The eighteenth batch

[git.git] / submodule-config.c

#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"
#include "dir.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "path.h"
#include "repository.h"
#include "config.h"
#include "submodule-config.h"
#include "submodule.h"
#include "strbuf.h"
#include "object-name.h"
#include "object-store-ll.h"
#include "parse-options.h"
#include "thread-utils.h"
#include "tree-walk.h"
#include "url.h"
#include "urlmatch.h"

/*
 * submodule cache lookup structure
 * There is one shared set of 'struct submodule' entries which can be
 * looked up by their sha1 blob id of the .gitmodules file and either
 * using path or name as key.
 * for_path stores submodule entries with path as key
 * for_name stores submodule entries with name as key
 */
struct submodule_cache {
        struct hashmap for_path;
        struct hashmap for_name;
        unsigned initialized:1;
        unsigned gitmodules_read:1;
};

/*
 * thin wrapper struct needed to insert 'struct submodule' entries to
 * the hashmap
 */
struct submodule_entry {
        struct hashmap_entry ent;
        struct submodule *config;
};

enum lookup_type {
        lookup_name,
        lookup_path
};

static int config_path_cmp(const void *cmp_data UNUSED,
                           const struct hashmap_entry *eptr,
                           const struct hashmap_entry *entry_or_key,
                           const void *keydata UNUSED)
{
        const struct submodule_entry *a, *b;

        a = container_of(eptr, const struct submodule_entry, ent);
        b = container_of(entry_or_key, const struct submodule_entry, ent);

        return strcmp(a->config->path, b->config->path) ||
               !oideq(&a->config->gitmodules_oid, &b->config->gitmodules_oid);
}

static int config_name_cmp(const void *cmp_data UNUSED,
                           const struct hashmap_entry *eptr,
                           const struct hashmap_entry *entry_or_key,
                           const void *keydata UNUSED)
{
        const struct submodule_entry *a, *b;

        a = container_of(eptr, const struct submodule_entry, ent);
        b = container_of(entry_or_key, const struct submodule_entry, ent);

        return strcmp(a->config->name, b->config->name) ||
               !oideq(&a->config->gitmodules_oid, &b->config->gitmodules_oid);
}

static struct submodule_cache *submodule_cache_alloc(void)
{
        return xcalloc(1, sizeof(struct submodule_cache));
}

static void submodule_cache_init(struct submodule_cache *cache)
{
        hashmap_init(&cache->for_path, config_path_cmp, NULL, 0);
        hashmap_init(&cache->for_name, config_name_cmp, NULL, 0);
        cache->initialized = 1;
}

static void free_one_config(struct submodule_entry *entry)
{
        free((void *) entry->config->path);
        free((void *) entry->config->name);
        free((void *) entry->config->branch);
        free((void *) entry->config->url);
        free((void *) entry->config->ignore);
        free((void *) entry->config->update_strategy.command);
        free(entry->config);
}

static void submodule_cache_clear(struct submodule_cache *cache)
{
        struct hashmap_iter iter;
        struct submodule_entry *entry;

        if (!cache->initialized)
                return;

        /*
         * We iterate over the name hash here to be symmetric with the
         * allocation of struct submodule entries. Each is allocated by
         * their .gitmodules blob sha1 and submodule name.
         */
        hashmap_for_each_entry(&cache->for_name, &iter, entry,
                                ent /* member name */)
                free_one_config(entry);

        hashmap_clear_and_free(&cache->for_path, struct submodule_entry, ent);
        hashmap_clear_and_free(&cache->for_name, struct submodule_entry, ent);
        cache->initialized = 0;
        cache->gitmodules_read = 0;
}

void submodule_cache_free(struct submodule_cache *cache)
{
        submodule_cache_clear(cache);
        free(cache);
}

static unsigned int hash_oid_string(const struct object_id *oid,
                                    const char *string)
{
        return memhash(oid->hash, the_hash_algo->rawsz) + strhash(string);
}

