#include "builtin.h"
#include "repository.h"
#include "cache.h"
#include "config.h"
#include "parse-options.h"
#include "quote.h"
#include "pathspec.h"
#include "dir.h"
#include "submodule.h"
#include "submodule-config.h"
#include "string-list.h"
#include "run-command.h"
#include "remote.h"
#include "refs.h"
#include "refspec.h"
#include "connect.h"
#include "revision.h"
#include "diffcore.h"
#include "diff.h"
#include "object-store.h"

#define OPT_QUIET (1 << 0)
#define OPT_CACHED (1 << 1)
#define OPT_RECURSIVE (1 << 2)
#define OPT_FORCE (1 << 3)

typedef void (*each_submodule_fn)(const struct cache_entry *list_item,
                                  void *cb_data);

static char *get_default_remote(void)
{
        char *dest = NULL, *ret;
        struct strbuf sb = STRBUF_INIT;
        const char *refname = resolve_ref_unsafe("HEAD", 0, NULL, NULL);

        if (!refname)
                die(_("No such ref: %s"), "HEAD");

        /* detached HEAD */
        if (!strcmp(refname, "HEAD"))
                return xstrdup("origin");

        if (!skip_prefix(refname, "refs/heads/", &refname))
                die(_("Expecting a full ref name, got %s"), refname);

        strbuf_addf(&sb, "branch.%s.remote", refname);
        if (git_config_get_string(sb.buf, &dest))
                ret = xstrdup("origin");
        else
                ret = dest;

        strbuf_release(&sb);
        return ret;
}

static int print_default_remote(int argc, const char **argv, const char *prefix)
{
        char *remote;

        if (argc != 1)
                die(_("submodule--helper print-default-remote takes no arguments"));

        remote = get_default_remote();
        if (remote)
                printf("%s\n", remote);

        free(remote);
        return 0;
}

static int starts_with_dot_slash(const char *str)
{
        return str[0] == '.' && is_dir_sep(str[1]);
}

static int starts_with_dot_dot_slash(const char *str)
{
        return str[0] == '.' && str[1] == '.' && is_dir_sep(str[2]);
}

/*
 * Returns 1 if it was the last chop before ':'.
 */
static int chop_last_dir(char **remoteurl, int is_relative)
{
        char *rfind = find_last_dir_sep(*remoteurl);
        if (rfind) {
                *rfind = '\0';
                return 0;
        }

        rfind = strrchr(*remoteurl, ':');
        if (rfind) {
                *rfind = '\0';
                return 1;
        }

        if (is_relative || !strcmp(".", *remoteurl))
                die(_("cannot strip one component off url '%s'"),
                        *remoteurl);

        free(*remoteurl);
        *remoteurl = xstrdup(".");
        return 0;
}

/*
 * The `url` argument is the URL that navigates to the submodule origin
 * repo. When relative, this URL is relative to the superproject origin
 * URL repo. The `up_path` argument, if specified, is the relative
 * path that navigates from the submodule working tree to the superproject
 * working tree. Returns the origin URL of the submodule.
 *
 * Return either an absolute URL or filesystem path (if the superproject
 * origin URL is an absolute URL or filesystem path, respectively) or a
 * relative file system path (if the superproject origin URL is a relative
 * file system path).
 *
 * When the output is a relative file system path, the path is either
 * relative to the submodule working tree, if up_path is specified, or to
 * the superproject working tree otherwise.
 *
 * NEEDSWORK: This works incorrectly on the domain and protocol part.
 * remote_url      url              outcome          expectation
 * http://a.com/b  ../c             http://a.com/c   as is
 * http://a.com/b/ ../c             http://a.com/c   same as previous line, but
 *                                                   ignore trailing slash in url
 * http://a.com/b  ../../c          http://c         error out
 * http://a.com/b  ../../../c       http:/c          error out
 * http://a.com/b  ../../../../c    http:c           error out
 * http://a.com/b  ../../../../../c    .:c           error out
 * NEEDSWORK: Given how chop_last_dir() works, this function is broken
 * when a local part has a colon in its path component, too.
 */
static char *relative_url(const char *remote_url,
                                const char *url,
                                const char *up_path)
{
        int is_relative = 0;
        int colonsep = 0;
        char *out;
        char *remoteurl = xstrdup(remote_url);
        struct strbuf sb = STRBUF_INIT;
        size_t len = strlen(remoteurl);

        if (is_dir_sep(remoteurl[len-1]))
                remoteurl[len-1] = '\0';

        if (!url_is_local_not_ssh(remoteurl) || is_absolute_path(remoteurl))
                is_relative = 0;
        else {
                is_relative = 1;
                /*
                 * Prepend a './' to ensure all relative
                 * remoteurls start with './' or '../'
                 */
                if (!starts_with_dot_slash(remoteurl) &&
                    !starts_with_dot_dot_slash(remoteurl)) {
                        strbuf_reset(&sb);
                        strbuf_addf(&sb, "./%s", remoteurl);
                        free(remoteurl);
                        remoteurl = strbuf_detach(&sb, NULL);
                }
        }
        /*
         * When the url starts with '../', remove that and the
         * last directory in remoteurl.
         */
        while (url) {
                if (starts_with_dot_dot_slash(url)) {
                        url += 3;
                        colonsep |= chop_last_dir(&remoteurl, is_relative);
                } else if (starts_with_dot_slash(url))
                        url += 2;
                else
                        break;
        }
        strbuf_reset(&sb);
        strbuf_addf(&sb, "%s%s%s", remoteurl, colonsep ? ":" : "/", url);
        if (ends_with(url, "/"))
                strbuf_setlen(&sb, sb.len - 1);
        free(remoteurl);

        if (starts_with_dot_slash(sb.buf))
                out = xstrdup(sb.buf + 2);
        else
                out = xstrdup(sb.buf);
        strbuf_reset(&sb);

        if (!up_path || !is_relative)
                return out;

        strbuf_addf(&sb, "%s%s", up_path, out);
        free(out);
        return strbuf_detach(&sb, NULL);
}

static int resolve_relative_url(int argc, const char **argv, const char *prefix)
{
        char *remoteurl = NULL;
        char *remote = get_default_remote();
        const char *up_path = NULL;
        char *res;
        const char *url;
        struct strbuf sb = STRBUF_INIT;

        if (argc != 2 && argc != 3)
                die("resolve-relative-url only accepts one or two arguments");

        url = argv[1];
        strbuf_addf(&sb, "remote.%s.url", remote);
        free(remote);

        if (git_config_get_string(sb.buf, &remoteurl))
                /* the repository is its own authoritative upstream */
                remoteurl = xgetcwd();

        if (argc == 3)
                up_path = argv[2];

        res = relative_url(remoteurl, url, up_path);
        puts(res);
        free(res);
        free(remoteurl);
        return 0;
}

static int resolve_relative_url_test(int argc, const char **argv, const char *prefix)
{
        char *remoteurl, *res;
        const char *up_path, *url;

        if (argc != 4)
                die("resolve-relative-url-test only accepts three arguments: <up_path> <remoteurl> <url>");

        up_path = argv[1];
        remoteurl = xstrdup(argv[2]);
        url = argv[3];

        if (!strcmp(up_path, "(null)"))
                up_path = NULL;

        res = relative_url(remoteurl, url, up_path);
        puts(res);
        free(res);
        free(remoteurl);
        return 0;
}

/* the result should be freed by the caller. */
static char *get_submodule_displaypath(const char *path, const char *prefix)
{
        const char *super_prefix = get_super_prefix();

        if (prefix && super_prefix) {
                BUG("cannot have prefix '%s' and superprefix '%s'",
                    prefix, super_prefix);
        } else if (prefix) {
                struct strbuf sb = STRBUF_INIT;
                char *displaypath = xstrdup(relative_path(path, prefix, &sb));
                strbuf_release(&sb);
                return displaypath;
        } else if (super_prefix) {
                return xstrfmt("%s%s", super_prefix, path);
        } else {
                return xstrdup(path);
        }
}

static char *compute_rev_name(const char *sub_path, const char* object_id)
{
        struct strbuf sb = STRBUF_INIT;
        const char ***d;

        static const char *describe_bare[] = { NULL };

        static const char *describe_tags[] = { "--tags", NULL };

        static const char *describe_contains[] = { "--contains", NULL };

        static const char *describe_all_always[] = { "--all", "--always", NULL };

        static const char **describe_argv[] = { describe_bare, describe_tags,
                                                describe_contains,
                                                describe_all_always, NULL };

        for (d = describe_argv; *d; d++) {
                struct child_process cp = CHILD_PROCESS_INIT;
                prepare_submodule_repo_env(&cp.env_array);
                cp.dir = sub_path;
                cp.git_cmd = 1;
                cp.no_stderr = 1;

