Merge branch 'ta/hash-function-transition-doc'

[git/debian.git] / builtin / fast-import.c

#include "builtin.h"
#include "cache.h"
#include "repository.h"
#include "config.h"
#include "lockfile.h"
#include "object.h"
#include "blob.h"
#include "tree.h"
#include "commit.h"
#include "delta.h"
#include "pack.h"
#include "refs.h"
#include "csum-file.h"
#include "quote.h"
#include "dir.h"
#include "run-command.h"
#include "packfile.h"
#include "object-store.h"
#include "mem-pool.h"
#include "commit-reach.h"
#include "khash.h"

#define PACK_ID_BITS 16
#define MAX_PACK_ID ((1<<PACK_ID_BITS)-1)
#define DEPTH_BITS 13
#define MAX_DEPTH ((1<<DEPTH_BITS)-1)

/*
 * We abuse the setuid bit on directories to mean "do not delta".
 */
#define NO_DELTA S_ISUID

/*
 * The amount of additional space required in order to write an object into the
 * current pack. This is the hash lengths at the end of the pack, plus the
 * length of one object ID.
 */
#define PACK_SIZE_THRESHOLD (the_hash_algo->rawsz * 3)

struct object_entry {
        struct pack_idx_entry idx;
        struct hashmap_entry ent;
        uint32_t type : TYPE_BITS,
                pack_id : PACK_ID_BITS,
                depth : DEPTH_BITS;
};

static int object_entry_hashcmp(const void *map_data,
                                const struct hashmap_entry *eptr,
                                const struct hashmap_entry *entry_or_key,
                                const void *keydata)
{
        const struct object_id *oid = keydata;
        const struct object_entry *e1, *e2;

        e1 = container_of(eptr, const struct object_entry, ent);
        if (oid)
                return oidcmp(&e1->idx.oid, oid);

        e2 = container_of(entry_or_key, const struct object_entry, ent);
        return oidcmp(&e1->idx.oid, &e2->idx.oid);
}

struct object_entry_pool {
        struct object_entry_pool *next_pool;
        struct object_entry *next_free;
        struct object_entry *end;
        struct object_entry entries[FLEX_ARRAY]; /* more */
};

struct mark_set {
        union {
                struct object_id *oids[1024];
                struct object_entry *marked[1024];
                struct mark_set *sets[1024];
        } data;
        unsigned int shift;
};

struct last_object {
        struct strbuf data;
        off_t offset;
        unsigned int depth;
        unsigned no_swap : 1;
};

struct atom_str {
        struct atom_str *next_atom;
        unsigned short str_len;
        char str_dat[FLEX_ARRAY]; /* more */
};

struct tree_content;
struct tree_entry {
        struct tree_content *tree;
        struct atom_str *name;
        struct tree_entry_ms {
                uint16_t mode;
                struct object_id oid;
        } versions[2];
};

struct tree_content {
        unsigned int entry_capacity; /* must match avail_tree_content */
        unsigned int entry_count;
        unsigned int delta_depth;
        struct tree_entry *entries[FLEX_ARRAY]; /* more */
};

struct avail_tree_content {
        unsigned int entry_capacity; /* must match tree_content */
        struct avail_tree_content *next_avail;
};

struct branch {
        struct branch *table_next_branch;
        struct branch *active_next_branch;
        const char *name;
        struct tree_entry branch_tree;
        uintmax_t last_commit;
        uintmax_t num_notes;
        unsigned active : 1;
        unsigned delete : 1;
        unsigned pack_id : PACK_ID_BITS;
        struct object_id oid;
};

struct tag {
        struct tag *next_tag;
        const char *name;
        unsigned int pack_id;
        struct object_id oid;
};

struct hash_list {
        struct hash_list *next;
        struct object_id oid;
};

typedef enum {
        WHENSPEC_RAW = 1,
        WHENSPEC_RAW_PERMISSIVE,
        WHENSPEC_RFC2822,
        WHENSPEC_NOW
} whenspec_type;

struct recent_command {
        struct recent_command *prev;
        struct recent_command *next;
        char *buf;
};

typedef void (*mark_set_inserter_t)(struct mark_set **s, struct object_id *oid, uintmax_t mark);
typedef void (*each_mark_fn_t)(uintmax_t mark, void *obj, void *cbp);

/* Configured limits on output */
static unsigned long max_depth = 50;
static off_t max_packsize;
static int unpack_limit = 100;
static int force_update;

/* Stats and misc. counters */
static uintmax_t alloc_count;
static uintmax_t marks_set_count;
static uintmax_t object_count_by_type[1 << TYPE_BITS];
static uintmax_t duplicate_count_by_type[1 << TYPE_BITS];
static uintmax_t delta_count_by_type[1 << TYPE_BITS];
static uintmax_t delta_count_attempts_by_type[1 << TYPE_BITS];
static unsigned long object_count;
static unsigned long branch_count;
static unsigned long branch_load_count;
static int failure;
static FILE *pack_edges;
static unsigned int show_stats = 1;
static int global_argc;
static const char **global_argv;

/* Memory pools */
static struct mem_pool fi_mem_pool =  {NULL, 2*1024*1024 -
                                       sizeof(struct mp_block), 0 };

/* Atom management */
static unsigned int atom_table_sz = 4451;
static unsigned int atom_cnt;
static struct atom_str **atom_table;

/* The .pack file being generated */
static struct pack_idx_option pack_idx_opts;
static unsigned int pack_id;
static struct hashfile *pack_file;
static struct packed_git *pack_data;
static struct packed_git **all_packs;
static off_t pack_size;

/* Table of objects we've written. */
static unsigned int object_entry_alloc = 5000;
static struct object_entry_pool *blocks;
static struct hashmap object_table;
static struct mark_set *marks;
static const char *export_marks_file;
static const char *import_marks_file;
static int import_marks_file_from_stream;
static int import_marks_file_ignore_missing;
static int import_marks_file_done;
static int relative_marks_paths;

/* Our last blob */
static struct last_object last_blob = { STRBUF_INIT, 0, 0, 0 };

/* Tree management */
static unsigned int tree_entry_alloc = 1000;
static void *avail_tree_entry;
static unsigned int avail_tree_table_sz = 100;
static struct avail_tree_content **avail_tree_table;
static size_t tree_entry_allocd;
static struct strbuf old_tree = STRBUF_INIT;
static struct strbuf new_tree = STRBUF_INIT;

/* Branch data */
static unsigned long max_active_branches = 5;
static unsigned long cur_active_branches;
static unsigned long branch_table_sz = 1039;
static struct branch **branch_table;
static struct branch *active_branches;

/* Tag data */
static struct tag *first_tag;
static struct tag *last_tag;

/* Input stream parsing */
static whenspec_type whenspec = WHENSPEC_RAW;
static struct strbuf command_buf = STRBUF_INIT;
static int unread_command_buf;
static struct recent_command cmd_hist = {&cmd_hist, &cmd_hist, NULL};
static struct recent_command *cmd_tail = &cmd_hist;
static struct recent_command *rc_free;
static unsigned int cmd_save = 100;
static uintmax_t next_mark;
static struct strbuf new_data = STRBUF_INIT;
static int seen_data_command;
static int require_explicit_termination;
static int allow_unsafe_features;

/* Signal handling */
static volatile sig_atomic_t checkpoint_requested;

/* Submodule marks */
static struct string_list sub_marks_from = STRING_LIST_INIT_DUP;
static struct string_list sub_marks_to = STRING_LIST_INIT_DUP;
static kh_oid_map_t *sub_oid_map;

/* Where to write output of cat-blob commands */
static int cat_blob_fd = STDOUT_FILENO;

static void parse_argv(void);
static void parse_get_mark(const char *p);
static void parse_cat_blob(const char *p);
static void parse_ls(const char *p, struct branch *b);

static void for_each_mark(struct mark_set *m, uintmax_t base, each_mark_fn_t callback, void *p)
{
        uintmax_t k;
        if (m->shift) {
                for (k = 0; k < 1024; k++) {
                        if (m->data.sets[k])
                                for_each_mark(m->data.sets[k], base + (k << m->shift), callback, p);
                }
        } else {
                for (k = 0; k < 1024; k++) {
                        if (m->data.marked[k])
                                callback(base + k, m->data.marked[k], p);
                }
        }
}

static void dump_marks_fn(uintmax_t mark, void *object, void *cbp) {
        struct object_entry *e = object;
        FILE *f = cbp;

        fprintf(f, ":%" PRIuMAX " %s\n", mark, oid_to_hex(&e->idx.oid));
}

static void write_branch_report(FILE *rpt, struct branch *b)
{
        fprintf(rpt, "%s:\n", b->name);

        fprintf(rpt, "  status      :");
        if (b->active)
                fputs(" active", rpt);
        if (b->branch_tree.tree)
                fputs(" loaded", rpt);
        if (is_null_oid(&b->branch_tree.versions[1].oid))
                fputs(" dirty", rpt);
        fputc('\n', rpt);

        fprintf(rpt, "  tip commit  : %s\n", oid_to_hex(&b->oid));
        fprintf(rpt, "  old tree    : %s\n",
                oid_to_hex(&b->branch_tree.versions[0].oid));
        fprintf(rpt, "  cur tree    : %s\n",
                oid_to_hex(&b->branch_tree.versions[1].oid));
        fprintf(rpt, "  commit clock: %" PRIuMAX "\n", b->last_commit);

        fputs("  last pack   : ", rpt);
        if (b->pack_id < MAX_PACK_ID)
                fprintf(rpt, "%u", b->pack_id);
        fputc('\n', rpt);

        fputc('\n', rpt);
}

static void write_crash_report(const char *err)
{
        char *loc = git_pathdup("fast_import_crash_%"PRIuMAX, (uintmax_t) getpid());
        FILE *rpt = fopen(loc, "w");
        struct branch *b;
        unsigned long lu;
        struct recent_command *rc;

        if (!rpt) {
                error_errno("can't write crash report %s", loc);
                free(loc);
                return;
        }

        fprintf(stderr, "fast-import: dumping crash report to %s\n", loc);

        fprintf(rpt, "fast-import crash report:\n");
        fprintf(rpt, "    fast-import process: %"PRIuMAX"\n", (uintmax_t) getpid());
        fprintf(rpt, "    parent process     : %"PRIuMAX"\n", (uintmax_t) getppid());
        fprintf(rpt, "    at %s\n", show_date(time(NULL), 0, DATE_MODE(ISO8601)));
        fputc('\n', rpt);

        fputs("fatal: ", rpt);
        fputs(err, rpt);
        fputc('\n', rpt);

        fputc('\n', rpt);
        fputs("Most Recent Commands Before Crash\n", rpt);
        fputs("---------------------------------\n", rpt);
        for (rc = cmd_hist.next; rc != &cmd_hist; rc = rc->next) {
                if (rc->next == &cmd_hist)
                        fputs("* ", rpt);
                else
                        fputs("  ", rpt);
                fputs(rc->buf, rpt);
                fputc('\n', rpt);
        }

        fputc('\n', rpt);
        fputs("Active Branch LRU\n", rpt);
        fputs("-----------------\n", rpt);
        fprintf(rpt, "    active_branches = %lu cur, %lu max\n",
                cur_active_branches,
                max_active_branches);
        fputc('\n', rpt);
        fputs("  pos  clock name\n", rpt);
        fputs("  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n", rpt);
        for (b = active_branches, lu = 0; b; b = b->active_next_branch)
                fprintf(rpt, "  %2lu) %6" PRIuMAX" %s\n",
                        ++lu, b->last_commit, b->name);

