builtin/repack.c: extract common cruft pack loop

[git/gitster.git] / builtin / repack.c

#include "builtin.h"
#include "config.h"
#include "dir.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "parse-options.h"
#include "path.h"
#include "run-command.h"
#include "server-info.h"
#include "sigchain.h"
#include "strbuf.h"
#include "string-list.h"
#include "strvec.h"
#include "midx.h"
#include "packfile.h"
#include "prune-packed.h"
#include "object-store-ll.h"
#include "promisor-remote.h"
#include "shallow.h"
#include "pack.h"
#include "pack-bitmap.h"
#include "refs.h"

#define ALL_INTO_ONE 1
#define LOOSEN_UNREACHABLE 2
#define PACK_CRUFT 4

#define DELETE_PACK 1

static int pack_everything;
static int delta_base_offset = 1;
static int pack_kept_objects = -1;
static int write_bitmaps = -1;
static int use_delta_islands;
static int run_update_server_info = 1;
static char *packdir, *packtmp_name, *packtmp;

static const char *const git_repack_usage[] = {
        N_("git repack [<options>]"),
        NULL
};

static const char incremental_bitmap_conflict_error[] = N_(
"Incremental repacks are incompatible with bitmap indexes.  Use\n"
"--no-write-bitmap-index or disable the pack.writeBitmaps configuration."
);

struct pack_objects_args {
        const char *window;
        const char *window_memory;
        const char *depth;
        const char *threads;
        const char *max_pack_size;
        int no_reuse_delta;
        int no_reuse_object;
        int quiet;
        int local;
};

static int repack_config(const char *var, const char *value,
                         const struct config_context *ctx, void *cb)
{
        struct pack_objects_args *cruft_po_args = cb;
        if (!strcmp(var, "repack.usedeltabaseoffset")) {
                delta_base_offset = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "repack.packkeptobjects")) {
                pack_kept_objects = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "repack.writebitmaps") ||
            !strcmp(var, "pack.writebitmaps")) {
                write_bitmaps = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "repack.usedeltaislands")) {
                use_delta_islands = git_config_bool(var, value);
                return 0;
        }
        if (strcmp(var, "repack.updateserverinfo") == 0) {
                run_update_server_info = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "repack.cruftwindow"))
                return git_config_string(&cruft_po_args->window, var, value);
        if (!strcmp(var, "repack.cruftwindowmemory"))
                return git_config_string(&cruft_po_args->window_memory, var, value);
        if (!strcmp(var, "repack.cruftdepth"))
                return git_config_string(&cruft_po_args->depth, var, value);
        if (!strcmp(var, "repack.cruftthreads"))
                return git_config_string(&cruft_po_args->threads, var, value);
        return git_default_config(var, value, ctx, cb);
}

struct existing_packs {
        struct string_list kept_packs;
        struct string_list non_kept_packs;
        struct string_list cruft_packs;
};

#define EXISTING_PACKS_INIT { \
        .kept_packs = STRING_LIST_INIT_DUP, \
        .non_kept_packs = STRING_LIST_INIT_DUP, \
        .cruft_packs = STRING_LIST_INIT_DUP, \
}

static int has_existing_non_kept_packs(const struct existing_packs *existing)
{
        return existing->non_kept_packs.nr || existing->cruft_packs.nr;
}

static void pack_mark_for_deletion(struct string_list_item *item)
{
        item->util = (void*)((uintptr_t)item->util | DELETE_PACK);
}

static int pack_is_marked_for_deletion(struct string_list_item *item)
{
        return (uintptr_t)item->util & DELETE_PACK;
}

static void mark_packs_for_deletion_1(struct string_list *names,
                                      struct string_list *list)
{
        struct string_list_item *item;
        const int hexsz = the_hash_algo->hexsz;

        for_each_string_list_item(item, list) {
                char *sha1;
                size_t len = strlen(item->string);
                if (len < hexsz)
                        continue;
                sha1 = item->string + len - hexsz;
                /*
                 * Mark this pack for deletion, which ensures that this
                 * pack won't be included in a MIDX (if `--write-midx`
                 * was given) and that we will actually delete this pack
                 * (if `-d` was given).
                 */
                if (!string_list_has_string(names, sha1))
                        pack_mark_for_deletion(item);
        }
}

static void mark_packs_for_deletion(struct existing_packs *existing,
                                    struct string_list *names)

{
        mark_packs_for_deletion_1(names, &existing->non_kept_packs);
        mark_packs_for_deletion_1(names, &existing->cruft_packs);
}

static void remove_redundant_pack(const char *dir_name, const char *base_name)
{
        struct strbuf buf = STRBUF_INIT;
        struct multi_pack_index *m = get_local_multi_pack_index(the_repository);
        strbuf_addf(&buf, "%s.pack", base_name);
        if (m && midx_contains_pack(m, buf.buf))
                clear_midx_file(the_repository);
        strbuf_insertf(&buf, 0, "%s/", dir_name);
        unlink_pack_path(buf.buf, 1);
        strbuf_release(&buf);
}

static void remove_redundant_packs_1(struct string_list *packs)
{
        struct string_list_item *item;
        for_each_string_list_item(item, packs) {
                if (!pack_is_marked_for_deletion(item))
                        continue;
                remove_redundant_pack(packdir, item->string);
        }
}

static void remove_redundant_existing_packs(struct existing_packs *existing)
{
        remove_redundant_packs_1(&existing->non_kept_packs);
        remove_redundant_packs_1(&existing->cruft_packs);
}

static void existing_packs_release(struct existing_packs *existing)
{
        string_list_clear(&existing->kept_packs, 0);
        string_list_clear(&existing->non_kept_packs, 0);
        string_list_clear(&existing->cruft_packs, 0);
}

