builtin/refs: add verify subcommand

Introduce a new subcommand "verify" in git-refs(1) to allow the user to
check the reference database consistency and also this subcommand will
be used as the entry point of checking refs for "git-fsck(1)".

Add "verbose" field into "fsck_options" to indicate whether we should
print verbose messages when checking refs and objects consistency.

Remove bit-field for "strict" field, this is because we cannot take
address of a bit-field which makes it unhandy to set member variables
when parsing the command line options.

The "git-fsck(1)" declares "fsck_options" variable with "static"
identifier which avoids complaint by the leak-checker. However, in
"git-refs verify", we need to do memory clean manually. Thus add
"fsck_options_clear" function in "fsck.c" to provide memory clean
operation.

Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-refs.txt

@@ -10,6 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git refs migrate' --ref-format=<format> [--dry-run]
+'git refs verify' [--strict] [--verbose]
 
 DESCRIPTION
 -----------
@@ -22,6 +23,9 @@ COMMANDS
 migrate::
 	Migrate ref store between different formats.
 
+verify::
+	Verify reference database consistency.
+
 OPTIONS
 -------
 
@@ -39,6 +43,15 @@ include::ref-storage-format.txt[]
 	can be used to double check that the migration works as expected before
 	performing the actual migration.
 
+The following options are specific to 'git refs verify':
+
+--strict::
+	Enable stricter error checking. This will cause warnings to be
+	reported as errors. See linkgit:git-fsck[1].
+
+--verbose::
+	When verifying the reference database consistency, be chatty.
+
 KNOWN LIMITATIONS
 -----------------
 

builtin/refs.c

@@ -1,4 +1,6 @@
 #include "builtin.h"
+#include "config.h"
+#include "fsck.h"
 #include "parse-options.h"
 #include "refs.h"
 #include "repository.h"
@@ -7,6 +9,9 @@
 #define REFS_MIGRATE_USAGE \
 	N_("git refs migrate --ref-format=<format> [--dry-run]")
 
+#define REFS_VERIFY_USAGE \
+	N_("git refs verify [--strict] [--verbose]")
+
 static int cmd_refs_migrate(int argc, const char **argv, const char *prefix)
 {
 	const char * const migrate_usage[] = {
@@ -58,15 +63,44 @@ out:
 	return err;
 }
 
+static int cmd_refs_verify(int argc, const char **argv, const char *prefix)
+{
+	struct fsck_options fsck_refs_options = FSCK_REFS_OPTIONS_DEFAULT;
+	const char * const verify_usage[] = {
+		REFS_VERIFY_USAGE,
+		NULL,
+	};
+	struct option options[] = {
+		OPT_BOOL(0, "verbose", &fsck_refs_options.verbose, N_("be verbose")),
+		OPT_BOOL(0, "strict", &fsck_refs_options.strict, N_("enable strict checking")),
+		OPT_END(),
+	};
+	int ret;
+
+	argc = parse_options(argc, argv, prefix, options, verify_usage, 0);
+	if (argc)
+		usage(_("'git refs verify' takes no arguments"));
+
+	git_config(git_fsck_config, &fsck_refs_options);
+	prepare_repo_settings(the_repository);
+
+	ret = refs_fsck(get_main_ref_store(the_repository), &fsck_refs_options);
+
+	fsck_options_clear(&fsck_refs_options);
+	return ret;
+}
+
 int cmd_refs(int argc, const char **argv, const char *prefix)
 {
 	const char * const refs_usage[] = {
 		REFS_MIGRATE_USAGE,
+		REFS_VERIFY_USAGE,
 		NULL,
 	};
 	parse_opt_subcommand_fn *fn = NULL;
 	struct option opts[] = {
 		OPT_SUBCOMMAND("migrate", &fn, cmd_refs_migrate),
+		OPT_SUBCOMMAND("verify", &fn, cmd_refs_verify),
 		OPT_END(),
 	};
 

fsck.c

@@ -1331,6 +1331,17 @@ int fsck_finish(struct fsck_options *options)
 	return ret;
 }
 
+void fsck_options_clear(struct fsck_options *options)
+{
+	free(options->msg_type);
+	oidset_clear(&options->skip_oids);
+	oidset_clear(&options->gitmodules_found);
+	oidset_clear(&options->gitmodules_done);
+	oidset_clear(&options->gitattributes_found);
+	oidset_clear(&options->gitattributes_done);
+	kh_clear_oid_map(options->object_names);
+}
+
 int git_fsck_config(const char *var, const char *value,
 		    const struct config_context *ctx, void *cb)
 {

fsck.h

@@ -153,7 +153,8 @@ struct fsck_ref_report {
 struct fsck_options {
 	fsck_walk_func walk;
 	fsck_error error_func;
-	unsigned strict:1;
+	unsigned strict;
+	unsigned verbose;
 	enum fsck_msg_type *msg_type;
 	struct oidset skip_oids;
 	struct oidset gitmodules_found;
@@ -231,6 +232,11 @@ int fsck_tag_standalone(const struct object_id *oid, const char *buffer,
  */
 int fsck_finish(struct fsck_options *options);
 
+/*
+ * Clear the fsck_options struct, freeing any allocated memory.
+ */
+void fsck_options_clear(struct fsck_options *options);
+
 /*
  * Report an error or warning for refs.
  */