        fputc('\n', rpt);
        fputs("Inactive Branches\n", rpt);
        fputs("-----------------\n", rpt);
        for (lu = 0; lu < branch_table_sz; lu++) {
                for (b = branch_table[lu]; b; b = b->table_next_branch)
                        write_branch_report(rpt, b);
        }

        if (first_tag) {
                struct tag *tg;
                fputc('\n', rpt);
                fputs("Annotated Tags\n", rpt);
                fputs("--------------\n", rpt);
                for (tg = first_tag; tg; tg = tg->next_tag) {
                        fputs(oid_to_hex(&tg->oid), rpt);
                        fputc(' ', rpt);
                        fputs(tg->name, rpt);
                        fputc('\n', rpt);
                }
        }

        fputc('\n', rpt);
        fputs("Marks\n", rpt);
        fputs("-----\n", rpt);
        if (export_marks_file)
                fprintf(rpt, "  exported to %s\n", export_marks_file);
        else
                for_each_mark(marks, 0, dump_marks_fn, rpt);

        fputc('\n', rpt);
        fputs("-------------------\n", rpt);
        fputs("END OF CRASH REPORT\n", rpt);
        fclose(rpt);
        free(loc);
}

static void end_packfile(void);
static void unkeep_all_packs(void);
static void dump_marks(void);

static NORETURN void die_nicely(const char *err, va_list params)
{
        static int zombie;
        char message[2 * PATH_MAX];

        vsnprintf(message, sizeof(message), err, params);
        fputs("fatal: ", stderr);
        fputs(message, stderr);
        fputc('\n', stderr);

        if (!zombie) {
                zombie = 1;
                write_crash_report(message);
                end_packfile();
                unkeep_all_packs();
                dump_marks();
        }
        exit(128);
}

#ifndef SIGUSR1 /* Windows, for example */

static void set_checkpoint_signal(void)
{
}

#else

static void checkpoint_signal(int signo)
{
        checkpoint_requested = 1;
}

static void set_checkpoint_signal(void)
{
        struct sigaction sa;

        memset(&sa, 0, sizeof(sa));
        sa.sa_handler = checkpoint_signal;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;
        sigaction(SIGUSR1, &sa, NULL);
}

#endif

static void alloc_objects(unsigned int cnt)
{
        struct object_entry_pool *b;

        b = xmalloc(sizeof(struct object_entry_pool)
                + cnt * sizeof(struct object_entry));
        b->next_pool = blocks;
        b->next_free = b->entries;
        b->end = b->entries + cnt;
        blocks = b;
        alloc_count += cnt;
}

static struct object_entry *new_object(struct object_id *oid)
{
        struct object_entry *e;

        if (blocks->next_free == blocks->end)
                alloc_objects(object_entry_alloc);

        e = blocks->next_free++;
        oidcpy(&e->idx.oid, oid);
        return e;
}

static struct object_entry *find_object(struct object_id *oid)
{
        return hashmap_get_entry_from_hash(&object_table, oidhash(oid), oid,
                                           struct object_entry, ent);
}

static struct object_entry *insert_object(struct object_id *oid)
{
        struct object_entry *e;
        unsigned int hash = oidhash(oid);

        e = hashmap_get_entry_from_hash(&object_table, hash, oid,
                                        struct object_entry, ent);
        if (!e) {
                e = new_object(oid);
                e->idx.offset = 0;
                hashmap_entry_init(&e->ent, hash);
                hashmap_add(&object_table, &e->ent);
        }

        return e;
}

static void invalidate_pack_id(unsigned int id)
{
        unsigned long lu;
        struct tag *t;
        struct hashmap_iter iter;
        struct object_entry *e;

        hashmap_for_each_entry(&object_table, &iter, e, ent) {
                if (e->pack_id == id)
                        e->pack_id = MAX_PACK_ID;
        }

        for (lu = 0; lu < branch_table_sz; lu++) {
                struct branch *b;

                for (b = branch_table[lu]; b; b = b->table_next_branch)
                        if (b->pack_id == id)
                                b->pack_id = MAX_PACK_ID;
        }

        for (t = first_tag; t; t = t->next_tag)
                if (t->pack_id == id)
                        t->pack_id = MAX_PACK_ID;
}

static unsigned int hc_str(const char *s, size_t len)
{
        unsigned int r = 0;
        while (len-- > 0)
                r = r * 31 + *s++;
        return r;
}

static void insert_mark(struct mark_set **top, uintmax_t idnum, struct object_entry *oe)
{
        struct mark_set *s = *top;

        while ((idnum >> s->shift) >= 1024) {
                s = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct mark_set));
                s->shift = (*top)->shift + 10;
                s->data.sets[0] = *top;
                *top = s;
        }
        while (s->shift) {
                uintmax_t i = idnum >> s->shift;
                idnum -= i << s->shift;
                if (!s->data.sets[i]) {
                        s->data.sets[i] = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct mark_set));
                        s->data.sets[i]->shift = s->shift - 10;
                }
                s = s->data.sets[i];
        }
        if (!s->data.marked[idnum])
                marks_set_count++;
        s->data.marked[idnum] = oe;
}

static void *find_mark(struct mark_set *s, uintmax_t idnum)
{
        uintmax_t orig_idnum = idnum;
        struct object_entry *oe = NULL;
        if ((idnum >> s->shift) < 1024) {
                while (s && s->shift) {
                        uintmax_t i = idnum >> s->shift;
                        idnum -= i << s->shift;
                        s = s->data.sets[i];
                }
                if (s)
                        oe = s->data.marked[idnum];
        }
        if (!oe)
                die("mark :%" PRIuMAX " not declared", orig_idnum);
        return oe;
}

static struct atom_str *to_atom(const char *s, unsigned short len)
{
        unsigned int hc = hc_str(s, len) % atom_table_sz;
        struct atom_str *c;

        for (c = atom_table[hc]; c; c = c->next_atom)
                if (c->str_len == len && !strncmp(s, c->str_dat, len))
                        return c;

        c = mem_pool_alloc(&fi_mem_pool, sizeof(struct atom_str) + len + 1);
        c->str_len = len;
        memcpy(c->str_dat, s, len);
        c->str_dat[len] = 0;
        c->next_atom = atom_table[hc];
        atom_table[hc] = c;
        atom_cnt++;
        return c;
}

static struct branch *lookup_branch(const char *name)
{
        unsigned int hc = hc_str(name, strlen(name)) % branch_table_sz;
        struct branch *b;

        for (b = branch_table[hc]; b; b = b->table_next_branch)
                if (!strcmp(name, b->name))
                        return b;
        return NULL;
}

static struct branch *new_branch(const char *name)
{
        unsigned int hc = hc_str(name, strlen(name)) % branch_table_sz;
        struct branch *b = lookup_branch(name);

        if (b)
                die("Invalid attempt to create duplicate branch: %s", name);
        if (check_refname_format(name, REFNAME_ALLOW_ONELEVEL))
                die("Branch name doesn't conform to GIT standards: %s", name);

        b = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct branch));
        b->name = mem_pool_strdup(&fi_mem_pool, name);
        b->table_next_branch = branch_table[hc];
        b->branch_tree.versions[0].mode = S_IFDIR;
        b->branch_tree.versions[1].mode = S_IFDIR;
        b->num_notes = 0;
        b->active = 0;
        b->pack_id = MAX_PACK_ID;
        branch_table[hc] = b;
        branch_count++;
        return b;
}

static unsigned int hc_entries(unsigned int cnt)
{
        cnt = cnt & 7 ? (cnt / 8) + 1 : cnt / 8;
        return cnt < avail_tree_table_sz ? cnt : avail_tree_table_sz - 1;
}

static struct tree_content *new_tree_content(unsigned int cnt)
{
        struct avail_tree_content *f, *l = NULL;
        struct tree_content *t;
        unsigned int hc = hc_entries(cnt);

        for (f = avail_tree_table[hc]; f; l = f, f = f->next_avail)
                if (f->entry_capacity >= cnt)
                        break;

        if (f) {
                if (l)
                        l->next_avail = f->next_avail;
                else
                        avail_tree_table[hc] = f->next_avail;
        } else {
                cnt = cnt & 7 ? ((cnt / 8) + 1) * 8 : cnt;
                f = mem_pool_alloc(&fi_mem_pool, sizeof(*t) + sizeof(t->entries[0]) * cnt);
                f->entry_capacity = cnt;
        }

        t = (struct tree_content*)f;
        t->entry_count = 0;
        t->delta_depth = 0;
        return t;
}

static void release_tree_entry(struct tree_entry *e);
static void release_tree_content(struct tree_content *t)
{
        struct avail_tree_content *f = (struct avail_tree_content*)t;
        unsigned int hc = hc_entries(f->entry_capacity);
        f->next_avail = avail_tree_table[hc];
        avail_tree_table[hc] = f;
}

static void release_tree_content_recursive(struct tree_content *t)
{
        unsigned int i;
        for (i = 0; i < t->entry_count; i++)
                release_tree_entry(t->entries[i]);
        release_tree_content(t);
}

static struct tree_content *grow_tree_content(
        struct tree_content *t,
        int amt)
{
        struct tree_content *r = new_tree_content(t->entry_count + amt);
        r->entry_count = t->entry_count;
        r->delta_depth = t->delta_depth;
        COPY_ARRAY(r->entries, t->entries, t->entry_count);
        release_tree_content(t);
        return r;
}

static struct tree_entry *new_tree_entry(void)
{
        struct tree_entry *e;

        if (!avail_tree_entry) {
                unsigned int n = tree_entry_alloc;
                tree_entry_allocd += n * sizeof(struct tree_entry);
                ALLOC_ARRAY(e, n);
                avail_tree_entry = e;
                while (n-- > 1) {
                        *((void**)e) = e + 1;
                        e++;
                }
                *((void**)e) = NULL;
        }

        e = avail_tree_entry;
        avail_tree_entry = *((void**)e);
        return e;
}

static void release_tree_entry(struct tree_entry *e)
{
        if (e->tree)
                release_tree_content_recursive(e->tree);
        *((void**)e) = avail_tree_entry;
        avail_tree_entry = e;
}

static struct tree_content *dup_tree_content(struct tree_content *s)
{
        struct tree_content *d;
        struct tree_entry *a, *b;
        unsigned int i;

        if (!s)
                return NULL;
        d = new_tree_content(s->entry_count);
        for (i = 0; i < s->entry_count; i++) {
                a = s->entries[i];
                b = new_tree_entry();
                memcpy(b, a, sizeof(*a));
                if (a->tree && is_null_oid(&b->versions[1].oid))
                        b->tree = dup_tree_content(a->tree);
                else
                        b->tree = NULL;
                d->entries[i] = b;
        }
        d->entry_count = s->entry_count;
        d->delta_depth = s->delta_depth;

        return d;
}

static void start_packfile(void)
{
        struct strbuf tmp_file = STRBUF_INIT;
        struct packed_git *p;
        int pack_fd;

        pack_fd = odb_mkstemp(&tmp_file, "pack/tmp_pack_XXXXXX");
        FLEX_ALLOC_STR(p, pack_name, tmp_file.buf);
        strbuf_release(&tmp_file);

        p->pack_fd = pack_fd;
        p->do_not_close = 1;
        pack_file = hashfd(pack_fd, p->pack_name);

        pack_data = p;
        pack_size = write_pack_header(pack_file, 0);
        object_count = 0;