/*
 * Adds all packs hex strings (pack-$HASH) to either packs->non_kept
 * or packs->kept based on whether each pack has a corresponding
 * .keep file or not.  Packs without a .keep file are not to be kept
 * if we are going to pack everything into one file.
 */
static void collect_pack_filenames(struct existing_packs *existing,
                                   const struct string_list *extra_keep)
{
        struct packed_git *p;
        struct strbuf buf = STRBUF_INIT;

        for (p = get_all_packs(the_repository); p; p = p->next) {
                int i;
                const char *base;

                if (!p->pack_local)
                        continue;

                base = pack_basename(p);

                for (i = 0; i < extra_keep->nr; i++)
                        if (!fspathcmp(base, extra_keep->items[i].string))
                                break;

                strbuf_reset(&buf);
                strbuf_addstr(&buf, base);
                strbuf_strip_suffix(&buf, ".pack");

                if ((extra_keep->nr > 0 && i < extra_keep->nr) || p->pack_keep)
                        string_list_append(&existing->kept_packs, buf.buf);
                else if (p->is_cruft)
                        string_list_append(&existing->cruft_packs, buf.buf);
                else
                        string_list_append(&existing->non_kept_packs, buf.buf);
        }

        string_list_sort(&existing->kept_packs);
        strbuf_release(&buf);
}

static void prepare_pack_objects(struct child_process *cmd,
                                 const struct pack_objects_args *args,
                                 const char *out)
{
        strvec_push(&cmd->args, "pack-objects");
        if (args->window)
                strvec_pushf(&cmd->args, "--window=%s", args->window);
        if (args->window_memory)
                strvec_pushf(&cmd->args, "--window-memory=%s", args->window_memory);
        if (args->depth)
                strvec_pushf(&cmd->args, "--depth=%s", args->depth);
        if (args->threads)
                strvec_pushf(&cmd->args, "--threads=%s", args->threads);
        if (args->max_pack_size)
                strvec_pushf(&cmd->args, "--max-pack-size=%s", args->max_pack_size);
        if (args->no_reuse_delta)
                strvec_pushf(&cmd->args, "--no-reuse-delta");
        if (args->no_reuse_object)
                strvec_pushf(&cmd->args, "--no-reuse-object");
        if (args->local)
                strvec_push(&cmd->args,  "--local");
        if (args->quiet)
                strvec_push(&cmd->args,  "--quiet");
        if (delta_base_offset)
                strvec_push(&cmd->args,  "--delta-base-offset");
        strvec_push(&cmd->args, out);
        cmd->git_cmd = 1;
        cmd->out = -1;
}

/*
 * Write oid to the given struct child_process's stdin, starting it first if
 * necessary.
 */
static int write_oid(const struct object_id *oid,
                     struct packed_git *pack UNUSED,
                     uint32_t pos UNUSED, void *data)
{
        struct child_process *cmd = data;

        if (cmd->in == -1) {
                if (start_command(cmd))
                        die(_("could not start pack-objects to repack promisor objects"));
        }

        xwrite(cmd->in, oid_to_hex(oid), the_hash_algo->hexsz);
        xwrite(cmd->in, "\n", 1);
        return 0;
}

static struct {
        const char *name;
        unsigned optional:1;
} exts[] = {
        {".pack"},
        {".rev", 1},
        {".mtimes", 1},
        {".bitmap", 1},
        {".promisor", 1},
        {".idx"},
};

struct generated_pack_data {
        struct tempfile *tempfiles[ARRAY_SIZE(exts)];
};

static struct generated_pack_data *populate_pack_exts(const char *name)
{
        struct stat statbuf;
        struct strbuf path = STRBUF_INIT;
        struct generated_pack_data *data = xcalloc(1, sizeof(*data));
        int i;

        for (i = 0; i < ARRAY_SIZE(exts); i++) {
                strbuf_reset(&path);
                strbuf_addf(&path, "%s-%s%s", packtmp, name, exts[i].name);

                if (stat(path.buf, &statbuf))
                        continue;

                data->tempfiles[i] = register_tempfile(path.buf);
        }

        strbuf_release(&path);
        return data;
}

static void repack_promisor_objects(const struct pack_objects_args *args,
                                    struct string_list *names)
{
        struct child_process cmd = CHILD_PROCESS_INIT;
        FILE *out;
        struct strbuf line = STRBUF_INIT;

        prepare_pack_objects(&cmd, args, packtmp);
        cmd.in = -1;

        /*
         * NEEDSWORK: Giving pack-objects only the OIDs without any ordering
         * hints may result in suboptimal deltas in the resulting pack. See if
         * the OIDs can be sent with fake paths such that pack-objects can use a
         * {type -> existing pack order} ordering when computing deltas instead
         * of a {type -> size} ordering, which may produce better deltas.
         */
        for_each_packed_object(write_oid, &cmd,
                               FOR_EACH_OBJECT_PROMISOR_ONLY);

        if (cmd.in == -1) {
                /* No packed objects; cmd was never started */
                child_process_clear(&cmd);
                return;
        }

        close(cmd.in);

        out = xfdopen(cmd.out, "r");
        while (strbuf_getline_lf(&line, out) != EOF) {
                struct string_list_item *item;
                char *promisor_name;

                if (line.len != the_hash_algo->hexsz)
                        die(_("repack: Expecting full hex object ID lines only from pack-objects."));
                item = string_list_append(names, line.buf);