                argv_array_push(&cp.args, "describe");
                argv_array_pushv(&cp.args, *d);
                argv_array_push(&cp.args, object_id);

                if (!capture_command(&cp, &sb, 0)) {
                        strbuf_strip_suffix(&sb, "\n");
                        return strbuf_detach(&sb, NULL);
                }
        }

        strbuf_release(&sb);
        return NULL;
}

struct module_list {
        const struct cache_entry **entries;
        int alloc, nr;
};
#define MODULE_LIST_INIT { NULL, 0, 0 }

static int module_list_compute(int argc, const char **argv,
                               const char *prefix,
                               struct pathspec *pathspec,
                               struct module_list *list)
{
        int i, result = 0;
        char *ps_matched = NULL;
        parse_pathspec(pathspec, 0,
                       PATHSPEC_PREFER_FULL,
                       prefix, argv);

        if (pathspec->nr)
                ps_matched = xcalloc(pathspec->nr, 1);

        if (read_cache() < 0)
                die(_("index file corrupt"));

        for (i = 0; i < active_nr; i++) {
                const struct cache_entry *ce = active_cache[i];

                if (!match_pathspec(&the_index, pathspec, ce->name, ce_namelen(ce),
                                    0, ps_matched, 1) ||
                    !S_ISGITLINK(ce->ce_mode))
                        continue;

                ALLOC_GROW(list->entries, list->nr + 1, list->alloc);
                list->entries[list->nr++] = ce;
                while (i + 1 < active_nr &&
                       !strcmp(ce->name, active_cache[i + 1]->name))
                        /*
                         * Skip entries with the same name in different stages
                         * to make sure an entry is returned only once.
                         */
                        i++;
        }

        if (ps_matched && report_path_error(ps_matched, pathspec, prefix))
                result = -1;

        free(ps_matched);

        return result;
}

static void module_list_active(struct module_list *list)
{
        int i;
        struct module_list active_modules = MODULE_LIST_INIT;

        for (i = 0; i < list->nr; i++) {
                const struct cache_entry *ce = list->entries[i];

                if (!is_submodule_active(the_repository, ce->name))
                        continue;

                ALLOC_GROW(active_modules.entries,
                           active_modules.nr + 1,
                           active_modules.alloc);
                active_modules.entries[active_modules.nr++] = ce;
        }

        free(list->entries);
        *list = active_modules;
}

static char *get_up_path(const char *path)
{
        int i;
        struct strbuf sb = STRBUF_INIT;

        for (i = count_slashes(path); i; i--)
                strbuf_addstr(&sb, "../");

        /*
         * Check if 'path' ends with slash or not
         * for having the same output for dir/sub_dir
         * and dir/sub_dir/
         */
        if (!is_dir_sep(path[strlen(path) - 1]))
                strbuf_addstr(&sb, "../");

        return strbuf_detach(&sb, NULL);
}

static int module_list(int argc, const char **argv, const char *prefix)
{
        int i;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;

        struct option module_list_options[] = {
                OPT_STRING(0, "prefix", &prefix,
                           N_("path"),
                           N_("alternative anchor for relative paths")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper list [--prefix=<path>] [<path>...]"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_list_options,
                             git_submodule_helper_usage, 0);

        if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
                return 1;

        for (i = 0; i < list.nr; i++) {
                const struct cache_entry *ce = list.entries[i];

                if (ce_stage(ce))
                        printf("%06o %s U\t", ce->ce_mode, sha1_to_hex(null_sha1));
                else
                        printf("%06o %s %d\t", ce->ce_mode,
                               oid_to_hex(&ce->oid), ce_stage(ce));

                fprintf(stdout, "%s\n", ce->name);
        }
        return 0;
}

static void for_each_listed_submodule(const struct module_list *list,
                                      each_submodule_fn fn, void *cb_data)
{
        int i;
        for (i = 0; i < list->nr; i++)
                fn(list->entries[i], cb_data);
}

struct cb_foreach {
        int argc;
        const char **argv;
        const char *prefix;
        int quiet;
        int recursive;
};
#define CB_FOREACH_INIT { 0 }

static void runcommand_in_submodule_cb(const struct cache_entry *list_item,
                                       void *cb_data)
{
        struct cb_foreach *info = cb_data;
        const char *path = list_item->name;
        const struct object_id *ce_oid = &list_item->oid;

        const struct submodule *sub;
        struct child_process cp = CHILD_PROCESS_INIT;
        char *displaypath;

        displaypath = get_submodule_displaypath(path, info->prefix);

        sub = submodule_from_path(the_repository, &null_oid, path);

        if (!sub)
                die(_("No url found for submodule path '%s' in .gitmodules"),
                        displaypath);

        if (!is_submodule_populated_gently(path, NULL))
                goto cleanup;

        prepare_submodule_repo_env(&cp.env_array);

        /*
         * For the purpose of executing <command> in the submodule,
         * separate shell is used for the purpose of running the
         * child process.
         */
        cp.use_shell = 1;
        cp.dir = path;

        /*
         * NEEDSWORK: the command currently has access to the variables $name,
         * $sm_path, $displaypath, $sha1 and $toplevel only when the command
         * contains a single argument. This is done for maintaining a faithful
         * translation from shell script.
         */
        if (info->argc == 1) {
                char *toplevel = xgetcwd();
                struct strbuf sb = STRBUF_INIT;

                argv_array_pushf(&cp.env_array, "name=%s", sub->name);
                argv_array_pushf(&cp.env_array, "sm_path=%s", path);
                argv_array_pushf(&cp.env_array, "displaypath=%s", displaypath);
                argv_array_pushf(&cp.env_array, "sha1=%s",
                                oid_to_hex(ce_oid));
                argv_array_pushf(&cp.env_array, "toplevel=%s", toplevel);

                /*
                 * Since the path variable was accessible from the script
                 * before porting, it is also made available after porting.
                 * The environment variable "PATH" has a very special purpose
                 * on windows. And since environment variables are
                 * case-insensitive in windows, it interferes with the
                 * existing PATH variable. Hence, to avoid that, we expose
                 * path via the args argv_array and not via env_array.
                 */
                sq_quote_buf(&sb, path);
                argv_array_pushf(&cp.args, "path=%s; %s",
                                 sb.buf, info->argv[0]);
                strbuf_release(&sb);
                free(toplevel);
        } else {
                argv_array_pushv(&cp.args, info->argv);
        }

        if (!info->quiet)
                printf(_("Entering '%s'\n"), displaypath);

        if (info->argv[0] && run_command(&cp))
                die(_("run_command returned non-zero status for %s\n."),
                        displaypath);

        if (info->recursive) {
                struct child_process cpr = CHILD_PROCESS_INIT;

                cpr.git_cmd = 1;
                cpr.dir = path;
                prepare_submodule_repo_env(&cpr.env_array);

                argv_array_pushl(&cpr.args, "--super-prefix", NULL);
                argv_array_pushf(&cpr.args, "%s/", displaypath);
                argv_array_pushl(&cpr.args, "submodule--helper", "foreach", "--recursive",
                                NULL);

                if (info->quiet)
                        argv_array_push(&cpr.args, "--quiet");

                argv_array_pushv(&cpr.args, info->argv);

                if (run_command(&cpr))
                        die(_("run_command returned non-zero status while "
                                "recursing in the nested submodules of %s\n."),
                                displaypath);
        }

cleanup:
        free(displaypath);
}

static int module_foreach(int argc, const char **argv, const char *prefix)
{
        struct cb_foreach info = CB_FOREACH_INIT;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;

        struct option module_foreach_options[] = {
                OPT__QUIET(&info.quiet, N_("Suppress output of entering each submodule command")),
                OPT_BOOL(0, "recursive", &info.recursive,
                         N_("Recurse into nested submodules")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper foreach [--quiet] [--recursive] <command>"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_foreach_options,
                             git_submodule_helper_usage, PARSE_OPT_KEEP_UNKNOWN);

        if (module_list_compute(0, NULL, prefix, &pathspec, &list) < 0)
                return 1;

        info.argc = argc;
        info.argv = argv;
        info.prefix = prefix;

        for_each_listed_submodule(&list, runcommand_in_submodule_cb, &info);

        return 0;
}

static char *compute_submodule_clone_url(const char *rel_url)
{
        char *remoteurl, *relurl;
        char *remote = get_default_remote();
        struct strbuf remotesb = STRBUF_INIT;

        strbuf_addf(&remotesb, "remote.%s.url", remote);
        if (git_config_get_string(remotesb.buf, &remoteurl)) {
                warning(_("could not look up configuration '%s'. Assuming this repository is its own authoritative upstream."), remotesb.buf);
                remoteurl = xgetcwd();
        }
        relurl = relative_url(remoteurl, rel_url, NULL);

        free(remote);
        free(remoteurl);
        strbuf_release(&remotesb);

        return relurl;
}

struct init_cb {
        const char *prefix;
        unsigned int flags;
};

