/*
 * "git fetch"
 */
#include "cache.h"
#include "refs.h"
#include "commit.h"
#include "builtin.h"
#include "string-list.h"
#include "remote.h"
#include "transport.h"
#include "run-command.h"
#include "parse-options.h"
#include "sigchain.h"
#include "transport.h"
#include "submodule.h"

static const char * const builtin_fetch_usage[] = {
        "git fetch [<options>] [<repository> [<refspec>...]]",
        "git fetch [<options>] <group>",
        "git fetch --multiple [<options>] [(<repository> | <group>)...]",
        "git fetch --all [<options>]",
        NULL
};

enum {
        TAGS_UNSET = 0,
        TAGS_DEFAULT = 1,
        TAGS_SET = 2
};

static int all, append, dry_run, force, keep, multiple, prune, update_head_ok, verbosity;
static int progress, recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
static int tags = TAGS_DEFAULT;
static const char *depth;
static const char *upload_pack;
static struct strbuf default_rla = STRBUF_INIT;
static struct transport *transport;
static const char *submodule_prefix = "";
static const char *recurse_submodules_default;

static int option_parse_recurse_submodules(const struct option *opt,
                                   const char *arg, int unset)
{
        if (unset) {
                recurse_submodules = RECURSE_SUBMODULES_OFF;
        } else {
                if (arg)
                        recurse_submodules = parse_fetch_recurse_submodules_arg(opt->long_name, arg);
                else
                        recurse_submodules = RECURSE_SUBMODULES_ON;
        }
        return 0;
}

static struct option builtin_fetch_options[] = {
        OPT__VERBOSITY(&verbosity),
        OPT_BOOLEAN(0, "all", &all,
                    "fetch from all remotes"),
        OPT_BOOLEAN('a', "append", &append,
                    "append to .git/FETCH_HEAD instead of overwriting"),
        OPT_STRING(0, "upload-pack", &upload_pack, "path",
                   "path to upload pack on remote end"),
        OPT__FORCE(&force, "force overwrite of local branch"),
        OPT_BOOLEAN('m', "multiple", &multiple,
                    "fetch from multiple remotes"),
        OPT_SET_INT('t', "tags", &tags,
                    "fetch all tags and associated objects", TAGS_SET),
        OPT_SET_INT('n', NULL, &tags,
                    "do not fetch all tags (--no-tags)", TAGS_UNSET),
        OPT_BOOLEAN('p', "prune", &prune,
                    "prune remote-tracking branches no longer on remote"),
        { OPTION_CALLBACK, 0, "recurse-submodules", NULL, "on-demand",
                    "control recursive fetching of submodules",
                    PARSE_OPT_OPTARG, option_parse_recurse_submodules },
        OPT_BOOLEAN(0, "dry-run", &dry_run,
                    "dry run"),
        OPT_BOOLEAN('k', "keep", &keep, "keep downloaded pack"),
        OPT_BOOLEAN('u', "update-head-ok", &update_head_ok,
                    "allow updating of HEAD ref"),
        OPT_BOOLEAN(0, "progress", &progress, "force progress reporting"),
        OPT_STRING(0, "depth", &depth, "depth",
                   "deepen history of shallow clone"),
        { OPTION_STRING, 0, "submodule-prefix", &submodule_prefix, "dir",
                   "prepend this to submodule path output", PARSE_OPT_HIDDEN },
        { OPTION_STRING, 0, "recurse-submodules-default",
                   &recurse_submodules_default, NULL,
                   "default mode for recursion", PARSE_OPT_HIDDEN },
        OPT_END()
};

static void unlock_pack(void)
{
        if (transport)
                transport_unlock_pack(transport);
}

static void unlock_pack_on_signal(int signo)
{
        unlock_pack();
        sigchain_pop(signo);
        raise(signo);
}

static void add_merge_config(struct ref **head,
                           const struct ref *remote_refs,
                           struct branch *branch,
                           struct ref ***tail)
{
        int i;

        for (i = 0; i < branch->merge_nr; i++) {
                struct ref *rm, **old_tail = *tail;
                struct refspec refspec;

                for (rm = *head; rm; rm = rm->next) {
                        if (branch_merge_matches(branch, i, rm->name)) {
                                rm->merge = 1;
                                break;
                        }
                }
                if (rm)
                        continue;