                /*
                 * pack-objects creates the .pack and .idx files, but not the
                 * .promisor file. Create the .promisor file, which is empty.
                 *
                 * NEEDSWORK: fetch-pack sometimes generates non-empty
                 * .promisor files containing the ref names and associated
                 * hashes at the point of generation of the corresponding
                 * packfile, but this would not preserve their contents. Maybe
                 * concatenate the contents of all .promisor files instead of
                 * just creating a new empty file.
                 */
                promisor_name = mkpathdup("%s-%s.promisor", packtmp,
                                          line.buf);
                write_promisor_file(promisor_name, NULL, 0);

                item->util = populate_pack_exts(item->string);

                free(promisor_name);
        }
        fclose(out);
        if (finish_command(&cmd))
                die(_("could not finish pack-objects to repack promisor objects"));
}

struct pack_geometry {
        struct packed_git **pack;
        uint32_t pack_nr, pack_alloc;
        uint32_t split;

        int split_factor;
};

static uint32_t geometry_pack_weight(struct packed_git *p)
{
        if (open_pack_index(p))
                die(_("cannot open index for %s"), p->pack_name);
        return p->num_objects;
}

static int geometry_cmp(const void *va, const void *vb)
{
        uint32_t aw = geometry_pack_weight(*(struct packed_git **)va),
                 bw = geometry_pack_weight(*(struct packed_git **)vb);

        if (aw < bw)
                return -1;
        if (aw > bw)
                return 1;
        return 0;
}

static void init_pack_geometry(struct pack_geometry *geometry,
                               struct existing_packs *existing,
                               const struct pack_objects_args *args)
{
        struct packed_git *p;
        struct strbuf buf = STRBUF_INIT;

        for (p = get_all_packs(the_repository); p; p = p->next) {
                if (args->local && !p->pack_local)
                        /*
                         * When asked to only repack local packfiles we skip
                         * over any packfiles that are borrowed from alternate
                         * object directories.
                         */
                        continue;

                if (!pack_kept_objects) {
                        /*
                         * Any pack that has its pack_keep bit set will
                         * appear in existing->kept_packs below, but
                         * this saves us from doing a more expensive
                         * check.
                         */
                        if (p->pack_keep)
                                continue;

                        /*
                         * The pack may be kept via the --keep-pack
                         * option; check 'existing->kept_packs' to
                         * determine whether to ignore it.
                         */
                        strbuf_reset(&buf);
                        strbuf_addstr(&buf, pack_basename(p));
                        strbuf_strip_suffix(&buf, ".pack");

                        if (string_list_has_string(&existing->kept_packs, buf.buf))
                                continue;
                }
                if (p->is_cruft)
                        continue;

                ALLOC_GROW(geometry->pack,
                           geometry->pack_nr + 1,
                           geometry->pack_alloc);

                geometry->pack[geometry->pack_nr] = p;
                geometry->pack_nr++;
        }

        QSORT(geometry->pack, geometry->pack_nr, geometry_cmp);
        strbuf_release(&buf);
}

static void split_pack_geometry(struct pack_geometry *geometry)
{
        uint32_t i;
        uint32_t split;
        off_t total_size = 0;

        if (!geometry->pack_nr) {
                geometry->split = geometry->pack_nr;
                return;
        }

        /*
         * First, count the number of packs (in descending order of size) which
         * already form a geometric progression.
         */
        for (i = geometry->pack_nr - 1; i > 0; i--) {
                struct packed_git *ours = geometry->pack[i];
                struct packed_git *prev = geometry->pack[i - 1];

                if (unsigned_mult_overflows(geometry->split_factor,
                                            geometry_pack_weight(prev)))
                        die(_("pack %s too large to consider in geometric "
                              "progression"),
                            prev->pack_name);

                if (geometry_pack_weight(ours) <
                    geometry->split_factor * geometry_pack_weight(prev))
                        break;
        }

        split = i;

        if (split) {
                /*
                 * Move the split one to the right, since the top element in the
                 * last-compared pair can't be in the progression. Only do this
                 * when we split in the middle of the array (otherwise if we got
                 * to the end, then the split is in the right place).
                 */
                split++;
        }

        /*
         * Then, anything to the left of 'split' must be in a new pack. But,
         * creating that new pack may cause packs in the heavy half to no longer
         * form a geometric progression.
         *
         * Compute an expected size of the new pack, and then determine how many
         * packs in the heavy half need to be joined into it (if any) to restore
         * the geometric progression.
         */
        for (i = 0; i < split; i++) {
                struct packed_git *p = geometry->pack[i];

                if (unsigned_add_overflows(total_size, geometry_pack_weight(p)))
                        die(_("pack %s too large to roll up"), p->pack_name);
                total_size += geometry_pack_weight(p);
        }
        for (i = split; i < geometry->pack_nr; i++) {
                struct packed_git *ours = geometry->pack[i];

                if (unsigned_mult_overflows(geometry->split_factor,
                                            total_size))
                        die(_("pack %s too large to roll up"), ours->pack_name);

                if (geometry_pack_weight(ours) <
                    geometry->split_factor * total_size) {
                        if (unsigned_add_overflows(total_size,
                                                   geometry_pack_weight(ours)))
                                die(_("pack %s too large to roll up"),
                                    ours->pack_name);

