Merge branch 'la/trailer-api'

[alt-git.git] / upload-pack.c

#include "git-compat-util.h"
#include "config.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "refs.h"
#include "pkt-line.h"
#include "sideband.h"
#include "repository.h"
#include "object-store-ll.h"
#include "oid-array.h"
#include "object.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "list-objects-filter-options.h"
#include "run-command.h"
#include "connect.h"
#include "sigchain.h"
#include "version.h"
#include "string-list.h"
#include "strvec.h"
#include "trace2.h"
#include "protocol.h"
#include "upload-pack.h"
#include "commit-graph.h"
#include "commit-reach.h"
#include "shallow.h"
#include "write-or-die.h"
#include "json-writer.h"
#include "strmap.h"

/* Remember to update object flag allocation in object.h */
#define THEY_HAVE       (1u << 11)
#define OUR_REF         (1u << 12)
#define WANTED          (1u << 13)
#define COMMON_KNOWN    (1u << 14)

#define SHALLOW         (1u << 16)
#define NOT_SHALLOW     (1u << 17)
#define CLIENT_SHALLOW  (1u << 18)
#define HIDDEN_REF      (1u << 19)

#define ALL_FLAGS (THEY_HAVE | OUR_REF | WANTED | COMMON_KNOWN | SHALLOW | \
                NOT_SHALLOW | CLIENT_SHALLOW | HIDDEN_REF)

/* Enum for allowed unadvertised object request (UOR) */
enum allow_uor {
        /* Allow specifying sha1 if it is a ref tip. */
        ALLOW_TIP_SHA1 = 0x01,
        /* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
        ALLOW_REACHABLE_SHA1 = 0x02,
        /* Allow request of any sha1. Implies ALLOW_TIP_SHA1 and ALLOW_REACHABLE_SHA1. */
        ALLOW_ANY_SHA1 = 0x07
};

/*
 * Please annotate, and if possible group together, fields used only
 * for protocol v0 or only for protocol v2.
 */
struct upload_pack_data {
        struct string_list symref;                              /* v0 only */
        struct object_array want_obj;
        struct object_array have_obj;
        struct strmap wanted_refs;                              /* v2 only */
        struct strvec hidden_refs;

        struct object_array shallows;
        struct oidset deepen_not;
        struct object_array extra_edge_obj;
        int depth;
        timestamp_t deepen_since;
        int deepen_rev_list;
        int deepen_relative;
        int keepalive;
        int shallow_nr;
        timestamp_t oldest_have;

        unsigned int timeout;                                   /* v0 only */
        enum {
                NO_MULTI_ACK = 0,
                MULTI_ACK = 1,
                MULTI_ACK_DETAILED = 2
        } multi_ack;                                            /* v0 only */

        /* 0 for no sideband, otherwise DEFAULT_PACKET_MAX or LARGE_PACKET_MAX */
        int use_sideband;

        struct string_list uri_protocols;
        enum allow_uor allow_uor;

        struct list_objects_filter_options filter_options;
        struct string_list allowed_filters;

        struct packet_writer writer;

        const char *pack_objects_hook;

        unsigned stateless_rpc : 1;                             /* v0 only */
        unsigned no_done : 1;                                   /* v0 only */
        unsigned daemon_mode : 1;                               /* v0 only */
        unsigned filter_capability_requested : 1;               /* v0 only */

        unsigned use_thin_pack : 1;
        unsigned use_ofs_delta : 1;
        unsigned no_progress : 1;
        unsigned use_include_tag : 1;
        unsigned wait_for_done : 1;
        unsigned allow_filter : 1;
        unsigned allow_filter_fallback : 1;
        unsigned long tree_filter_max_depth;

        unsigned done : 1;                                      /* v2 only */
        unsigned allow_ref_in_want : 1;                         /* v2 only */
        unsigned allow_sideband_all : 1;                        /* v2 only */
        unsigned seen_haves : 1;                                /* v2 only */
        unsigned allow_packfile_uris : 1;                       /* v2 only */
        unsigned advertise_sid : 1;
        unsigned sent_capabilities : 1;
};

static void upload_pack_data_init(struct upload_pack_data *data)
{
        struct string_list symref = STRING_LIST_INIT_DUP;
        struct strmap wanted_refs = STRMAP_INIT;
        struct strvec hidden_refs = STRVEC_INIT;
        struct object_array want_obj = OBJECT_ARRAY_INIT;
        struct object_array have_obj = OBJECT_ARRAY_INIT;
        struct object_array shallows = OBJECT_ARRAY_INIT;
        struct oidset deepen_not = OID_ARRAY_INIT;
        struct string_list uri_protocols = STRING_LIST_INIT_DUP;
        struct object_array extra_edge_obj = OBJECT_ARRAY_INIT;
        struct string_list allowed_filters = STRING_LIST_INIT_DUP;

        memset(data, 0, sizeof(*data));
        data->symref = symref;
        data->wanted_refs = wanted_refs;
        data->hidden_refs = hidden_refs;
        data->want_obj = want_obj;
        data->have_obj = have_obj;
        data->shallows = shallows;
        data->deepen_not = deepen_not;
        data->uri_protocols = uri_protocols;
        data->extra_edge_obj = extra_edge_obj;
        data->allowed_filters = allowed_filters;
        data->allow_filter_fallback = 1;
        data->tree_filter_max_depth = ULONG_MAX;
        packet_writer_init(&data->writer, 1);
        list_objects_filter_init(&data->filter_options);

        data->keepalive = 5;
        data->advertise_sid = 0;
}

static void upload_pack_data_clear(struct upload_pack_data *data)
{
        string_list_clear(&data->symref, 1);
        strmap_clear(&data->wanted_refs, 1);
        strvec_clear(&data->hidden_refs);
        object_array_clear(&data->want_obj);
        object_array_clear(&data->have_obj);
        object_array_clear(&data->shallows);
        oidset_clear(&data->deepen_not);
        object_array_clear(&data->extra_edge_obj);
        list_objects_filter_release(&data->filter_options);
        string_list_clear(&data->allowed_filters, 0);

        free((char *)data->pack_objects_hook);
}

static void reset_timeout(unsigned int timeout)
{
        alarm(timeout);
}

static void send_client_data(int fd, const char *data, ssize_t sz,
                             int use_sideband)
{
        if (use_sideband) {
                send_sideband(1, fd, data, sz, use_sideband);
                return;
        }
        if (fd == 3)
                /* emergency quit */
                fd = 2;
        if (fd == 2) {
                /* XXX: are we happy to lose stuff here? */
                xwrite(fd, data, sz);
                return;
        }
        write_or_die(fd, data, sz);
}

static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
{
        FILE *fp = cb_data;
        if (graft->nr_parent == -1)
                fprintf(fp, "--shallow %s\n", oid_to_hex(&graft->oid));
        return 0;
}

struct output_state {
        /*
         * We do writes no bigger than LARGE_PACKET_DATA_MAX - 1, because with
         * sideband-64k the band designator takes up 1 byte of space. Because
         * relay_pack_data keeps the last byte to itself, we make the buffer 1
         * byte bigger than the intended maximum write size.
         */
        char buffer[(LARGE_PACKET_DATA_MAX - 1) + 1];
        int used;
        unsigned packfile_uris_started : 1;
        unsigned packfile_started : 1;
};

static int relay_pack_data(int pack_objects_out, struct output_state *os,
                           int use_sideband, int write_packfile_line)
{
        /*
         * We keep the last byte to ourselves
         * in case we detect broken rev-list, so that we
         * can leave the stream corrupted.  This is
         * unfortunate -- unpack-objects would happily
         * accept a valid packdata with trailing garbage,
         * so appending garbage after we pass all the
         * pack data is not good enough to signal
         * breakage to downstream.
         */
        ssize_t readsz;

