[OE-core][PATCH 3/3] bitbake: git-make-shallow: support git's safe.bareRepository

["André Draszik" <andre.draszik@linaro.org>]

When git is configured with safe.bareRepository=explicit [1], the
git-make-shallow fails miserably. LWN has an article about the
problem that this configuration option addresses and why it is useful
in [2].

It also seems that it is being rolled out in some environments as a
default for users.

In order to allow having this configuration turned on for a user's
environment in general, the fetcher has to be tought to use --git-dir=
for all relevent git operations.

The alternative, implemented here, is to forcibly turn off that option
for all git operations. In the future, we could look into converting
these to using the --git-dir= command line argument instead.

Link: https://git.kernel.org/pub/scm/git/git.git/tree/Documentation/config/safe.txt#n1 [1]
Link: https://lwn.net/Articles/892755/ [2]
Signed-off-by: André Draszik <andre.draszik@linaro.org>
---
 bitbake/bin/git-make-shallow | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/bitbake/bin/git-make-shallow b/bitbake/bin/git-make-shallow
index d0532c5ab85e..9de557c10e4a 100755
--- a/bitbake/bin/git-make-shallow
+++ b/bitbake/bin/git-make-shallow
@@ -24,15 +24,17 @@ warnings.simplefilter("default")
 version = 1.0
 
 
+git_cmd = ['git', '-c', 'safe.bareRepository=all']
+
 def main():
     if sys.version_info < (3, 4, 0):
         sys.exit('Python 3.4 or greater is required')
 
-    git_dir = check_output(['git', 'rev-parse', '--git-dir']).rstrip()
+    git_dir = check_output(git_cmd + ['rev-parse', '--git-dir']).rstrip()
     shallow_file = os.path.join(git_dir, 'shallow')
     if os.path.exists(shallow_file):
         try:
-            check_output(['git', 'fetch', '--unshallow'])
+            check_output(git_cmd + ['fetch', '--unshallow'])
         except subprocess.CalledProcessError:
             try:
                 os.unlink(shallow_file)
@@ -41,21 +43,21 @@ def main():
                     raise
 
     args = process_args()
-    revs = check_output(['git', 'rev-list'] + args.revisions).splitlines()
+    revs = check_output(git_cmd + ['rev-list'] + args.revisions).splitlines()
 
     make_shallow(shallow_file, args.revisions, args.refs)
 
-    ref_revs = check_output(['git', 'rev-list'] + args.refs).splitlines()
+    ref_revs = check_output(git_cmd + ['rev-list'] + args.refs).splitlines()
     remaining_history = set(revs) & set(ref_revs)
     for rev in remaining_history:
-        if check_output(['git', 'rev-parse', '{}^@'.format(rev)]):
+        if check_output(git_cmd + ['rev-parse', '{}^@'.format(rev)]):
             sys.exit('Error: %s was not made shallow' % rev)
 
     filter_refs(args.refs)
 
     if args.shrink:
         shrink_repo(git_dir)
-        subprocess.check_call(['git', 'fsck', '--unreachable'])
+        subprocess.check_call(git_cmd + ['fsck', '--unreachable'])
 
 
 def process_args():
@@ -72,12 +74,12 @@ def process_args():
     args = parser.parse_args()
 
     if args.refs:
-        args.refs = check_output(['git', 'rev-parse', '--symbolic-full-name'] + args.refs).splitlines()
+        args.refs = check_output(git_cmd + ['rev-parse', '--symbolic-full-name'] + args.refs).splitlines()
     else:
         args.refs = get_all_refs(lambda r, t, tt: t == 'commit' or tt == 'commit')
 
     args.refs = list(filter(lambda r: not r.endswith('/HEAD'), args.refs))
-    args.revisions = check_output(['git', 'rev-parse'] + ['%s^{}' % i for i in args.revisions]).splitlines()
+    args.revisions = check_output(git_cmd + ['rev-parse'] + ['%s^{}' % i for i in args.revisions]).splitlines()
     return args
 
 
@@ -95,7 +97,7 @@ def make_shallow(shallow_file, revisions, refs):
 
 def get_all_refs(ref_filter=None):
     """Return all the existing refs in this repository, optionally filtering the refs."""
-    ref_output = check_output(['git', 'for-each-ref', '--format=%(refname)\t%(objecttype)\t%(*objecttype)'])
+    ref_output = check_output(git_cmd + ['for-each-ref', '--format=%(refname)\t%(objecttype)\t%(*objecttype)'])
     ref_split = [tuple(iter_extend(l.rsplit('\t'), 3)) for l in ref_output.splitlines()]
     if ref_filter:
         ref_split = (e for e in ref_split if ref_filter(*e))
@@ -113,7 +115,7 @@ def filter_refs(refs):
     all_refs = get_all_refs()
     to_remove = set(all_refs) - set(refs)
     if to_remove:
-        check_output(['xargs', '-0', '-n', '1', 'git', 'update-ref', '-d', '--no-deref'],
+        check_output(['xargs', '-0', '-n', '1'] + git_cmd + ['update-ref', '-d', '--no-deref'],
                      input=''.join(l + '\0' for l in to_remove))
 
 
@@ -126,7 +128,7 @@ def follow_history_intersections(revisions, refs):
         if rev in seen:
             continue
 
-        parents = check_output(['git', 'rev-parse', '%s^@' % rev]).splitlines()
+        parents = check_output(git_cmd + ['rev-parse', '%s^@' % rev]).splitlines()
 
         yield rev
         seen.add(rev)
@@ -134,12 +136,12 @@ def follow_history_intersections(revisions, refs):
         if not parents:
             continue
 
-        check_refs = check_output(['git', 'merge-base', '--independent'] + sorted(refs)).splitlines()
+        check_refs = check_output(git_cmd + ['merge-base', '--independent'] + sorted(refs)).splitlines()
         for parent in parents:
             for ref in check_refs:
                 print("Checking %s vs %s" % (parent, ref))
                 try:
-                    merge_base = check_output(['git', 'merge-base', parent, ref]).rstrip()
+                    merge_base = check_output(git_cmd + ['merge-base', parent, ref]).rstrip()
                 except subprocess.CalledProcessError:
                     continue
                 else:
@@ -159,14 +161,14 @@ def iter_except(func, exception, start=None):
 
 def shrink_repo(git_dir):
     """Shrink the newly shallow repository, removing the unreachable objects."""
-    subprocess.check_call(['git', 'reflog', 'expire', '--expire-unreachable=now', '--all'])
-    subprocess.check_call(['git', 'repack', '-ad'])
+    subprocess.check_call(git_cmd + ['reflog', 'expire', '--expire-unreachable=now', '--all'])
+    subprocess.check_call(git_cmd + ['repack', '-ad'])
     try:
         os.unlink(os.path.join(git_dir, 'objects', 'info', 'alternates'))
     except OSError as exc:
         if exc.errno != errno.ENOENT:
             raise
-    subprocess.check_call(['git', 'prune', '--expire', 'now'])
+    subprocess.check_call(git_cmd + ['prune', '--expire', 'now'])
 
 
 if __name__ == '__main__':
-- 
2.44.0.rc0.258.g7320e95886-goog