                        split++;
                        total_size += geometry_pack_weight(ours);
                } else
                        break;
        }

        geometry->split = split;
}

static struct packed_git *get_preferred_pack(struct pack_geometry *geometry)
{
        uint32_t i;

        if (!geometry) {
                /*
                 * No geometry means either an all-into-one repack (in which
                 * case there is only one pack left and it is the largest) or an
                 * incremental one.
                 *
                 * If repacking incrementally, then we could check the size of
                 * all packs to determine which should be preferred, but leave
                 * this for later.
                 */
                return NULL;
        }
        if (geometry->split == geometry->pack_nr)
                return NULL;

        /*
         * The preferred pack is the largest pack above the split line. In
         * other words, it is the largest pack that does not get rolled up in
         * the geometric repack.
         */
        for (i = geometry->pack_nr; i > geometry->split; i--)
                /*
                 * A pack that is not local would never be included in a
                 * multi-pack index. We thus skip over any non-local packs.
                 */
                if (geometry->pack[i - 1]->pack_local)
                        return geometry->pack[i - 1];

        return NULL;
}

static void geometry_remove_redundant_packs(struct pack_geometry *geometry,
                                            struct string_list *names,
                                            struct existing_packs *existing)
{
        struct strbuf buf = STRBUF_INIT;
        uint32_t i;

        for (i = 0; i < geometry->split; i++) {
                struct packed_git *p = geometry->pack[i];
                if (string_list_has_string(names, hash_to_hex(p->hash)))
                        continue;

                strbuf_reset(&buf);
                strbuf_addstr(&buf, pack_basename(p));
                strbuf_strip_suffix(&buf, ".pack");

                if ((p->pack_keep) ||
                    (string_list_has_string(&existing->kept_packs, buf.buf)))
                        continue;

                remove_redundant_pack(packdir, buf.buf);
        }

        strbuf_release(&buf);
}

static void free_pack_geometry(struct pack_geometry *geometry)
{
        if (!geometry)
                return;

        free(geometry->pack);
}

struct midx_snapshot_ref_data {
        struct tempfile *f;
        struct oidset seen;
        int preferred;
};

static int midx_snapshot_ref_one(const char *refname UNUSED,
                                 const struct object_id *oid,
                                 int flag UNUSED, void *_data)
{
        struct midx_snapshot_ref_data *data = _data;
        struct object_id peeled;

        if (!peel_iterated_oid(oid, &peeled))
                oid = &peeled;

        if (oidset_insert(&data->seen, oid))
                return 0; /* already seen */

        if (oid_object_info(the_repository, oid, NULL) != OBJ_COMMIT)
                return 0;

        fprintf(data->f->fp, "%s%s\n", data->preferred ? "+" : "",
                oid_to_hex(oid));

        return 0;
}

static void midx_snapshot_refs(struct tempfile *f)
{
        struct midx_snapshot_ref_data data;
        const struct string_list *preferred = bitmap_preferred_tips(the_repository);

        data.f = f;
        data.preferred = 0;
        oidset_init(&data.seen, 0);

        if (!fdopen_tempfile(f, "w"))
                 die(_("could not open tempfile %s for writing"),
                     get_tempfile_path(f));

        if (preferred) {
                struct string_list_item *item;

                data.preferred = 1;
                for_each_string_list_item(item, preferred)
                        for_each_ref_in(item->string, midx_snapshot_ref_one, &data);
                data.preferred = 0;
        }

        for_each_ref(midx_snapshot_ref_one, &data);

        if (close_tempfile_gently(f)) {
                int save_errno = errno;
                delete_tempfile(&f);
                errno = save_errno;
                die_errno(_("could not close refs snapshot tempfile"));
        }

        oidset_clear(&data.seen);
}

static void midx_included_packs(struct string_list *include,
                                struct existing_packs *existing,
                                struct string_list *names,
                                struct pack_geometry *geometry)
{
        struct string_list_item *item;

        for_each_string_list_item(item, &existing->kept_packs)
                string_list_insert(include, xstrfmt("%s.idx", item->string));
        for_each_string_list_item(item, names)
                string_list_insert(include, xstrfmt("pack-%s.idx", item->string));
        if (geometry->split_factor) {
                struct strbuf buf = STRBUF_INIT;
                uint32_t i;
                for (i = geometry->split; i < geometry->pack_nr; i++) {
                        struct packed_git *p = geometry->pack[i];

                        /*
                         * The multi-pack index never refers to packfiles part
                         * of an alternate object database, so we skip these.
                         * While git-multi-pack-index(1) would silently ignore
                         * them anyway, this allows us to skip executing the
                         * command completely when we have only non-local
                         * packfiles.
                         */
                        if (!p->pack_local)
                                continue;

                        strbuf_addstr(&buf, pack_basename(p));
                        strbuf_strip_suffix(&buf, ".pack");
                        strbuf_addstr(&buf, ".idx");