                /*
                 * Not fetched to a remote-tracking branch?  We need to fetch
                 * it anyway to allow this branch's "branch.$name.merge"
                 * to be honored by 'git pull', but we do not have to
                 * fail if branch.$name.merge is misconfigured to point
                 * at a nonexisting branch.  If we were indeed called by
                 * 'git pull', it will notice the misconfiguration because
                 * there is no entry in the resulting FETCH_HEAD marked
                 * for merging.
                 */
                memset(&refspec, 0, sizeof(refspec));
                refspec.src = branch->merge[i]->src;
                get_fetch_map(remote_refs, &refspec, tail, 1);
                for (rm = *old_tail; rm; rm = rm->next)
                        rm->merge = 1;
        }
}

static void find_non_local_tags(struct transport *transport,
                        struct ref **head,
                        struct ref ***tail);

static struct ref *get_ref_map(struct transport *transport,
                               struct refspec *refs, int ref_count, int tags,
                               int *autotags)
{
        int i;
        struct ref *rm;
        struct ref *ref_map = NULL;
        struct ref **tail = &ref_map;

        const struct ref *remote_refs = transport_get_remote_refs(transport);

        if (ref_count || tags == TAGS_SET) {
                for (i = 0; i < ref_count; i++) {
                        get_fetch_map(remote_refs, &refs[i], &tail, 0);
                        if (refs[i].dst && refs[i].dst[0])
                                *autotags = 1;
                }
                /* Merge everything on the command line, but not --tags */
                for (rm = ref_map; rm; rm = rm->next)
                        rm->merge = 1;
                if (tags == TAGS_SET)
                        get_fetch_map(remote_refs, tag_refspec, &tail, 0);
        } else {
                /* Use the defaults */
                struct remote *remote = transport->remote;
                struct branch *branch = branch_get(NULL);
                int has_merge = branch_has_merge_config(branch);
                if (remote &&
                    (remote->fetch_refspec_nr ||
                     /* Note: has_merge implies non-NULL branch->remote_name */
                     (has_merge && !strcmp(branch->remote_name, remote->name)))) {
                        for (i = 0; i < remote->fetch_refspec_nr; i++) {
                                get_fetch_map(remote_refs, &remote->fetch[i], &tail, 0);
                                if (remote->fetch[i].dst &&
                                    remote->fetch[i].dst[0])
                                        *autotags = 1;
                                if (!i && !has_merge && ref_map &&
                                    !remote->fetch[0].pattern)
                                        ref_map->merge = 1;
                        }
                        /*
                         * if the remote we're fetching from is the same
                         * as given in branch.<name>.remote, we add the
                         * ref given in branch.<name>.merge, too.
                         *
                         * Note: has_merge implies non-NULL branch->remote_name
                         */
                        if (has_merge &&
                            !strcmp(branch->remote_name, remote->name))
                                add_merge_config(&ref_map, remote_refs, branch, &tail);
                } else {
                        ref_map = get_remote_ref(remote_refs, "HEAD");
                        if (!ref_map)
                                die(_("Couldn't find remote ref HEAD"));
                        ref_map->merge = 1;
                        tail = &ref_map->next;
                }
        }
        if (tags == TAGS_DEFAULT && *autotags)
                find_non_local_tags(transport, &ref_map, &tail);
        ref_remove_duplicates(ref_map);

        return ref_map;
}

#define STORE_REF_ERROR_OTHER 1
#define STORE_REF_ERROR_DF_CONFLICT 2

static int s_update_ref(const char *action,
                        struct ref *ref,
                        int check_old)
{
        char msg[1024];
        char *rla = getenv("GIT_REFLOG_ACTION");
        static struct ref_lock *lock;

        if (dry_run)
                return 0;
        if (!rla)
                rla = default_rla.buf;
        snprintf(msg, sizeof(msg), "%s: %s", rla, action);
        lock = lock_any_ref_for_update(ref->name,
                                       check_old ? ref->old_sha1 : NULL, 0);
        if (!lock)
                return errno == ENOTDIR ? STORE_REF_ERROR_DF_CONFLICT :
                                          STORE_REF_ERROR_OTHER;
        if (write_ref_sha1(lock, ref->new_sha1, msg) < 0)
                return errno == ENOTDIR ? STORE_REF_ERROR_DF_CONFLICT :
                                          STORE_REF_ERROR_OTHER;
        return 0;
}