        readsz = xread(pack_objects_out, os->buffer + os->used,
                       sizeof(os->buffer) - os->used);
        if (readsz < 0) {
                return readsz;
        }
        os->used += readsz;

        while (!os->packfile_started) {
                char *p;
                if (os->used >= 4 && !memcmp(os->buffer, "PACK", 4)) {
                        os->packfile_started = 1;
                        if (write_packfile_line) {
                                if (os->packfile_uris_started)
                                        packet_delim(1);
                                packet_write_fmt(1, "\1packfile\n");
                        }
                        break;
                }
                if ((p = memchr(os->buffer, '\n', os->used))) {
                        if (!os->packfile_uris_started) {
                                os->packfile_uris_started = 1;
                                if (!write_packfile_line)
                                        BUG("packfile_uris requires sideband-all");
                                packet_write_fmt(1, "\1packfile-uris\n");
                        }
                        *p = '\0';
                        packet_write_fmt(1, "\1%s\n", os->buffer);

                        os->used -= p - os->buffer + 1;
                        memmove(os->buffer, p + 1, os->used);
                } else {
                        /*
                         * Incomplete line.
                         */
                        return readsz;
                }
        }

        if (os->used > 1) {
                send_client_data(1, os->buffer, os->used - 1, use_sideband);
                os->buffer[0] = os->buffer[os->used - 1];
                os->used = 1;
        } else {
                send_client_data(1, os->buffer, os->used, use_sideband);
                os->used = 0;
        }

        return readsz;
}

static void create_pack_file(struct upload_pack_data *pack_data,
                             const struct string_list *uri_protocols)
{
        struct child_process pack_objects = CHILD_PROCESS_INIT;
        struct output_state *output_state = xcalloc(1, sizeof(struct output_state));
        char progress[128];
        char abort_msg[] = "aborting due to possible repository "
                "corruption on the remote side.";
        ssize_t sz;
        int i;
        FILE *pipe_fd;

        if (!pack_data->pack_objects_hook)
                pack_objects.git_cmd = 1;
        else {
                strvec_push(&pack_objects.args, pack_data->pack_objects_hook);
                strvec_push(&pack_objects.args, "git");
                pack_objects.use_shell = 1;
        }

        if (pack_data->shallow_nr) {
                strvec_push(&pack_objects.args, "--shallow-file");
                strvec_push(&pack_objects.args, "");
        }
        strvec_push(&pack_objects.args, "pack-objects");
        strvec_push(&pack_objects.args, "--revs");
        if (pack_data->use_thin_pack)
                strvec_push(&pack_objects.args, "--thin");

        strvec_push(&pack_objects.args, "--stdout");
        if (pack_data->shallow_nr)
                strvec_push(&pack_objects.args, "--shallow");
        if (!pack_data->no_progress)
                strvec_push(&pack_objects.args, "--progress");
        if (pack_data->use_ofs_delta)
                strvec_push(&pack_objects.args, "--delta-base-offset");
        if (pack_data->use_include_tag)
                strvec_push(&pack_objects.args, "--include-tag");
        if (pack_data->filter_options.choice) {
                const char *spec =
                        expand_list_objects_filter_spec(&pack_data->filter_options);
                strvec_pushf(&pack_objects.args, "--filter=%s", spec);
        }
        if (uri_protocols) {
                for (i = 0; i < uri_protocols->nr; i++)
                        strvec_pushf(&pack_objects.args, "--uri-protocol=%s",
                                         uri_protocols->items[i].string);
        }

        pack_objects.in = -1;
        pack_objects.out = -1;
        pack_objects.err = -1;
        pack_objects.clean_on_exit = 1;

        if (start_command(&pack_objects))
                die("git upload-pack: unable to fork git-pack-objects");

        pipe_fd = xfdopen(pack_objects.in, "w");

        if (pack_data->shallow_nr)
                for_each_commit_graft(write_one_shallow, pipe_fd);

        for (i = 0; i < pack_data->want_obj.nr; i++)
                fprintf(pipe_fd, "%s\n",
                        oid_to_hex(&pack_data->want_obj.objects[i].item->oid));
        fprintf(pipe_fd, "--not\n");
        for (i = 0; i < pack_data->have_obj.nr; i++)
                fprintf(pipe_fd, "%s\n",
                        oid_to_hex(&pack_data->have_obj.objects[i].item->oid));
        for (i = 0; i < pack_data->extra_edge_obj.nr; i++)
                fprintf(pipe_fd, "%s\n",
                        oid_to_hex(&pack_data->extra_edge_obj.objects[i].item->oid));
        fprintf(pipe_fd, "\n");
        fflush(pipe_fd);
        fclose(pipe_fd);

        /* We read from pack_objects.err to capture stderr output for
         * progress bar, and pack_objects.out to capture the pack data.
         */

        while (1) {
                struct pollfd pfd[2];
                int pe, pu, pollsize, polltimeout;
                int ret;

                reset_timeout(pack_data->timeout);

                pollsize = 0;
                pe = pu = -1;

                if (0 <= pack_objects.out) {
                        pfd[pollsize].fd = pack_objects.out;
                        pfd[pollsize].events = POLLIN;
                        pu = pollsize;
                        pollsize++;
                }
                if (0 <= pack_objects.err) {
                        pfd[pollsize].fd = pack_objects.err;
                        pfd[pollsize].events = POLLIN;
                        pe = pollsize;
                        pollsize++;
                }

                if (!pollsize)
                        break;

                polltimeout = pack_data->keepalive < 0
                        ? -1
                        : 1000 * pack_data->keepalive;

                ret = poll(pfd, pollsize, polltimeout);

                if (ret < 0) {
                        if (errno != EINTR) {
                                error_errno("poll failed, resuming");
                                sleep(1);
                        }
                        continue;
                }
                if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
                        /* Status ready; we ship that in the side-band
                         * or dump to the standard error.
                         */
                        sz = xread(pack_objects.err, progress,
                                  sizeof(progress));
                        if (0 < sz)
                                send_client_data(2, progress, sz,
                                                 pack_data->use_sideband);
                        else if (sz == 0) {
                                close(pack_objects.err);
                                pack_objects.err = -1;
                        }
                        else
                                goto fail;
                        /* give priority to status messages */
                        continue;
                }
                if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
                        int result = relay_pack_data(pack_objects.out,
                                                     output_state,
                                                     pack_data->use_sideband,
                                                     !!uri_protocols);

                        if (result == 0) {
                                close(pack_objects.out);
                                pack_objects.out = -1;
                        } else if (result < 0) {
                                goto fail;
                        }
                }

                /*
                 * We hit the keepalive timeout without saying anything; send
                 * an empty message on the data sideband just to let the other
                 * side know we're still working on it, but don't have any data
                 * yet.
                 *
                 * If we don't have a sideband channel, there's no room in the
                 * protocol to say anything, so those clients are just out of
                 * luck.
                 */
                if (!ret && pack_data->use_sideband) {
                        static const char buf[] = "0005\1";
                        write_or_die(1, buf, 5);
                }
        }

        if (finish_command(&pack_objects)) {
                error("git upload-pack: git-pack-objects died with error.");
                goto fail;
        }