#define INIT_CB_INIT { NULL, 0 }

static void init_submodule(const char *path, const char *prefix,
                           unsigned int flags)
{
        const struct submodule *sub;
        struct strbuf sb = STRBUF_INIT;
        char *upd = NULL, *url = NULL, *displaypath;

        displaypath = get_submodule_displaypath(path, prefix);

        sub = submodule_from_path(the_repository, &null_oid, path);

        if (!sub)
                die(_("No url found for submodule path '%s' in .gitmodules"),
                        displaypath);

        /*
         * NEEDSWORK: In a multi-working-tree world, this needs to be
         * set in the per-worktree config.
         *
         * Set active flag for the submodule being initialized
         */
        if (!is_submodule_active(the_repository, path)) {
                strbuf_addf(&sb, "submodule.%s.active", sub->name);
                git_config_set_gently(sb.buf, "true");
                strbuf_reset(&sb);
        }

        /*
         * Copy url setting when it is not set yet.
         * To look up the url in .git/config, we must not fall back to
         * .gitmodules, so look it up directly.
         */
        strbuf_addf(&sb, "submodule.%s.url", sub->name);
        if (git_config_get_string(sb.buf, &url)) {
                if (!sub->url)
                        die(_("No url found for submodule path '%s' in .gitmodules"),
                                displaypath);

                url = xstrdup(sub->url);

                /* Possibly a url relative to parent */
                if (starts_with_dot_dot_slash(url) ||
                    starts_with_dot_slash(url)) {
                        char *oldurl = url;
                        url = compute_submodule_clone_url(oldurl);
                        free(oldurl);
                }

                if (git_config_set_gently(sb.buf, url))
                        die(_("Failed to register url for submodule path '%s'"),
                            displaypath);
                if (!(flags & OPT_QUIET))
                        fprintf(stderr,
                                _("Submodule '%s' (%s) registered for path '%s'\n"),
                                sub->name, url, displaypath);
        }
        strbuf_reset(&sb);

        /* Copy "update" setting when it is not set yet */
        strbuf_addf(&sb, "submodule.%s.update", sub->name);
        if (git_config_get_string(sb.buf, &upd) &&
            sub->update_strategy.type != SM_UPDATE_UNSPECIFIED) {
                if (sub->update_strategy.type == SM_UPDATE_COMMAND) {
                        fprintf(stderr, _("warning: command update mode suggested for submodule '%s'\n"),
                                sub->name);
                        upd = xstrdup("none");
                } else
                        upd = xstrdup(submodule_strategy_to_string(&sub->update_strategy));

                if (git_config_set_gently(sb.buf, upd))
                        die(_("Failed to register update mode for submodule path '%s'"), displaypath);
        }
        strbuf_release(&sb);
        free(displaypath);
        free(url);
        free(upd);
}

static void init_submodule_cb(const struct cache_entry *list_item, void *cb_data)
{
        struct init_cb *info = cb_data;
        init_submodule(list_item->name, info->prefix, info->flags);
}

static int module_init(int argc, const char **argv, const char *prefix)
{
        struct init_cb info = INIT_CB_INIT;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;
        int quiet = 0;

        struct option module_init_options[] = {
                OPT__QUIET(&quiet, N_("Suppress output for initializing a submodule")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper init [<path>]"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_init_options,
                             git_submodule_helper_usage, 0);

        if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
                return 1;

        /*
         * If there are no path args and submodule.active is set then,
         * by default, only initialize 'active' modules.
         */
        if (!argc && git_config_get_value_multi("submodule.active"))
                module_list_active(&list);

        info.prefix = prefix;
        if (quiet)
                info.flags |= OPT_QUIET;

        for_each_listed_submodule(&list, init_submodule_cb, &info);

        return 0;
}

struct status_cb {
        const char *prefix;
        unsigned int flags;
};

#define STATUS_CB_INIT { NULL, 0 }

static void print_status(unsigned int flags, char state, const char *path,
                         const struct object_id *oid, const char *displaypath)
{
        if (flags & OPT_QUIET)
                return;

        printf("%c%s %s", state, oid_to_hex(oid), displaypath);

        if (state == ' ' || state == '+') {
                const char *name = compute_rev_name(path, oid_to_hex(oid));

                if (name)
                        printf(" (%s)", name);
        }

        printf("\n");
}

static int handle_submodule_head_ref(const char *refname,
                                     const struct object_id *oid, int flags,
                                     void *cb_data)
{
        struct object_id *output = cb_data;
        if (oid)
                oidcpy(output, oid);

        return 0;
}

static void status_submodule(const char *path, const struct object_id *ce_oid,
                             unsigned int ce_flags, const char *prefix,
                             unsigned int flags)
{
        char *displaypath;
        struct argv_array diff_files_args = ARGV_ARRAY_INIT;
        struct rev_info rev;
        int diff_files_result;

        if (!submodule_from_path(the_repository, &null_oid, path))
                die(_("no submodule mapping found in .gitmodules for path '%s'"),
                      path);

        displaypath = get_submodule_displaypath(path, prefix);

        if ((CE_STAGEMASK & ce_flags) >> CE_STAGESHIFT) {
                print_status(flags, 'U', path, &null_oid, displaypath);
                goto cleanup;
        }

        if (!is_submodule_active(the_repository, path)) {
                print_status(flags, '-', path, ce_oid, displaypath);
                goto cleanup;
        }

        argv_array_pushl(&diff_files_args, "diff-files",
                         "--ignore-submodules=dirty", "--quiet", "--",
                         path, NULL);

        git_config(git_diff_basic_config, NULL);
        repo_init_revisions(the_repository, &rev, prefix);
        rev.abbrev = 0;
        diff_files_args.argc = setup_revisions(diff_files_args.argc,
                                               diff_files_args.argv,
                                               &rev, NULL);
        diff_files_result = run_diff_files(&rev, 0);

        if (!diff_result_code(&rev.diffopt, diff_files_result)) {
                print_status(flags, ' ', path, ce_oid,
                             displaypath);
        } else if (!(flags & OPT_CACHED)) {
                struct object_id oid;
                struct ref_store *refs = get_submodule_ref_store(path);

                if (!refs) {
                        print_status(flags, '-', path, ce_oid, displaypath);
                        goto cleanup;
                }
                if (refs_head_ref(refs, handle_submodule_head_ref, &oid))
                        die(_("could not resolve HEAD ref inside the "
                              "submodule '%s'"), path);

                print_status(flags, '+', path, &oid, displaypath);
        } else {
                print_status(flags, '+', path, ce_oid, displaypath);
        }

        if (flags & OPT_RECURSIVE) {
                struct child_process cpr = CHILD_PROCESS_INIT;

                cpr.git_cmd = 1;
                cpr.dir = path;
                prepare_submodule_repo_env(&cpr.env_array);

                argv_array_push(&cpr.args, "--super-prefix");
                argv_array_pushf(&cpr.args, "%s/", displaypath);
                argv_array_pushl(&cpr.args, "submodule--helper", "status",
                                 "--recursive", NULL);

                if (flags & OPT_CACHED)
                        argv_array_push(&cpr.args, "--cached");

                if (flags & OPT_QUIET)
                        argv_array_push(&cpr.args, "--quiet");

                if (run_command(&cpr))
                        die(_("failed to recurse into submodule '%s'"), path);
        }

cleanup:
        argv_array_clear(&diff_files_args);
        free(displaypath);
}

static void status_submodule_cb(const struct cache_entry *list_item,
                                void *cb_data)
{
        struct status_cb *info = cb_data;
        status_submodule(list_item->name, &list_item->oid, list_item->ce_flags,
                         info->prefix, info->flags);
}

static int module_status(int argc, const char **argv, const char *prefix)
{
        struct status_cb info = STATUS_CB_INIT;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;
        int quiet = 0;

        struct option module_status_options[] = {
                OPT__QUIET(&quiet, N_("Suppress submodule status output")),
                OPT_BIT(0, "cached", &info.flags, N_("Use commit stored in the index instead of the one stored in the submodule HEAD"), OPT_CACHED),
                OPT_BIT(0, "recursive", &info.flags, N_("recurse into nested submodules"), OPT_RECURSIVE),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule status [--quiet] [--cached] [--recursive] [<path>...]"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_status_options,
                             git_submodule_helper_usage, 0);

        if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
                return 1;

        info.prefix = prefix;
        if (quiet)
                info.flags |= OPT_QUIET;

        for_each_listed_submodule(&list, status_submodule_cb, &info);

        return 0;
}

static int module_name(int argc, const char **argv, const char *prefix)
{
        const struct submodule *sub;

        if (argc != 2)
                usage(_("git submodule--helper name <path>"));

        sub = submodule_from_path(the_repository, &null_oid, argv[1]);

        if (!sub)
                die(_("no submodule mapping found in .gitmodules for path '%s'"),
                    argv[1]);

        printf("%s\n", sub->name);

        return 0;
}

struct sync_cb {
        const char *prefix;
        unsigned int flags;
};