                        string_list_insert(include, strbuf_detach(&buf, NULL));
                }
        } else {
                for_each_string_list_item(item, &existing->non_kept_packs) {
                        if (pack_is_marked_for_deletion(item))
                                continue;
                        string_list_insert(include, xstrfmt("%s.idx", item->string));
                }
        }

        for_each_string_list_item(item, &existing->cruft_packs) {
                /*
                 * When doing a --geometric repack, there is no need to check
                 * for deleted packs, since we're by definition not doing an
                 * ALL_INTO_ONE repack (hence no packs will be deleted).
                 * Otherwise we must check for and exclude any packs which are
                 * enqueued for deletion.
                 *
                 * So we could omit the conditional below in the --geometric
                 * case, but doing so is unnecessary since no packs are marked
                 * as pending deletion (since we only call
                 * `mark_packs_for_deletion()` when doing an all-into-one
                 * repack).
                 */
                if (pack_is_marked_for_deletion(item))
                        continue;
                string_list_insert(include, xstrfmt("%s.idx", item->string));
        }
}

static int write_midx_included_packs(struct string_list *include,
                                     struct pack_geometry *geometry,
                                     const char *refs_snapshot,
                                     int show_progress, int write_bitmaps)
{
        struct child_process cmd = CHILD_PROCESS_INIT;
        struct string_list_item *item;
        struct packed_git *preferred = get_preferred_pack(geometry);
        FILE *in;
        int ret;

        if (!include->nr)
                return 0;

        cmd.in = -1;
        cmd.git_cmd = 1;

        strvec_push(&cmd.args, "multi-pack-index");
        strvec_pushl(&cmd.args, "write", "--stdin-packs", NULL);

        if (show_progress)
                strvec_push(&cmd.args, "--progress");
        else
                strvec_push(&cmd.args, "--no-progress");

        if (write_bitmaps)
                strvec_push(&cmd.args, "--bitmap");

        if (preferred)
                strvec_pushf(&cmd.args, "--preferred-pack=%s",
                             pack_basename(preferred));

        if (refs_snapshot)
                strvec_pushf(&cmd.args, "--refs-snapshot=%s", refs_snapshot);

        ret = start_command(&cmd);
        if (ret)
                return ret;

        in = xfdopen(cmd.in, "w");
        for_each_string_list_item(item, include)
                fprintf(in, "%s\n", item->string);
        fclose(in);

        return finish_command(&cmd);
}

static void remove_redundant_bitmaps(struct string_list *include,
                                     const char *packdir)
{
        struct strbuf path = STRBUF_INIT;
        struct string_list_item *item;
        size_t packdir_len;

        strbuf_addstr(&path, packdir);
        strbuf_addch(&path, '/');
        packdir_len = path.len;

        /*
         * Remove any pack bitmaps corresponding to packs which are now
         * included in the MIDX.
         */
        for_each_string_list_item(item, include) {
                strbuf_addstr(&path, item->string);
                strbuf_strip_suffix(&path, ".idx");
                strbuf_addstr(&path, ".bitmap");

                if (unlink(path.buf) && errno != ENOENT)
                        warning_errno(_("could not remove stale bitmap: %s"),
                                      path.buf);

                strbuf_setlen(&path, packdir_len);
        }
        strbuf_release(&path);
}

static int write_cruft_pack(const struct pack_objects_args *args,
                            const char *destination,
                            const char *pack_prefix,
                            const char *cruft_expiration,
                            struct string_list *names,
                            struct existing_packs *existing)
{
        struct child_process cmd = CHILD_PROCESS_INIT;
        struct strbuf line = STRBUF_INIT;
        struct string_list_item *item;
        FILE *in, *out;
        int ret;
        const char *scratch;
        int local = skip_prefix(destination, packdir, &scratch);

        prepare_pack_objects(&cmd, args, destination);

        strvec_push(&cmd.args, "--cruft");
        if (cruft_expiration)
                strvec_pushf(&cmd.args, "--cruft-expiration=%s",
                             cruft_expiration);

        strvec_push(&cmd.args, "--honor-pack-keep");
        strvec_push(&cmd.args, "--non-empty");
        strvec_push(&cmd.args, "--max-pack-size=0");

        cmd.in = -1;

        ret = start_command(&cmd);
        if (ret)
                return ret;

        /*
         * names has a confusing double use: it both provides the list
         * of just-written new packs, and accepts the name of the cruft
         * pack we are writing.
         *
         * By the time it is read here, it contains only the pack(s)
         * that were just written, which is exactly the set of packs we
         * want to consider kept.
         *
         * If `--expire-to` is given, the double-use served by `names`
         * ensures that the pack written to `--expire-to` excludes any
         * objects contained in the cruft pack.
         */
        in = xfdopen(cmd.in, "w");
        for_each_string_list_item(item, names)
                fprintf(in, "%s-%s.pack\n", pack_prefix, item->string);
        for_each_string_list_item(item, &existing->non_kept_packs)
                fprintf(in, "-%s.pack\n", item->string);
        for_each_string_list_item(item, &existing->cruft_packs)
                fprintf(in, "-%s.pack\n", item->string);
        for_each_string_list_item(item, &existing->kept_packs)
                fprintf(in, "%s.pack\n", item->string);
        fclose(in);

        out = xfdopen(cmd.out, "r");
        while (strbuf_getline_lf(&line, out) != EOF) {
                struct string_list_item *item;

                if (line.len != the_hash_algo->hexsz)
                        die(_("repack: Expecting full hex object ID lines only "
                              "from pack-objects."));
                /*
                 * avoid putting packs written outside of the repository in the
                 * list of names
                 */
                if (local) {
                        item = string_list_append(names, line.buf);
                        item->util = populate_pack_exts(line.buf);
                }
        }
        fclose(out);

        strbuf_release(&line);

        return finish_command(&cmd);
}

int cmd_repack(int argc, const char **argv, const char *prefix)
{
        struct child_process cmd = CHILD_PROCESS_INIT;
        struct string_list_item *item;
        struct string_list names = STRING_LIST_INIT_DUP;
        struct existing_packs existing = EXISTING_PACKS_INIT;
        struct pack_geometry geometry = { 0 };
        struct strbuf line = STRBUF_INIT;
        struct tempfile *refs_snapshot = NULL;
        int i, ext, ret;
        FILE *out;
        int show_progress;