#define REFCOL_WIDTH  10

static int update_local_ref(struct ref *ref,
                            const char *remote,
                            char *display)
{
        struct commit *current = NULL, *updated;
        enum object_type type;
        struct branch *current_branch = branch_get(NULL);
        const char *pretty_ref = prettify_refname(ref->name);

        *display = 0;
        type = sha1_object_info(ref->new_sha1, NULL);
        if (type < 0)
                die(_("object %s not found"), sha1_to_hex(ref->new_sha1));

        if (!hashcmp(ref->old_sha1, ref->new_sha1)) {
                if (verbosity > 0)
                        sprintf(display, "= %-*s %-*s -> %s", TRANSPORT_SUMMARY_WIDTH,
                                _("[up to date]"), REFCOL_WIDTH, remote,
                                pretty_ref);
                return 0;
        }

        if (current_branch &&
            !strcmp(ref->name, current_branch->name) &&
            !(update_head_ok || is_bare_repository()) &&
            !is_null_sha1(ref->old_sha1)) {
                /*
                 * If this is the head, and it's not okay to update
                 * the head, and the old value of the head isn't empty...
                 */
                sprintf(display, _("! %-*s %-*s -> %s  (can't fetch in current branch)"),
                        TRANSPORT_SUMMARY_WIDTH, _("[rejected]"), REFCOL_WIDTH, remote,
                        pretty_ref);
                return 1;
        }

        if (!is_null_sha1(ref->old_sha1) &&
            !prefixcmp(ref->name, "refs/tags/")) {
                int r;
                r = s_update_ref("updating tag", ref, 0);
                sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : '-',
                        TRANSPORT_SUMMARY_WIDTH, _("[tag update]"), REFCOL_WIDTH, remote,
                        pretty_ref, r ? _("  (unable to update local ref)") : "");
                return r;
        }

        current = lookup_commit_reference_gently(ref->old_sha1, 1);
        updated = lookup_commit_reference_gently(ref->new_sha1, 1);
        if (!current || !updated) {
                const char *msg;
                const char *what;
                int r;
                if (!strncmp(ref->name, "refs/tags/", 10)) {
                        msg = "storing tag";
                        what = _("[new tag]");
                }
                else {
                        msg = "storing head";
                        what = _("[new branch]");
                        if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
                            (recurse_submodules != RECURSE_SUBMODULES_ON))
                                check_for_new_submodule_commits(ref->new_sha1);
                }

                r = s_update_ref(msg, ref, 0);
                sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : '*',
                        TRANSPORT_SUMMARY_WIDTH, what, REFCOL_WIDTH, remote, pretty_ref,
                        r ? _("  (unable to update local ref)") : "");
                return r;
        }

        if (in_merge_bases(current, &updated, 1)) {
                char quickref[83];
                int r;
                strcpy(quickref, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
                strcat(quickref, "..");
                strcat(quickref, find_unique_abbrev(ref->new_sha1, DEFAULT_ABBREV));
                if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(ref->new_sha1);
                r = s_update_ref("fast-forward", ref, 1);
                sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : ' ',
                        TRANSPORT_SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
                        pretty_ref, r ? _("  (unable to update local ref)") : "");
                return r;
        } else if (force || ref->force) {
                char quickref[84];
                int r;
                strcpy(quickref, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
                strcat(quickref, "...");
                strcat(quickref, find_unique_abbrev(ref->new_sha1, DEFAULT_ABBREV));
                if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(ref->new_sha1);
                r = s_update_ref("forced-update", ref, 1);
                sprintf(display, "%c %-*s %-*s -> %s  (%s)", r ? '!' : '+',
                        TRANSPORT_SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
                        pretty_ref,
                        r ? _("unable to update local ref") : _("forced update"));
                return r;
        } else {
                sprintf(display, "! %-*s %-*s -> %s  %s",
                        TRANSPORT_SUMMARY_WIDTH, _("[rejected]"), REFCOL_WIDTH, remote,
                        pretty_ref, _("(non-fast-forward)"));
                return 1;
        }
}