#define SYNC_CB_INIT { NULL, 0 }

static void sync_submodule(const char *path, const char *prefix,
                           unsigned int flags)
{
        const struct submodule *sub;
        char *remote_key = NULL;
        char *sub_origin_url, *super_config_url, *displaypath;
        struct strbuf sb = STRBUF_INIT;
        struct child_process cp = CHILD_PROCESS_INIT;
        char *sub_config_path = NULL;

        if (!is_submodule_active(the_repository, path))
                return;

        sub = submodule_from_path(the_repository, &null_oid, path);

        if (sub && sub->url) {
                if (starts_with_dot_dot_slash(sub->url) ||
                    starts_with_dot_slash(sub->url)) {
                        char *remote_url, *up_path;
                        char *remote = get_default_remote();
                        strbuf_addf(&sb, "remote.%s.url", remote);

                        if (git_config_get_string(sb.buf, &remote_url))
                                remote_url = xgetcwd();

                        up_path = get_up_path(path);
                        sub_origin_url = relative_url(remote_url, sub->url, up_path);
                        super_config_url = relative_url(remote_url, sub->url, NULL);

                        free(remote);
                        free(up_path);
                        free(remote_url);
                } else {
                        sub_origin_url = xstrdup(sub->url);
                        super_config_url = xstrdup(sub->url);
                }
        } else {
                sub_origin_url = xstrdup("");
                super_config_url = xstrdup("");
        }

        displaypath = get_submodule_displaypath(path, prefix);

        if (!(flags & OPT_QUIET))
                printf(_("Synchronizing submodule url for '%s'\n"),
                         displaypath);

        strbuf_reset(&sb);
        strbuf_addf(&sb, "submodule.%s.url", sub->name);
        if (git_config_set_gently(sb.buf, super_config_url))
                die(_("failed to register url for submodule path '%s'"),
                      displaypath);

        if (!is_submodule_populated_gently(path, NULL))
                goto cleanup;

        prepare_submodule_repo_env(&cp.env_array);
        cp.git_cmd = 1;
        cp.dir = path;
        argv_array_pushl(&cp.args, "submodule--helper",
                         "print-default-remote", NULL);

        strbuf_reset(&sb);
        if (capture_command(&cp, &sb, 0))
                die(_("failed to get the default remote for submodule '%s'"),
                      path);

        strbuf_strip_suffix(&sb, "\n");
        remote_key = xstrfmt("remote.%s.url", sb.buf);

        strbuf_reset(&sb);
        submodule_to_gitdir(&sb, path);
        strbuf_addstr(&sb, "/config");

        if (git_config_set_in_file_gently(sb.buf, remote_key, sub_origin_url))
                die(_("failed to update remote for submodule '%s'"),
                      path);

        if (flags & OPT_RECURSIVE) {
                struct child_process cpr = CHILD_PROCESS_INIT;

                cpr.git_cmd = 1;
                cpr.dir = path;
                prepare_submodule_repo_env(&cpr.env_array);

                argv_array_push(&cpr.args, "--super-prefix");
                argv_array_pushf(&cpr.args, "%s/", displaypath);
                argv_array_pushl(&cpr.args, "submodule--helper", "sync",
                                 "--recursive", NULL);

                if (flags & OPT_QUIET)
                        argv_array_push(&cpr.args, "--quiet");

                if (run_command(&cpr))
                        die(_("failed to recurse into submodule '%s'"),
                              path);
        }

cleanup:
        free(super_config_url);
        free(sub_origin_url);
        strbuf_release(&sb);
        free(remote_key);
        free(displaypath);
        free(sub_config_path);
}

static void sync_submodule_cb(const struct cache_entry *list_item, void *cb_data)
{
        struct sync_cb *info = cb_data;
        sync_submodule(list_item->name, info->prefix, info->flags);
}

static int module_sync(int argc, const char **argv, const char *prefix)
{
        struct sync_cb info = SYNC_CB_INIT;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;
        int quiet = 0;
        int recursive = 0;

        struct option module_sync_options[] = {
                OPT__QUIET(&quiet, N_("Suppress output of synchronizing submodule url")),
                OPT_BOOL(0, "recursive", &recursive,
                        N_("Recurse into nested submodules")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper sync [--quiet] [--recursive] [<path>]"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_sync_options,
                             git_submodule_helper_usage, 0);

        if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
                return 1;

        info.prefix = prefix;
        if (quiet)
                info.flags |= OPT_QUIET;
        if (recursive)
                info.flags |= OPT_RECURSIVE;

        for_each_listed_submodule(&list, sync_submodule_cb, &info);

        return 0;
}

struct deinit_cb {
        const char *prefix;
        unsigned int flags;
};
#define DEINIT_CB_INIT { NULL, 0 }

static void deinit_submodule(const char *path, const char *prefix,
                             unsigned int flags)
{
        const struct submodule *sub;
        char *displaypath = NULL;
        struct child_process cp_config = CHILD_PROCESS_INIT;
        struct strbuf sb_config = STRBUF_INIT;
        char *sub_git_dir = xstrfmt("%s/.git", path);

        sub = submodule_from_path(the_repository, &null_oid, path);

        if (!sub || !sub->name)
                goto cleanup;

        displaypath = get_submodule_displaypath(path, prefix);

        /* remove the submodule work tree (unless the user already did it) */
        if (is_directory(path)) {
                struct strbuf sb_rm = STRBUF_INIT;
                const char *format;

                /*
                 * protect submodules containing a .git directory
                 * NEEDSWORK: instead of dying, automatically call
                 * absorbgitdirs and (possibly) warn.
                 */
                if (is_directory(sub_git_dir))
                        die(_("Submodule work tree '%s' contains a .git "
                              "directory (use 'rm -rf' if you really want "
                              "to remove it including all of its history)"),
                            displaypath);

                if (!(flags & OPT_FORCE)) {
                        struct child_process cp_rm = CHILD_PROCESS_INIT;
                        cp_rm.git_cmd = 1;
                        argv_array_pushl(&cp_rm.args, "rm", "-qn",
                                         path, NULL);

                        if (run_command(&cp_rm))
                                die(_("Submodule work tree '%s' contains local "
                                      "modifications; use '-f' to discard them"),
                                      displaypath);
                }

                strbuf_addstr(&sb_rm, path);

                if (!remove_dir_recursively(&sb_rm, 0))
                        format = _("Cleared directory '%s'\n");
                else
                        format = _("Could not remove submodule work tree '%s'\n");

                if (!(flags & OPT_QUIET))
                        printf(format, displaypath);

                submodule_unset_core_worktree(sub);

                strbuf_release(&sb_rm);
        }

        if (mkdir(path, 0777))
                printf(_("could not create empty submodule directory %s"),
                      displaypath);

        cp_config.git_cmd = 1;
        argv_array_pushl(&cp_config.args, "config", "--get-regexp", NULL);
        argv_array_pushf(&cp_config.args, "submodule.%s\\.", sub->name);