static void cache_put_path(struct submodule_cache *cache,
                           struct submodule *submodule)
{
        unsigned int hash = hash_oid_string(&submodule->gitmodules_oid,
                                            submodule->path);
        struct submodule_entry *e = xmalloc(sizeof(*e));
        hashmap_entry_init(&e->ent, hash);
        e->config = submodule;
        hashmap_put(&cache->for_path, &e->ent);
}

static void cache_remove_path(struct submodule_cache *cache,
                              struct submodule *submodule)
{
        unsigned int hash = hash_oid_string(&submodule->gitmodules_oid,
                                            submodule->path);
        struct submodule_entry e;
        struct submodule_entry *removed;
        hashmap_entry_init(&e.ent, hash);
        e.config = submodule;
        removed = hashmap_remove_entry(&cache->for_path, &e, ent, NULL);
        free(removed);
}

static void cache_add(struct submodule_cache *cache,
                      struct submodule *submodule)
{
        unsigned int hash = hash_oid_string(&submodule->gitmodules_oid,
                                            submodule->name);
        struct submodule_entry *e = xmalloc(sizeof(*e));
        hashmap_entry_init(&e->ent, hash);
        e->config = submodule;
        hashmap_add(&cache->for_name, &e->ent);
}

static const struct submodule *cache_lookup_path(struct submodule_cache *cache,
                const struct object_id *gitmodules_oid, const char *path)
{
        struct submodule_entry *entry;
        unsigned int hash = hash_oid_string(gitmodules_oid, path);
        struct submodule_entry key;
        struct submodule key_config;

        oidcpy(&key_config.gitmodules_oid, gitmodules_oid);
        key_config.path = path;

        hashmap_entry_init(&key.ent, hash);
        key.config = &key_config;

        entry = hashmap_get_entry(&cache->for_path, &key, ent, NULL);
        if (entry)
                return entry->config;
        return NULL;
}

static struct submodule *cache_lookup_name(struct submodule_cache *cache,
                const struct object_id *gitmodules_oid, const char *name)
{
        struct submodule_entry *entry;
        unsigned int hash = hash_oid_string(gitmodules_oid, name);
        struct submodule_entry key;
        struct submodule key_config;

        oidcpy(&key_config.gitmodules_oid, gitmodules_oid);
        key_config.name = name;

        hashmap_entry_init(&key.ent, hash);
        key.config = &key_config;

        entry = hashmap_get_entry(&cache->for_name, &key, ent, NULL);
        if (entry)
                return entry->config;
        return NULL;
}

int check_submodule_name(const char *name)
{
        /* Disallow empty names */
        if (!*name)
                return -1;

        /*
         * Look for '..' as a path component. Check is_xplatform_dir_sep() as
         * separators rather than is_dir_sep(), because we want the name rules
         * to be consistent across platforms.
         */
        goto in_component; /* always start inside component */
        while (*name) {
                char c = *name++;
                if (is_xplatform_dir_sep(c)) {
in_component:
                        if (name[0] == '.' && name[1] == '.' &&
                            (!name[2] || is_xplatform_dir_sep(name[2])))
                                return -1;
                }
        }

        return 0;
}

static int starts_with_dot_slash(const char *const path)
{
        return path_match_flags(path, PATH_MATCH_STARTS_WITH_DOT_SLASH |
                                PATH_MATCH_XPLATFORM);
}

static int starts_with_dot_dot_slash(const char *const path)
{
        return path_match_flags(path, PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH |
                                PATH_MATCH_XPLATFORM);
}

static int submodule_url_is_relative(const char *url)
{
        return starts_with_dot_slash(url) || starts_with_dot_dot_slash(url);
}