        REALLOC_ARRAY(all_packs, pack_id + 1);
        all_packs[pack_id] = p;
}

static const char *create_index(void)
{
        const char *tmpfile;
        struct pack_idx_entry **idx, **c, **last;
        struct object_entry *e;
        struct object_entry_pool *o;

        /* Build the table of object IDs. */
        ALLOC_ARRAY(idx, object_count);
        c = idx;
        for (o = blocks; o; o = o->next_pool)
                for (e = o->next_free; e-- != o->entries;)
                        if (pack_id == e->pack_id)
                                *c++ = &e->idx;
        last = idx + object_count;
        if (c != last)
                die("internal consistency error creating the index");

        tmpfile = write_idx_file(NULL, idx, object_count, &pack_idx_opts,
                                 pack_data->hash);
        free(idx);
        return tmpfile;
}

static char *keep_pack(const char *curr_index_name)
{
        static const char *keep_msg = "fast-import";
        struct strbuf name = STRBUF_INIT;
        int keep_fd;

        odb_pack_name(&name, pack_data->hash, "keep");
        keep_fd = odb_pack_keep(name.buf);
        if (keep_fd < 0)
                die_errno("cannot create keep file");
        write_or_die(keep_fd, keep_msg, strlen(keep_msg));
        if (close(keep_fd))
                die_errno("failed to write keep file");

        odb_pack_name(&name, pack_data->hash, "pack");
        if (finalize_object_file(pack_data->pack_name, name.buf))
                die("cannot store pack file");

        odb_pack_name(&name, pack_data->hash, "idx");
        if (finalize_object_file(curr_index_name, name.buf))
                die("cannot store index file");
        free((void *)curr_index_name);
        return strbuf_detach(&name, NULL);
}

static void unkeep_all_packs(void)
{
        struct strbuf name = STRBUF_INIT;
        int k;

        for (k = 0; k < pack_id; k++) {
                struct packed_git *p = all_packs[k];
                odb_pack_name(&name, p->hash, "keep");
                unlink_or_warn(name.buf);
        }
        strbuf_release(&name);
}

static int loosen_small_pack(const struct packed_git *p)
{
        struct child_process unpack = CHILD_PROCESS_INIT;

        if (lseek(p->pack_fd, 0, SEEK_SET) < 0)
                die_errno("Failed seeking to start of '%s'", p->pack_name);

        unpack.in = p->pack_fd;
        unpack.git_cmd = 1;
        unpack.stdout_to_stderr = 1;
        strvec_push(&unpack.args, "unpack-objects");
        if (!show_stats)
                strvec_push(&unpack.args, "-q");

        return run_command(&unpack);
}

static void end_packfile(void)
{
        static int running;

        if (running || !pack_data)
                return;

        running = 1;
        clear_delta_base_cache();
        if (object_count) {
                struct packed_git *new_p;
                struct object_id cur_pack_oid;
                char *idx_name;
                int i;
                struct branch *b;
                struct tag *t;

                close_pack_windows(pack_data);
                finalize_hashfile(pack_file, cur_pack_oid.hash, 0);
                fixup_pack_header_footer(pack_data->pack_fd, pack_data->hash,
                                         pack_data->pack_name, object_count,
                                         cur_pack_oid.hash, pack_size);

                if (object_count <= unpack_limit) {
                        if (!loosen_small_pack(pack_data)) {
                                invalidate_pack_id(pack_id);
                                goto discard_pack;
                        }
                }

                close(pack_data->pack_fd);
                idx_name = keep_pack(create_index());

                /* Register the packfile with core git's machinery. */
                new_p = add_packed_git(idx_name, strlen(idx_name), 1);
                if (!new_p)
                        die("core git rejected index %s", idx_name);
                all_packs[pack_id] = new_p;
                install_packed_git(the_repository, new_p);
                free(idx_name);

                /* Print the boundary */
                if (pack_edges) {
                        fprintf(pack_edges, "%s:", new_p->pack_name);
                        for (i = 0; i < branch_table_sz; i++) {
                                for (b = branch_table[i]; b; b = b->table_next_branch) {
                                        if (b->pack_id == pack_id)
                                                fprintf(pack_edges, " %s",
                                                        oid_to_hex(&b->oid));
                                }
                        }
                        for (t = first_tag; t; t = t->next_tag) {
                                if (t->pack_id == pack_id)
                                        fprintf(pack_edges, " %s",
                                                oid_to_hex(&t->oid));
                        }
                        fputc('\n', pack_edges);
                        fflush(pack_edges);
                }

                pack_id++;
        }
        else {
discard_pack:
                close(pack_data->pack_fd);
                unlink_or_warn(pack_data->pack_name);
        }
        FREE_AND_NULL(pack_data);
        running = 0;

        /* We can't carry a delta across packfiles. */
        strbuf_release(&last_blob.data);
        last_blob.offset = 0;
        last_blob.depth = 0;
}

static void cycle_packfile(void)
{
        end_packfile();
        start_packfile();
}

static int store_object(
        enum object_type type,
        struct strbuf *dat,
        struct last_object *last,
        struct object_id *oidout,
        uintmax_t mark)
{
        void *out, *delta;
        struct object_entry *e;
        unsigned char hdr[96];
        struct object_id oid;
        unsigned long hdrlen, deltalen;
        git_hash_ctx c;
        git_zstream s;

        hdrlen = xsnprintf((char *)hdr, sizeof(hdr), "%s %lu",
                           type_name(type), (unsigned long)dat->len) + 1;
        the_hash_algo->init_fn(&c);
        the_hash_algo->update_fn(&c, hdr, hdrlen);
        the_hash_algo->update_fn(&c, dat->buf, dat->len);
        the_hash_algo->final_fn(oid.hash, &c);
        if (oidout)
                oidcpy(oidout, &oid);

        e = insert_object(&oid);
        if (mark)
                insert_mark(&marks, mark, e);
        if (e->idx.offset) {
                duplicate_count_by_type[type]++;
                return 1;
        } else if (find_sha1_pack(oid.hash,
                                  get_all_packs(the_repository))) {
                e->type = type;
                e->pack_id = MAX_PACK_ID;
                e->idx.offset = 1; /* just not zero! */
                duplicate_count_by_type[type]++;
                return 1;
        }

        if (last && last->data.len && last->data.buf && last->depth < max_depth
                && dat->len > the_hash_algo->rawsz) {

                delta_count_attempts_by_type[type]++;
                delta = diff_delta(last->data.buf, last->data.len,
                        dat->buf, dat->len,
                        &deltalen, dat->len - the_hash_algo->rawsz);
        } else
                delta = NULL;

        git_deflate_init(&s, pack_compression_level);
        if (delta) {
                s.next_in = delta;
                s.avail_in = deltalen;
        } else {
                s.next_in = (void *)dat->buf;
                s.avail_in = dat->len;
        }
        s.avail_out = git_deflate_bound(&s, s.avail_in);
        s.next_out = out = xmalloc(s.avail_out);
        while (git_deflate(&s, Z_FINISH) == Z_OK)
                ; /* nothing */
        git_deflate_end(&s);

        /* Determine if we should auto-checkpoint. */
        if ((max_packsize
                && (pack_size + PACK_SIZE_THRESHOLD + s.total_out) > max_packsize)
                || (pack_size + PACK_SIZE_THRESHOLD + s.total_out) < pack_size) {

                /* This new object needs to *not* have the current pack_id. */
                e->pack_id = pack_id + 1;
                cycle_packfile();

                /* We cannot carry a delta into the new pack. */
                if (delta) {
                        FREE_AND_NULL(delta);

                        git_deflate_init(&s, pack_compression_level);
                        s.next_in = (void *)dat->buf;
                        s.avail_in = dat->len;
                        s.avail_out = git_deflate_bound(&s, s.avail_in);
                        s.next_out = out = xrealloc(out, s.avail_out);
                        while (git_deflate(&s, Z_FINISH) == Z_OK)
                                ; /* nothing */
                        git_deflate_end(&s);
                }
        }

        e->type = type;
        e->pack_id = pack_id;
        e->idx.offset = pack_size;
        object_count++;
        object_count_by_type[type]++;

        crc32_begin(pack_file);

        if (delta) {
                off_t ofs = e->idx.offset - last->offset;
                unsigned pos = sizeof(hdr) - 1;

                delta_count_by_type[type]++;
                e->depth = last->depth + 1;

                hdrlen = encode_in_pack_object_header(hdr, sizeof(hdr),
                                                      OBJ_OFS_DELTA, deltalen);
                hashwrite(pack_file, hdr, hdrlen);
                pack_size += hdrlen;

                hdr[pos] = ofs & 127;
                while (ofs >>= 7)
                        hdr[--pos] = 128 | (--ofs & 127);
                hashwrite(pack_file, hdr + pos, sizeof(hdr) - pos);
                pack_size += sizeof(hdr) - pos;
        } else {
                e->depth = 0;
                hdrlen = encode_in_pack_object_header(hdr, sizeof(hdr),
                                                      type, dat->len);
                hashwrite(pack_file, hdr, hdrlen);
                pack_size += hdrlen;
        }

        hashwrite(pack_file, out, s.total_out);
        pack_size += s.total_out;

        e->idx.crc32 = crc32_end(pack_file);

        free(out);
        free(delta);
        if (last) {
                if (last->no_swap) {
                        last->data = *dat;
                } else {
                        strbuf_swap(&last->data, dat);
                }
                last->offset = e->idx.offset;
                last->depth = e->depth;
        }
        return 0;
}

static void truncate_pack(struct hashfile_checkpoint *checkpoint)
{
        if (hashfile_truncate(pack_file, checkpoint))
                die_errno("cannot truncate pack to skip duplicate");
        pack_size = checkpoint->offset;
}

static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
{
        size_t in_sz = 64 * 1024, out_sz = 64 * 1024;
        unsigned char *in_buf = xmalloc(in_sz);
        unsigned char *out_buf = xmalloc(out_sz);
        struct object_entry *e;
        struct object_id oid;
        unsigned long hdrlen;
        off_t offset;
        git_hash_ctx c;
        git_zstream s;
        struct hashfile_checkpoint checkpoint;
        int status = Z_OK;

        /* Determine if we should auto-checkpoint. */
        if ((max_packsize
                && (pack_size + PACK_SIZE_THRESHOLD + len) > max_packsize)
                || (pack_size + PACK_SIZE_THRESHOLD + len) < pack_size)
                cycle_packfile();

        hashfile_checkpoint(pack_file, &checkpoint);
        offset = checkpoint.offset;

        hdrlen = xsnprintf((char *)out_buf, out_sz, "blob %" PRIuMAX, len) + 1;

        the_hash_algo->init_fn(&c);
        the_hash_algo->update_fn(&c, out_buf, hdrlen);

        crc32_begin(pack_file);

        git_deflate_init(&s, pack_compression_level);

        hdrlen = encode_in_pack_object_header(out_buf, out_sz, OBJ_BLOB, len);

        s.next_out = out_buf + hdrlen;
        s.avail_out = out_sz - hdrlen;

        while (status != Z_STREAM_END) {
                if (0 < len && !s.avail_in) {
                        size_t cnt = in_sz < len ? in_sz : (size_t)len;
                        size_t n = fread(in_buf, 1, cnt, stdin);
                        if (!n && feof(stdin))
                                die("EOF in data (%" PRIuMAX " bytes remaining)", len);

