new-workdir works
at least.

+
+  return 0
+
+def make_workdir(repository, new_workdir):
+  print("Creating: " + new_workdir)
+  os.makedirs(new_workdir)
+  make_symlink(repository, new_workdir, "config")
+  make_symlink(repository, new_workdir, "refs")
+  if os.path.exists(repository + os.sep + "logs"):
+    os.makedirs(new_workdir + os.sep + "logs")

[iannucci, 2013/11/04 22:30:43]

os.path.join

+  make_symlink(repository, new_workdir, "logs" + os.sep + "refs")
+  make_symlink(repository, new_workdir, "objects")
+  make_symlink(repository, new_workdir, "info")
+  make_symlink(repository, new_workdir, "hooks")
+  make_symlink(repository, new_workdir, "packed-refs")
+  make_symlink(repository, new_workdir, "remotes")
+  make_symlink(repository, new_workdir, "rr-cache")
+  make_symlink(repository, new_workdir, "svn")

[iannucci, 2013/11/04 22:30:43]

I wonder if a blacklist would be more correct than this whitelist?

Also, I would probably put all of these strings into an actual list, and then
loop over them with make_symlink.

[atreat, 2013/11/04 22:51:35]

The whitelist was explicitly taken from git-new-workdir which is authored by the
git folks.

[atreat, 2013/11/04 22:51:35]

Hmm, I am not sure that a list would make it any more readable given the 80 char
limit.  I can do it if you insist though.

[iannucci, 2013/11/04 22:54:51]

I'm thinking like:

GIT_DIRECTORY_WHITELIST = ['config', 'refs', ...]


...

for entry in GIT_DIRECTORY_WHITELIST:
  make_symlink(repository, new_workdir, entry)

Just cuts out a lot of copy/paste repetition in this function

+  shutil.copy2(repository + os.sep + "HEAD", new_workdir + os.sep + "HEAD")

[iannucci, 2013/11/04 22:30:43]

os.path.join

+  subprocess.check_call(["git", "checkout", "-f"], cwd=new_workdir.rstrip(".git"))
+
+def make_symlink(repository, new_workdir, link):
+  if not os.path.exists(os.path.join(repository, link)):
+    return
+  os.symlink(os.path.join(repository, link), os.path.join(new_workdir, link))
+
+def usage():
+  print("usage: gclient-new-workdir.py <repository> <new_workdir>")

[iannucci, 2013/11/04 22:30:43]

Maybe since this is used in exactly 1 place, just put the print inline?

+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))