/*
 * Count directory components that a relative submodule URL should chop
 * from the remote_url it is to be resolved against.
 *
 * In other words, this counts "../" components at the start of a
 * submodule URL.
 *
 * Returns the number of directory components to chop and writes a
 * pointer to the next character of url after all leading "./" and
 * "../" components to out.
 */
static int count_leading_dotdots(const char *url, const char **out)
{
        int result = 0;
        while (1) {
                if (starts_with_dot_dot_slash(url)) {
                        result++;
                        url += strlen("../");
                        continue;
                }
                if (starts_with_dot_slash(url)) {
                        url += strlen("./");
                        continue;
                }
                *out = url;
                return result;
        }
}
/*
 * Check whether a transport is implemented by git-remote-curl.
 *
 * If it is, returns 1 and writes the URL that would be passed to
 * git-remote-curl to the "out" parameter.
 *
 * Otherwise, returns 0 and leaves "out" untouched.
 *
 * Examples:
 *   http::https://example.com/repo.git -> 1, https://example.com/repo.git
 *   https://example.com/repo.git -> 1, https://example.com/repo.git
 *   git://example.com/repo.git -> 0
 *
 * This is for use in checking for previously exploitable bugs that
 * required a submodule URL to be passed to git-remote-curl.
 */
static int url_to_curl_url(const char *url, const char **out)
{
        /*
         * We don't need to check for case-aliases, "http.exe", and so
         * on because in the default configuration, is_transport_allowed
         * prevents URLs with those schemes from being cloned
         * automatically.
         */
        if (skip_prefix(url, "http::", out) ||
            skip_prefix(url, "https::", out) ||
            skip_prefix(url, "ftp::", out) ||
            skip_prefix(url, "ftps::", out))
                return 1;
        if (starts_with(url, "http://") ||
            starts_with(url, "https://") ||
            starts_with(url, "ftp://") ||
            starts_with(url, "ftps://")) {
                *out = url;
                return 1;
        }
        return 0;
}

int check_submodule_url(const char *url)
{
        const char *curl_url;

        if (looks_like_command_line_option(url))
                return -1;

        if (submodule_url_is_relative(url) || starts_with(url, "git://")) {
                char *decoded;
                const char *next;
                int has_nl;

                /*
                 * This could be appended to an http URL and url-decoded;
                 * check for malicious characters.
                 */
                decoded = url_decode(url);
                has_nl = !!strchr(decoded, '\n');

                free(decoded);
                if (has_nl)
                        return -1;

                /*
                 * URLs which escape their root via "../" can overwrite
                 * the host field and previous components, resolving to
                 * URLs like https::example.com/submodule.git and
                 * https:///example.com/submodule.git that were
                 * susceptible to CVE-2020-11008.
                 */
                if (count_leading_dotdots(url, &next) > 0 &&
                    (*next == ':' || *next == '/'))
                        return -1;
        }

        else if (url_to_curl_url(url, &curl_url)) {
                int ret = 0;
                char *normalized = url_normalize(curl_url, NULL);
                if (normalized) {
                        char *decoded = url_decode(normalized);
                        if (strchr(decoded, '\n'))
                                ret = -1;
                        free(normalized);
                        free(decoded);
                } else {
                        ret = -1;
                }

                return ret;
        }

        return 0;
}

static int name_and_item_from_var(const char *var, struct strbuf *name,
                                  struct strbuf *item)
{
        const char *subsection, *key;
        size_t subsection_len;
        int parse;
        parse = parse_config_key(var, "submodule", &subsection,
                        &subsection_len, &key);
        if (parse < 0 || !subsection)
                return 0;

        strbuf_add(name, subsection, subsection_len);
        if (check_submodule_name(name->buf) < 0) {
                warning(_("ignoring suspicious submodule name: %s"), name->buf);
                strbuf_release(name);
                return 0;
        }

        strbuf_addstr(item, key);

        return 1;
}

static struct submodule *lookup_or_create_by_name(struct submodule_cache *cache,
                const struct object_id *gitmodules_oid, const char *name)
{
        struct submodule *submodule;
        struct strbuf name_buf = STRBUF_INIT;

        submodule = cache_lookup_name(cache, gitmodules_oid, name);
        if (submodule)
                return submodule;

        submodule = xmalloc(sizeof(*submodule));

        strbuf_addstr(&name_buf, name);
        submodule->name = strbuf_detach(&name_buf, NULL);