/*
 * Take callback data, and return next object name in the buffer.
 * When called after returning the name for the last object, return -1
 * to signal EOF, otherwise return 0.
 */
typedef int (*sha1_iterate_fn)(void *, unsigned char [20]);

/*
 * If we feed all the commits we want to verify to this command
 *
 *  $ git rev-list --verify-objects --stdin --not --all
 *
 * and if it does not error out, that means everything reachable from
 * these commits locally exists and is connected to some of our
 * existing refs.
 *
 * Returns 0 if everything is connected, non-zero otherwise.
 */
static int check_everything_connected(sha1_iterate_fn fn, int quiet, void *cb_data)
{
        struct child_process rev_list;
        const char *argv[] = {"rev-list", "--verify-objects",
                              "--stdin", "--not", "--all", NULL, NULL};
        char commit[41];
        unsigned char sha1[20];
        int err = 0;

        if (fn(cb_data, sha1))
                return err;

        if (quiet)
                argv[5] = "--quiet";

        memset(&rev_list, 0, sizeof(rev_list));
        rev_list.argv = argv;
        rev_list.git_cmd = 1;
        rev_list.in = -1;
        rev_list.no_stdout = 1;
        rev_list.no_stderr = quiet;
        if (start_command(&rev_list))
                return error(_("Could not run 'git rev-list'"));

        sigchain_push(SIGPIPE, SIG_IGN);

        commit[40] = '\n';
        do {
                memcpy(commit, sha1_to_hex(sha1), 40);
                if (write_in_full(rev_list.in, commit, 41) < 0) {
                        if (errno != EPIPE && errno != EINVAL)
                                error(_("failed write to rev-list: %s"),
                                      strerror(errno));
                        err = -1;
                        break;
                }
        } while (!fn(cb_data, sha1));

        if (close(rev_list.in)) {
                error(_("failed to close rev-list's stdin: %s"), strerror(errno));
                err = -1;
        }

        sigchain_pop(SIGPIPE);
        return finish_command(&rev_list) || err;
}

static int iterate_ref_map(void *cb_data, unsigned char sha1[20])
{
        struct ref **rm = cb_data;
        struct ref *ref = *rm;

        if (!ref)
                return -1; /* end of the list */
        *rm = ref->next;
        hashcpy(sha1, ref->old_sha1);
        return 0;
}

static int store_updated_refs(const char *raw_url, const char *remote_name,
                struct ref *ref_map)
{
        FILE *fp;
        struct commit *commit;
        int url_len, i, note_len, shown_url = 0, rc = 0;
        char note[1024];
        const char *what, *kind;
        struct ref *rm;
        char *url, *filename = dry_run ? "/dev/null" : git_path("FETCH_HEAD");

        fp = fopen(filename, "a");
        if (!fp)
                return error(_("cannot open %s: %s\n"), filename, strerror(errno));

        if (raw_url)
                url = transport_anonymize_url(raw_url);
        else
                url = xstrdup("foreign");

        rm = ref_map;
        if (check_everything_connected(iterate_ref_map, 0, &rm))
                return error(_("%s did not send all necessary objects\n"), url);

        for (rm = ref_map; rm; rm = rm->next) {
                struct ref *ref = NULL;

                if (rm->peer_ref) {
                        ref = xcalloc(1, sizeof(*ref) + strlen(rm->peer_ref->name) + 1);
                        strcpy(ref->name, rm->peer_ref->name);
                        hashcpy(ref->old_sha1, rm->peer_ref->old_sha1);
                        hashcpy(ref->new_sha1, rm->old_sha1);
                        ref->force = rm->peer_ref->force;
                }

                commit = lookup_commit_reference_gently(rm->old_sha1, 1);
                if (!commit)
                        rm->merge = 0;

                if (!strcmp(rm->name, "HEAD")) {
                        kind = "";
                        what = "";
                }
                else if (!prefixcmp(rm->name, "refs/heads/")) {
                        kind = "branch";
                        what = rm->name + 11;
                }
                else if (!prefixcmp(rm->name, "refs/tags/")) {
                        kind = "tag";
                        what = rm->name + 10;
                }
                else if (!prefixcmp(rm->name, "refs/remotes/")) {
                        kind = "remote-tracking branch";
                        what = rm->name + 13;
                }
                else {
                        kind = "";
                        what = rm->name;
                }