        /* flush the data */
        if (output_state->used > 0) {
                send_client_data(1, output_state->buffer, output_state->used,
                                 pack_data->use_sideband);
                fprintf(stderr, "flushed.\n");
        }
        free(output_state);
        if (pack_data->use_sideband)
                packet_flush(1);
        return;

 fail:
        free(output_state);
        send_client_data(3, abort_msg, strlen(abort_msg),
                         pack_data->use_sideband);
        die("git upload-pack: %s", abort_msg);
}

static int do_got_oid(struct upload_pack_data *data, const struct object_id *oid)
{
        int we_knew_they_have = 0;
        struct object *o = parse_object_with_flags(the_repository, oid,
                                                   PARSE_OBJECT_SKIP_HASH_CHECK |
                                                   PARSE_OBJECT_DISCARD_TREE);

        if (!o)
                die("oops (%s)", oid_to_hex(oid));
        if (o->type == OBJ_COMMIT) {
                struct commit_list *parents;
                struct commit *commit = (struct commit *)o;
                if (o->flags & THEY_HAVE)
                        we_knew_they_have = 1;
                else
                        o->flags |= THEY_HAVE;
                if (!data->oldest_have || (commit->date < data->oldest_have))
                        data->oldest_have = commit->date;
                for (parents = commit->parents;
                     parents;
                     parents = parents->next)
                        parents->item->object.flags |= THEY_HAVE;
        }
        if (!we_knew_they_have) {
                add_object_array(o, NULL, &data->have_obj);
                return 1;
        }
        return 0;
}

static int got_oid(struct upload_pack_data *data,
                   const char *hex, struct object_id *oid)
{
        if (get_oid_hex(hex, oid))
                die("git upload-pack: expected SHA1 object, got '%s'", hex);
        if (!repo_has_object_file_with_flags(the_repository, oid,
                                             OBJECT_INFO_QUICK | OBJECT_INFO_SKIP_FETCH_OBJECT))
                return -1;
        return do_got_oid(data, oid);
}

static int ok_to_give_up(struct upload_pack_data *data)
{
        timestamp_t min_generation = GENERATION_NUMBER_ZERO;

        if (!data->have_obj.nr)
                return 0;

        return can_all_from_reach_with_flag(&data->want_obj, THEY_HAVE,
                                            COMMON_KNOWN, data->oldest_have,
                                            min_generation);
}

static int get_common_commits(struct upload_pack_data *data,
                              struct packet_reader *reader)
{
        struct object_id oid;
        char last_hex[GIT_MAX_HEXSZ + 1];
        int got_common = 0;
        int got_other = 0;
        int sent_ready = 0;

        for (;;) {
                const char *arg;

                reset_timeout(data->timeout);

                if (packet_reader_read(reader) != PACKET_READ_NORMAL) {
                        if (data->multi_ack == MULTI_ACK_DETAILED
                            && got_common
                            && !got_other
                            && ok_to_give_up(data)) {
                                sent_ready = 1;
                                packet_write_fmt(1, "ACK %s ready\n", last_hex);
                        }
                        if (data->have_obj.nr == 0 || data->multi_ack)
                                packet_write_fmt(1, "NAK\n");

                        if (data->no_done && sent_ready) {
                                packet_write_fmt(1, "ACK %s\n", last_hex);
                                return 0;
                        }
                        if (data->stateless_rpc)
                                exit(0);
                        got_common = 0;
                        got_other = 0;
                        continue;
                }
                if (skip_prefix(reader->line, "have ", &arg)) {
                        switch (got_oid(data, arg, &oid)) {
                        case -1: /* they have what we do not */
                                got_other = 1;
                                if (data->multi_ack
                                    && ok_to_give_up(data)) {
                                        const char *hex = oid_to_hex(&oid);
                                        if (data->multi_ack == MULTI_ACK_DETAILED) {
                                                sent_ready = 1;
                                                packet_write_fmt(1, "ACK %s ready\n", hex);
                                        } else
                                                packet_write_fmt(1, "ACK %s continue\n", hex);
                                }
                                break;
                        default:
                                got_common = 1;
                                oid_to_hex_r(last_hex, &oid);
                                if (data->multi_ack == MULTI_ACK_DETAILED)
                                        packet_write_fmt(1, "ACK %s common\n", last_hex);
                                else if (data->multi_ack)
                                        packet_write_fmt(1, "ACK %s continue\n", last_hex);
                                else if (data->have_obj.nr == 1)
                                        packet_write_fmt(1, "ACK %s\n", last_hex);
                                break;
                        }
                        continue;
                }
                if (!strcmp(reader->line, "done")) {
                        if (data->have_obj.nr > 0) {
                                if (data->multi_ack)
                                        packet_write_fmt(1, "ACK %s\n", last_hex);
                                return 0;
                        }
                        packet_write_fmt(1, "NAK\n");
                        return -1;
                }
                die("git upload-pack: expected SHA1 list, got '%s'", reader->line);
        }
}

static int allow_hidden_refs(enum allow_uor allow_uor)
{
        if ((allow_uor & ALLOW_ANY_SHA1) == ALLOW_ANY_SHA1)
                return 1;
        return !(allow_uor & (ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1));
}

static void for_each_namespaced_ref_1(each_ref_fn fn,
                                      struct upload_pack_data *data)
{
        const char **excludes = NULL;
        /*
         * If `data->allow_uor` allows fetching hidden refs, we need to
         * mark all references (including hidden ones), to check in
         * `is_our_ref()` below.
         *
         * Otherwise, we only care about whether each reference's object
         * has the OUR_REF bit set or not, so do not need to visit
         * hidden references.
         */
        if (allow_hidden_refs(data->allow_uor))
                excludes = hidden_refs_to_excludes(&data->hidden_refs);

        for_each_namespaced_ref(excludes, fn, data);
}


static int is_our_ref(struct object *o, enum allow_uor allow_uor)
{
        return o->flags & ((allow_hidden_refs(allow_uor) ? 0 : HIDDEN_REF) | OUR_REF);
}

/*
 * on successful case, it's up to the caller to close cmd->out
 */
static int do_reachable_revlist(struct child_process *cmd,
                                struct object_array *src,
                                struct object_array *reachable,
                                enum allow_uor allow_uor)
{
        struct object *o;
        FILE *cmd_in = NULL;
        int i;

        strvec_pushl(&cmd->args, "rev-list", "--stdin", NULL);
        cmd->git_cmd = 1;
        cmd->no_stderr = 1;
        cmd->in = -1;
        cmd->out = -1;

        /*
         * If the next rev-list --stdin encounters an unknown commit,
         * it terminates, which will cause SIGPIPE in the write loop
         * below.
         */
        sigchain_push(SIGPIPE, SIG_IGN);

        if (start_command(cmd))
                goto error;

        cmd_in = xfdopen(cmd->in, "w");

        for (i = get_max_object_index(); 0 < i; ) {
                o = get_indexed_object(--i);
                if (!o)
                        continue;
                if (reachable && o->type == OBJ_COMMIT)
                        o->flags &= ~TMP_MARK;
                if (!is_our_ref(o, allow_uor))
                        continue;
                if (fprintf(cmd_in, "^%s\n", oid_to_hex(&o->oid)) < 0)
                        goto error;
        }
        for (i = 0; i < src->nr; i++) {
                o = src->objects[i].item;
                if (is_our_ref(o, allow_uor)) {
                        if (reachable)
                                add_object_array(o, NULL, reachable);
                        continue;
                }
                if (reachable && o->type == OBJ_COMMIT)
                        o->flags |= TMP_MARK;
                if (fprintf(cmd_in, "%s\n", oid_to_hex(&o->oid)) < 0)
                        goto error;
        }
        if (ferror(cmd_in) || fflush(cmd_in))
                goto error;
        fclose(cmd_in);
        cmd->in = -1;
        sigchain_pop(SIGPIPE);