        /* remove the .git/config entries (unless the user already did it) */
        if (!capture_command(&cp_config, &sb_config, 0) && sb_config.len) {
                char *sub_key = xstrfmt("submodule.%s", sub->name);
                /*
                 * remove the whole section so we have a clean state when
                 * the user later decides to init this submodule again
                 */
                git_config_rename_section_in_file(NULL, sub_key, NULL);
                if (!(flags & OPT_QUIET))
                        printf(_("Submodule '%s' (%s) unregistered for path '%s'\n"),
                                 sub->name, sub->url, displaypath);
                free(sub_key);
        }

cleanup:
        free(displaypath);
        free(sub_git_dir);
        strbuf_release(&sb_config);
}

static void deinit_submodule_cb(const struct cache_entry *list_item,
                                void *cb_data)
{
        struct deinit_cb *info = cb_data;
        deinit_submodule(list_item->name, info->prefix, info->flags);
}

static int module_deinit(int argc, const char **argv, const char *prefix)
{
        struct deinit_cb info = DEINIT_CB_INIT;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;
        int quiet = 0;
        int force = 0;
        int all = 0;

        struct option module_deinit_options[] = {
                OPT__QUIET(&quiet, N_("Suppress submodule status output")),
                OPT__FORCE(&force, N_("Remove submodule working trees even if they contain local changes"), 0),
                OPT_BOOL(0, "all", &all, N_("Unregister all submodules")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule deinit [--quiet] [-f | --force] [--all | [--] [<path>...]]"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_deinit_options,
                             git_submodule_helper_usage, 0);

        if (all && argc) {
                error("pathspec and --all are incompatible");
                usage_with_options(git_submodule_helper_usage,
                                   module_deinit_options);
        }

        if (!argc && !all)
                die(_("Use '--all' if you really want to deinitialize all submodules"));

        if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
                return 1;

        info.prefix = prefix;
        if (quiet)
                info.flags |= OPT_QUIET;
        if (force)
                info.flags |= OPT_FORCE;

        for_each_listed_submodule(&list, deinit_submodule_cb, &info);

        return 0;
}

static int clone_submodule(const char *path, const char *gitdir, const char *url,
                           const char *depth, struct string_list *reference, int dissociate,
                           int quiet, int progress)
{
        struct child_process cp = CHILD_PROCESS_INIT;

        argv_array_push(&cp.args, "clone");
        argv_array_push(&cp.args, "--no-checkout");
        if (quiet)
                argv_array_push(&cp.args, "--quiet");
        if (progress)
                argv_array_push(&cp.args, "--progress");
        if (depth && *depth)
                argv_array_pushl(&cp.args, "--depth", depth, NULL);
        if (reference->nr) {
                struct string_list_item *item;
                for_each_string_list_item(item, reference)
                        argv_array_pushl(&cp.args, "--reference",
                                         item->string, NULL);
        }
        if (dissociate)
                argv_array_push(&cp.args, "--dissociate");
        if (gitdir && *gitdir)
                argv_array_pushl(&cp.args, "--separate-git-dir", gitdir, NULL);

        argv_array_push(&cp.args, "--");
        argv_array_push(&cp.args, url);
        argv_array_push(&cp.args, path);

        cp.git_cmd = 1;
        prepare_submodule_repo_env(&cp.env_array);
        cp.no_stdin = 1;

        return run_command(&cp);
}

struct submodule_alternate_setup {
        const char *submodule_name;
        enum SUBMODULE_ALTERNATE_ERROR_MODE {
                SUBMODULE_ALTERNATE_ERROR_DIE,
                SUBMODULE_ALTERNATE_ERROR_INFO,
                SUBMODULE_ALTERNATE_ERROR_IGNORE
        } error_mode;
        struct string_list *reference;
};
#define SUBMODULE_ALTERNATE_SETUP_INIT { NULL, \
        SUBMODULE_ALTERNATE_ERROR_IGNORE, NULL }

static int add_possible_reference_from_superproject(
                struct alternate_object_database *alt, void *sas_cb)
{
        struct submodule_alternate_setup *sas = sas_cb;

        /*
         * If the alternate object store is another repository, try the
         * standard layout with .git/(modules/<name>)+/objects
         */
        if (ends_with(alt->path, "/objects")) {
                char *sm_alternate;
                struct strbuf sb = STRBUF_INIT;
                struct strbuf err = STRBUF_INIT;
                strbuf_add(&sb, alt->path, strlen(alt->path) - strlen("objects"));

                /*
                 * We need to end the new path with '/' to mark it as a dir,
                 * otherwise a submodule name containing '/' will be broken
                 * as the last part of a missing submodule reference would
                 * be taken as a file name.
                 */
                strbuf_addf(&sb, "modules/%s/", sas->submodule_name);

                sm_alternate = compute_alternate_path(sb.buf, &err);
                if (sm_alternate) {
                        string_list_append(sas->reference, xstrdup(sb.buf));
                        free(sm_alternate);
                } else {
                        switch (sas->error_mode) {
                        case SUBMODULE_ALTERNATE_ERROR_DIE:
                                die(_("submodule '%s' cannot add alternate: %s"),
                                    sas->submodule_name, err.buf);
                        case SUBMODULE_ALTERNATE_ERROR_INFO:
                                fprintf(stderr, _("submodule '%s' cannot add alternate: %s"),
                                        sas->submodule_name, err.buf);
                        case SUBMODULE_ALTERNATE_ERROR_IGNORE:
                                ; /* nothing */
                        }
                }
                strbuf_release(&sb);
        }

        return 0;
}

static void prepare_possible_alternates(const char *sm_name,
                struct string_list *reference)
{
        char *sm_alternate = NULL, *error_strategy = NULL;
        struct submodule_alternate_setup sas = SUBMODULE_ALTERNATE_SETUP_INIT;

        git_config_get_string("submodule.alternateLocation", &sm_alternate);
        if (!sm_alternate)
                return;

        git_config_get_string("submodule.alternateErrorStrategy", &error_strategy);

        if (!error_strategy)
                error_strategy = xstrdup("die");

        sas.submodule_name = sm_name;
        sas.reference = reference;
        if (!strcmp(error_strategy, "die"))
                sas.error_mode = SUBMODULE_ALTERNATE_ERROR_DIE;
        else if (!strcmp(error_strategy, "info"))
                sas.error_mode = SUBMODULE_ALTERNATE_ERROR_INFO;
        else if (!strcmp(error_strategy, "ignore"))
                sas.error_mode = SUBMODULE_ALTERNATE_ERROR_IGNORE;
        else
                die(_("Value '%s' for submodule.alternateErrorStrategy is not recognized"), error_strategy);

        if (!strcmp(sm_alternate, "superproject"))
                foreach_alt_odb(add_possible_reference_from_superproject, &sas);
        else if (!strcmp(sm_alternate, "no"))
                ; /* do nothing */
        else
                die(_("Value '%s' for submodule.alternateLocation is not recognized"), sm_alternate);

        free(sm_alternate);
        free(error_strategy);
}

static int module_clone(int argc, const char **argv, const char *prefix)
{
        const char *name = NULL, *url = NULL, *depth = NULL;
        int quiet = 0;
        int progress = 0;
        char *p, *path = NULL, *sm_gitdir;
        struct strbuf sb = STRBUF_INIT;
        struct string_list reference = STRING_LIST_INIT_NODUP;
        int dissociate = 0;
        char *sm_alternate = NULL, *error_strategy = NULL;

        struct option module_clone_options[] = {
                OPT_STRING(0, "prefix", &prefix,
                           N_("path"),
                           N_("alternative anchor for relative paths")),
                OPT_STRING(0, "path", &path,
                           N_("path"),
                           N_("where the new submodule will be cloned to")),
                OPT_STRING(0, "name", &name,
                           N_("string"),
                           N_("name of the new submodule")),
                OPT_STRING(0, "url", &url,
                           N_("string"),
                           N_("url where to clone the submodule from")),
                OPT_STRING_LIST(0, "reference", &reference,
                           N_("repo"),
                           N_("reference repository")),
                OPT_BOOL(0, "dissociate", &dissociate,
                           N_("use --reference only while cloning")),
                OPT_STRING(0, "depth", &depth,
                           N_("string"),
                           N_("depth for shallow clones")),
                OPT__QUIET(&quiet, "Suppress output for cloning a submodule"),
                OPT_BOOL(0, "progress", &progress,
                           N_("force cloning progress")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper clone [--prefix=<path>] [--quiet] "
                   "[--reference <repository>] [--name <name>] [--depth <depth>] "
                   "--url <url> --path <path>"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_clone_options,
                             git_submodule_helper_usage, 0);

        if (argc || !url || !path || !*path)
                usage_with_options(git_submodule_helper_usage,
                                   module_clone_options);

        strbuf_addf(&sb, "%s/modules/%s", get_git_dir(), name);
        sm_gitdir = absolute_pathdup(sb.buf);
        strbuf_reset(&sb);

        if (!is_absolute_path(path)) {
                strbuf_addf(&sb, "%s/%s", get_git_work_tree(), path);
                path = strbuf_detach(&sb, NULL);
        } else
                path = xstrdup(path);

        if (!file_exists(sm_gitdir)) {
                if (safe_create_leading_directories_const(sm_gitdir) < 0)
                        die(_("could not create directory '%s'"), sm_gitdir);

                prepare_possible_alternates(name, &reference);

                if (clone_submodule(path, sm_gitdir, url, depth, &reference, dissociate,
                                    quiet, progress))
                        die(_("clone of '%s' into submodule path '%s' failed"),
                            url, path);
        } else {
                if (safe_create_leading_directories_const(path) < 0)
                        die(_("could not create directory '%s'"), path);
                strbuf_addf(&sb, "%s/index", sm_gitdir);
                unlink_or_warn(sb.buf);
                strbuf_reset(&sb);
        }

        connect_work_tree_and_git_dir(path, sm_gitdir, 0);

        p = git_pathdup_submodule(path, "config");
        if (!p)
                die(_("could not get submodule directory for '%s'"), path);

