Merge branch 'ps/ref-consistency-checks'

Update code paths that check data integrity around refs subsystem.
cf. <CAOLa=ZShPP3BPXa=YnC-vuX4zF=pUTFdUidZwOdna8bfVTNM9w@mail.gmail.com>

* ps/ref-consistency-checks:
  builtin/fsck: drop `fsck_head_link()`
  builtin/fsck: move generic HEAD check into `refs_fsck()`
  builtin/fsck: move generic object ID checks into `refs_fsck()`
  refs/reftable: introduce generic checks for refs
  refs/reftable: fix consistency checks with worktrees
  refs/reftable: extract function to retrieve backend for worktree
  refs/reftable: adapt includes to become consistent
  refs/files: introduce function to perform normal ref checks
  refs/files: extract generic symref target checks
  fsck: drop unused fields from `struct fsck_ref_report`
  refs/files: perform consistency checks for root refs
  refs/files: improve error handling when verifying symrefs
  refs/files: extract function to check single ref
  refs/files: remove useless indirection
  refs/files: remove `refs_check_dir` parameter
  refs/files: move fsck functions into global scope
  refs/files: simplify iterating through root refs

1 files changed, 43 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index 046b695bb2..627b7f8698 100644
--- a/refs.c
+++ b/refs.c
@@ -320,6 +320,49 @@ int check_refname_format(const char *refname, int flags)
 	return check_or_sanitize_refname(refname, flags, NULL);
 }
 
+int refs_fsck_ref(struct ref_store *refs UNUSED, struct fsck_options *o,
+		  struct fsck_ref_report *report,
+		  const char *refname UNUSED, const struct object_id *oid)
+{
+	if (is_null_oid(oid))
+		return fsck_report_ref(o, report, FSCK_MSG_BAD_REF_OID,
+				       "points to invalid object ID '%s'",
+				       oid_to_hex(oid));
+
+	return 0;
+}
+
+int refs_fsck_symref(struct ref_store *refs UNUSED, struct fsck_options *o,
+		     struct fsck_ref_report *report,
+		     const char *refname, const char *target)
+{
+	const char *stripped_refname;
+
+	parse_worktree_ref(refname, NULL, NULL, &stripped_refname);
+
+	if (!strcmp(stripped_refname, "HEAD") &&
+	    !starts_with(target, "refs/heads/") &&
+	    fsck_report_ref(o, report, FSCK_MSG_BAD_HEAD_TARGET,
+			    "HEAD points to non-branch '%s'", target))
+		return -1;
+
+	if (is_root_ref(target))
+		return 0;
+
+	if (check_refname_format(target, 0) &&
+	    fsck_report_ref(o, report, FSCK_MSG_BAD_REFERENT_NAME,
+			    "points to invalid refname '%s'", target))
+		return -1;
+
+	if (!starts_with(target, "refs/") &&
+	    !starts_with(target, "worktrees/") &&
+	    fsck_report_ref(o, report, FSCK_MSG_SYMREF_TARGET_IS_NOT_A_REF,
+			    "points to non-ref target '%s'", target))
+		return -1;
+
+	return 0;
+}
+
 int refs_fsck(struct ref_store *refs, struct fsck_options *o,
 	      struct worktree *wt)
 {