                url_len = strlen(url);
                for (i = url_len - 1; url[i] == '/' && 0 <= i; i--)
                        ;
                url_len = i + 1;
                if (4 < i && !strncmp(".git", url + i - 3, 4))
                        url_len = i - 3;

                note_len = 0;
                if (*what) {
                        if (*kind)
                                note_len += sprintf(note + note_len, "%s ",
                                                    kind);
                        note_len += sprintf(note + note_len, "'%s' of ", what);
                }
                note[note_len] = '\0';
                fprintf(fp, "%s\t%s\t%s",
                        sha1_to_hex(commit ? commit->object.sha1 :
                                    rm->old_sha1),
                        rm->merge ? "" : "not-for-merge",
                        note);
                for (i = 0; i < url_len; ++i)
                        if ('\n' == url[i])
                                fputs("\\n", fp);
                        else
                                fputc(url[i], fp);
                fputc('\n', fp);

                if (ref) {
                        rc |= update_local_ref(ref, what, note);
                        free(ref);
                } else
                        sprintf(note, "* %-*s %-*s -> FETCH_HEAD",
                                TRANSPORT_SUMMARY_WIDTH, *kind ? kind : "branch",
                                 REFCOL_WIDTH, *what ? what : "HEAD");
                if (*note) {
                        if (verbosity >= 0 && !shown_url) {
                                fprintf(stderr, _("From %.*s\n"),
                                                url_len, url);
                                shown_url = 1;
                        }
                        if (verbosity >= 0)
                                fprintf(stderr, " %s\n", note);
                }
        }
        free(url);
        fclose(fp);
        if (rc & STORE_REF_ERROR_DF_CONFLICT)
                error(_("some local refs could not be updated; try running\n"
                      " 'git remote prune %s' to remove any old, conflicting "
                      "branches"), remote_name);
        return rc;
}

/*
 * We would want to bypass the object transfer altogether if
 * everything we are going to fetch already exists and is connected
 * locally.
 */
static int quickfetch(struct ref *ref_map)
{
        struct ref *rm = ref_map;

        /*
         * If we are deepening a shallow clone we already have these
         * objects reachable.  Running rev-list here will return with
         * a good (0) exit status and we'll bypass the fetch that we
         * really need to perform.  Claiming failure now will ensure
         * we perform the network exchange to deepen our history.
         */
        if (depth)
                return -1;
        return check_everything_connected(iterate_ref_map, 1, &rm);
}

static int fetch_refs(struct transport *transport, struct ref *ref_map)
{
        int ret = quickfetch(ref_map);
        if (ret)
                ret = transport_fetch_refs(transport, ref_map);
        if (!ret)
                ret |= store_updated_refs(transport->url,
                                transport->remote->name,
                                ref_map);
        transport_unlock_pack(transport);
        return ret;
}

static int prune_refs(struct transport *transport, struct ref *ref_map)
{
        int result = 0;
        struct ref *ref, *stale_refs = get_stale_heads(transport->remote, ref_map);
        const char *dangling_msg = dry_run
                ? _("   (%s will become dangling)\n")
                : _("   (%s has become dangling)\n");

        for (ref = stale_refs; ref; ref = ref->next) {
                if (!dry_run)
                        result |= delete_ref(ref->name, NULL, 0);
                if (verbosity >= 0) {
                        fprintf(stderr, " x %-*s %-*s -> %s\n",
                                TRANSPORT_SUMMARY_WIDTH, _("[deleted]"),
                                REFCOL_WIDTH, _("(none)"), prettify_refname(ref->name));
                        warn_dangling_symref(stderr, dangling_msg, ref->name);
                }
        }
        free_refs(stale_refs);
        return result;
}

static int add_existing(const char *refname, const unsigned char *sha1,
                        int flag, void *cbdata)
{
        struct string_list *list = (struct string_list *)cbdata;
        struct string_list_item *item = string_list_insert(list, refname);
        item->util = (void *)sha1;
        return 0;
}

static int will_fetch(struct ref **head, const unsigned char *sha1)
{
        struct ref *rm = *head;
        while (rm) {
                if (!hashcmp(rm->old_sha1, sha1))
                        return 1;
                rm = rm->next;
        }
        return 0;
}

static void find_non_local_tags(struct transport *transport,
                        struct ref **head,
                        struct ref ***tail)
{
        struct string_list existing_refs = STRING_LIST_INIT_NODUP;
        struct string_list remote_refs = STRING_LIST_INIT_NODUP;
        const struct ref *ref;
        struct string_list_item *item = NULL;

        for_each_ref(add_existing, &existing_refs);
        for (ref = transport_get_remote_refs(transport); ref; ref = ref->next) {
                if (prefixcmp(ref->name, "refs/tags"))
                        continue;