        return 0;

error:
        sigchain_pop(SIGPIPE);

        if (cmd_in)
                fclose(cmd_in);
        if (cmd->out >= 0)
                close(cmd->out);
        return -1;
}

static int get_reachable_list(struct upload_pack_data *data,
                              struct object_array *reachable)
{
        struct child_process cmd = CHILD_PROCESS_INIT;
        int i;
        struct object *o;
        char namebuf[GIT_MAX_HEXSZ + 2]; /* ^ + hash + LF */
        const unsigned hexsz = the_hash_algo->hexsz;

        if (do_reachable_revlist(&cmd, &data->shallows, reachable,
                                 data->allow_uor) < 0)
                return -1;

        while ((i = read_in_full(cmd.out, namebuf, hexsz + 1)) == hexsz + 1) {
                struct object_id oid;
                const char *p;

                if (parse_oid_hex(namebuf, &oid, &p) || *p != '\n')
                        break;

                o = lookup_object(the_repository, &oid);
                if (o && o->type == OBJ_COMMIT) {
                        o->flags &= ~TMP_MARK;
                }
        }
        for (i = get_max_object_index(); 0 < i; i--) {
                o = get_indexed_object(i - 1);
                if (o && o->type == OBJ_COMMIT &&
                    (o->flags & TMP_MARK)) {
                        add_object_array(o, NULL, reachable);
                                o->flags &= ~TMP_MARK;
                }
        }
        close(cmd.out);

        if (finish_command(&cmd))
                return -1;

        return 0;
}

static int has_unreachable(struct object_array *src, enum allow_uor allow_uor)
{
        struct child_process cmd = CHILD_PROCESS_INIT;
        char buf[1];
        int i;

        if (do_reachable_revlist(&cmd, src, NULL, allow_uor) < 0)
                return 1;

        /*
         * The commits out of the rev-list are not ancestors of
         * our ref.
         */
        i = read_in_full(cmd.out, buf, 1);
        if (i)
                goto error;
        close(cmd.out);
        cmd.out = -1;

        /*
         * rev-list may have died by encountering a bad commit
         * in the history, in which case we do want to bail out
         * even when it showed no commit.
         */
        if (finish_command(&cmd))
                goto error;

        /* All the non-tip ones are ancestors of what we advertised */
        return 0;

error:
        if (cmd.out >= 0)
                close(cmd.out);
        return 1;
}

static void check_non_tip(struct upload_pack_data *data)
{
        int i;

        /*
         * In the normal in-process case without
         * uploadpack.allowReachableSHA1InWant,
         * non-tip requests can never happen.
         */
        if (!data->stateless_rpc && !(data->allow_uor & ALLOW_REACHABLE_SHA1))
                goto error;
        if (!has_unreachable(&data->want_obj, data->allow_uor))
                /* All the non-tip ones are ancestors of what we advertised */
                return;

error:
        /* Pick one of them (we know there at least is one) */
        for (i = 0; i < data->want_obj.nr; i++) {
                struct object *o = data->want_obj.objects[i].item;
                if (!is_our_ref(o, data->allow_uor)) {
                        error("git upload-pack: not our ref %s",
                              oid_to_hex(&o->oid));
                        packet_writer_error(&data->writer,
                                            "upload-pack: not our ref %s",
                                            oid_to_hex(&o->oid));
                        exit(128);
                }
        }
}

static void send_shallow(struct upload_pack_data *data,
                         struct commit_list *result)
{
        while (result) {
                struct object *object = &result->item->object;
                if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
                        packet_writer_write(&data->writer, "shallow %s",
                                            oid_to_hex(&object->oid));
                        register_shallow(the_repository, &object->oid);
                        data->shallow_nr++;
                }
                result = result->next;
        }
}

static void send_unshallow(struct upload_pack_data *data)
{
        int i;

        for (i = 0; i < data->shallows.nr; i++) {
                struct object *object = data->shallows.objects[i].item;
                if (object->flags & NOT_SHALLOW) {
                        struct commit_list *parents;
                        packet_writer_write(&data->writer, "unshallow %s",
                                            oid_to_hex(&object->oid));
                        object->flags &= ~CLIENT_SHALLOW;
                        /*
                         * We want to _register_ "object" as shallow, but we
                         * also need to traverse object's parents to deepen a
                         * shallow clone. Unregister it for now so we can
                         * parse and add the parents to the want list, then
                         * re-register it.
                         */
                        unregister_shallow(&object->oid);
                        object->parsed = 0;
                        parse_commit_or_die((struct commit *)object);
                        parents = ((struct commit *)object)->parents;
                        while (parents) {
                                add_object_array(&parents->item->object,
                                                 NULL, &data->want_obj);
                                parents = parents->next;
                        }
                        add_object_array(object, NULL, &data->extra_edge_obj);
                }
                /* make sure commit traversal conforms to client */
                register_shallow(the_repository, &object->oid);
        }
}

static int check_ref(const char *refname_full, const struct object_id *oid,
                     int flag, void *cb_data);
static void deepen(struct upload_pack_data *data, int depth)
{
        if (depth == INFINITE_DEPTH && !is_repository_shallow(the_repository)) {
                int i;

                for (i = 0; i < data->shallows.nr; i++) {
                        struct object *object = data->shallows.objects[i].item;
                        object->flags |= NOT_SHALLOW;
                }
        } else if (data->deepen_relative) {
                struct object_array reachable_shallows = OBJECT_ARRAY_INIT;
                struct commit_list *result;

                /*
                 * Checking for reachable shallows requires that our refs be
                 * marked with OUR_REF.
                 */
                head_ref_namespaced(check_ref, data);
                for_each_namespaced_ref_1(check_ref, data);

                get_reachable_list(data, &reachable_shallows);
                result = get_shallow_commits(&reachable_shallows,
                                             depth + 1,
                                             SHALLOW, NOT_SHALLOW);
                send_shallow(data, result);
                free_commit_list(result);
                object_array_clear(&reachable_shallows);
        } else {
                struct commit_list *result;

                result = get_shallow_commits(&data->want_obj, depth,
                                             SHALLOW, NOT_SHALLOW);
                send_shallow(data, result);
                free_commit_list(result);
        }

        send_unshallow(data);
}

static void deepen_by_rev_list(struct upload_pack_data *data,
                               int ac,
                               const char **av)
{
        struct commit_list *result;

        disable_commit_graph(the_repository);
        result = get_shallow_commits_by_rev_list(ac, av, SHALLOW, NOT_SHALLOW);
        send_shallow(data, result);
        free_commit_list(result);
        send_unshallow(data);
}