        submodule->path = NULL;
        submodule->url = NULL;
        submodule->update_strategy.type = SM_UPDATE_UNSPECIFIED;
        submodule->update_strategy.command = NULL;
        submodule->fetch_recurse = RECURSE_SUBMODULES_NONE;
        submodule->ignore = NULL;
        submodule->branch = NULL;
        submodule->recommend_shallow = -1;

        oidcpy(&submodule->gitmodules_oid, gitmodules_oid);

        cache_add(cache, submodule);

        return submodule;
}

static int parse_fetch_recurse(const char *opt, const char *arg,
                               int die_on_error)
{
        switch (git_parse_maybe_bool(arg)) {
        case 1:
                return RECURSE_SUBMODULES_ON;
        case 0:
                return RECURSE_SUBMODULES_OFF;
        default:
                if (!strcmp(arg, "on-demand"))
                        return RECURSE_SUBMODULES_ON_DEMAND;
                /*
                 * Please update $__git_fetch_recurse_submodules in
                 * git-completion.bash when you add new options.
                 */
                if (die_on_error)
                        die("bad %s argument: %s", opt, arg);
                else
                        return RECURSE_SUBMODULES_ERROR;
        }
}

int parse_submodule_fetchjobs(const char *var, const char *value,
                              const struct key_value_info *kvi)
{
        int fetchjobs = git_config_int(var, value, kvi);
        if (fetchjobs < 0)
                die(_("negative values not allowed for submodule.fetchJobs"));
        if (!fetchjobs)
                fetchjobs = online_cpus();
        return fetchjobs;
}

int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
{
        return parse_fetch_recurse(opt, arg, 1);
}

int option_fetch_parse_recurse_submodules(const struct option *opt,
                                          const char *arg, int unset)
{
        int *v;

        if (!opt->value)
                return -1;

        v = opt->value;

        if (unset) {
                *v = RECURSE_SUBMODULES_OFF;
        } else {
                if (arg)
                        *v = parse_fetch_recurse_submodules_arg(opt->long_name, arg);
                else
                        *v = RECURSE_SUBMODULES_ON;
        }
        return 0;
}

static int parse_update_recurse(const char *opt, const char *arg,
                                int die_on_error)
{
        switch (git_parse_maybe_bool(arg)) {
        case 1:
                return RECURSE_SUBMODULES_ON;
        case 0:
                return RECURSE_SUBMODULES_OFF;
        default:
                if (die_on_error)
                        die("bad %s argument: %s", opt, arg);
                return RECURSE_SUBMODULES_ERROR;
        }
}

int parse_update_recurse_submodules_arg(const char *opt, const char *arg)
{
        return parse_update_recurse(opt, arg, 1);
}

static int parse_push_recurse(const char *opt, const char *arg,
                               int die_on_error)
{
        switch (git_parse_maybe_bool(arg)) {
        case 1:
                /* There's no simple "on" value when pushing */
                if (die_on_error)
                        die("bad %s argument: %s", opt, arg);
                else
                        return RECURSE_SUBMODULES_ERROR;
        case 0:
                return RECURSE_SUBMODULES_OFF;
        default:
                if (!strcmp(arg, "on-demand"))
                        return RECURSE_SUBMODULES_ON_DEMAND;
                else if (!strcmp(arg, "check"))
                        return RECURSE_SUBMODULES_CHECK;
                else if (!strcmp(arg, "only"))
                        return RECURSE_SUBMODULES_ONLY;
                /*
                 * Please update $__git_push_recurse_submodules in
                 * git-completion.bash when you add new modes.
                 */
                else if (die_on_error)
                        die("bad %s argument: %s", opt, arg);
                else
                        return RECURSE_SUBMODULES_ERROR;
        }
}

int parse_push_recurse_submodules_arg(const char *opt, const char *arg)
{
        return parse_push_recurse(opt, arg, 1);
}