                        the_hash_algo->update_fn(&c, in_buf, n);
                        s.next_in = in_buf;
                        s.avail_in = n;
                        len -= n;
                }

                status = git_deflate(&s, len ? 0 : Z_FINISH);

                if (!s.avail_out || status == Z_STREAM_END) {
                        size_t n = s.next_out - out_buf;
                        hashwrite(pack_file, out_buf, n);
                        pack_size += n;
                        s.next_out = out_buf;
                        s.avail_out = out_sz;
                }

                switch (status) {
                case Z_OK:
                case Z_BUF_ERROR:
                case Z_STREAM_END:
                        continue;
                default:
                        die("unexpected deflate failure: %d", status);
                }
        }
        git_deflate_end(&s);
        the_hash_algo->final_fn(oid.hash, &c);

        if (oidout)
                oidcpy(oidout, &oid);

        e = insert_object(&oid);

        if (mark)
                insert_mark(&marks, mark, e);

        if (e->idx.offset) {
                duplicate_count_by_type[OBJ_BLOB]++;
                truncate_pack(&checkpoint);

        } else if (find_sha1_pack(oid.hash,
                                  get_all_packs(the_repository))) {
                e->type = OBJ_BLOB;
                e->pack_id = MAX_PACK_ID;
                e->idx.offset = 1; /* just not zero! */
                duplicate_count_by_type[OBJ_BLOB]++;
                truncate_pack(&checkpoint);

        } else {
                e->depth = 0;
                e->type = OBJ_BLOB;
                e->pack_id = pack_id;
                e->idx.offset = offset;
                e->idx.crc32 = crc32_end(pack_file);
                object_count++;
                object_count_by_type[OBJ_BLOB]++;
        }

        free(in_buf);
        free(out_buf);
}

/* All calls must be guarded by find_object() or find_mark() to
 * ensure the 'struct object_entry' passed was written by this
 * process instance.  We unpack the entry by the offset, avoiding
 * the need for the corresponding .idx file.  This unpacking rule
 * works because we only use OBJ_REF_DELTA within the packfiles
 * created by fast-import.
 *
 * oe must not be NULL.  Such an oe usually comes from giving
 * an unknown SHA-1 to find_object() or an undefined mark to
 * find_mark().  Callers must test for this condition and use
 * the standard read_sha1_file() when it happens.
 *
 * oe->pack_id must not be MAX_PACK_ID.  Such an oe is usually from
 * find_mark(), where the mark was reloaded from an existing marks
 * file and is referencing an object that this fast-import process
 * instance did not write out to a packfile.  Callers must test for
 * this condition and use read_sha1_file() instead.
 */
static void *gfi_unpack_entry(
        struct object_entry *oe,
        unsigned long *sizep)
{
        enum object_type type;
        struct packed_git *p = all_packs[oe->pack_id];
        if (p == pack_data && p->pack_size < (pack_size + the_hash_algo->rawsz)) {
                /* The object is stored in the packfile we are writing to
                 * and we have modified it since the last time we scanned
                 * back to read a previously written object.  If an old
                 * window covered [p->pack_size, p->pack_size + rawsz) its
                 * data is stale and is not valid.  Closing all windows
                 * and updating the packfile length ensures we can read
                 * the newly written data.
                 */
                close_pack_windows(p);
                hashflush(pack_file);

                /* We have to offer rawsz bytes additional on the end of
                 * the packfile as the core unpacker code assumes the
                 * footer is present at the file end and must promise
                 * at least rawsz bytes within any window it maps.  But
                 * we don't actually create the footer here.
                 */
                p->pack_size = pack_size + the_hash_algo->rawsz;
        }
        return unpack_entry(the_repository, p, oe->idx.offset, &type, sizep);
}

static const char *get_mode(const char *str, uint16_t *modep)
{
        unsigned char c;
        uint16_t mode = 0;

        while ((c = *str++) != ' ') {
                if (c < '0' || c > '7')
                        return NULL;
                mode = (mode << 3) + (c - '0');
        }
        *modep = mode;
        return str;
}

static void load_tree(struct tree_entry *root)
{
        struct object_id *oid = &root->versions[1].oid;
        struct object_entry *myoe;
        struct tree_content *t;
        unsigned long size;
        char *buf;
        const char *c;

        root->tree = t = new_tree_content(8);
        if (is_null_oid(oid))
                return;

        myoe = find_object(oid);
        if (myoe && myoe->pack_id != MAX_PACK_ID) {
                if (myoe->type != OBJ_TREE)
                        die("Not a tree: %s", oid_to_hex(oid));
                t->delta_depth = myoe->depth;
                buf = gfi_unpack_entry(myoe, &size);
                if (!buf)
                        die("Can't load tree %s", oid_to_hex(oid));
        } else {
                enum object_type type;
                buf = read_object_file(oid, &type, &size);
                if (!buf || type != OBJ_TREE)
                        die("Can't load tree %s", oid_to_hex(oid));
        }

        c = buf;
        while (c != (buf + size)) {
                struct tree_entry *e = new_tree_entry();

                if (t->entry_count == t->entry_capacity)
                        root->tree = t = grow_tree_content(t, t->entry_count);
                t->entries[t->entry_count++] = e;

                e->tree = NULL;
                c = get_mode(c, &e->versions[1].mode);
                if (!c)
                        die("Corrupt mode in %s", oid_to_hex(oid));
                e->versions[0].mode = e->versions[1].mode;
                e->name = to_atom(c, strlen(c));
                c += e->name->str_len + 1;
                hashcpy(e->versions[0].oid.hash, (unsigned char *)c);
                hashcpy(e->versions[1].oid.hash, (unsigned char *)c);
                c += the_hash_algo->rawsz;
        }
        free(buf);
}

static int tecmp0 (const void *_a, const void *_b)
{
        struct tree_entry *a = *((struct tree_entry**)_a);
        struct tree_entry *b = *((struct tree_entry**)_b);
        return base_name_compare(
                a->name->str_dat, a->name->str_len, a->versions[0].mode,
                b->name->str_dat, b->name->str_len, b->versions[0].mode);
}

static int tecmp1 (const void *_a, const void *_b)
{
        struct tree_entry *a = *((struct tree_entry**)_a);
        struct tree_entry *b = *((struct tree_entry**)_b);
        return base_name_compare(
                a->name->str_dat, a->name->str_len, a->versions[1].mode,
                b->name->str_dat, b->name->str_len, b->versions[1].mode);
}

static void mktree(struct tree_content *t, int v, struct strbuf *b)
{
        size_t maxlen = 0;
        unsigned int i;

        if (!v)
                QSORT(t->entries, t->entry_count, tecmp0);
        else
                QSORT(t->entries, t->entry_count, tecmp1);

        for (i = 0; i < t->entry_count; i++) {
                if (t->entries[i]->versions[v].mode)
                        maxlen += t->entries[i]->name->str_len + 34;
        }

        strbuf_reset(b);
        strbuf_grow(b, maxlen);
        for (i = 0; i < t->entry_count; i++) {
                struct tree_entry *e = t->entries[i];
                if (!e->versions[v].mode)
                        continue;
                strbuf_addf(b, "%o %s%c",
                        (unsigned int)(e->versions[v].mode & ~NO_DELTA),
                        e->name->str_dat, '\0');
                strbuf_add(b, e->versions[v].oid.hash, the_hash_algo->rawsz);
        }
}

static void store_tree(struct tree_entry *root)
{
        struct tree_content *t;
        unsigned int i, j, del;
        struct last_object lo = { STRBUF_INIT, 0, 0, /* no_swap */ 1 };
        struct object_entry *le = NULL;

        if (!is_null_oid(&root->versions[1].oid))
                return;

        if (!root->tree)
                load_tree(root);
        t = root->tree;

        for (i = 0; i < t->entry_count; i++) {
                if (t->entries[i]->tree)
                        store_tree(t->entries[i]);
        }

        if (!(root->versions[0].mode & NO_DELTA))
                le = find_object(&root->versions[0].oid);
        if (S_ISDIR(root->versions[0].mode) && le && le->pack_id == pack_id) {
                mktree(t, 0, &old_tree);
                lo.data = old_tree;
                lo.offset = le->idx.offset;
                lo.depth = t->delta_depth;
        }

        mktree(t, 1, &new_tree);
        store_object(OBJ_TREE, &new_tree, &lo, &root->versions[1].oid, 0);

        t->delta_depth = lo.depth;
        for (i = 0, j = 0, del = 0; i < t->entry_count; i++) {
                struct tree_entry *e = t->entries[i];
                if (e->versions[1].mode) {
                        e->versions[0].mode = e->versions[1].mode;
                        oidcpy(&e->versions[0].oid, &e->versions[1].oid);
                        t->entries[j++] = e;
                } else {
                        release_tree_entry(e);
                        del++;
                }
        }
        t->entry_count -= del;
}

static void tree_content_replace(
        struct tree_entry *root,
        const struct object_id *oid,
        const uint16_t mode,
        struct tree_content *newtree)
{
        if (!S_ISDIR(mode))
                die("Root cannot be a non-directory");
        oidclr(&root->versions[0].oid);
        oidcpy(&root->versions[1].oid, oid);
        if (root->tree)
                release_tree_content_recursive(root->tree);
        root->tree = newtree;
}

static int tree_content_set(
        struct tree_entry *root,
        const char *p,
        const struct object_id *oid,
        const uint16_t mode,
        struct tree_content *subtree)
{
        struct tree_content *t;
        const char *slash1;
        unsigned int i, n;
        struct tree_entry *e;

        slash1 = strchrnul(p, '/');
        n = slash1 - p;
        if (!n)
                die("Empty path component found in input");
        if (!*slash1 && !S_ISDIR(mode) && subtree)
                die("Non-directories cannot have subtrees");

        if (!root->tree)
                load_tree(root);
        t = root->tree;
        for (i = 0; i < t->entry_count; i++) {
                e = t->entries[i];
                if (e->name->str_len == n && !fspathncmp(p, e->name->str_dat, n)) {
                        if (!*slash1) {
                                if (!S_ISDIR(mode)
                                                && e->versions[1].mode == mode
                                                && oideq(&e->versions[1].oid, oid))
                                        return 0;
                                e->versions[1].mode = mode;
                                oidcpy(&e->versions[1].oid, oid);
                                if (e->tree)
                                        release_tree_content_recursive(e->tree);
                                e->tree = subtree;

                                /*
                                 * We need to leave e->versions[0].sha1 alone
                                 * to avoid modifying the preimage tree used
                                 * when writing out the parent directory.
                                 * But after replacing the subdir with a
                                 * completely different one, it's not a good
                                 * delta base any more, and besides, we've
                                 * thrown away the tree entries needed to
                                 * make a delta against it.
                                 *
                                 * So let's just explicitly disable deltas
                                 * for the subtree.
                                 */
                                if (S_ISDIR(e->versions[0].mode))
                                        e->versions[0].mode |= NO_DELTA;