/* Returns 1 if a shallow list is sent or 0 otherwise */
static int send_shallow_list(struct upload_pack_data *data)
{
        int ret = 0;

        if (data->depth > 0 && data->deepen_rev_list)
                die("git upload-pack: deepen and deepen-since (or deepen-not) cannot be used together");
        if (data->depth > 0) {
                deepen(data, data->depth);
                ret = 1;
        } else if (data->deepen_rev_list) {
                struct strvec av = STRVEC_INIT;
                int i;

                strvec_push(&av, "rev-list");
                if (data->deepen_since)
                        strvec_pushf(&av, "--max-age=%"PRItime, data->deepen_since);
                if (oidset_size(&data->deepen_not)) {
                        const struct object_id *oid;
                        struct oidset_iter iter;
                        strvec_push(&av, "--not");
                        oidset_iter_init(&data->deepen_not, &iter);
                        while ((oid = oidset_iter_next(&iter)))
                                strvec_push(&av, oid_to_hex(oid));
                        strvec_push(&av, "--not");
                }
                for (i = 0; i < data->want_obj.nr; i++) {
                        struct object *o = data->want_obj.objects[i].item;
                        strvec_push(&av, oid_to_hex(&o->oid));
                }
                deepen_by_rev_list(data, av.nr, av.v);
                strvec_clear(&av);
                ret = 1;
        } else {
                if (data->shallows.nr > 0) {
                        int i;
                        for (i = 0; i < data->shallows.nr; i++)
                                register_shallow(the_repository,
                                                 &data->shallows.objects[i].item->oid);
                }
        }

        data->shallow_nr += data->shallows.nr;
        return ret;
}

static int process_shallow(const char *line, struct object_array *shallows)
{
        const char *arg;
        if (skip_prefix(line, "shallow ", &arg)) {
                struct object_id oid;
                struct object *object;
                if (get_oid_hex(arg, &oid))
                        die("invalid shallow line: %s", line);
                object = parse_object(the_repository, &oid);
                if (!object)
                        return 1;
                if (object->type != OBJ_COMMIT)
                        die("invalid shallow object %s", oid_to_hex(&oid));
                if (!(object->flags & CLIENT_SHALLOW)) {
                        object->flags |= CLIENT_SHALLOW;
                        add_object_array(object, NULL, shallows);
                }
                return 1;
        }

        return 0;
}

static int process_deepen(const char *line, int *depth)
{
        const char *arg;
        if (skip_prefix(line, "deepen ", &arg)) {
                char *end = NULL;
                *depth = (int)strtol(arg, &end, 0);
                if (!end || *end || *depth <= 0)
                        die("Invalid deepen: %s", line);
                return 1;
        }

        return 0;
}

static int process_deepen_since(const char *line, timestamp_t *deepen_since, int *deepen_rev_list)
{
        const char *arg;
        if (skip_prefix(line, "deepen-since ", &arg)) {
                char *end = NULL;
                *deepen_since = parse_timestamp(arg, &end, 0);
                if (!end || *end || !deepen_since ||
                    /* revisions.c's max_age -1 is special */
                    *deepen_since == -1)
                        die("Invalid deepen-since: %s", line);
                *deepen_rev_list = 1;
                return 1;
        }
        return 0;
}

static int process_deepen_not(const char *line, struct oidset *deepen_not, int *deepen_rev_list)
{
        const char *arg;
        if (skip_prefix(line, "deepen-not ", &arg)) {
                char *ref = NULL;
                struct object_id oid;
                if (expand_ref(the_repository, arg, strlen(arg), &oid, &ref) != 1)
                        die("git upload-pack: ambiguous deepen-not: %s", line);
                oidset_insert(deepen_not, &oid);
                free(ref);
                *deepen_rev_list = 1;
                return 1;
        }
        return 0;
}

NORETURN __attribute__((format(printf,2,3)))
static void send_err_and_die(struct upload_pack_data *data,
                             const char *fmt, ...)
{
        struct strbuf buf = STRBUF_INIT;
        va_list ap;

        va_start(ap, fmt);
        strbuf_vaddf(&buf, fmt, ap);
        va_end(ap);

        packet_writer_error(&data->writer, "%s", buf.buf);
        die("%s", buf.buf);
}

static void check_one_filter(struct upload_pack_data *data,
                             struct list_objects_filter_options *opts)
{
        const char *key = list_object_filter_config_name(opts->choice);
        struct string_list_item *item = string_list_lookup(&data->allowed_filters,
                                                           key);
        int allowed;

        if (item)
                allowed = (intptr_t)item->util;
        else
                allowed = data->allow_filter_fallback;

        if (!allowed)
                send_err_and_die(data, "filter '%s' not supported", key);

        if (opts->choice == LOFC_TREE_DEPTH &&
            opts->tree_exclude_depth > data->tree_filter_max_depth)
                send_err_and_die(data,
                                 "tree filter allows max depth %lu, but got %lu",
                                 data->tree_filter_max_depth,
                                 opts->tree_exclude_depth);
}

static void check_filter_recurse(struct upload_pack_data *data,
                                 struct list_objects_filter_options *opts)
{
        size_t i;

        check_one_filter(data, opts);
        if (opts->choice != LOFC_COMBINE)
                return;

        for (i = 0; i < opts->sub_nr; i++)
                check_filter_recurse(data, &opts->sub[i]);
}

static void die_if_using_banned_filter(struct upload_pack_data *data)
{
        check_filter_recurse(data, &data->filter_options);
}

static void receive_needs(struct upload_pack_data *data,
                          struct packet_reader *reader)
{
        int has_non_tip = 0;

        data->shallow_nr = 0;
        for (;;) {
                struct object *o;
                const char *features;
                struct object_id oid_buf;
                const char *arg;
                size_t feature_len;

                reset_timeout(data->timeout);
                if (packet_reader_read(reader) != PACKET_READ_NORMAL)
                        break;

                if (process_shallow(reader->line, &data->shallows))
                        continue;
                if (process_deepen(reader->line, &data->depth))
                        continue;
                if (process_deepen_since(reader->line, &data->deepen_since, &data->deepen_rev_list))
                        continue;
                if (process_deepen_not(reader->line, &data->deepen_not, &data->deepen_rev_list))
                        continue;

                if (skip_prefix(reader->line, "filter ", &arg)) {
                        if (!data->filter_capability_requested)
                                die("git upload-pack: filtering capability not negotiated");
                        list_objects_filter_die_if_populated(&data->filter_options);
                        parse_list_objects_filter(&data->filter_options, arg);
                        die_if_using_banned_filter(data);
                        continue;
                }

                if (!skip_prefix(reader->line, "want ", &arg) ||
                    parse_oid_hex(arg, &oid_buf, &features))
                        die("git upload-pack: protocol error, "
                            "expected to get object ID, not '%s'", reader->line);

                if (parse_feature_request(features, "deepen-relative"))
                        data->deepen_relative = 1;
                if (parse_feature_request(features, "multi_ack_detailed"))
                        data->multi_ack = MULTI_ACK_DETAILED;
                else if (parse_feature_request(features, "multi_ack"))
                        data->multi_ack = MULTI_ACK;
                if (parse_feature_request(features, "no-done"))
                        data->no_done = 1;
                if (parse_feature_request(features, "thin-pack"))
                        data->use_thin_pack = 1;
                if (parse_feature_request(features, "ofs-delta"))
                        data->use_ofs_delta = 1;
                if (parse_feature_request(features, "side-band-64k"))
                        data->use_sideband = LARGE_PACKET_MAX;
                else if (parse_feature_request(features, "side-band"))
                        data->use_sideband = DEFAULT_PACKET_MAX;
                if (parse_feature_request(features, "no-progress"))
                        data->no_progress = 1;
                if (parse_feature_request(features, "include-tag"))
                        data->use_include_tag = 1;
                if (data->allow_filter &&
                    parse_feature_request(features, "filter"))
                        data->filter_capability_requested = 1;

                arg = parse_feature_value(features, "session-id", &feature_len, NULL);
                if (arg) {
                        char *client_sid = xstrndup(arg, feature_len);
                        trace2_data_string("transfer", NULL, "client-sid", client_sid);
                        free(client_sid);
                }

                o = parse_object_with_flags(the_repository, &oid_buf,
                                            PARSE_OBJECT_SKIP_HASH_CHECK |
                                            PARSE_OBJECT_DISCARD_TREE);
                if (!o) {
                        packet_writer_error(&data->writer,
                                            "upload-pack: not our ref %s",
                                            oid_to_hex(&oid_buf));
                        die("git upload-pack: not our ref %s",
                            oid_to_hex(&oid_buf));
                }
                if (!(o->flags & WANTED)) {
                        o->flags |= WANTED;
                        if (!((data->allow_uor & ALLOW_ANY_SHA1) == ALLOW_ANY_SHA1
                              || is_our_ref(o, data->allow_uor)))
                                has_non_tip = 1;
                        add_object_array(o, NULL, &data->want_obj);
                }
        }