static void warn_multiple_config(const struct object_id *treeish_name,
                                 const char *name, const char *option)
{
        const char *commit_string = "WORKTREE";
        if (treeish_name)
                commit_string = oid_to_hex(treeish_name);
        warning("%s:.gitmodules, multiple configurations found for "
                        "'submodule.%s.%s'. Skipping second one!",
                        commit_string, name, option);
}

static void warn_command_line_option(const char *var, const char *value)
{
        warning(_("ignoring '%s' which may be interpreted as"
                  " a command-line option: %s"), var, value);
}

struct parse_config_parameter {
        struct submodule_cache *cache;
        const struct object_id *treeish_name;
        const struct object_id *gitmodules_oid;
        int overwrite;
};

/*
 * Parse a config item from .gitmodules.
 *
 * This does not handle submodule-related configuration from the main
 * config store (.git/config, etc).  Callers are responsible for
 * checking for overrides in the main config store when appropriate.
 */
static int parse_config(const char *var, const char *value,
                        const struct config_context *ctx UNUSED, void *data)
{
        struct parse_config_parameter *me = data;
        struct submodule *submodule;
        struct strbuf name = STRBUF_INIT, item = STRBUF_INIT;
        int ret = 0;

        /* this also ensures that we only parse submodule entries */
        if (!name_and_item_from_var(var, &name, &item))
                return 0;

        submodule = lookup_or_create_by_name(me->cache,
                                             me->gitmodules_oid,
                                             name.buf);

        if (!strcmp(item.buf, "path")) {
                if (!value)
                        ret = config_error_nonbool(var);
                else if (looks_like_command_line_option(value))
                        warn_command_line_option(var, value);
                else if (!me->overwrite && submodule->path)
                        warn_multiple_config(me->treeish_name, submodule->name,
                                        "path");
                else {
                        if (submodule->path)
                                cache_remove_path(me->cache, submodule);
                        free((void *) submodule->path);
                        submodule->path = xstrdup(value);
                        cache_put_path(me->cache, submodule);
                }
        } else if (!strcmp(item.buf, "fetchrecursesubmodules")) {
                /* when parsing worktree configurations we can die early */
                int die_on_error = is_null_oid(me->gitmodules_oid);
                if (!me->overwrite &&
                    submodule->fetch_recurse != RECURSE_SUBMODULES_NONE)
                        warn_multiple_config(me->treeish_name, submodule->name,
                                        "fetchrecursesubmodules");
                else
                        submodule->fetch_recurse = parse_fetch_recurse(
                                                                var, value,
                                                                die_on_error);
        } else if (!strcmp(item.buf, "ignore")) {
                if (!value)
                        ret = config_error_nonbool(var);
                else if (!me->overwrite && submodule->ignore)
                        warn_multiple_config(me->treeish_name, submodule->name,
                                        "ignore");
                else if (strcmp(value, "untracked") &&
                         strcmp(value, "dirty") &&
                         strcmp(value, "all") &&
                         strcmp(value, "none"))
                        warning("Invalid parameter '%s' for config option "
                                        "'submodule.%s.ignore'", value, name.buf);
                else {
                        free((void *) submodule->ignore);
                        submodule->ignore = xstrdup(value);
                }
        } else if (!strcmp(item.buf, "url")) {
                if (!value) {
                        ret = config_error_nonbool(var);
                } else if (looks_like_command_line_option(value)) {
                        warn_command_line_option(var, value);
                } else if (!me->overwrite && submodule->url) {
                        warn_multiple_config(me->treeish_name, submodule->name,
                                        "url");
                } else {
                        free((void *) submodule->url);
                        submodule->url = xstrdup(value);
                }
        } else if (!strcmp(item.buf, "update")) {
                if (!value)
                        ret = config_error_nonbool(var);
                else if (!me->overwrite &&
                         submodule->update_strategy.type != SM_UPDATE_UNSPECIFIED)
                        warn_multiple_config(me->treeish_name, submodule->name,
                                             "update");
                else if (parse_submodule_update_strategy(value,
                         &submodule->update_strategy) < 0 ||
                         submodule->update_strategy.type == SM_UPDATE_COMMAND)
                        die(_("invalid value for '%s'"), var);
        } else if (!strcmp(item.buf, "shallow")) {
                if (!me->overwrite && submodule->recommend_shallow != -1)
                        warn_multiple_config(me->treeish_name, submodule->name,
                                             "shallow");
                else
                        submodule->recommend_shallow =
                                git_config_bool(var, value);
        } else if (!strcmp(item.buf, "branch")) {
                if (!value)
                        ret = config_error_nonbool(var);
                else if (!me->overwrite && submodule->branch)
                        warn_multiple_config(me->treeish_name, submodule->name,
                                             "branch");
                else {
                        free((void *)submodule->branch);
                        submodule->branch = xstrdup(value);
                }
        }