                /*
                 * The peeled ref always follows the matching base
                 * ref, so if we see a peeled ref that we don't want
                 * to fetch then we can mark the ref entry in the list
                 * as one to ignore by setting util to NULL.
                 */
                if (!suffixcmp(ref->name, "^{}")) {
                        if (item && !has_sha1_file(ref->old_sha1) &&
                            !will_fetch(head, ref->old_sha1) &&
                            !has_sha1_file(item->util) &&
                            !will_fetch(head, item->util))
                                item->util = NULL;
                        item = NULL;
                        continue;
                }

                /*
                 * If item is non-NULL here, then we previously saw a
                 * ref not followed by a peeled reference, so we need
                 * to check if it is a lightweight tag that we want to
                 * fetch.
                 */
                if (item && !has_sha1_file(item->util) &&
                    !will_fetch(head, item->util))
                        item->util = NULL;

                item = NULL;

                /* skip duplicates and refs that we already have */
                if (string_list_has_string(&remote_refs, ref->name) ||
                    string_list_has_string(&existing_refs, ref->name))
                        continue;

                item = string_list_insert(&remote_refs, ref->name);
                item->util = (void *)ref->old_sha1;
        }
        string_list_clear(&existing_refs, 0);

        /*
         * We may have a final lightweight tag that needs to be
         * checked to see if it needs fetching.
         */
        if (item && !has_sha1_file(item->util) &&
            !will_fetch(head, item->util))
                item->util = NULL;

        /*
         * For all the tags in the remote_refs string list,
         * add them to the list of refs to be fetched
         */
        for_each_string_list_item(item, &remote_refs) {
                /* Unless we have already decided to ignore this item... */
                if (item->util)
                {
                        struct ref *rm = alloc_ref(item->string);
                        rm->peer_ref = alloc_ref(item->string);
                        hashcpy(rm->old_sha1, item->util);
                        **tail = rm;
                        *tail = &rm->next;
                }
        }

        string_list_clear(&remote_refs, 0);
}

static void check_not_current_branch(struct ref *ref_map)
{
        struct branch *current_branch = branch_get(NULL);

        if (is_bare_repository() || !current_branch)
                return;

        for (; ref_map; ref_map = ref_map->next)
                if (ref_map->peer_ref && !strcmp(current_branch->refname,
                                        ref_map->peer_ref->name))
                        die(_("Refusing to fetch into current branch %s "
                            "of non-bare repository"), current_branch->refname);
}

static int truncate_fetch_head(void)
{
        char *filename = git_path("FETCH_HEAD");
        FILE *fp = fopen(filename, "w");

        if (!fp)
                return error(_("cannot open %s: %s\n"), filename, strerror(errno));
        fclose(fp);
        return 0;
}

static int do_fetch(struct transport *transport,
                    struct refspec *refs, int ref_count)
{
        struct string_list existing_refs = STRING_LIST_INIT_NODUP;
        struct string_list_item *peer_item = NULL;
        struct ref *ref_map;
        struct ref *rm;
        int autotags = (transport->remote->fetch_tags == 1);

        for_each_ref(add_existing, &existing_refs);

        if (tags == TAGS_DEFAULT) {
                if (transport->remote->fetch_tags == 2)
                        tags = TAGS_SET;
                if (transport->remote->fetch_tags == -1)
                        tags = TAGS_UNSET;
        }

        if (!transport->get_refs_list || !transport->fetch)
                die(_("Don't know how to fetch from %s"), transport->url);