        /* setup alternateLocation and alternateErrorStrategy in the cloned submodule if needed */
        git_config_get_string("submodule.alternateLocation", &sm_alternate);
        if (sm_alternate)
                git_config_set_in_file(p, "submodule.alternateLocation",
                                           sm_alternate);
        git_config_get_string("submodule.alternateErrorStrategy", &error_strategy);
        if (error_strategy)
                git_config_set_in_file(p, "submodule.alternateErrorStrategy",
                                           error_strategy);

        free(sm_alternate);
        free(error_strategy);

        strbuf_release(&sb);
        free(sm_gitdir);
        free(path);
        free(p);
        return 0;
}

static void determine_submodule_update_strategy(struct repository *r,
                                                int just_cloned,
                                                const char *path,
                                                const char *update,
                                                struct submodule_update_strategy *out)
{
        const struct submodule *sub = submodule_from_path(r, &null_oid, path);
        char *key;
        const char *val;

        key = xstrfmt("submodule.%s.update", sub->name);

        if (update) {
                if (parse_submodule_update_strategy(update, out) < 0)
                        die(_("Invalid update mode '%s' for submodule path '%s'"),
                                update, path);
        } else if (!repo_config_get_string_const(r, key, &val)) {
                if (parse_submodule_update_strategy(val, out) < 0)
                        die(_("Invalid update mode '%s' configured for submodule path '%s'"),
                                val, path);
        } else if (sub->update_strategy.type != SM_UPDATE_UNSPECIFIED) {
                out->type = sub->update_strategy.type;
                out->command = sub->update_strategy.command;
        } else
                out->type = SM_UPDATE_CHECKOUT;

        if (just_cloned &&
            (out->type == SM_UPDATE_MERGE ||
             out->type == SM_UPDATE_REBASE ||
             out->type == SM_UPDATE_NONE))
                out->type = SM_UPDATE_CHECKOUT;

        free(key);
}

static int module_update_module_mode(int argc, const char **argv, const char *prefix)
{
        const char *path, *update = NULL;
        int just_cloned;
        struct submodule_update_strategy update_strategy = { .type = SM_UPDATE_CHECKOUT };

        if (argc < 3 || argc > 4)
                die("submodule--helper update-module-clone expects <just-cloned> <path> [<update>]");

        just_cloned = git_config_int("just_cloned", argv[1]);
        path = argv[2];

        if (argc == 4)
                update = argv[3];

        determine_submodule_update_strategy(the_repository,
                                            just_cloned, path, update,
                                            &update_strategy);
        fputs(submodule_strategy_to_string(&update_strategy), stdout);

        return 0;
}

struct update_clone_data {
        const struct submodule *sub;
        struct object_id oid;
        unsigned just_cloned;
};

struct submodule_update_clone {
        /* index into 'list', the list of submodules to look into for cloning */
        int current;
        struct module_list list;
        unsigned warn_if_uninitialized : 1;

        /* update parameter passed via commandline */
        struct submodule_update_strategy update;

        /* configuration parameters which are passed on to the children */
        int progress;
        int quiet;
        int recommend_shallow;
        struct string_list references;
        int dissociate;
        const char *depth;
        const char *recursive_prefix;
        const char *prefix;

        /* to be consumed by git-submodule.sh */
        struct update_clone_data *update_clone;
        int update_clone_nr; int update_clone_alloc;

        /* If we want to stop as fast as possible and return an error */
        unsigned quickstop : 1;

        /* failed clones to be retried again */
        const struct cache_entry **failed_clones;
        int failed_clones_nr, failed_clones_alloc;

        int max_jobs;
};
#define SUBMODULE_UPDATE_CLONE_INIT {0, MODULE_LIST_INIT, 0, \
        SUBMODULE_UPDATE_STRATEGY_INIT, 0, 0, -1, STRING_LIST_INIT_DUP, 0, \
        NULL, NULL, NULL, \
        NULL, 0, 0, 0, NULL, 0, 0, 0}


static void next_submodule_warn_missing(struct submodule_update_clone *suc,
                struct strbuf *out, const char *displaypath)
{
        /*
         * Only mention uninitialized submodules when their
         * paths have been specified.
         */
        if (suc->warn_if_uninitialized) {
                strbuf_addf(out,
                        _("Submodule path '%s' not initialized"),
                        displaypath);
                strbuf_addch(out, '\n');
                strbuf_addstr(out,
                        _("Maybe you want to use 'update --init'?"));
                strbuf_addch(out, '\n');
        }
}

/**
 * Determine whether 'ce' needs to be cloned. If so, prepare the 'child' to
 * run the clone. Returns 1 if 'ce' needs to be cloned, 0 otherwise.
 */
static int prepare_to_clone_next_submodule(const struct cache_entry *ce,
                                           struct child_process *child,
                                           struct submodule_update_clone *suc,
                                           struct strbuf *out)
{
        const struct submodule *sub = NULL;
        const char *url = NULL;
        const char *update_string;
        enum submodule_update_type update_type;
        char *key;
        struct strbuf displaypath_sb = STRBUF_INIT;
        struct strbuf sb = STRBUF_INIT;
        const char *displaypath = NULL;
        int needs_cloning = 0;
        int need_free_url = 0;

        if (ce_stage(ce)) {
                if (suc->recursive_prefix)
                        strbuf_addf(&sb, "%s/%s", suc->recursive_prefix, ce->name);
                else
                        strbuf_addstr(&sb, ce->name);
                strbuf_addf(out, _("Skipping unmerged submodule %s"), sb.buf);
                strbuf_addch(out, '\n');
                goto cleanup;
        }

        sub = submodule_from_path(the_repository, &null_oid, ce->name);

        if (suc->recursive_prefix)
                displaypath = relative_path(suc->recursive_prefix,
                                            ce->name, &displaypath_sb);
        else
                displaypath = ce->name;

        if (!sub) {
                next_submodule_warn_missing(suc, out, displaypath);
                goto cleanup;
        }

        key = xstrfmt("submodule.%s.update", sub->name);
        if (!repo_config_get_string_const(the_repository, key, &update_string)) {
                update_type = parse_submodule_update_type(update_string);
        } else {
                update_type = sub->update_strategy.type;
        }
        free(key);

        if (suc->update.type == SM_UPDATE_NONE
            || (suc->update.type == SM_UPDATE_UNSPECIFIED
                && update_type == SM_UPDATE_NONE)) {
                strbuf_addf(out, _("Skipping submodule '%s'"), displaypath);
                strbuf_addch(out, '\n');
                goto cleanup;
        }

        /* Check if the submodule has been initialized. */
        if (!is_submodule_active(the_repository, ce->name)) {
                next_submodule_warn_missing(suc, out, displaypath);
                goto cleanup;
        }

        strbuf_reset(&sb);
        strbuf_addf(&sb, "submodule.%s.url", sub->name);
        if (repo_config_get_string_const(the_repository, sb.buf, &url)) {
                if (starts_with_dot_slash(sub->url) ||
                    starts_with_dot_dot_slash(sub->url)) {
                        url = compute_submodule_clone_url(sub->url);
                        need_free_url = 1;
                } else
                        url = sub->url;
        }

        strbuf_reset(&sb);
        strbuf_addf(&sb, "%s/.git", ce->name);
        needs_cloning = !file_exists(sb.buf);