        /* variables to be filled by option parsing */
        int delete_redundant = 0;
        const char *unpack_unreachable = NULL;
        int keep_unreachable = 0;
        struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
        struct pack_objects_args po_args = {NULL};
        struct pack_objects_args cruft_po_args = {NULL};
        int write_midx = 0;
        const char *cruft_expiration = NULL;
        const char *expire_to = NULL;

        struct option builtin_repack_options[] = {
                OPT_BIT('a', NULL, &pack_everything,
                                N_("pack everything in a single pack"), ALL_INTO_ONE),
                OPT_BIT('A', NULL, &pack_everything,
                                N_("same as -a, and turn unreachable objects loose"),
                                   LOOSEN_UNREACHABLE | ALL_INTO_ONE),
                OPT_BIT(0, "cruft", &pack_everything,
                                N_("same as -a, pack unreachable cruft objects separately"),
                                   PACK_CRUFT),
                OPT_STRING(0, "cruft-expiration", &cruft_expiration, N_("approxidate"),
                                N_("with --cruft, expire objects older than this")),
                OPT_BOOL('d', NULL, &delete_redundant,
                                N_("remove redundant packs, and run git-prune-packed")),
                OPT_BOOL('f', NULL, &po_args.no_reuse_delta,
                                N_("pass --no-reuse-delta to git-pack-objects")),
                OPT_BOOL('F', NULL, &po_args.no_reuse_object,
                                N_("pass --no-reuse-object to git-pack-objects")),
                OPT_NEGBIT('n', NULL, &run_update_server_info,
                                N_("do not run git-update-server-info"), 1),
                OPT__QUIET(&po_args.quiet, N_("be quiet")),
                OPT_BOOL('l', "local", &po_args.local,
                                N_("pass --local to git-pack-objects")),
                OPT_BOOL('b', "write-bitmap-index", &write_bitmaps,
                                N_("write bitmap index")),
                OPT_BOOL('i', "delta-islands", &use_delta_islands,
                                N_("pass --delta-islands to git-pack-objects")),
                OPT_STRING(0, "unpack-unreachable", &unpack_unreachable, N_("approxidate"),
                                N_("with -A, do not loosen objects older than this")),
                OPT_BOOL('k', "keep-unreachable", &keep_unreachable,
                                N_("with -a, repack unreachable objects")),
                OPT_STRING(0, "window", &po_args.window, N_("n"),
                                N_("size of the window used for delta compression")),
                OPT_STRING(0, "window-memory", &po_args.window_memory, N_("bytes"),
                                N_("same as the above, but limit memory size instead of entries count")),
                OPT_STRING(0, "depth", &po_args.depth, N_("n"),
                                N_("limits the maximum delta depth")),
                OPT_STRING(0, "threads", &po_args.threads, N_("n"),
                                N_("limits the maximum number of threads")),
                OPT_STRING(0, "max-pack-size", &po_args.max_pack_size, N_("bytes"),
                                N_("maximum size of each packfile")),
                OPT_BOOL(0, "pack-kept-objects", &pack_kept_objects,
                                N_("repack objects in packs marked with .keep")),
                OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
                                N_("do not repack this pack")),
                OPT_INTEGER('g', "geometric", &geometry.split_factor,
                            N_("find a geometric progression with factor <N>")),
                OPT_BOOL('m', "write-midx", &write_midx,
                           N_("write a multi-pack index of the resulting packs")),
                OPT_STRING(0, "expire-to", &expire_to, N_("dir"),
                           N_("pack prefix to store a pack containing pruned objects")),
                OPT_END()
        };

        git_config(repack_config, &cruft_po_args);

        argc = parse_options(argc, argv, prefix, builtin_repack_options,
                                git_repack_usage, 0);

        if (delete_redundant && repository_format_precious_objects)
                die(_("cannot delete packs in a precious-objects repo"));

        if (keep_unreachable &&
            (unpack_unreachable || (pack_everything & LOOSEN_UNREACHABLE)))
                die(_("options '%s' and '%s' cannot be used together"), "--keep-unreachable", "-A");

        if (pack_everything & PACK_CRUFT) {
                pack_everything |= ALL_INTO_ONE;

                if (unpack_unreachable || (pack_everything & LOOSEN_UNREACHABLE))
                        die(_("options '%s' and '%s' cannot be used together"), "--cruft", "-A");
                if (keep_unreachable)
                        die(_("options '%s' and '%s' cannot be used together"), "--cruft", "-k");
        }

        if (write_bitmaps < 0) {
                if (!write_midx &&
                    (!(pack_everything & ALL_INTO_ONE) || !is_bare_repository()))
                        write_bitmaps = 0;
        } else if (write_bitmaps &&
                   git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0) &&
                   git_env_bool(GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP, 0)) {
                write_bitmaps = 0;
        }
        if (pack_kept_objects < 0)
                pack_kept_objects = write_bitmaps > 0 && !write_midx;