                                oidclr(&root->versions[1].oid);
                                return 1;
                        }
                        if (!S_ISDIR(e->versions[1].mode)) {
                                e->tree = new_tree_content(8);
                                e->versions[1].mode = S_IFDIR;
                        }
                        if (!e->tree)
                                load_tree(e);
                        if (tree_content_set(e, slash1 + 1, oid, mode, subtree)) {
                                oidclr(&root->versions[1].oid);
                                return 1;
                        }
                        return 0;
                }
        }

        if (t->entry_count == t->entry_capacity)
                root->tree = t = grow_tree_content(t, t->entry_count);
        e = new_tree_entry();
        e->name = to_atom(p, n);
        e->versions[0].mode = 0;
        oidclr(&e->versions[0].oid);
        t->entries[t->entry_count++] = e;
        if (*slash1) {
                e->tree = new_tree_content(8);
                e->versions[1].mode = S_IFDIR;
                tree_content_set(e, slash1 + 1, oid, mode, subtree);
        } else {
                e->tree = subtree;
                e->versions[1].mode = mode;
                oidcpy(&e->versions[1].oid, oid);
        }
        oidclr(&root->versions[1].oid);
        return 1;
}

static int tree_content_remove(
        struct tree_entry *root,
        const char *p,
        struct tree_entry *backup_leaf,
        int allow_root)
{
        struct tree_content *t;
        const char *slash1;
        unsigned int i, n;
        struct tree_entry *e;

        slash1 = strchrnul(p, '/');
        n = slash1 - p;

        if (!root->tree)
                load_tree(root);

        if (!*p && allow_root) {
                e = root;
                goto del_entry;
        }

        t = root->tree;
        for (i = 0; i < t->entry_count; i++) {
                e = t->entries[i];
                if (e->name->str_len == n && !fspathncmp(p, e->name->str_dat, n)) {
                        if (*slash1 && !S_ISDIR(e->versions[1].mode))
                                /*
                                 * If p names a file in some subdirectory, and a
                                 * file or symlink matching the name of the
                                 * parent directory of p exists, then p cannot
                                 * exist and need not be deleted.
                                 */
                                return 1;
                        if (!*slash1 || !S_ISDIR(e->versions[1].mode))
                                goto del_entry;
                        if (!e->tree)
                                load_tree(e);
                        if (tree_content_remove(e, slash1 + 1, backup_leaf, 0)) {
                                for (n = 0; n < e->tree->entry_count; n++) {
                                        if (e->tree->entries[n]->versions[1].mode) {
                                                oidclr(&root->versions[1].oid);
                                                return 1;
                                        }
                                }
                                backup_leaf = NULL;
                                goto del_entry;
                        }
                        return 0;
                }
        }
        return 0;

del_entry:
        if (backup_leaf)
                memcpy(backup_leaf, e, sizeof(*backup_leaf));
        else if (e->tree)
                release_tree_content_recursive(e->tree);
        e->tree = NULL;
        e->versions[1].mode = 0;
        oidclr(&e->versions[1].oid);
        oidclr(&root->versions[1].oid);
        return 1;
}

static int tree_content_get(
        struct tree_entry *root,
        const char *p,
        struct tree_entry *leaf,
        int allow_root)
{
        struct tree_content *t;
        const char *slash1;
        unsigned int i, n;
        struct tree_entry *e;

        slash1 = strchrnul(p, '/');
        n = slash1 - p;
        if (!n && !allow_root)
                die("Empty path component found in input");

        if (!root->tree)
                load_tree(root);

        if (!n) {
                e = root;
                goto found_entry;
        }

        t = root->tree;
        for (i = 0; i < t->entry_count; i++) {
                e = t->entries[i];
                if (e->name->str_len == n && !fspathncmp(p, e->name->str_dat, n)) {
                        if (!*slash1)
                                goto found_entry;
                        if (!S_ISDIR(e->versions[1].mode))
                                return 0;
                        if (!e->tree)
                                load_tree(e);
                        return tree_content_get(e, slash1 + 1, leaf, 0);
                }
        }
        return 0;

found_entry:
        memcpy(leaf, e, sizeof(*leaf));
        if (e->tree && is_null_oid(&e->versions[1].oid))
                leaf->tree = dup_tree_content(e->tree);
        else
                leaf->tree = NULL;
        return 1;
}

static int update_branch(struct branch *b)
{
        static const char *msg = "fast-import";
        struct ref_transaction *transaction;
        struct object_id old_oid;
        struct strbuf err = STRBUF_INIT;

        if (is_null_oid(&b->oid)) {
                if (b->delete)
                        delete_ref(NULL, b->name, NULL, 0);
                return 0;
        }
        if (read_ref(b->name, &old_oid))
                oidclr(&old_oid);
        if (!force_update && !is_null_oid(&old_oid)) {
                struct commit *old_cmit, *new_cmit;

                old_cmit = lookup_commit_reference_gently(the_repository,
                                                          &old_oid, 0);
                new_cmit = lookup_commit_reference_gently(the_repository,
                                                          &b->oid, 0);
                if (!old_cmit || !new_cmit)
                        return error("Branch %s is missing commits.", b->name);

                if (!in_merge_bases(old_cmit, new_cmit)) {
                        warning("Not updating %s"
                                " (new tip %s does not contain %s)",
                                b->name, oid_to_hex(&b->oid),
                                oid_to_hex(&old_oid));
                        return -1;
                }
        }
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_update(transaction, b->name, &b->oid, &old_oid,
                                   0, msg, &err) ||
            ref_transaction_commit(transaction, &err)) {
                ref_transaction_free(transaction);
                error("%s", err.buf);
                strbuf_release(&err);
                return -1;
        }
        ref_transaction_free(transaction);
        strbuf_release(&err);
        return 0;
}

static void dump_branches(void)
{
        unsigned int i;
        struct branch *b;

        for (i = 0; i < branch_table_sz; i++) {
                for (b = branch_table[i]; b; b = b->table_next_branch)
                        failure |= update_branch(b);
        }
}

static void dump_tags(void)
{
        static const char *msg = "fast-import";
        struct tag *t;
        struct strbuf ref_name = STRBUF_INIT;
        struct strbuf err = STRBUF_INIT;
        struct ref_transaction *transaction;

        transaction = ref_transaction_begin(&err);
        if (!transaction) {
                failure |= error("%s", err.buf);
                goto cleanup;
        }
        for (t = first_tag; t; t = t->next_tag) {
                strbuf_reset(&ref_name);
                strbuf_addf(&ref_name, "refs/tags/%s", t->name);

                if (ref_transaction_update(transaction, ref_name.buf,
                                           &t->oid, NULL, 0, msg, &err)) {
                        failure |= error("%s", err.buf);
                        goto cleanup;
                }
        }
        if (ref_transaction_commit(transaction, &err))
                failure |= error("%s", err.buf);

 cleanup:
        ref_transaction_free(transaction);
        strbuf_release(&ref_name);
        strbuf_release(&err);
}

static void dump_marks(void)
{
        struct lock_file mark_lock = LOCK_INIT;
        FILE *f;

        if (!export_marks_file || (import_marks_file && !import_marks_file_done))
                return;

        if (safe_create_leading_directories_const(export_marks_file)) {
                failure |= error_errno("unable to create leading directories of %s",
                                       export_marks_file);
                return;
        }

        if (hold_lock_file_for_update(&mark_lock, export_marks_file, 0) < 0) {
                failure |= error_errno("Unable to write marks file %s",
                                       export_marks_file);
                return;
        }

        f = fdopen_lock_file(&mark_lock, "w");
        if (!f) {
                int saved_errno = errno;
                rollback_lock_file(&mark_lock);
                failure |= error("Unable to write marks file %s: %s",
                        export_marks_file, strerror(saved_errno));
                return;
        }

        for_each_mark(marks, 0, dump_marks_fn, f);
        if (commit_lock_file(&mark_lock)) {
                failure |= error_errno("Unable to write file %s",
                                       export_marks_file);
                return;
        }
}

static void insert_object_entry(struct mark_set **s, struct object_id *oid, uintmax_t mark)
{
        struct object_entry *e;
        e = find_object(oid);
        if (!e) {
                enum object_type type = oid_object_info(the_repository,
                                                        oid, NULL);
                if (type < 0)
                        die("object not found: %s", oid_to_hex(oid));
                e = insert_object(oid);
                e->type = type;
                e->pack_id = MAX_PACK_ID;
                e->idx.offset = 1; /* just not zero! */
        }
        insert_mark(s, mark, e);
}

static void insert_oid_entry(struct mark_set **s, struct object_id *oid, uintmax_t mark)
{
        insert_mark(s, mark, xmemdupz(oid, sizeof(*oid)));
}

static void read_mark_file(struct mark_set **s, FILE *f, mark_set_inserter_t inserter)
{
        char line[512];
        while (fgets(line, sizeof(line), f)) {
                uintmax_t mark;
                char *end;
                struct object_id oid;

                /* Ensure SHA-1 objects are padded with zeros. */
                memset(oid.hash, 0, sizeof(oid.hash));

                end = strchr(line, '\n');
                if (line[0] != ':' || !end)
                        die("corrupt mark line: %s", line);
                *end = 0;
                mark = strtoumax(line + 1, &end, 10);
                if (!mark || end == line + 1
                        || *end != ' '
                        || get_oid_hex_any(end + 1, &oid) == GIT_HASH_UNKNOWN)
                        die("corrupt mark line: %s", line);
                inserter(s, &oid, mark);
        }
}

static void read_marks(void)
{
        FILE *f = fopen(import_marks_file, "r");
        if (f)
                ;
        else if (import_marks_file_ignore_missing && errno == ENOENT)
                goto done; /* Marks file does not exist */
        else
                die_errno("cannot read '%s'", import_marks_file);
        read_mark_file(&marks, f, insert_object_entry);
        fclose(f);
done:
        import_marks_file_done = 1;
}


static int read_next_command(void)
{
        static int stdin_eof = 0;

        if (stdin_eof) {
                unread_command_buf = 0;
                return EOF;
        }

        for (;;) {
                if (unread_command_buf) {
                        unread_command_buf = 0;
                } else {
                        struct recent_command *rc;

                        stdin_eof = strbuf_getline_lf(&command_buf, stdin);
                        if (stdin_eof)
                                return EOF;

                        if (!seen_data_command
                                && !starts_with(command_buf.buf, "feature ")
                                && !starts_with(command_buf.buf, "option ")) {
                                parse_argv();
                        }

                        rc = rc_free;
                        if (rc)
                                rc_free = rc->next;
                        else {
                                rc = cmd_hist.next;
                                cmd_hist.next = rc->next;
                                cmd_hist.next->prev = &cmd_hist;
                                free(rc->buf);
                        }