        strbuf_release(&name);
        strbuf_release(&item);

        return ret;
}

static int gitmodule_oid_from_commit(const struct object_id *treeish_name,
                                     struct object_id *gitmodules_oid,
                                     struct strbuf *rev)
{
        int ret = 0;

        if (is_null_oid(treeish_name)) {
                oidclr(gitmodules_oid, the_repository->hash_algo);
                return 1;
        }

        strbuf_addf(rev, "%s:.gitmodules", oid_to_hex(treeish_name));
        if (repo_get_oid(the_repository, rev->buf, gitmodules_oid) >= 0)
                ret = 1;

        return ret;
}

/* This does a lookup of a submodule configuration by name or by path
 * (key) with on-demand reading of the appropriate .gitmodules from
 * revisions.
 */
static const struct submodule *config_from(struct submodule_cache *cache,
                const struct object_id *treeish_name, const char *key,
                enum lookup_type lookup_type)
{
        struct strbuf rev = STRBUF_INIT;
        unsigned long config_size;
        char *config = NULL;
        struct object_id oid;
        enum object_type type;
        const struct submodule *submodule = NULL;
        struct parse_config_parameter parameter;

        /*
         * If any parameter except the cache is a NULL pointer just
         * return the first submodule. Can be used to check whether
         * there are any submodules parsed.
         */
        if (!treeish_name || !key) {
                struct hashmap_iter iter;
                struct submodule_entry *entry;

                entry = hashmap_iter_first_entry(&cache->for_name, &iter,
                                                struct submodule_entry,
                                                ent /* member name */);
                if (!entry)
                        return NULL;
                return entry->config;
        }

        if (!gitmodule_oid_from_commit(treeish_name, &oid, &rev))
                goto out;

        switch (lookup_type) {
        case lookup_name:
                submodule = cache_lookup_name(cache, &oid, key);
                break;
        case lookup_path:
                submodule = cache_lookup_path(cache, &oid, key);
                break;
        }
        if (submodule)
                goto out;

        config = repo_read_object_file(the_repository, &oid, &type,
                                       &config_size);
        if (!config || type != OBJ_BLOB)
                goto out;

        /* fill the submodule config into the cache */
        parameter.cache = cache;
        parameter.treeish_name = treeish_name;
        parameter.gitmodules_oid = &oid;
        parameter.overwrite = 0;
        git_config_from_mem(parse_config, CONFIG_ORIGIN_SUBMODULE_BLOB, rev.buf,
                            config, config_size, &parameter, CONFIG_SCOPE_UNKNOWN, NULL);
        strbuf_release(&rev);
        free(config);

        switch (lookup_type) {
        case lookup_name:
                return cache_lookup_name(cache, &oid, key);
        case lookup_path:
                return cache_lookup_path(cache, &oid, key);
        default:
                return NULL;
        }

out:
        strbuf_release(&rev);
        free(config);
        return submodule;
}

static void submodule_cache_check_init(struct repository *repo)
{
        if (repo->submodule_cache && repo->submodule_cache->initialized)
                return;

        if (!repo->submodule_cache)
                repo->submodule_cache = submodule_cache_alloc();