        if (write_bitmaps && !(pack_everything & ALL_INTO_ONE) && !write_midx)
                die(_(incremental_bitmap_conflict_error));

        if (write_bitmaps && po_args.local && has_alt_odb(the_repository)) {
                /*
                 * When asked to do a local repack, but we have
                 * packfiles that are inherited from an alternate, then
                 * we cannot guarantee that the multi-pack-index would
                 * have full coverage of all objects. We thus disable
                 * writing bitmaps in that case.
                 */
                warning(_("disabling bitmap writing, as some objects are not being packed"));
                write_bitmaps = 0;
        }

        if (write_midx && write_bitmaps) {
                struct strbuf path = STRBUF_INIT;

                strbuf_addf(&path, "%s/%s_XXXXXX", get_object_directory(),
                            "bitmap-ref-tips");

                refs_snapshot = xmks_tempfile(path.buf);
                midx_snapshot_refs(refs_snapshot);

                strbuf_release(&path);
        }

        packdir = mkpathdup("%s/pack", get_object_directory());
        packtmp_name = xstrfmt(".tmp-%d-pack", (int)getpid());
        packtmp = mkpathdup("%s/%s", packdir, packtmp_name);

        collect_pack_filenames(&existing, &keep_pack_list);

        if (geometry.split_factor) {
                if (pack_everything)
                        die(_("options '%s' and '%s' cannot be used together"), "--geometric", "-A/-a");
                init_pack_geometry(&geometry, &existing, &po_args);
                split_pack_geometry(&geometry);
        }

        prepare_pack_objects(&cmd, &po_args, packtmp);

        show_progress = !po_args.quiet && isatty(2);

        strvec_push(&cmd.args, "--keep-true-parents");
        if (!pack_kept_objects)
                strvec_push(&cmd.args, "--honor-pack-keep");
        for (i = 0; i < keep_pack_list.nr; i++)
                strvec_pushf(&cmd.args, "--keep-pack=%s",
                             keep_pack_list.items[i].string);
        strvec_push(&cmd.args, "--non-empty");
        if (!geometry.split_factor) {
                /*
                 * We need to grab all reachable objects, including those that
                 * are reachable from reflogs and the index.
                 *
                 * When repacking into a geometric progression of packs,
                 * however, we ask 'git pack-objects --stdin-packs', and it is
                 * not about packing objects based on reachability but about
                 * repacking all the objects in specified packs and loose ones
                 * (indeed, --stdin-packs is incompatible with these options).
                 */
                strvec_push(&cmd.args, "--all");
                strvec_push(&cmd.args, "--reflog");
                strvec_push(&cmd.args, "--indexed-objects");
        }
        if (repo_has_promisor_remote(the_repository))
                strvec_push(&cmd.args, "--exclude-promisor-objects");
        if (!write_midx) {
                if (write_bitmaps > 0)
                        strvec_push(&cmd.args, "--write-bitmap-index");
                else if (write_bitmaps < 0)
                        strvec_push(&cmd.args, "--write-bitmap-index-quiet");
        }
        if (use_delta_islands)
                strvec_push(&cmd.args, "--delta-islands");

        if (pack_everything & ALL_INTO_ONE) {
                repack_promisor_objects(&po_args, &names);

                if (has_existing_non_kept_packs(&existing) &&
                    delete_redundant &&
                    !(pack_everything & PACK_CRUFT)) {
                        for_each_string_list_item(item, &names) {
                                strvec_pushf(&cmd.args, "--keep-pack=%s-%s.pack",
                                             packtmp_name, item->string);
                        }
                        if (unpack_unreachable) {
                                strvec_pushf(&cmd.args,
                                             "--unpack-unreachable=%s",
                                             unpack_unreachable);
                        } else if (pack_everything & LOOSEN_UNREACHABLE) {
                                strvec_push(&cmd.args,
                                            "--unpack-unreachable");
                        } else if (keep_unreachable) {
                                strvec_push(&cmd.args, "--keep-unreachable");
                                strvec_push(&cmd.args, "--pack-loose-unreachable");
                        }
                }
        } else if (geometry.split_factor) {
                strvec_push(&cmd.args, "--stdin-packs");
                strvec_push(&cmd.args, "--unpacked");
        } else {
                strvec_push(&cmd.args, "--unpacked");
                strvec_push(&cmd.args, "--incremental");
        }

        if (geometry.split_factor)
                cmd.in = -1;
        else
                cmd.no_stdin = 1;

        ret = start_command(&cmd);
        if (ret)
                goto cleanup;

        if (geometry.split_factor) {
                FILE *in = xfdopen(cmd.in, "w");
                /*
                 * The resulting pack should contain all objects in packs that
                 * are going to be rolled up, but exclude objects in packs which
                 * are being left alone.
                 */
                for (i = 0; i < geometry.split; i++)
                        fprintf(in, "%s\n", pack_basename(geometry.pack[i]));
                for (i = geometry.split; i < geometry.pack_nr; i++)
                        fprintf(in, "^%s\n", pack_basename(geometry.pack[i]));
                fclose(in);
        }

        out = xfdopen(cmd.out, "r");
        while (strbuf_getline_lf(&line, out) != EOF) {
                struct string_list_item *item;