                        rc->buf = xstrdup(command_buf.buf);
                        rc->prev = cmd_tail;
                        rc->next = cmd_hist.prev;
                        rc->prev->next = rc;
                        cmd_tail = rc;
                }
                if (command_buf.buf[0] == '#')
                        continue;
                return 0;
        }
}

static void skip_optional_lf(void)
{
        int term_char = fgetc(stdin);
        if (term_char != '\n' && term_char != EOF)
                ungetc(term_char, stdin);
}

static void parse_mark(void)
{
        const char *v;
        if (skip_prefix(command_buf.buf, "mark :", &v)) {
                next_mark = strtoumax(v, NULL, 10);
                read_next_command();
        }
        else
                next_mark = 0;
}

static void parse_original_identifier(void)
{
        const char *v;
        if (skip_prefix(command_buf.buf, "original-oid ", &v))
                read_next_command();
}

static int parse_data(struct strbuf *sb, uintmax_t limit, uintmax_t *len_res)
{
        const char *data;
        strbuf_reset(sb);

        if (!skip_prefix(command_buf.buf, "data ", &data))
                die("Expected 'data n' command, found: %s", command_buf.buf);

        if (skip_prefix(data, "<<", &data)) {
                char *term = xstrdup(data);
                size_t term_len = command_buf.len - (data - command_buf.buf);

                for (;;) {
                        if (strbuf_getline_lf(&command_buf, stdin) == EOF)
                                die("EOF in data (terminator '%s' not found)", term);
                        if (term_len == command_buf.len
                                && !strcmp(term, command_buf.buf))
                                break;
                        strbuf_addbuf(sb, &command_buf);
                        strbuf_addch(sb, '\n');
                }
                free(term);
        }
        else {
                uintmax_t len = strtoumax(data, NULL, 10);
                size_t n = 0, length = (size_t)len;

                if (limit && limit < len) {
                        *len_res = len;
                        return 0;
                }
                if (length < len)
                        die("data is too large to use in this context");

                while (n < length) {
                        size_t s = strbuf_fread(sb, length - n, stdin);
                        if (!s && feof(stdin))
                                die("EOF in data (%lu bytes remaining)",
                                        (unsigned long)(length - n));
                        n += s;
                }
        }

        skip_optional_lf();
        return 1;
}

static int validate_raw_date(const char *src, struct strbuf *result, int strict)
{
        const char *orig_src = src;
        char *endp;
        unsigned long num;

        errno = 0;

        num = strtoul(src, &endp, 10);
        /*
         * NEEDSWORK: perhaps check for reasonable values? For example, we
         *            could error on values representing times more than a
         *            day in the future.
         */
        if (errno || endp == src || *endp != ' ')
                return -1;

        src = endp + 1;
        if (*src != '-' && *src != '+')
                return -1;

        num = strtoul(src + 1, &endp, 10);
        /*
         * NEEDSWORK: check for brokenness other than num > 1400, such as
         *            (num % 100) >= 60, or ((num % 100) % 15) != 0 ?
         */
        if (errno || endp == src + 1 || *endp || /* did not parse */
            (strict && (1400 < num))             /* parsed a broken timezone */
           )
                return -1;

        strbuf_addstr(result, orig_src);
        return 0;
}

static char *parse_ident(const char *buf)
{
        const char *ltgt;
        size_t name_len;
        struct strbuf ident = STRBUF_INIT;

        /* ensure there is a space delimiter even if there is no name */
        if (*buf == '<')
                --buf;

        ltgt = buf + strcspn(buf, "<>");
        if (*ltgt != '<')
                die("Missing < in ident string: %s", buf);
        if (ltgt != buf && ltgt[-1] != ' ')
                die("Missing space before < in ident string: %s", buf);
        ltgt = ltgt + 1 + strcspn(ltgt + 1, "<>");
        if (*ltgt != '>')
                die("Missing > in ident string: %s", buf);
        ltgt++;
        if (*ltgt != ' ')
                die("Missing space after > in ident string: %s", buf);
        ltgt++;
        name_len = ltgt - buf;
        strbuf_add(&ident, buf, name_len);

        switch (whenspec) {
        case WHENSPEC_RAW:
                if (validate_raw_date(ltgt, &ident, 1) < 0)
                        die("Invalid raw date \"%s\" in ident: %s", ltgt, buf);
                break;
        case WHENSPEC_RAW_PERMISSIVE:
                if (validate_raw_date(ltgt, &ident, 0) < 0)
                        die("Invalid raw date \"%s\" in ident: %s", ltgt, buf);
                break;
        case WHENSPEC_RFC2822:
                if (parse_date(ltgt, &ident) < 0)
                        die("Invalid rfc2822 date \"%s\" in ident: %s", ltgt, buf);
                break;
        case WHENSPEC_NOW:
                if (strcmp("now", ltgt))
                        die("Date in ident must be 'now': %s", buf);
                datestamp(&ident);
                break;
        }

        return strbuf_detach(&ident, NULL);
}

static void parse_and_store_blob(
        struct last_object *last,
        struct object_id *oidout,
        uintmax_t mark)
{
        static struct strbuf buf = STRBUF_INIT;
        uintmax_t len;

        if (parse_data(&buf, big_file_threshold, &len))
                store_object(OBJ_BLOB, &buf, last, oidout, mark);
        else {
                if (last) {
                        strbuf_release(&last->data);
                        last->offset = 0;
                        last->depth = 0;
                }
                stream_blob(len, oidout, mark);
                skip_optional_lf();
        }
}

static void parse_new_blob(void)
{
        read_next_command();
        parse_mark();
        parse_original_identifier();
        parse_and_store_blob(&last_blob, NULL, next_mark);
}

static void unload_one_branch(void)
{
        while (cur_active_branches
                && cur_active_branches >= max_active_branches) {
                uintmax_t min_commit = ULONG_MAX;
                struct branch *e, *l = NULL, *p = NULL;

                for (e = active_branches; e; e = e->active_next_branch) {
                        if (e->last_commit < min_commit) {
                                p = l;
                                min_commit = e->last_commit;
                        }
                        l = e;
                }

                if (p) {
                        e = p->active_next_branch;
                        p->active_next_branch = e->active_next_branch;
                } else {
                        e = active_branches;
                        active_branches = e->active_next_branch;
                }
                e->active = 0;
                e->active_next_branch = NULL;
                if (e->branch_tree.tree) {
                        release_tree_content_recursive(e->branch_tree.tree);
                        e->branch_tree.tree = NULL;
                }
                cur_active_branches--;
        }
}

static void load_branch(struct branch *b)
{
        load_tree(&b->branch_tree);
        if (!b->active) {
                b->active = 1;
                b->active_next_branch = active_branches;
                active_branches = b;
                cur_active_branches++;
                branch_load_count++;
        }
}

static unsigned char convert_num_notes_to_fanout(uintmax_t num_notes)
{
        unsigned char fanout = 0;
        while ((num_notes >>= 8))
                fanout++;
        return fanout;
}

static void construct_path_with_fanout(const char *hex_sha1,
                unsigned char fanout, char *path)
{
        unsigned int i = 0, j = 0;
        if (fanout >= the_hash_algo->rawsz)
                die("Too large fanout (%u)", fanout);
        while (fanout) {
                path[i++] = hex_sha1[j++];
                path[i++] = hex_sha1[j++];
                path[i++] = '/';
                fanout--;
        }
        memcpy(path + i, hex_sha1 + j, the_hash_algo->hexsz - j);
        path[i + the_hash_algo->hexsz - j] = '\0';
}

static uintmax_t do_change_note_fanout(
                struct tree_entry *orig_root, struct tree_entry *root,
                char *hex_oid, unsigned int hex_oid_len,
                char *fullpath, unsigned int fullpath_len,
                unsigned char fanout)
{
        struct tree_content *t;
        struct tree_entry *e, leaf;
        unsigned int i, tmp_hex_oid_len, tmp_fullpath_len;
        uintmax_t num_notes = 0;
        struct object_id oid;
        /* hex oid + '/' between each pair of hex digits + NUL */
        char realpath[GIT_MAX_HEXSZ + ((GIT_MAX_HEXSZ / 2) - 1) + 1];
        const unsigned hexsz = the_hash_algo->hexsz;

        if (!root->tree)
                load_tree(root);
        t = root->tree;

        for (i = 0; t && i < t->entry_count; i++) {
                e = t->entries[i];
                tmp_hex_oid_len = hex_oid_len + e->name->str_len;
                tmp_fullpath_len = fullpath_len;

                /*
                 * We're interested in EITHER existing note entries (entries
                 * with exactly 40 hex chars in path, not including directory
                 * separators), OR directory entries that may contain note
                 * entries (with < 40 hex chars in path).
                 * Also, each path component in a note entry must be a multiple
                 * of 2 chars.
                 */
                if (!e->versions[1].mode ||
                    tmp_hex_oid_len > hexsz ||
                    e->name->str_len % 2)
                        continue;

                /* This _may_ be a note entry, or a subdir containing notes */
                memcpy(hex_oid + hex_oid_len, e->name->str_dat,
                       e->name->str_len);
                if (tmp_fullpath_len)
                        fullpath[tmp_fullpath_len++] = '/';
                memcpy(fullpath + tmp_fullpath_len, e->name->str_dat,
                       e->name->str_len);
                tmp_fullpath_len += e->name->str_len;
                fullpath[tmp_fullpath_len] = '\0';

                if (tmp_hex_oid_len == hexsz && !get_oid_hex(hex_oid, &oid)) {
                        /* This is a note entry */
                        if (fanout == 0xff) {
                                /* Counting mode, no rename */
                                num_notes++;
                                continue;
                        }
                        construct_path_with_fanout(hex_oid, fanout, realpath);
                        if (!strcmp(fullpath, realpath)) {
                                /* Note entry is in correct location */
                                num_notes++;
                                continue;
                        }

                        /* Rename fullpath to realpath */
                        if (!tree_content_remove(orig_root, fullpath, &leaf, 0))
                                die("Failed to remove path %s", fullpath);
                        tree_content_set(orig_root, realpath,
                                &leaf.versions[1].oid,
                                leaf.versions[1].mode,
                                leaf.tree);
                } else if (S_ISDIR(e->versions[1].mode)) {
                        /* This is a subdir that may contain note entries */
                        num_notes += do_change_note_fanout(orig_root, e,
                                hex_oid, tmp_hex_oid_len,
                                fullpath, tmp_fullpath_len, fanout);
                }

                /* The above may have reallocated the current tree_content */
                t = root->tree;
        }
        return num_notes;
}

static uintmax_t change_note_fanout(struct tree_entry *root,
                unsigned char fanout)
{
        /*
         * The size of path is due to one slash between every two hex digits,
         * plus the terminating NUL.  Note that there is no slash at the end, so
         * the number of slashes is one less than half the number of hex
         * characters.
         */
        char hex_oid[GIT_MAX_HEXSZ], path[GIT_MAX_HEXSZ + (GIT_MAX_HEXSZ / 2) - 1 + 1];
        return do_change_note_fanout(root, root, hex_oid, 0, path, 0, fanout);
}

static int parse_mapped_oid_hex(const char *hex, struct object_id *oid, const char **end)
{
        int algo;
        khiter_t it;

        /* Make SHA-1 object IDs have all-zero padding. */
        memset(oid->hash, 0, sizeof(oid->hash));

        algo = parse_oid_hex_any(hex, oid, end);
        if (algo == GIT_HASH_UNKNOWN)
                return -1;

        it = kh_get_oid_map(sub_oid_map, *oid);
        /* No such object? */
        if (it == kh_end(sub_oid_map)) {
                /* If we're using the same algorithm, pass it through. */
                if (hash_algos[algo].format_id == the_hash_algo->format_id)
                        return 0;
                return -1;
        }
        oidcpy(oid, kh_value(sub_oid_map, it));
        return 0;
}

