[PATCH v2 0/4] Handle FETCH_HEAD and MERGE_HEAD generically

This moves the FETCH_HEAD handling into refs.c as discussed in https://public-inbox.org/git/xmqq5z9pav01.fsf@gitster.c.googlers.com/

Han-Wen Nienhuys (4):
  refs: split off reading loose ref data in separate function
  refs: fix comment about submodule ref_stores
  refs: move gitdir into base ref_store
  refs: read FETCH_HEAD and MERGE_HEAD generically

 refs.c                | 28 ++++++++++++++++++++++++-
 refs/files-backend.c  | 49 ++++++++++++++++++++++---------------------
 refs/packed-backend.c |  1 +
 refs/refs-internal.h  | 11 +++++++++-
 4 files changed, 63 insertions(+), 26 deletions(-)

base-commit: 2befe97201e1f3175cce557866c5822793624b5a
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-705%2Fhanwen%2Ffetch-head-generically-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-705/hanwen/fetch-head-generically-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/705

Range-diff vs v1:

 1:  10b333695e ! 1:  557727064d Split off reading loose ref data in separate function
     @@ Metadata
      Author: Han-Wen Nienhuys <hanwen@google.com>
      
       ## Commit message ##
     -    Split off reading loose ref data in separate function
     +    refs: split off reading loose ref data in separate function
      
          This prepares for handling FETCH_HEAD (which is not a regular ref)
          separately from the ref backend.
 2:  52b397ec9e = 2:  6da0e62e73 refs: fix comment about submodule ref_stores
 3:  c624e17dc6 = 3:  6263b4b3f2 refs: move gitdir into base ref_store
 4:  d4e9c5f499 ! 4:  a3e903e4c0 refs: read FETCH_HEAD generically
     @@ Metadata
      Author: Han-Wen Nienhuys <hanwen@google.com>
      
       ## Commit message ##
     -    refs: read FETCH_HEAD generically
     +    refs: read FETCH_HEAD and MERGE_HEAD generically
      
     -    The FETCH_HEAD ref must be stored in a file, regardless of the type of
     -    ref backend. This is because it can hold more than just a single ref.
     +    The FETCH_HEAD and MERGE_HEAD refs must be stored in a file, regardless of the
     +    type of ref backend. This is because they can hold more than just a single ref.
      
     -    To accomodate FETCH_HEAD for alternate ref backends, read FETCH_HEAD
     -    from a file generically in refs_read_raw_ref()
     +    To accomodate them for alternate ref backends, read them from a file generically
     +    in refs_read_raw_ref()
      
          Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
      
     @@ refs.c: int for_each_rawref(each_ref_fn fn, void *cb_data)
       	return refs_for_each_rawref(get_main_ref_store(the_repository), fn, cb_data);
       }
       
     -+static int refs_read_fetch_head(struct ref_store *ref_store,
     -+				struct object_id *oid, struct strbuf *referent,
     -+				unsigned int *type)
     ++static int refs_read_special_head(struct ref_store *ref_store,
     ++				  const char *refname, struct object_id *oid,
     ++				  struct strbuf *referent, unsigned int *type)
      +{
      +	struct strbuf full_path = STRBUF_INIT;
      +	struct strbuf content = STRBUF_INIT;
      +	int result = -1;
     -+	strbuf_addf(&full_path, "%s/%s", ref_store->gitdir, "FETCH_HEAD");
     ++	strbuf_addf(&full_path, "%s/%s", ref_store->gitdir, refname);
      +
      +	if (strbuf_read_file(&content, full_path.buf, 0) < 0)
      +		goto done;
     @@ refs.c: int for_each_rawref(each_ref_fn fn, void *cb_data)
       		      struct strbuf *referent, unsigned int *type)
       {
      -	return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, type);
     -+	if (!strcmp(refname, "FETCH_HEAD")) {
     -+		return refs_read_fetch_head(ref_store, oid, referent, type);
     ++	if (!strcmp(refname, "FETCH_HEAD") || !strcmp(refname, "MERGE_HEAD")) {
     ++		return refs_read_special_head(ref_store, refname, oid, referent,
     ++					      type);
      +	}
      +
      +	return ref_store->be->read_raw_ref(ref_store, refname, oid, referent,