        ALLOC_GROW(suc->update_clone, suc->update_clone_nr + 1,
                   suc->update_clone_alloc);
        oidcpy(&suc->update_clone[suc->update_clone_nr].oid, &ce->oid);
        suc->update_clone[suc->update_clone_nr].just_cloned = needs_cloning;
        suc->update_clone[suc->update_clone_nr].sub = sub;
        suc->update_clone_nr++;

        if (!needs_cloning)
                goto cleanup;

        child->git_cmd = 1;
        child->no_stdin = 1;
        child->stdout_to_stderr = 1;
        child->err = -1;
        argv_array_push(&child->args, "submodule--helper");
        argv_array_push(&child->args, "clone");
        if (suc->progress)
                argv_array_push(&child->args, "--progress");
        if (suc->quiet)
                argv_array_push(&child->args, "--quiet");
        if (suc->prefix)
                argv_array_pushl(&child->args, "--prefix", suc->prefix, NULL);
        if (suc->recommend_shallow && sub->recommend_shallow == 1)
                argv_array_push(&child->args, "--depth=1");
        argv_array_pushl(&child->args, "--path", sub->path, NULL);
        argv_array_pushl(&child->args, "--name", sub->name, NULL);
        argv_array_pushl(&child->args, "--url", url, NULL);
        if (suc->references.nr) {
                struct string_list_item *item;
                for_each_string_list_item(item, &suc->references)
                        argv_array_pushl(&child->args, "--reference", item->string, NULL);
        }
        if (suc->dissociate)
                argv_array_push(&child->args, "--dissociate");
        if (suc->depth)
                argv_array_push(&child->args, suc->depth);

cleanup:
        strbuf_reset(&displaypath_sb);
        strbuf_reset(&sb);
        if (need_free_url)
                free((void*)url);

        return needs_cloning;
}

static int update_clone_get_next_task(struct child_process *child,
                                      struct strbuf *err,
                                      void *suc_cb,
                                      void **idx_task_cb)
{
        struct submodule_update_clone *suc = suc_cb;
        const struct cache_entry *ce;
        int index;

        for (; suc->current < suc->list.nr; suc->current++) {
                ce = suc->list.entries[suc->current];
                if (prepare_to_clone_next_submodule(ce, child, suc, err)) {
                        int *p = xmalloc(sizeof(*p));
                        *p = suc->current;
                        *idx_task_cb = p;
                        suc->current++;
                        return 1;
                }
        }

        /*
         * The loop above tried cloning each submodule once, now try the
         * stragglers again, which we can imagine as an extension of the
         * entry list.
         */
        index = suc->current - suc->list.nr;
        if (index < suc->failed_clones_nr) {
                int *p;
                ce = suc->failed_clones[index];
                if (!prepare_to_clone_next_submodule(ce, child, suc, err)) {
                        suc->current ++;
                        strbuf_addstr(err, "BUG: submodule considered for "
                                           "cloning, doesn't need cloning "
                                           "any more?\n");
                        return 0;
                }
                p = xmalloc(sizeof(*p));
                *p = suc->current;
                *idx_task_cb = p;
                suc->current ++;
                return 1;
        }

        return 0;
}

static int update_clone_start_failure(struct strbuf *err,
                                      void *suc_cb,
                                      void *idx_task_cb)
{
        struct submodule_update_clone *suc = suc_cb;
        suc->quickstop = 1;
        return 1;
}

static int update_clone_task_finished(int result,
                                      struct strbuf *err,
                                      void *suc_cb,
                                      void *idx_task_cb)
{
        const struct cache_entry *ce;
        struct submodule_update_clone *suc = suc_cb;

        int *idxP = idx_task_cb;
        int idx = *idxP;
        free(idxP);

        if (!result)
                return 0;

        if (idx < suc->list.nr) {
                ce  = suc->list.entries[idx];
                strbuf_addf(err, _("Failed to clone '%s'. Retry scheduled"),
                            ce->name);
                strbuf_addch(err, '\n');
                ALLOC_GROW(suc->failed_clones,
                           suc->failed_clones_nr + 1,
                           suc->failed_clones_alloc);
                suc->failed_clones[suc->failed_clones_nr++] = ce;
                return 0;
        } else {
                idx -= suc->list.nr;
                ce  = suc->failed_clones[idx];
                strbuf_addf(err, _("Failed to clone '%s' a second time, aborting"),
                            ce->name);
                strbuf_addch(err, '\n');
                suc->quickstop = 1;
                return 1;
        }

        return 0;
}

static int git_update_clone_config(const char *var, const char *value,
                                   void *cb)
{
        int *max_jobs = cb;
        if (!strcmp(var, "submodule.fetchjobs"))
                *max_jobs = parse_submodule_fetchjobs(var, value);
        return 0;
}

static void update_submodule(struct update_clone_data *ucd)
{
        fprintf(stdout, "dummy %s %d\t%s\n",
                oid_to_hex(&ucd->oid),
                ucd->just_cloned,
                ucd->sub->path);
}

static int update_submodules(struct submodule_update_clone *suc)
{
        int i;

        run_processes_parallel(suc->max_jobs,
                               update_clone_get_next_task,
                               update_clone_start_failure,
                               update_clone_task_finished,
                               suc);

        /*
         * We saved the output and put it out all at once now.
         * That means:
         * - the listener does not have to interleave their (checkout)
         *   work with our fetching.  The writes involved in a
         *   checkout involve more straightforward sequential I/O.
         * - the listener can avoid doing any work if fetching failed.
         */
        if (suc->quickstop)
                return 1;

        for (i = 0; i < suc->update_clone_nr; i++)
                update_submodule(&suc->update_clone[i]);

        return 0;
}

static int update_clone(int argc, const char **argv, const char *prefix)
{
        const char *update = NULL;
        struct pathspec pathspec;
        struct submodule_update_clone suc = SUBMODULE_UPDATE_CLONE_INIT;

        struct option module_update_clone_options[] = {
                OPT_STRING(0, "prefix", &prefix,
                           N_("path"),
                           N_("path into the working tree")),
                OPT_STRING(0, "recursive-prefix", &suc.recursive_prefix,
                           N_("path"),
                           N_("path into the working tree, across nested "
                              "submodule boundaries")),
                OPT_STRING(0, "update", &update,
                           N_("string"),
                           N_("rebase, merge, checkout or none")),
                OPT_STRING_LIST(0, "reference", &suc.references, N_("repo"),
                           N_("reference repository")),
                OPT_BOOL(0, "dissociate", &suc.dissociate,
                           N_("use --reference only while cloning")),
                OPT_STRING(0, "depth", &suc.depth, "<depth>",
                           N_("Create a shallow clone truncated to the "
                              "specified number of revisions")),
                OPT_INTEGER('j', "jobs", &suc.max_jobs,
                            N_("parallel jobs")),
                OPT_BOOL(0, "recommend-shallow", &suc.recommend_shallow,
                            N_("whether the initial clone should follow the shallow recommendation")),
                OPT__QUIET(&suc.quiet, N_("don't print cloning progress")),
                OPT_BOOL(0, "progress", &suc.progress,
                            N_("force cloning progress")),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper update_clone [--prefix=<path>] [<path>...]"),
                NULL
        };
        suc.prefix = prefix;

        update_clone_config_from_gitmodules(&suc.max_jobs);
        git_config(git_update_clone_config, &suc.max_jobs);

        argc = parse_options(argc, argv, prefix, module_update_clone_options,
                             git_submodule_helper_usage, 0);

        if (update)
                if (parse_submodule_update_strategy(update, &suc.update) < 0)
                        die(_("bad value for update parameter"));

        if (module_list_compute(argc, argv, prefix, &pathspec, &suc.list) < 0)
                return 1;

        if (pathspec.nr)
                suc.warn_if_uninitialized = 1;

        return update_submodules(&suc);
}

static int resolve_relative_path(int argc, const char **argv, const char *prefix)
{
        struct strbuf sb = STRBUF_INIT;
        if (argc != 3)
                die("submodule--helper relative-path takes exactly 2 arguments, got %d", argc);

        printf("%s", relative_path(argv[1], argv[2], &sb));
        strbuf_release(&sb);
        return 0;
}

static const char *remote_submodule_branch(const char *path)
{
        const struct submodule *sub;
        const char *branch = NULL;
        char *key;

        sub = submodule_from_path(the_repository, &null_oid, path);
        if (!sub)
                return NULL;

        key = xstrfmt("submodule.%s.branch", sub->name);
        if (repo_config_get_string_const(the_repository, key, &branch))
                branch = sub->branch;
        free(key);

        if (!branch)
                return "master";

        if (!strcmp(branch, ".")) {
                const char *refname = resolve_ref_unsafe("HEAD", 0, NULL, NULL);

                if (!refname)
                        die(_("No such ref: %s"), "HEAD");

                /* detached HEAD */
                if (!strcmp(refname, "HEAD"))
                        die(_("Submodule (%s) branch configured to inherit "
                              "branch from superproject, but the superproject "
                              "is not on any branch"), sub->name);

                if (!skip_prefix(refname, "refs/heads/", &refname))
                        die(_("Expecting a full ref name, got %s"), refname);
                return refname;
        }

        return branch;
}

static int resolve_remote_submodule_branch(int argc, const char **argv,
                const char *prefix)
{
        const char *ret;
        struct strbuf sb = STRBUF_INIT;
        if (argc != 2)
                die("submodule--helper remote-branch takes exactly one arguments, got %d", argc);

        ret = remote_submodule_branch(argv[1]);
        if (!ret)
                die("submodule %s doesn't exist", argv[1]);

        printf("%s", ret);
        strbuf_release(&sb);
        return 0;
}

static int push_check(int argc, const char **argv, const char *prefix)
{
        struct remote *remote;
        const char *superproject_head;
        char *head;
        int detached_head = 0;
        struct object_id head_oid;

        if (argc < 3)
                die("submodule--helper push-check requires at least 2 arguments");