        submodule_cache_init(repo->submodule_cache);
}

/*
 * Note: This function is private for a reason, the '.gitmodules' file should
 * not be used as a mechanism to retrieve arbitrary configuration stored in
 * the repository.
 *
 * Runs the provided config function on the '.gitmodules' file found in the
 * working directory.
 */
static void config_from_gitmodules(config_fn_t fn, struct repository *repo, void *data)
{
        if (repo->worktree) {
                struct git_config_source config_source = {
                        0, .scope = CONFIG_SCOPE_SUBMODULE
                };
                const struct config_options opts = { 0 };
                struct object_id oid;
                char *file;
                char *oidstr = NULL;

                file = repo_worktree_path(repo, GITMODULES_FILE);
                if (file_exists(file)) {
                        config_source.file = file;
                } else if (repo_get_oid(repo, GITMODULES_INDEX, &oid) >= 0 ||
                           repo_get_oid(repo, GITMODULES_HEAD, &oid) >= 0) {
                        config_source.blob = oidstr = xstrdup(oid_to_hex(&oid));
                        if (repo != the_repository)
                                add_submodule_odb_by_path(repo->objects->odb->path);
                } else {
                        goto out;
                }

                config_with_options(fn, data, &config_source, repo, &opts);

out:
                free(oidstr);
                free(file);
        }
}

static int gitmodules_cb(const char *var, const char *value,
                         const struct config_context *ctx, void *data)
{
        struct repository *repo = data;
        struct parse_config_parameter parameter;

        parameter.cache = repo->submodule_cache;
        parameter.treeish_name = NULL;
        parameter.gitmodules_oid = null_oid();
        parameter.overwrite = 1;

        return parse_config(var, value, ctx, &parameter);
}

void repo_read_gitmodules(struct repository *repo, int skip_if_read)
{
        submodule_cache_check_init(repo);

        if (repo->submodule_cache->gitmodules_read && skip_if_read)
                return;

        if (repo_read_index(repo) < 0)
                return;

        if (!is_gitmodules_unmerged(repo->index))
                config_from_gitmodules(gitmodules_cb, repo, repo);

        repo->submodule_cache->gitmodules_read = 1;
}

void gitmodules_config_oid(const struct object_id *commit_oid)
{
        struct strbuf rev = STRBUF_INIT;
        struct object_id oid;

        submodule_cache_check_init(the_repository);

        if (gitmodule_oid_from_commit(commit_oid, &oid, &rev)) {
                git_config_from_blob_oid(gitmodules_cb, rev.buf,
                                         the_repository, &oid, the_repository,
                                         CONFIG_SCOPE_UNKNOWN);
        }
        strbuf_release(&rev);

        the_repository->submodule_cache->gitmodules_read = 1;
}

const struct submodule *submodule_from_name(struct repository *r,
                                            const struct object_id *treeish_name,
                const char *name)
{
        repo_read_gitmodules(r, 1);
        return config_from(r->submodule_cache, treeish_name, name, lookup_name);
}

const struct submodule *submodule_from_path(struct repository *r,
                                            const struct object_id *treeish_name,
                const char *path)
{
        repo_read_gitmodules(r, 1);
        return config_from(r->submodule_cache, treeish_name, path, lookup_path);
}

/**
 * Used internally by submodules_of_tree(). Recurses into 'treeish_name'
 * and appends submodule entries to 'out'. The submodule_cache expects
 * a root-level treeish_name and paths, so keep track of these values
 * with 'root_tree' and 'prefix'.
 */
static void traverse_tree_submodules(struct repository *r,
                                     const struct object_id *root_tree,
                                     char *prefix,
                                     const struct object_id *treeish_name,
                                     struct submodule_entry_list *out)
{
        struct tree_desc tree;
        struct submodule_tree_entry *st_entry;
        struct name_entry name_entry;
        char *tree_path = NULL;

        fill_tree_descriptor(r, &tree, treeish_name);
        while (tree_entry(&tree, &name_entry)) {
                if (prefix)
                        tree_path =
                                mkpathdup("%s/%s", prefix, name_entry.path);
                else
                        tree_path = xstrdup(name_entry.path);

                if (S_ISGITLINK(name_entry.mode) &&
                    is_tree_submodule_active(r, root_tree, tree_path)) {
                        ALLOC_GROW(out->entries, out->entry_nr + 1,
                                   out->entry_alloc);
                        st_entry = &out->entries[out->entry_nr++];