        /*
         * We have sent all our refs already, and the other end
         * should have chosen out of them. When we are operating
         * in the stateless RPC mode, however, their choice may
         * have been based on the set of older refs advertised
         * by another process that handled the initial request.
         */
        if (has_non_tip)
                check_non_tip(data);

        if (!data->use_sideband && data->daemon_mode)
                data->no_progress = 1;

        if (data->depth == 0 && !data->deepen_rev_list && data->shallows.nr == 0)
                return;

        if (send_shallow_list(data))
                packet_flush(1);
}

/* return non-zero if the ref is hidden, otherwise 0 */
static int mark_our_ref(const char *refname, const char *refname_full,
                        const struct object_id *oid, const struct strvec *hidden_refs)
{
        struct object *o = lookup_unknown_object(the_repository, oid);

        if (ref_is_hidden(refname, refname_full, hidden_refs)) {
                o->flags |= HIDDEN_REF;
                return 1;
        }
        o->flags |= OUR_REF;
        return 0;
}

static int check_ref(const char *refname_full, const struct object_id *oid,
                     int flag UNUSED, void *cb_data)
{
        const char *refname = strip_namespace(refname_full);
        struct upload_pack_data *data = cb_data;

        mark_our_ref(refname, refname_full, oid, &data->hidden_refs);
        return 0;
}

static void format_symref_info(struct strbuf *buf, struct string_list *symref)
{
        struct string_list_item *item;

        if (!symref->nr)
                return;
        for_each_string_list_item(item, symref)
                strbuf_addf(buf, " symref=%s:%s", item->string, (char *)item->util);
}

static void format_session_id(struct strbuf *buf, struct upload_pack_data *d) {
        if (d->advertise_sid)
                strbuf_addf(buf, " session-id=%s", trace2_session_id());
}

static void write_v0_ref(struct upload_pack_data *data,
                        const char *refname, const char *refname_nons,
                        const struct object_id *oid)
{
        static const char *capabilities = "multi_ack thin-pack side-band"
                " side-band-64k ofs-delta shallow deepen-since deepen-not"
                " deepen-relative no-progress include-tag multi_ack_detailed";
        struct object_id peeled;

        if (mark_our_ref(refname_nons, refname, oid, &data->hidden_refs))
                return;

        if (capabilities) {
                struct strbuf symref_info = STRBUF_INIT;
                struct strbuf session_id = STRBUF_INIT;

                format_symref_info(&symref_info, &data->symref);
                format_session_id(&session_id, data);
                packet_fwrite_fmt(stdout, "%s %s%c%s%s%s%s%s%s%s object-format=%s agent=%s\n",
                             oid_to_hex(oid), refname_nons,
                             0, capabilities,
                             (data->allow_uor & ALLOW_TIP_SHA1) ?
                                     " allow-tip-sha1-in-want" : "",
                             (data->allow_uor & ALLOW_REACHABLE_SHA1) ?
                                     " allow-reachable-sha1-in-want" : "",
                             data->no_done ? " no-done" : "",
                             symref_info.buf,
                             data->allow_filter ? " filter" : "",
                             session_id.buf,
                             the_hash_algo->name,
                             git_user_agent_sanitized());
                strbuf_release(&symref_info);
                strbuf_release(&session_id);
                data->sent_capabilities = 1;
        } else {
                packet_fwrite_fmt(stdout, "%s %s\n", oid_to_hex(oid), refname_nons);
        }
        capabilities = NULL;
        if (!peel_iterated_oid(oid, &peeled))
                packet_fwrite_fmt(stdout, "%s %s^{}\n", oid_to_hex(&peeled), refname_nons);
        return;
}

static int send_ref(const char *refname, const struct object_id *oid,
                    int flag UNUSED, void *cb_data)
{
        write_v0_ref(cb_data, refname, strip_namespace(refname), oid);
        return 0;
}

static int find_symref(const char *refname,
                       const struct object_id *oid UNUSED,
                       int flag, void *cb_data)
{
        const char *symref_target;
        struct string_list_item *item;

        if ((flag & REF_ISSYMREF) == 0)
                return 0;
        symref_target = resolve_ref_unsafe(refname, 0, NULL, &flag);
        if (!symref_target || (flag & REF_ISSYMREF) == 0)
                die("'%s' is a symref but it is not?", refname);
        item = string_list_append(cb_data, strip_namespace(refname));
        item->util = xstrdup(strip_namespace(symref_target));
        return 0;
}

static int parse_object_filter_config(const char *var, const char *value,
                                      const struct key_value_info *kvi,
                                      struct upload_pack_data *data)
{
        struct strbuf buf = STRBUF_INIT;
        const char *sub, *key;
        size_t sub_len;

        if (parse_config_key(var, "uploadpackfilter", &sub, &sub_len, &key))
                return 0;

        if (!sub) {
                if (!strcmp(key, "allow"))
                        data->allow_filter_fallback = git_config_bool(var, value);
                return 0;
        }

        strbuf_add(&buf, sub, sub_len);

        if (!strcmp(key, "allow"))
                string_list_insert(&data->allowed_filters, buf.buf)->util =
                        (void *)(intptr_t)git_config_bool(var, value);
        else if (!strcmp(buf.buf, "tree") && !strcmp(key, "maxdepth")) {
                if (!value) {
                        strbuf_release(&buf);
                        return config_error_nonbool(var);
                }
                string_list_insert(&data->allowed_filters, buf.buf)->util =
                        (void *)(intptr_t)1;
                data->tree_filter_max_depth = git_config_ulong(var, value,
                                                               kvi);
        }

        strbuf_release(&buf);
        return 0;
}

static int upload_pack_config(const char *var, const char *value,
                              const struct config_context *ctx,
                              void *cb_data)
{
        struct upload_pack_data *data = cb_data;

        if (!strcmp("uploadpack.allowtipsha1inwant", var)) {
                if (git_config_bool(var, value))
                        data->allow_uor |= ALLOW_TIP_SHA1;
                else
                        data->allow_uor &= ~ALLOW_TIP_SHA1;
        } else if (!strcmp("uploadpack.allowreachablesha1inwant", var)) {
                if (git_config_bool(var, value))
                        data->allow_uor |= ALLOW_REACHABLE_SHA1;
                else
                        data->allow_uor &= ~ALLOW_REACHABLE_SHA1;
        } else if (!strcmp("uploadpack.allowanysha1inwant", var)) {
                if (git_config_bool(var, value))
                        data->allow_uor |= ALLOW_ANY_SHA1;
                else
                        data->allow_uor &= ~ALLOW_ANY_SHA1;
        } else if (!strcmp("uploadpack.keepalive", var)) {
                data->keepalive = git_config_int(var, value, ctx->kvi);
                if (!data->keepalive)
                        data->keepalive = -1;
        } else if (!strcmp("uploadpack.allowfilter", var)) {
                data->allow_filter = git_config_bool(var, value);
        } else if (!strcmp("uploadpack.allowrefinwant", var)) {
                data->allow_ref_in_want = git_config_bool(var, value);
        } else if (!strcmp("uploadpack.allowsidebandall", var)) {
                data->allow_sideband_all = git_config_bool(var, value);
        } else if (!strcmp("uploadpack.blobpackfileuri", var)) {
                if (value)
                        data->allow_packfile_uris = 1;
        } else if (!strcmp("core.precomposeunicode", var)) {
                precomposed_unicode = git_config_bool(var, value);
        } else if (!strcmp("transfer.advertisesid", var)) {
                data->advertise_sid = git_config_bool(var, value);
        }

