Handle FETCH_HEAD and MERGE_HEAD generically

This moves the FETCH_HEAD handling into refs.c as discussed in
https://public-inbox.org/git/[email protected]/

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 <[email protected]>

## 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 <[email protected]>

## 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()

@@ 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,

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