                        st_entry->name_entry = xmalloc(sizeof(*st_entry->name_entry));
                        *st_entry->name_entry = name_entry;
                        st_entry->submodule =
                                submodule_from_path(r, root_tree, tree_path);
                        st_entry->repo = xmalloc(sizeof(*st_entry->repo));
                        if (repo_submodule_init(st_entry->repo, r, tree_path,
                                                root_tree))
                                FREE_AND_NULL(st_entry->repo);

                } else if (S_ISDIR(name_entry.mode))
                        traverse_tree_submodules(r, root_tree, tree_path,
                                                 &name_entry.oid, out);
                free(tree_path);
        }
}

void submodules_of_tree(struct repository *r,
                        const struct object_id *treeish_name,
                        struct submodule_entry_list *out)
{
        CALLOC_ARRAY(out->entries, 0);
        out->entry_nr = 0;
        out->entry_alloc = 0;

        traverse_tree_submodules(r, treeish_name, NULL, treeish_name, out);
}

void submodule_free(struct repository *r)
{
        if (r->submodule_cache)
                submodule_cache_clear(r->submodule_cache);
}

static int config_print_callback(const char *var, const char *value,
                                 const struct config_context *ctx UNUSED,
                                 void *cb_data)
{
        char *wanted_key = cb_data;

        if (!strcmp(wanted_key, var))
                printf("%s\n", value);

        return 0;
}

int print_config_from_gitmodules(struct repository *repo, const char *key)
{
        int ret;
        char *store_key;

        ret = git_config_parse_key(key, &store_key, NULL);
        if (ret < 0)
                return CONFIG_INVALID_KEY;

        config_from_gitmodules(config_print_callback, repo, store_key);

        free(store_key);
        return 0;
}

int config_set_in_gitmodules_file_gently(const char *key, const char *value)
{
        int ret;

        ret = git_config_set_in_file_gently(GITMODULES_FILE, key, NULL, value);
        if (ret < 0)
                /* Maybe the user already did that, don't error out here */
                warning(_("Could not update .gitmodules entry %s"), key);

        return ret;
}

struct fetch_config {
        int *max_children;
        int *recurse_submodules;
};

static int gitmodules_fetch_config(const char *var, const char *value,
                                   const struct config_context *ctx,
                                   void *cb)
{
        struct fetch_config *config = cb;
        if (!strcmp(var, "submodule.fetchjobs")) {
                if (config->max_children)
                        *(config->max_children) =
                                parse_submodule_fetchjobs(var, value, ctx->kvi);
                return 0;
        } else if (!strcmp(var, "fetch.recursesubmodules")) {
                if (config->recurse_submodules)
                        *(config->recurse_submodules) =
                                parse_fetch_recurse_submodules_arg(var, value);
                return 0;
        }

        return 0;
}

void fetch_config_from_gitmodules(int *max_children, int *recurse_submodules)
{
        struct fetch_config config = {
                .max_children = max_children,
                .recurse_submodules = recurse_submodules
        };
        config_from_gitmodules(gitmodules_fetch_config, the_repository, &config);
}

static int gitmodules_update_clone_config(const char *var, const char *value,
                                          const struct config_context *ctx,
                                          void *cb)
{
        int *max_jobs = cb;
        if (!strcmp(var, "submodule.fetchjobs"))
                *max_jobs = parse_submodule_fetchjobs(var, value, ctx->kvi);
        return 0;
}

void update_clone_config_from_gitmodules(int *max_jobs)
{
        config_from_gitmodules(gitmodules_update_clone_config, the_repository, &max_jobs);
}