        if (parse_object_filter_config(var, value, ctx->kvi, data) < 0)
                return -1;

        return parse_hide_refs_config(var, value, "uploadpack", &data->hidden_refs);
}

static int upload_pack_protected_config(const char *var, const char *value,
                                        const struct config_context *ctx UNUSED,
                                        void *cb_data)
{
        struct upload_pack_data *data = cb_data;

        if (!strcmp("uploadpack.packobjectshook", var))
                return git_config_string(&data->pack_objects_hook, var, value);
        return 0;
}

static void get_upload_pack_config(struct repository *r,
                                   struct upload_pack_data *data)
{
        repo_config(r, upload_pack_config, data);
        git_protected_config(upload_pack_protected_config, data);

        data->allow_sideband_all |= git_env_bool("GIT_TEST_SIDEBAND_ALL", 0);
}

void upload_pack(const int advertise_refs, const int stateless_rpc,
                 const int timeout)
{
        struct packet_reader reader;
        struct upload_pack_data data;

        upload_pack_data_init(&data);
        get_upload_pack_config(the_repository, &data);

        data.stateless_rpc = stateless_rpc;
        data.timeout = timeout;
        if (data.timeout)
                data.daemon_mode = 1;

        head_ref_namespaced(find_symref, &data.symref);

        if (advertise_refs || !data.stateless_rpc) {
                reset_timeout(data.timeout);
                if (advertise_refs)
                        data.no_done = 1;
                head_ref_namespaced(send_ref, &data);
                for_each_namespaced_ref_1(send_ref, &data);
                if (!data.sent_capabilities) {
                        const char *refname = "capabilities^{}";
                        write_v0_ref(&data, refname, refname, null_oid());
                }
                /*
                 * fflush stdout before calling advertise_shallow_grafts because send_ref
                 * uses stdio.
                 */
                fflush_or_die(stdout);
                advertise_shallow_grafts(1);
                packet_flush(1);
        } else {
                head_ref_namespaced(check_ref, &data);
                for_each_namespaced_ref_1(check_ref, &data);
        }

        if (!advertise_refs) {
                packet_reader_init(&reader, 0, NULL, 0,
                                   PACKET_READ_CHOMP_NEWLINE |
                                   PACKET_READ_DIE_ON_ERR_PACKET);

                receive_needs(&data, &reader);

                /*
                 * An EOF at this exact point in negotiation should be
                 * acceptable from stateless clients as they will consume the
                 * shallow list before doing subsequent rpc with haves/etc.
                 */
                if (data.stateless_rpc)
                        reader.options |= PACKET_READ_GENTLE_ON_EOF;

                if (data.want_obj.nr &&
                    packet_reader_peek(&reader) != PACKET_READ_EOF) {
                        reader.options &= ~PACKET_READ_GENTLE_ON_EOF;
                        get_common_commits(&data, &reader);
                        create_pack_file(&data, NULL);
                }
        }

        upload_pack_data_clear(&data);
}

static int parse_want(struct packet_writer *writer, const char *line,
                      struct object_array *want_obj)
{
        const char *arg;
        if (skip_prefix(line, "want ", &arg)) {
                struct object_id oid;
                struct object *o;

                if (get_oid_hex(arg, &oid))
                        die("git upload-pack: protocol error, "
                            "expected to get oid, not '%s'", line);

                o = parse_object_with_flags(the_repository, &oid,
                                            PARSE_OBJECT_SKIP_HASH_CHECK |
                                            PARSE_OBJECT_DISCARD_TREE);

                if (!o) {
                        packet_writer_error(writer,
                                            "upload-pack: not our ref %s",
                                            oid_to_hex(&oid));
                        die("git upload-pack: not our ref %s",
                            oid_to_hex(&oid));
                }

                if (!(o->flags & WANTED)) {
                        o->flags |= WANTED;
                        add_object_array(o, NULL, want_obj);
                }

                return 1;
        }

        return 0;
}

static int parse_want_ref(struct packet_writer *writer, const char *line,
                          struct strmap *wanted_refs,
                          struct strvec *hidden_refs,
                          struct object_array *want_obj)
{
        const char *refname_nons;
        if (skip_prefix(line, "want-ref ", &refname_nons)) {
                struct object_id oid;
                struct object *o = NULL;
                struct strbuf refname = STRBUF_INIT;

                strbuf_addf(&refname, "%s%s", get_git_namespace(), refname_nons);
                if (ref_is_hidden(refname_nons, refname.buf, hidden_refs) ||
                    read_ref(refname.buf, &oid)) {
                        packet_writer_error(writer, "unknown ref %s", refname_nons);
                        die("unknown ref %s", refname_nons);
                }
                strbuf_release(&refname);

                if (strmap_put(wanted_refs, refname_nons, oiddup(&oid))) {
                        packet_writer_error(writer, "duplicate want-ref %s",
                                            refname_nons);
                        die("duplicate want-ref %s", refname_nons);
                }

                if (!starts_with(refname_nons, "refs/tags/")) {
                        struct commit *commit = lookup_commit_in_graph(the_repository, &oid);
                        if (commit)
                                o = &commit->object;
                }

                if (!o)
                        o = parse_object_or_die(&oid, refname_nons);

                if (!(o->flags & WANTED)) {
                        o->flags |= WANTED;
                        add_object_array(o, NULL, want_obj);
                }

                return 1;
        }

        return 0;
}

static int parse_have(const char *line, struct upload_pack_data *data)
{
        const char *arg;
        if (skip_prefix(line, "have ", &arg)) {
                struct object_id oid;

                got_oid(data, arg, &oid);
                data->seen_haves = 1;
                return 1;
        }

        return 0;
}

static void trace2_fetch_info(struct upload_pack_data *data)
{
        struct json_writer jw = JSON_WRITER_INIT;

        jw_object_begin(&jw, 0);
        jw_object_intmax(&jw, "haves", data->have_obj.nr);
        jw_object_intmax(&jw, "wants", data->want_obj.nr);
        jw_object_intmax(&jw, "want-refs", strmap_get_size(&data->wanted_refs));
        jw_object_intmax(&jw, "depth", data->depth);
        jw_object_intmax(&jw, "shallows", data->shallows.nr);
        jw_object_bool(&jw, "deepen-since", data->deepen_since);
        jw_object_intmax(&jw, "deepen-not", oidset_size(&data->deepen_not));
        jw_object_bool(&jw, "deepen-relative", data->deepen_relative);
        if (data->filter_options.choice)
                jw_object_string(&jw, "filter", list_object_filter_config_name(data->filter_options.choice));
        else
                jw_object_null(&jw, "filter");
        jw_end(&jw);

        trace2_data_json("upload-pack", the_repository, "fetch-info", &jw);

        jw_release(&jw);
}

static void process_args(struct packet_reader *request,
                         struct upload_pack_data *data)
{
        while (packet_reader_read(request) == PACKET_READ_NORMAL) {
                const char *arg = request->line;
                const char *p;