        /* if not appending, truncate FETCH_HEAD */
        if (!append && !dry_run) {
                int errcode = truncate_fetch_head();
                if (errcode)
                        return errcode;
        }

        ref_map = get_ref_map(transport, refs, ref_count, tags, &autotags);
        if (!update_head_ok)
                check_not_current_branch(ref_map);

        for (rm = ref_map; rm; rm = rm->next) {
                if (rm->peer_ref) {
                        peer_item = string_list_lookup(&existing_refs,
                                                       rm->peer_ref->name);
                        if (peer_item)
                                hashcpy(rm->peer_ref->old_sha1,
                                        peer_item->util);
                }
        }

        if (tags == TAGS_DEFAULT && autotags)
                transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
        if (fetch_refs(transport, ref_map)) {
                free_refs(ref_map);
                return 1;
        }
        if (prune)
                prune_refs(transport, ref_map);
        free_refs(ref_map);

        /* if neither --no-tags nor --tags was specified, do automated tag
         * following ... */
        if (tags == TAGS_DEFAULT && autotags) {
                struct ref **tail = &ref_map;
                ref_map = NULL;
                find_non_local_tags(transport, &ref_map, &tail);
                if (ref_map) {
                        transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL);
                        transport_set_option(transport, TRANS_OPT_DEPTH, "0");
                        fetch_refs(transport, ref_map);
                }
                free_refs(ref_map);
        }

        return 0;
}

static void set_option(const char *name, const char *value)
{
        int r = transport_set_option(transport, name, value);
        if (r < 0)
                die(_("Option \"%s\" value \"%s\" is not valid for %s"),
                        name, value, transport->url);
        if (r > 0)
                warning(_("Option \"%s\" is ignored for %s\n"),
                        name, transport->url);
}

static int get_one_remote_for_fetch(struct remote *remote, void *priv)
{
        struct string_list *list = priv;
        if (!remote->skip_default_update)
                string_list_append(list, remote->name);
        return 0;
}

struct remote_group_data {
        const char *name;
        struct string_list *list;
};

static int get_remote_group(const char *key, const char *value, void *priv)
{
        struct remote_group_data *g = priv;

        if (!prefixcmp(key, "remotes.") &&
                        !strcmp(key + 8, g->name)) {
                /* split list by white space */
                int space = strcspn(value, " \t\n");
                while (*value) {
                        if (space > 1) {
                                string_list_append(g->list,
                                                   xstrndup(value, space));
                        }
                        value += space + (value[space] != '\0');
                        space = strcspn(value, " \t\n");
                }
        }

        return 0;
}

static int add_remote_or_group(const char *name, struct string_list *list)
{
        int prev_nr = list->nr;
        struct remote_group_data g;
        g.name = name; g.list = list;

        git_config(get_remote_group, &g);
        if (list->nr == prev_nr) {
                struct remote *remote;
                if (!remote_is_configured(name))
                        return 0;
                remote = remote_get(name);
                string_list_append(list, remote->name);
        }
        return 1;
}

static void add_options_to_argv(int *argc, const char **argv)
{
        if (dry_run)
                argv[(*argc)++] = "--dry-run";
        if (prune)
                argv[(*argc)++] = "--prune";
        if (update_head_ok)
                argv[(*argc)++] = "--update-head-ok";
        if (force)
                argv[(*argc)++] = "--force";
        if (keep)
                argv[(*argc)++] = "--keep";
        if (recurse_submodules == RECURSE_SUBMODULES_ON)
                argv[(*argc)++] = "--recurse-submodules";
        else if (recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND)
                argv[(*argc)++] = "--recurse-submodules=on-demand";
        if (verbosity >= 2)
                argv[(*argc)++] = "-v";
        if (verbosity >= 1)
                argv[(*argc)++] = "-v";
        else if (verbosity < 0)
                argv[(*argc)++] = "-q";