                if (line.len != the_hash_algo->hexsz)
                        die(_("repack: Expecting full hex object ID lines only from pack-objects."));
                item = string_list_append(&names, line.buf);
                item->util = populate_pack_exts(item->string);
        }
        strbuf_release(&line);
        fclose(out);
        ret = finish_command(&cmd);
        if (ret)
                goto cleanup;

        if (!names.nr && !po_args.quiet)
                printf_ln(_("Nothing new to pack."));

        if (pack_everything & PACK_CRUFT) {
                const char *pack_prefix;
                if (!skip_prefix(packtmp, packdir, &pack_prefix))
                        die(_("pack prefix %s does not begin with objdir %s"),
                            packtmp, packdir);
                if (*pack_prefix == '/')
                        pack_prefix++;

                if (!cruft_po_args.window)
                        cruft_po_args.window = po_args.window;
                if (!cruft_po_args.window_memory)
                        cruft_po_args.window_memory = po_args.window_memory;
                if (!cruft_po_args.depth)
                        cruft_po_args.depth = po_args.depth;
                if (!cruft_po_args.threads)
                        cruft_po_args.threads = po_args.threads;

                cruft_po_args.local = po_args.local;
                cruft_po_args.quiet = po_args.quiet;

                ret = write_cruft_pack(&cruft_po_args, packtmp, pack_prefix,
                                       cruft_expiration, &names,
                                       &existing);
                if (ret)
                        goto cleanup;

                if (delete_redundant && expire_to) {
                        /*
                         * If `--expire-to` is given with `-d`, it's possible
                         * that we're about to prune some objects. With cruft
                         * packs, pruning is implicit: any objects from existing
                         * packs that weren't picked up by new packs are removed
                         * when their packs are deleted.
                         *
                         * Generate an additional cruft pack, with one twist:
                         * `names` now includes the name of the cruft pack
                         * written in the previous step. So the contents of
                         * _this_ cruft pack exclude everything contained in the
                         * existing cruft pack (that is, all of the unreachable
                         * objects which are no older than
                         * `--cruft-expiration`).
                         *
                         * To make this work, cruft_expiration must become NULL
                         * so that this cruft pack doesn't actually prune any
                         * objects. If it were non-NULL, this call would always
                         * generate an empty pack (since every object not in the
                         * cruft pack generated above will have an mtime older
                         * than the expiration).
                         */
                        ret = write_cruft_pack(&cruft_po_args, expire_to,
                                               pack_prefix,
                                               NULL,
                                               &names,
                                               &existing);
                        if (ret)
                                goto cleanup;
                }
        }

        string_list_sort(&names);

        close_object_store(the_repository->objects);

        /*
         * Ok we have prepared all new packfiles.
         */
        for_each_string_list_item(item, &names) {
                struct generated_pack_data *data = item->util;

                for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
                        char *fname;

                        fname = mkpathdup("%s/pack-%s%s",
                                        packdir, item->string, exts[ext].name);

                        if (data->tempfiles[ext]) {
                                const char *fname_old = get_tempfile_path(data->tempfiles[ext]);
                                struct stat statbuffer;

                                if (!stat(fname_old, &statbuffer)) {
                                        statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
                                        chmod(fname_old, statbuffer.st_mode);
                                }

                                if (rename_tempfile(&data->tempfiles[ext], fname))
                                        die_errno(_("renaming pack to '%s' failed"), fname);
                        } else if (!exts[ext].optional)
                                die(_("pack-objects did not write a '%s' file for pack %s-%s"),
                                    exts[ext].name, packtmp, item->string);
                        else if (unlink(fname) < 0 && errno != ENOENT)
                                die_errno(_("could not unlink: %s"), fname);

                        free(fname);
                }
        }
        /* End of pack replacement. */

        if (delete_redundant && pack_everything & ALL_INTO_ONE)
                mark_packs_for_deletion(&existing, &names);

        if (write_midx) {
                struct string_list include = STRING_LIST_INIT_NODUP;
                midx_included_packs(&include, &existing, &names, &geometry);

                ret = write_midx_included_packs(&include, &geometry,
                                                refs_snapshot ? get_tempfile_path(refs_snapshot) : NULL,
                                                show_progress, write_bitmaps > 0);

                if (!ret && write_bitmaps)
                        remove_redundant_bitmaps(&include, packdir);

                string_list_clear(&include, 0);

                if (ret)
                        goto cleanup;
        }

        reprepare_packed_git(the_repository);

        if (delete_redundant) {
                int opts = 0;
                remove_redundant_existing_packs(&existing);

                if (geometry.split_factor)
                        geometry_remove_redundant_packs(&geometry, &names,
                                                        &existing);
                if (show_progress)
                        opts |= PRUNE_PACKED_VERBOSE;
                prune_packed_objects(opts);

                if (!keep_unreachable &&
                    (!(pack_everything & LOOSEN_UNREACHABLE) ||
                     unpack_unreachable) &&
                    is_repository_shallow(the_repository))
                        prune_shallow(PRUNE_QUICK);
        }

        if (run_update_server_info)
                update_server_info(0);

        if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0)) {
                unsigned flags = 0;
                if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP, 0))
                        flags |= MIDX_WRITE_BITMAP | MIDX_WRITE_REV_INDEX;
                write_midx_file(get_object_directory(), NULL, NULL, flags);
        }

cleanup:
        string_list_clear(&names, 1);
        existing_packs_release(&existing);
        free_pack_geometry(&geometry);

        return ret;
}