/*
 * Given a pointer into a string, parse a mark reference:
 *
 *   idnum ::= ':' bigint;
 *
 * Return the first character after the value in *endptr.
 *
 * Complain if the following character is not what is expected,
 * either a space or end of the string.
 */
static uintmax_t parse_mark_ref(const char *p, char **endptr)
{
        uintmax_t mark;

        assert(*p == ':');
        p++;
        mark = strtoumax(p, endptr, 10);
        if (*endptr == p)
                die("No value after ':' in mark: %s", command_buf.buf);
        return mark;
}

/*
 * Parse the mark reference, and complain if this is not the end of
 * the string.
 */
static uintmax_t parse_mark_ref_eol(const char *p)
{
        char *end;
        uintmax_t mark;

        mark = parse_mark_ref(p, &end);
        if (*end != '\0')
                die("Garbage after mark: %s", command_buf.buf);
        return mark;
}

/*
 * Parse the mark reference, demanding a trailing space.  Return a
 * pointer to the space.
 */
static uintmax_t parse_mark_ref_space(const char **p)
{
        uintmax_t mark;
        char *end;

        mark = parse_mark_ref(*p, &end);
        if (*end++ != ' ')
                die("Missing space after mark: %s", command_buf.buf);
        *p = end;
        return mark;
}

static void file_change_m(const char *p, struct branch *b)
{
        static struct strbuf uq = STRBUF_INIT;
        const char *endp;
        struct object_entry *oe;
        struct object_id oid;
        uint16_t mode, inline_data = 0;

        p = get_mode(p, &mode);
        if (!p)
                die("Corrupt mode: %s", command_buf.buf);
        switch (mode) {
        case 0644:
        case 0755:
                mode |= S_IFREG;
        case S_IFREG | 0644:
        case S_IFREG | 0755:
        case S_IFLNK:
        case S_IFDIR:
        case S_IFGITLINK:
                /* ok */
                break;
        default:
                die("Corrupt mode: %s", command_buf.buf);
        }

        if (*p == ':') {
                oe = find_mark(marks, parse_mark_ref_space(&p));
                oidcpy(&oid, &oe->idx.oid);
        } else if (skip_prefix(p, "inline ", &p)) {
                inline_data = 1;
                oe = NULL; /* not used with inline_data, but makes gcc happy */
        } else {
                if (parse_mapped_oid_hex(p, &oid, &p))
                        die("Invalid dataref: %s", command_buf.buf);
                oe = find_object(&oid);
                if (*p++ != ' ')
                        die("Missing space after SHA1: %s", command_buf.buf);
        }

        strbuf_reset(&uq);
        if (!unquote_c_style(&uq, p, &endp)) {
                if (*endp)
                        die("Garbage after path in: %s", command_buf.buf);
                p = uq.buf;
        }

        /* Git does not track empty, non-toplevel directories. */
        if (S_ISDIR(mode) && is_empty_tree_oid(&oid) && *p) {
                tree_content_remove(&b->branch_tree, p, NULL, 0);
                return;
        }

        if (S_ISGITLINK(mode)) {
                if (inline_data)
                        die("Git links cannot be specified 'inline': %s",
                                command_buf.buf);
                else if (oe) {
                        if (oe->type != OBJ_COMMIT)
                                die("Not a commit (actually a %s): %s",
                                        type_name(oe->type), command_buf.buf);
                }
                /*
                 * Accept the sha1 without checking; it expected to be in
                 * another repository.
                 */
        } else if (inline_data) {
                if (S_ISDIR(mode))
                        die("Directories cannot be specified 'inline': %s",
                                command_buf.buf);
                if (p != uq.buf) {
                        strbuf_addstr(&uq, p);
                        p = uq.buf;
                }
                while (read_next_command() != EOF) {
                        const char *v;
                        if (skip_prefix(command_buf.buf, "cat-blob ", &v))
                                parse_cat_blob(v);
                        else {
                                parse_and_store_blob(&last_blob, &oid, 0);
                                break;
                        }
                }
        } else {
                enum object_type expected = S_ISDIR(mode) ?
                                                OBJ_TREE: OBJ_BLOB;
                enum object_type type = oe ? oe->type :
                                        oid_object_info(the_repository, &oid,
                                                        NULL);
                if (type < 0)
                        die("%s not found: %s",
                                        S_ISDIR(mode) ?  "Tree" : "Blob",
                                        command_buf.buf);
                if (type != expected)
                        die("Not a %s (actually a %s): %s",
                                type_name(expected), type_name(type),
                                command_buf.buf);
        }

        if (!*p) {
                tree_content_replace(&b->branch_tree, &oid, mode, NULL);
                return;
        }
        tree_content_set(&b->branch_tree, p, &oid, mode, NULL);
}

static void file_change_d(const char *p, struct branch *b)
{
        static struct strbuf uq = STRBUF_INIT;
        const char *endp;

        strbuf_reset(&uq);
        if (!unquote_c_style(&uq, p, &endp)) {
                if (*endp)
                        die("Garbage after path in: %s", command_buf.buf);
                p = uq.buf;
        }
        tree_content_remove(&b->branch_tree, p, NULL, 1);
}

static void file_change_cr(const char *s, struct branch *b, int rename)
{
        const char *d;
        static struct strbuf s_uq = STRBUF_INIT;
        static struct strbuf d_uq = STRBUF_INIT;
        const char *endp;
        struct tree_entry leaf;

        strbuf_reset(&s_uq);
        if (!unquote_c_style(&s_uq, s, &endp)) {
                if (*endp != ' ')
                        die("Missing space after source: %s", command_buf.buf);
        } else {
                endp = strchr(s, ' ');
                if (!endp)
                        die("Missing space after source: %s", command_buf.buf);
                strbuf_add(&s_uq, s, endp - s);
        }
        s = s_uq.buf;

        endp++;
        if (!*endp)
                die("Missing dest: %s", command_buf.buf);

        d = endp;
        strbuf_reset(&d_uq);
        if (!unquote_c_style(&d_uq, d, &endp)) {
                if (*endp)
                        die("Garbage after dest in: %s", command_buf.buf);
                d = d_uq.buf;
        }

        memset(&leaf, 0, sizeof(leaf));
        if (rename)
                tree_content_remove(&b->branch_tree, s, &leaf, 1);
        else
                tree_content_get(&b->branch_tree, s, &leaf, 1);
        if (!leaf.versions[1].mode)
                die("Path %s not in branch", s);
        if (!*d) {      /* C "path/to/subdir" "" */
                tree_content_replace(&b->branch_tree,
                        &leaf.versions[1].oid,
                        leaf.versions[1].mode,
                        leaf.tree);
                return;
        }
        tree_content_set(&b->branch_tree, d,
                &leaf.versions[1].oid,
                leaf.versions[1].mode,
                leaf.tree);
}

static void note_change_n(const char *p, struct branch *b, unsigned char *old_fanout)
{
        static struct strbuf uq = STRBUF_INIT;
        struct object_entry *oe;
        struct branch *s;
        struct object_id oid, commit_oid;
        char path[GIT_MAX_RAWSZ * 3];
        uint16_t inline_data = 0;
        unsigned char new_fanout;

        /*
         * When loading a branch, we don't traverse its tree to count the real
         * number of notes (too expensive to do this for all non-note refs).
         * This means that recently loaded notes refs might incorrectly have
         * b->num_notes == 0, and consequently, old_fanout might be wrong.
         *
         * Fix this by traversing the tree and counting the number of notes
         * when b->num_notes == 0. If the notes tree is truly empty, the
         * calculation should not take long.
         */
        if (b->num_notes == 0 && *old_fanout == 0) {
                /* Invoke change_note_fanout() in "counting mode". */
                b->num_notes = change_note_fanout(&b->branch_tree, 0xff);
                *old_fanout = convert_num_notes_to_fanout(b->num_notes);
        }

        /* Now parse the notemodify command. */
        /* <dataref> or 'inline' */
        if (*p == ':') {
                oe = find_mark(marks, parse_mark_ref_space(&p));
                oidcpy(&oid, &oe->idx.oid);
        } else if (skip_prefix(p, "inline ", &p)) {
                inline_data = 1;
                oe = NULL; /* not used with inline_data, but makes gcc happy */
        } else {
                if (parse_mapped_oid_hex(p, &oid, &p))
                        die("Invalid dataref: %s", command_buf.buf);
                oe = find_object(&oid);
                if (*p++ != ' ')
                        die("Missing space after SHA1: %s", command_buf.buf);
        }

        /* <commit-ish> */
        s = lookup_branch(p);
        if (s) {
                if (is_null_oid(&s->oid))
                        die("Can't add a note on empty branch.");
                oidcpy(&commit_oid, &s->oid);
        } else if (*p == ':') {
                uintmax_t commit_mark = parse_mark_ref_eol(p);
                struct object_entry *commit_oe = find_mark(marks, commit_mark);
                if (commit_oe->type != OBJ_COMMIT)
                        die("Mark :%" PRIuMAX " not a commit", commit_mark);
                oidcpy(&commit_oid, &commit_oe->idx.oid);
        } else if (!get_oid(p, &commit_oid)) {
                unsigned long size;
                char *buf = read_object_with_reference(the_repository,
                                                       &commit_oid,
                                                       commit_type, &size,
                                                       &commit_oid);
                if (!buf || size < the_hash_algo->hexsz + 6)
                        die("Not a valid commit: %s", p);
                free(buf);
        } else
                die("Invalid ref name or SHA1 expression: %s", p);

        if (inline_data) {
                if (p != uq.buf) {
                        strbuf_addstr(&uq, p);
                        p = uq.buf;
                }
                read_next_command();
                parse_and_store_blob(&last_blob, &oid, 0);
        } else if (oe) {
                if (oe->type != OBJ_BLOB)
                        die("Not a blob (actually a %s): %s",
                                type_name(oe->type), command_buf.buf);
        } else if (!is_null_oid(&oid)) {
                enum object_type type = oid_object_info(the_repository, &oid,
                                                        NULL);
                if (type < 0)
                        die("Blob not found: %s", command_buf.buf);
                if (type != OBJ_BLOB)
                        die("Not a blob (actually a %s): %s",
                            type_name(type), command_buf.buf);
        }

        construct_path_with_fanout(oid_to_hex(&commit_oid), *old_fanout, path);
        if (tree_content_remove(&b->branch_tree, path, NULL, 0))
                b->num_notes--;

        if (is_null_oid(&oid))
                return; /* nothing to insert */

        b->num_notes++;
        new_fanout = convert_num_notes_to_fanout(b->num_notes);
        construct_path_with_fanout(oid_to_hex(&commit_oid), new_fanout, path);
        tree_content_set(&b->branch_tree, path, &oid, S_IFREG | 0644, NULL);
}

static void file_change_deleteall(struct branch *b)
{
        release_tree_content_recursive(b->branch_tree.tree);
        oidclr(&b->branch_tree.versions[0].oid);
        oidclr(&b->branch_tree.versions[1].oid);
        load_tree(&b->branch_tree);
        b->num_notes = 0;
}

static void parse_from_commit(struct branch *b, char *buf, unsigned long size)
{
        if (!buf || size < the_hash_algo->hexsz + 6)
                die("Not a valid commit: %s", oid_to_hex(&b->oid));
        if (memcmp("tree ", buf, 5)
                || get_oid_hex(buf + 5, &b->branch_tree.versions[1].oid))
                die("The commit %s is corrupt", oid_to_hex(&b->oid));
        oidcpy(&b->branch_tree.versions[0].oid,
               &b->branch_tree.versions[1].oid);
}