}

static int fetch_multiple(struct string_list *list)
{
        int i, result = 0;
        const char *argv[12] = { "fetch", "--append" };
        int argc = 2;

        add_options_to_argv(&argc, argv);

        if (!append && !dry_run) {
                int errcode = truncate_fetch_head();
                if (errcode)
                        return errcode;
        }

        for (i = 0; i < list->nr; i++) {
                const char *name = list->items[i].string;
                argv[argc] = name;
                argv[argc + 1] = NULL;
                if (verbosity >= 0)
                        printf(_("Fetching %s\n"), name);
                if (run_command_v_opt(argv, RUN_GIT_CMD)) {
                        error(_("Could not fetch %s"), name);
                        result = 1;
                }
        }

        return result;
}

static int fetch_one(struct remote *remote, int argc, const char **argv)
{
        int i;
        static const char **refs = NULL;
        int ref_nr = 0;
        int exit_code;

        if (!remote)
                die(_("No remote repository specified.  Please, specify either a URL or a\n"
                    "remote name from which new revisions should be fetched."));

        transport = transport_get(remote, NULL);
        transport_set_verbosity(transport, verbosity, progress);
        if (upload_pack)
                set_option(TRANS_OPT_UPLOADPACK, upload_pack);
        if (keep)
                set_option(TRANS_OPT_KEEP, "yes");
        if (depth)
                set_option(TRANS_OPT_DEPTH, depth);

        if (argc > 0) {
                int j = 0;
                refs = xcalloc(argc + 1, sizeof(const char *));
                for (i = 0; i < argc; i++) {
                        if (!strcmp(argv[i], "tag")) {
                                char *ref;
                                i++;
                                if (i >= argc)
                                        die(_("You need to specify a tag name."));
                                ref = xmalloc(strlen(argv[i]) * 2 + 22);
                                strcpy(ref, "refs/tags/");
                                strcat(ref, argv[i]);
                                strcat(ref, ":refs/tags/");
                                strcat(ref, argv[i]);
                                refs[j++] = ref;
                        } else
                                refs[j++] = argv[i];
                }
                refs[j] = NULL;
                ref_nr = j;
        }

        sigchain_push_common(unlock_pack_on_signal);
        atexit(unlock_pack);
        exit_code = do_fetch(transport,
                        parse_fetch_refspec(ref_nr, refs), ref_nr);
        transport_disconnect(transport);
        transport = NULL;
        return exit_code;
}

int cmd_fetch(int argc, const char **argv, const char *prefix)
{
        int i;
        struct string_list list = STRING_LIST_INIT_NODUP;
        struct remote *remote;
        int result = 0;

        packet_trace_identity("fetch");

        /* Record the command line for the reflog */
        strbuf_addstr(&default_rla, "fetch");
        for (i = 1; i < argc; i++)
                strbuf_addf(&default_rla, " %s", argv[i]);

        argc = parse_options(argc, argv, prefix,
                             builtin_fetch_options, builtin_fetch_usage, 0);

        if (all) {
                if (argc == 1)
                        die(_("fetch --all does not take a repository argument"));
                else if (argc > 1)
                        die(_("fetch --all does not make sense with refspecs"));
                (void) for_each_remote(get_one_remote_for_fetch, &list);
                result = fetch_multiple(&list);
        } else if (argc == 0) {
                /* No arguments -- use default remote */
                remote = remote_get(NULL);
                result = fetch_one(remote, argc, argv);
        } else if (multiple) {
                /* All arguments are assumed to be remotes or groups */
                for (i = 0; i < argc; i++)
                        if (!add_remote_or_group(argv[i], &list))
                                die(_("No such remote or remote group: %s"), argv[i]);
                result = fetch_multiple(&list);
        } else {
                /* Single remote or group */
                (void) add_remote_or_group(argv[0], &list);
                if (list.nr > 1) {
                        /* More than one remote */
                        if (argc > 1)
                                die(_("Fetching a group and specifying refspecs does not make sense"));
                        result = fetch_multiple(&list);
                } else {
                        /* Zero or one remotes */
                        remote = remote_get(argv[0]);
                        result = fetch_one(remote, argc-1, argv+1);
                }
        }

        if (!result && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
                const char *options[10];
                int num_options = 0;
                if (recurse_submodules_default) {
                        int arg = parse_fetch_recurse_submodules_arg("--recurse-submodules-default", recurse_submodules_default);
                        set_config_fetch_recurse_submodules(arg);
                }
                gitmodules_config();
                git_config(submodule_config, NULL);
                add_options_to_argv(&num_options, options);
                result = fetch_populated_submodules(num_options, options,
                                                    submodule_prefix,
                                                    recurse_submodules,
                                                    verbosity < 0);
        }

        /* All names were strdup()ed or strndup()ed */
        list.strdup_strings = 1;
        string_list_clear(&list, 0);

        return result;
}