[PATCH 2/2] reflog: implement subcommand to drop reflogs

[Karthik Nayak <karthik.188@gmail.com>]

Add a new 'drop' subcommand to git-reflog that allows users to delete
the entire reflog for a specified reference. Include a '--all' flag to
enable dropping all reflogs in a repository.

While 'git-reflog(1)' currently allows users to expire reflogs and
delete individual entries, it lacks functionality to completely remove
reflogs for specific references. This becomes problematic in
repositories where reflogs are not needed but continue to accumulate
entries despite setting 'core.logAllRefUpdates=false'.

While here, remove an erranous newline in the file.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 Documentation/git-reflog.adoc |  6 +++++
 builtin/reflog.c              | 58 ++++++++++++++++++++++++++++++++++++++++++-
 t/t1410-reflog.sh             | 55 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-reflog.adoc b/Documentation/git-reflog.adoc
index a929c52982..4ecee297de 100644
--- a/Documentation/git-reflog.adoc
+++ b/Documentation/git-reflog.adoc
@@ -17,6 +17,7 @@ SYNOPSIS
 'git reflog delete' [--rewrite] [--updateref]
 	[--dry-run | -n] [--verbose] <ref>@{<specifier>}...
 'git reflog exists' <ref>
+'git reflog drop' [--all | <refs>...]
 
 DESCRIPTION
 -----------
@@ -57,6 +58,11 @@ The "exists" subcommand checks whether a ref has a reflog.  It exits
 with zero status if the reflog exists, and non-zero status if it does
 not.
 
+The "drop" subcommand removes the reflog for the specified references.
+In contrast, "expire" can be used to prune all entries from a reflog,
+but the reflog itself will still exist for that reference. To fully
+remove the reflog for specific references, use the "drop" subcommand.
+
 OPTIONS
 -------
 
diff --git a/builtin/reflog.c b/builtin/reflog.c
index f92258f6b6..232602c1a6 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -27,6 +27,9 @@
 #define BUILTIN_REFLOG_EXISTS_USAGE \
 	N_("git reflog exists <ref>")
 
+#define BUILTIN_REFLOG_DROP_USAGE \
+	N_("git reflog drop [--all | <refs>...]")
+
 static const char *const reflog_show_usage[] = {
 	BUILTIN_REFLOG_SHOW_USAGE,
 	NULL,
@@ -52,12 +55,18 @@ static const char *const reflog_exists_usage[] = {
 	NULL,
 };
 
+static const char *const reflog_drop_usage[] = {
+	BUILTIN_REFLOG_DROP_USAGE,
+	NULL,
+};
+
 static const char *const reflog_usage[] = {
 	BUILTIN_REFLOG_SHOW_USAGE,
 	BUILTIN_REFLOG_LIST_USAGE,
 	BUILTIN_REFLOG_EXPIRE_USAGE,
 	BUILTIN_REFLOG_DELETE_USAGE,
 	BUILTIN_REFLOG_EXISTS_USAGE,
+	BUILTIN_REFLOG_DROP_USAGE,
 	NULL
 };
 
@@ -447,10 +456,56 @@ static int cmd_reflog_exists(int argc, const char **argv, const char *prefix,
 				   refname);
 }
 
+static int cmd_reflog_drop(int argc, const char **argv, const char *prefix,
+			   struct repository *repo)
+{
+	int i, ret, do_all;
+	const struct option options[] = {
+		OPT_BOOL(0, "all", &do_all, N_("process the reflogs of all references")),
+		OPT_END()
+	};
+
+	do_all = ret = 0;
+	argc = parse_options(argc, argv, prefix, options, reflog_drop_usage, 0);
+
+	if (do_all) {
+		struct worktree_reflogs collected = {
+			.reflogs = STRING_LIST_INIT_DUP,
+		};
+		struct string_list_item *item;
+		struct worktree **worktrees, **p;
+
+		worktrees = get_worktrees();
+		for (p = worktrees; *p; p++) {
+			collected.worktree = *p;
+			refs_for_each_reflog(get_worktree_ref_store(*p),
+					     collect_reflog, &collected);
+		}
+		free_worktrees(worktrees);
+
+		for_each_string_list_item(item, &collected.reflogs)
+			ret |= refs_delete_reflog(get_main_ref_store(repo),
+						     item->string);
+		string_list_clear(&collected.reflogs, 0);
+	}
+
+	for (i = 0; i < argc; i++) {
+		char *ref;
+		if (!repo_dwim_log(repo, argv[i], strlen(argv[i]), NULL, &ref)) {
+			ret |= error(_("%s points nowhere!"), argv[i]);
+			continue;
+		}
+
+		ret |= refs_delete_reflog(get_main_ref_store(repo), ref);
+		free(ref);
+	}
+
+	return ret;
+}
+
 /*
  * main "reflog"
  */
-
 int cmd_reflog(int argc,
 	       const char **argv,
 	       const char *prefix,
@@ -463,6 +518,7 @@ int cmd_reflog(int argc,
 		OPT_SUBCOMMAND("expire", &fn, cmd_reflog_expire),
 		OPT_SUBCOMMAND("delete", &fn, cmd_reflog_delete),
 		OPT_SUBCOMMAND("exists", &fn, cmd_reflog_exists),
+		OPT_SUBCOMMAND("drop", &fn, cmd_reflog_drop),
 		OPT_END()
 	};
 
diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
index 388fdf9ae5..b6e44ce6b9 100755
--- a/t/t1410-reflog.sh
+++ b/t/t1410-reflog.sh
@@ -551,4 +551,59 @@ test_expect_success 'reflog with invalid object ID can be listed' '
 	)
 '
 
+test_expect_success 'reflog drop non-existent ref' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_must_fail git reflog exists refs/heads/non-existent &&
+		test_must_fail git reflog drop refs/heads/non-existent
+	)
+'
+
+test_expect_success 'reflog drop' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit A &&
+		test_commit_bulk --ref=refs/heads/branch 1 &&
+		git reflog exists refs/heads/main &&
+		git reflog exists refs/heads/branch &&
+		git reflog drop refs/heads/main &&
+		test_must_fail git reflog exists refs/heads/main &&
+		git reflog exists refs/heads/branch
+	)
+'
+
+test_expect_success 'reflog drop multiple references' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit A &&
+		test_commit_bulk --ref=refs/heads/branch 1 &&
+		git reflog exists refs/heads/main &&
+		git reflog exists refs/heads/branch &&
+		git reflog drop refs/heads/main refs/heads/branch &&
+		test_must_fail git reflog exists refs/heads/main &&
+		test_must_fail git reflog exists refs/heads/branch
+	)
+'
+
+test_expect_success 'reflog drop --all' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit A &&
+		test_commit_bulk --ref=refs/heads/branch 1 &&
+		git reflog exists refs/heads/main &&
+		git reflog exists refs/heads/branch &&
+		git reflog drop --all &&
+		test_must_fail git reflog exists refs/heads/main &&
+		test_must_fail git reflog exists refs/heads/branch
+	)
+'
+
 test_done

-- 
2.48.1