[PATCH v2 1/3] scripts/scriptutils: Convert nested git repos to standalone clones in devtool workspace

[Jamin Lin <jamin_lin@aspeedtech.com>]

When a recipe uses multiple git SRC_URI entries with different destsuffix
values (e.g. Zephyr-based recipes with separate repositories for the
kernel, modules and application), do_unpack clones each source tree with
'git clone -n -s'.

The -s flag uses git's shared-object mechanism:
instead of copying objects locally it writes a .git/objects/info/alternates file
pointing back to the bare repository under the downloads directory (DL_DIR/git2/).

git_convert_standalone_clone() is called by devtool_post_unpack to make
the workspace standalone: it runs 'git repack -a' to copy all objects
into the local object store and then removes the alternates file.

However it only processes the top-level source directory.  Each nested
git repo created by a separate SRC_URI entry retains its own alternates
file still pointing into downloads/.

Steps to reproduce:
  1. devtool modify <recipe-with-multiple-git-SRC_URI>
  2. bitbake -c cleanall <recipe>
  3. bitbake <recipe>

At step 2, 'bitbake -c cleanall' calls fetcher.clean() which deletes
the bare repositories from downloads/git2/. The top-level workspace
repo is standalone (alternates already removed by the original code),
but the nested repos still hold alternates pointing to the now-deleted
paths.

At step 3, srctree_hash_files() runs 'git add -A .' with a custom
GIT_INDEX_FILE. Git internally calls 'git status --porcelain=2' on
each nested repo to check for changes; this fails with exit 128 because
the nested alternates are broken:
  error: unable to normalize alternate object path:
         .../downloads/git2/github.com.zephyrproject-rtos.acpica//objects
  fatal: bad object HEAD
  fatal: 'git status --porcelain=2' failed in submodule modules/lib/acpica

This halts the BitBake parse phase with a CalledProcessError and leaves
the workspace in an unrecoverable state without manual intervention.

Fix by extending git_convert_standalone_clone() to walk the source tree
and apply the same 'git repack -a' + remove-alternates treatment to
every nested git repository found, making the entire workspace fully
standalone at devtool modify time.  The walk uses dirs[:] = [] to stop
at each git boundary so it never descends into already-converted repos.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 scripts/lib/scriptutils.py | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/scripts/lib/scriptutils.py b/scripts/lib/scriptutils.py
index 32e749dbb1..0a83470373 100644
--- a/scripts/lib/scriptutils.py
+++ b/scripts/lib/scriptutils.py
@@ -100,16 +100,36 @@ def load_plugins(logger, plugins, pluginpath):
 
 
 def git_convert_standalone_clone(repodir):
-    """If specified directory is a git repository, ensure it's a standalone clone"""
+    """
+    If specified directory is a git repository, ensure it's a standalone clone.
+    Also converts any nested git repositories (created by multiple SRC_URI git
+    entries with different destsuffix values) so that none of their contents
+    depend on the shared downloads directory via alternates.
+    """
+
     import bb.process
-    if os.path.exists(os.path.join(repodir, '.git')):
-        alternatesfile = os.path.join(repodir, '.git', 'objects', 'info', 'alternates')
+
+    def _convert(gitdir, workdir):
+        alternatesfile = os.path.join(gitdir, 'objects', 'info', 'alternates')
         if os.path.exists(alternatesfile):
             # This will have been cloned with -s, so we need to convert it so none
             # of the contents is shared
-            bb.process.run('git repack -a', cwd=repodir)
+            bb.process.run('git repack -a', cwd=workdir)
             os.remove(alternatesfile)
 
+    if os.path.exists(os.path.join(repodir, '.git')):
+        _convert(os.path.join(repodir, '.git'), repodir)
+
+    # Also handle nested git repos created by multiple SRC_URI git entries
+    # with different destsuffix values. Each nested repo is cloned with -s
+    # and has its own alternates pointing to the downloads directory.
+    for root, dirs, files in os.walk(repodir):
+        if root == repodir:
+            continue
+        if '.git' in dirs:
+            _convert(os.path.join(root, '.git'), root)
+            dirs[:] = []  # don't recurse into nested repos
+
 def _get_temp_recipe_dir(d):
     # This is a little bit hacky but we need to find a place where we can put
     # the recipe so that bitbake can find it. We're going to delete it at the
-- 
2.43.0