                /* process want */
                if (parse_want(&data->writer, arg, &data->want_obj))
                        continue;
                if (data->allow_ref_in_want &&
                    parse_want_ref(&data->writer, arg, &data->wanted_refs,
                                   &data->hidden_refs, &data->want_obj))
                        continue;
                /* process have line */
                if (parse_have(arg, data))
                        continue;

                /* process args like thin-pack */
                if (!strcmp(arg, "thin-pack")) {
                        data->use_thin_pack = 1;
                        continue;
                }
                if (!strcmp(arg, "ofs-delta")) {
                        data->use_ofs_delta = 1;
                        continue;
                }
                if (!strcmp(arg, "no-progress")) {
                        data->no_progress = 1;
                        continue;
                }
                if (!strcmp(arg, "include-tag")) {
                        data->use_include_tag = 1;
                        continue;
                }
                if (!strcmp(arg, "done")) {
                        data->done = 1;
                        continue;
                }
                if (!strcmp(arg, "wait-for-done")) {
                        data->wait_for_done = 1;
                        continue;
                }

                /* Shallow related arguments */
                if (process_shallow(arg, &data->shallows))
                        continue;
                if (process_deepen(arg, &data->depth))
                        continue;
                if (process_deepen_since(arg, &data->deepen_since,
                                         &data->deepen_rev_list))
                        continue;
                if (process_deepen_not(arg, &data->deepen_not,
                                       &data->deepen_rev_list))
                        continue;
                if (!strcmp(arg, "deepen-relative")) {
                        data->deepen_relative = 1;
                        continue;
                }

                if (data->allow_filter && skip_prefix(arg, "filter ", &p)) {
                        list_objects_filter_die_if_populated(&data->filter_options);
                        parse_list_objects_filter(&data->filter_options, p);
                        die_if_using_banned_filter(data);
                        continue;
                }

                if (data->allow_sideband_all &&
                    !strcmp(arg, "sideband-all")) {
                        data->writer.use_sideband = 1;
                        continue;
                }

                if (data->allow_packfile_uris &&
                    skip_prefix(arg, "packfile-uris ", &p)) {
                        if (data->uri_protocols.nr)
                                send_err_and_die(data,
                                                 "multiple packfile-uris lines forbidden");
                        string_list_split(&data->uri_protocols, p, ',', -1);
                        continue;
                }

                /* ignore unknown lines maybe? */
                die("unexpected line: '%s'", arg);
        }

        if (data->uri_protocols.nr && !data->writer.use_sideband)
                string_list_clear(&data->uri_protocols, 0);

        if (request->status != PACKET_READ_FLUSH)
                die(_("expected flush after fetch arguments"));

        if (trace2_is_enabled())
                trace2_fetch_info(data);
}

static int send_acks(struct upload_pack_data *data, struct object_array *acks)
{
        int i;

        packet_writer_write(&data->writer, "acknowledgments\n");

        /* Send Acks */
        if (!acks->nr)
                packet_writer_write(&data->writer, "NAK\n");

        for (i = 0; i < acks->nr; i++) {
                packet_writer_write(&data->writer, "ACK %s\n",
                                    oid_to_hex(&acks->objects[i].item->oid));
        }

        if (!data->wait_for_done && ok_to_give_up(data)) {
                /* Send Ready */
                packet_writer_write(&data->writer, "ready\n");
                return 1;
        }

        return 0;
}

static int process_haves_and_send_acks(struct upload_pack_data *data)
{
        int ret = 0;

        if (data->done) {
                ret = 1;
        } else if (send_acks(data, &data->have_obj)) {
                packet_writer_delim(&data->writer);
                ret = 1;
        } else {
                /* Add Flush */
                packet_writer_flush(&data->writer);
                ret = 0;
        }

        return ret;
}

static void send_wanted_ref_info(struct upload_pack_data *data)
{
        struct hashmap_iter iter;
        const struct strmap_entry *e;

        if (strmap_empty(&data->wanted_refs))
                return;

        packet_writer_write(&data->writer, "wanted-refs\n");

        strmap_for_each_entry(&data->wanted_refs, &iter, e) {
                packet_writer_write(&data->writer, "%s %s\n",
                                    oid_to_hex(e->value),
                                    e->key);
        }

        packet_writer_delim(&data->writer);
}

static void send_shallow_info(struct upload_pack_data *data)
{
        /* No shallow info needs to be sent */
        if (!data->depth && !data->deepen_rev_list && !data->shallows.nr &&
            !is_repository_shallow(the_repository))
                return;

        packet_writer_write(&data->writer, "shallow-info\n");

        if (!send_shallow_list(data) &&
            is_repository_shallow(the_repository))
                deepen(data, INFINITE_DEPTH);

        packet_delim(1);
}

enum fetch_state {
        FETCH_PROCESS_ARGS = 0,
        FETCH_SEND_ACKS,
        FETCH_SEND_PACK,
        FETCH_DONE,
};

int upload_pack_v2(struct repository *r, struct packet_reader *request)
{
        enum fetch_state state = FETCH_PROCESS_ARGS;
        struct upload_pack_data data;

        clear_object_flags(ALL_FLAGS);

        upload_pack_data_init(&data);
        data.use_sideband = LARGE_PACKET_MAX;
        get_upload_pack_config(r, &data);

        while (state != FETCH_DONE) {
                switch (state) {
                case FETCH_PROCESS_ARGS:
                        process_args(request, &data);

                        if (!data.want_obj.nr && !data.wait_for_done) {
                                /*
                                 * Request didn't contain any 'want' lines (and
                                 * the request does not contain
                                 * "wait-for-done", in which it is reasonable
                                 * to just send 'have's without 'want's); guess
                                 * they didn't want anything.
                                 */
                                state = FETCH_DONE;
                        } else if (data.seen_haves) {
                                /*
                                 * Request had 'have' lines, so lets ACK them.
                                 */
                                state = FETCH_SEND_ACKS;
                        } else {
                                /*
                                 * Request had 'want's but no 'have's so we can
                                 * immedietly go to construct and send a pack.
                                 */
                                state = FETCH_SEND_PACK;
                        }
                        break;
                case FETCH_SEND_ACKS:
                        if (process_haves_and_send_acks(&data))
                                state = FETCH_SEND_PACK;
                        else
                                state = FETCH_DONE;
                        break;
                case FETCH_SEND_PACK:
                        send_wanted_ref_info(&data);
                        send_shallow_info(&data);

                        if (data.uri_protocols.nr) {
                                create_pack_file(&data, &data.uri_protocols);
                        } else {
                                packet_writer_write(&data.writer, "packfile\n");
                                create_pack_file(&data, NULL);
                        }
                        state = FETCH_DONE;
                        break;
                case FETCH_DONE:
                        continue;
                }
        }

        upload_pack_data_clear(&data);
        return 0;
}

int upload_pack_advertise(struct repository *r,
                          struct strbuf *value)
{
        struct upload_pack_data data;

        upload_pack_data_init(&data);
        get_upload_pack_config(r, &data);

        if (value) {
                strbuf_addstr(value, "shallow wait-for-done");

                if (data.allow_filter)
                        strbuf_addstr(value, " filter");

                if (data.allow_ref_in_want)
                        strbuf_addstr(value, " ref-in-want");

                if (data.allow_sideband_all)
                        strbuf_addstr(value, " sideband-all");

                if (data.allow_packfile_uris)
                        strbuf_addstr(value, " packfile-uris");
        }

        upload_pack_data_clear(&data);

        return 1;
}