        /*
         * superproject's resolved head ref.
         * if HEAD then the superproject is in a detached head state, otherwise
         * it will be the resolved head ref.
         */
        superproject_head = argv[1];
        argv++;
        argc--;
        /* Get the submodule's head ref and determine if it is detached */
        head = resolve_refdup("HEAD", 0, &head_oid, NULL);
        if (!head)
                die(_("Failed to resolve HEAD as a valid ref."));
        if (!strcmp(head, "HEAD"))
                detached_head = 1;

        /*
         * The remote must be configured.
         * This is to avoid pushing to the exact same URL as the parent.
         */
        remote = pushremote_get(argv[1]);
        if (!remote || remote->origin == REMOTE_UNCONFIGURED)
                die("remote '%s' not configured", argv[1]);

        /* Check the refspec */
        if (argc > 2) {
                int i;
                struct ref *local_refs = get_local_heads();
                struct refspec refspec = REFSPEC_INIT_PUSH;

                refspec_appendn(&refspec, argv + 2, argc - 2);

                for (i = 0; i < refspec.nr; i++) {
                        const struct refspec_item *rs = &refspec.items[i];

                        if (rs->pattern || rs->matching)
                                continue;

                        /* LHS must match a single ref */
                        switch (count_refspec_match(rs->src, local_refs, NULL)) {
                        case 1:
                                break;
                        case 0:
                                /*
                                 * If LHS matches 'HEAD' then we need to ensure
                                 * that it matches the same named branch
                                 * checked out in the superproject.
                                 */
                                if (!strcmp(rs->src, "HEAD")) {
                                        if (!detached_head &&
                                            !strcmp(head, superproject_head))
                                                break;
                                        die("HEAD does not match the named branch in the superproject");
                                }
                                /* fallthrough */
                        default:
                                die("src refspec '%s' must name a ref",
                                    rs->src);
                        }
                }
                refspec_clear(&refspec);
        }
        free(head);

        return 0;
}

static int ensure_core_worktree(int argc, const char **argv, const char *prefix)
{
        const struct submodule *sub;
        const char *path;
        char *cw;
        struct repository subrepo;

        if (argc != 2)
                BUG("submodule--helper ensure-core-worktree <path>");

        path = argv[1];

        sub = submodule_from_path(the_repository, &null_oid, path);
        if (!sub)
                BUG("We could get the submodule handle before?");

        if (repo_submodule_init(&subrepo, the_repository, path))
                die(_("could not get a repository handle for submodule '%s'"), path);

        if (!repo_config_get_string(&subrepo, "core.worktree", &cw)) {
                char *cfg_file, *abs_path;
                const char *rel_path;
                struct strbuf sb = STRBUF_INIT;

                cfg_file = repo_git_path(&subrepo, "config");

                abs_path = absolute_pathdup(path);
                rel_path = relative_path(abs_path, subrepo.gitdir, &sb);

                git_config_set_in_file(cfg_file, "core.worktree", rel_path);

                free(cfg_file);
                free(abs_path);
                strbuf_release(&sb);
        }

        return 0;
}

static int absorb_git_dirs(int argc, const char **argv, const char *prefix)
{
        int i;
        struct pathspec pathspec;
        struct module_list list = MODULE_LIST_INIT;
        unsigned flags = ABSORB_GITDIR_RECURSE_SUBMODULES;

        struct option embed_gitdir_options[] = {
                OPT_STRING(0, "prefix", &prefix,
                           N_("path"),
                           N_("path into the working tree")),
                OPT_BIT(0, "--recursive", &flags, N_("recurse into submodules"),
                        ABSORB_GITDIR_RECURSE_SUBMODULES),
                OPT_END()
        };

        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper embed-git-dir [<path>...]"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, embed_gitdir_options,
                             git_submodule_helper_usage, 0);

        if (module_list_compute(argc, argv, prefix, &pathspec, &list) < 0)
                return 1;

        for (i = 0; i < list.nr; i++)
                absorb_git_dir_into_superproject(prefix,
                                list.entries[i]->name, flags);

        return 0;
}

static int is_active(int argc, const char **argv, const char *prefix)
{
        if (argc != 2)
                die("submodule--helper is-active takes exactly 1 argument");

        return !is_submodule_active(the_repository, argv[1]);
}

/*
 * Exit non-zero if any of the submodule names given on the command line is
 * invalid. If no names are given, filter stdin to print only valid names
 * (which is primarily intended for testing).
 */
static int check_name(int argc, const char **argv, const char *prefix)
{
        if (argc > 1) {
                while (*++argv) {
                        if (check_submodule_name(*argv) < 0)
                                return 1;
                }
        } else {
                struct strbuf buf = STRBUF_INIT;
                while (strbuf_getline(&buf, stdin) != EOF) {
                        if (!check_submodule_name(buf.buf))
                                printf("%s\n", buf.buf);
                }
                strbuf_release(&buf);
        }
        return 0;
}

static int module_config(int argc, const char **argv, const char *prefix)
{
        enum {
                CHECK_WRITEABLE = 1
        } command = 0;

        struct option module_config_options[] = {
                OPT_CMDMODE(0, "check-writeable", &command,
                            N_("check if it is safe to write to the .gitmodules file"),
                            CHECK_WRITEABLE),
                OPT_END()
        };
        const char *const git_submodule_helper_usage[] = {
                N_("git submodule--helper config name [value]"),
                N_("git submodule--helper config --check-writeable"),
                NULL
        };

        argc = parse_options(argc, argv, prefix, module_config_options,
                             git_submodule_helper_usage, PARSE_OPT_KEEP_ARGV0);

        if (argc == 1 && command == CHECK_WRITEABLE)
                return is_writing_gitmodules_ok() ? 0 : -1;

        /* Equivalent to ACTION_GET in builtin/config.c */
        if (argc == 2)
                return print_config_from_gitmodules(the_repository, argv[1]);

        /* Equivalent to ACTION_SET in builtin/config.c */
        if (argc == 3) {
                if (!is_writing_gitmodules_ok())
                        die(_("please make sure that the .gitmodules file is in the working tree"));

                return config_set_in_gitmodules_file_gently(argv[1], argv[2]);
        }

        usage_with_options(git_submodule_helper_usage, module_config_options);
}

#define SUPPORT_SUPER_PREFIX (1<<0)

struct cmd_struct {
        const char *cmd;
        int (*fn)(int, const char **, const char *);
        unsigned option;
};

static struct cmd_struct commands[] = {
        {"list", module_list, 0},
        {"name", module_name, 0},
        {"clone", module_clone, 0},
        {"update-module-mode", module_update_module_mode, 0},
        {"update-clone", update_clone, 0},
        {"ensure-core-worktree", ensure_core_worktree, 0},
        {"relative-path", resolve_relative_path, 0},
        {"resolve-relative-url", resolve_relative_url, 0},
        {"resolve-relative-url-test", resolve_relative_url_test, 0},
        {"foreach", module_foreach, SUPPORT_SUPER_PREFIX},
        {"init", module_init, SUPPORT_SUPER_PREFIX},
        {"status", module_status, SUPPORT_SUPER_PREFIX},
        {"print-default-remote", print_default_remote, 0},
        {"sync", module_sync, SUPPORT_SUPER_PREFIX},
        {"deinit", module_deinit, 0},
        {"remote-branch", resolve_remote_submodule_branch, 0},
        {"push-check", push_check, 0},
        {"absorb-git-dirs", absorb_git_dirs, SUPPORT_SUPER_PREFIX},
        {"is-active", is_active, 0},
        {"check-name", check_name, 0},
        {"config", module_config, 0},
};

int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
{
        int i;
        if (argc < 2 || !strcmp(argv[1], "-h"))
                usage("git submodule--helper <command>");

        for (i = 0; i < ARRAY_SIZE(commands); i++) {
                if (!strcmp(argv[1], commands[i].cmd)) {
                        if (get_super_prefix() &&
                            !(commands[i].option & SUPPORT_SUPER_PREFIX))
                                die(_("%s doesn't support --super-prefix"),
                                    commands[i].cmd);
                        return commands[i].fn(argc - 1, argv + 1, prefix);
                }
        }

        die(_("'%s' is not a valid submodule--helper "
              "subcommand"), argv[1]);
}