static void parse_from_existing(struct branch *b)
{
        if (is_null_oid(&b->oid)) {
                oidclr(&b->branch_tree.versions[0].oid);
                oidclr(&b->branch_tree.versions[1].oid);
        } else {
                unsigned long size;
                char *buf;

                buf = read_object_with_reference(the_repository,
                                                 &b->oid, commit_type, &size,
                                                 &b->oid);
                parse_from_commit(b, buf, size);
                free(buf);
        }
}

static int parse_objectish(struct branch *b, const char *objectish)
{
        struct branch *s;
        struct object_id oid;

        oidcpy(&oid, &b->branch_tree.versions[1].oid);

        s = lookup_branch(objectish);
        if (b == s)
                die("Can't create a branch from itself: %s", b->name);
        else if (s) {
                struct object_id *t = &s->branch_tree.versions[1].oid;
                oidcpy(&b->oid, &s->oid);
                oidcpy(&b->branch_tree.versions[0].oid, t);
                oidcpy(&b->branch_tree.versions[1].oid, t);
        } else if (*objectish == ':') {
                uintmax_t idnum = parse_mark_ref_eol(objectish);
                struct object_entry *oe = find_mark(marks, idnum);
                if (oe->type != OBJ_COMMIT)
                        die("Mark :%" PRIuMAX " not a commit", idnum);
                if (!oideq(&b->oid, &oe->idx.oid)) {
                        oidcpy(&b->oid, &oe->idx.oid);
                        if (oe->pack_id != MAX_PACK_ID) {
                                unsigned long size;
                                char *buf = gfi_unpack_entry(oe, &size);
                                parse_from_commit(b, buf, size);
                                free(buf);
                        } else
                                parse_from_existing(b);
                }
        } else if (!get_oid(objectish, &b->oid)) {
                parse_from_existing(b);
                if (is_null_oid(&b->oid))
                        b->delete = 1;
        }
        else
                die("Invalid ref name or SHA1 expression: %s", objectish);

        if (b->branch_tree.tree && !oideq(&oid, &b->branch_tree.versions[1].oid)) {
                release_tree_content_recursive(b->branch_tree.tree);
                b->branch_tree.tree = NULL;
        }

        read_next_command();
        return 1;
}

static int parse_from(struct branch *b)
{
        const char *from;

        if (!skip_prefix(command_buf.buf, "from ", &from))
                return 0;

        return parse_objectish(b, from);
}

static int parse_objectish_with_prefix(struct branch *b, const char *prefix)
{
        const char *base;

        if (!skip_prefix(command_buf.buf, prefix, &base))
                return 0;

        return parse_objectish(b, base);
}

static struct hash_list *parse_merge(unsigned int *count)
{
        struct hash_list *list = NULL, **tail = &list, *n;
        const char *from;
        struct branch *s;

        *count = 0;
        while (skip_prefix(command_buf.buf, "merge ", &from)) {
                n = xmalloc(sizeof(*n));
                s = lookup_branch(from);
                if (s)
                        oidcpy(&n->oid, &s->oid);
                else if (*from == ':') {
                        uintmax_t idnum = parse_mark_ref_eol(from);
                        struct object_entry *oe = find_mark(marks, idnum);
                        if (oe->type != OBJ_COMMIT)
                                die("Mark :%" PRIuMAX " not a commit", idnum);
                        oidcpy(&n->oid, &oe->idx.oid);
                } else if (!get_oid(from, &n->oid)) {
                        unsigned long size;
                        char *buf = read_object_with_reference(the_repository,
                                                               &n->oid,
                                                               commit_type,
                                                               &size, &n->oid);
                        if (!buf || size < the_hash_algo->hexsz + 6)
                                die("Not a valid commit: %s", from);
                        free(buf);
                } else
                        die("Invalid ref name or SHA1 expression: %s", from);

                n->next = NULL;
                *tail = n;
                tail = &n->next;

                (*count)++;
                read_next_command();
        }
        return list;
}

static void parse_new_commit(const char *arg)
{
        static struct strbuf msg = STRBUF_INIT;
        struct branch *b;
        char *author = NULL;
        char *committer = NULL;
        char *encoding = NULL;
        struct hash_list *merge_list = NULL;
        unsigned int merge_count;
        unsigned char prev_fanout, new_fanout;
        const char *v;

        b = lookup_branch(arg);
        if (!b)
                b = new_branch(arg);

        read_next_command();
        parse_mark();
        parse_original_identifier();
        if (skip_prefix(command_buf.buf, "author ", &v)) {
                author = parse_ident(v);
                read_next_command();
        }
        if (skip_prefix(command_buf.buf, "committer ", &v)) {
                committer = parse_ident(v);
                read_next_command();
        }
        if (!committer)
                die("Expected committer but didn't get one");
        if (skip_prefix(command_buf.buf, "encoding ", &v)) {
                encoding = xstrdup(v);
                read_next_command();
        }
        parse_data(&msg, 0, NULL);
        read_next_command();
        parse_from(b);
        merge_list = parse_merge(&merge_count);

        /* ensure the branch is active/loaded */
        if (!b->branch_tree.tree || !max_active_branches) {
                unload_one_branch();
                load_branch(b);
        }

        prev_fanout = convert_num_notes_to_fanout(b->num_notes);

        /* file_change* */
        while (command_buf.len > 0) {
                if (skip_prefix(command_buf.buf, "M ", &v))
                        file_change_m(v, b);
                else if (skip_prefix(command_buf.buf, "D ", &v))
                        file_change_d(v, b);
                else if (skip_prefix(command_buf.buf, "R ", &v))
                        file_change_cr(v, b, 1);
                else if (skip_prefix(command_buf.buf, "C ", &v))
                        file_change_cr(v, b, 0);
                else if (skip_prefix(command_buf.buf, "N ", &v))
                        note_change_n(v, b, &prev_fanout);
                else if (!strcmp("deleteall", command_buf.buf))
                        file_change_deleteall(b);
                else if (skip_prefix(command_buf.buf, "ls ", &v))
                        parse_ls(v, b);
                else if (skip_prefix(command_buf.buf, "cat-blob ", &v))
                        parse_cat_blob(v);
                else {
                        unread_command_buf = 1;
                        break;
                }
                if (read_next_command() == EOF)
                        break;
        }

        new_fanout = convert_num_notes_to_fanout(b->num_notes);
        if (new_fanout != prev_fanout)
                b->num_notes = change_note_fanout(&b->branch_tree, new_fanout);

        /* build the tree and the commit */
        store_tree(&b->branch_tree);
        oidcpy(&b->branch_tree.versions[0].oid,
               &b->branch_tree.versions[1].oid);

        strbuf_reset(&new_data);
        strbuf_addf(&new_data, "tree %s\n",
                oid_to_hex(&b->branch_tree.versions[1].oid));
        if (!is_null_oid(&b->oid))
                strbuf_addf(&new_data, "parent %s\n",
                            oid_to_hex(&b->oid));
        while (merge_list) {
                struct hash_list *next = merge_list->next;
                strbuf_addf(&new_data, "parent %s\n",
                            oid_to_hex(&merge_list->oid));
                free(merge_list);
                merge_list = next;
        }
        strbuf_addf(&new_data,
                "author %s\n"
                "committer %s\n",
                author ? author : committer, committer);
        if (encoding)
                strbuf_addf(&new_data,
                        "encoding %s\n",
                        encoding);
        strbuf_addch(&new_data, '\n');
        strbuf_addbuf(&new_data, &msg);
        free(author);
        free(committer);
        free(encoding);

        if (!store_object(OBJ_COMMIT, &new_data, NULL, &b->oid, next_mark))
                b->pack_id = pack_id;
        b->last_commit = object_count_by_type[OBJ_COMMIT];
}

static void parse_new_tag(const char *arg)
{
        static struct strbuf msg = STRBUF_INIT;
        const char *from;
        char *tagger;
        struct branch *s;
        struct tag *t;
        uintmax_t from_mark = 0;
        struct object_id oid;
        enum object_type type;
        const char *v;

        t = mem_pool_alloc(&fi_mem_pool, sizeof(struct tag));
        memset(t, 0, sizeof(struct tag));
        t->name = mem_pool_strdup(&fi_mem_pool, arg);
        if (last_tag)
                last_tag->next_tag = t;
        else
                first_tag = t;
        last_tag = t;
        read_next_command();
        parse_mark();

        /* from ... */
        if (!skip_prefix(command_buf.buf, "from ", &from))
                die("Expected from command, got %s", command_buf.buf);
        s = lookup_branch(from);
        if (s) {
                if (is_null_oid(&s->oid))
                        die("Can't tag an empty branch.");
                oidcpy(&oid, &s->oid);
                type = OBJ_COMMIT;
        } else if (*from == ':') {
                struct object_entry *oe;
                from_mark = parse_mark_ref_eol(from);
                oe = find_mark(marks, from_mark);
                type = oe->type;
                oidcpy(&oid, &oe->idx.oid);
        } else if (!get_oid(from, &oid)) {
                struct object_entry *oe = find_object(&oid);
                if (!oe) {
                        type = oid_object_info(the_repository, &oid, NULL);
                        if (type < 0)
                                die("Not a valid object: %s", from);
                } else
                        type = oe->type;
        } else
                die("Invalid ref name or SHA1 expression: %s", from);
        read_next_command();

        /* original-oid ... */
        parse_original_identifier();

        /* tagger ... */
        if (skip_prefix(command_buf.buf, "tagger ", &v)) {
                tagger = parse_ident(v);
                read_next_command();
        } else
                tagger = NULL;

        /* tag payload/message */
        parse_data(&msg, 0, NULL);

        /* build the tag object */
        strbuf_reset(&new_data);

        strbuf_addf(&new_data,
                    "object %s\n"
                    "type %s\n"
                    "tag %s\n",
                    oid_to_hex(&oid), type_name(type), t->name);
        if (tagger)
                strbuf_addf(&new_data,
                            "tagger %s\n", tagger);
        strbuf_addch(&new_data, '\n');
        strbuf_addbuf(&new_data, &msg);
        free(tagger);

        if (store_object(OBJ_TAG, &new_data, NULL, &t->oid, next_mark))
                t->pack_id = MAX_PACK_ID;
        else
                t->pack_id = pack_id;
}

static void parse_reset_branch(const char *arg)
{
        struct branch *b;
        const char *tag_name;

        b = lookup_branch(arg);
        if (b) {
                oidclr(&b->oid);
                oidclr(&b->branch_tree.versions[0].oid);
                oidclr(&b->branch_tree.versions[1].oid);
                if (b->branch_tree.tree) {
                        release_tree_content_recursive(b->branch_tree.tree);
                        b->branch_tree.tree = NULL;
                }
        }
        else
                b = new_branch(arg);
        read_next_command();
        parse_from(b);
        if (b->delete && skip_prefix(b->name, "refs/tags/", &tag_name)) {
                /*
                 * Elsewhere, we call dump_branches() before dump_tags(),
                 * and dump_branches() will handle ref deletions first, so
                 * in order to make sure the deletion actually takes effect,
                 * we need to remove the tag from our list of tags to update.
                 *
                 * NEEDSWORK: replace list of tags with hashmap for faster
                 * deletion?
                 */
                struct tag *t, *prev = NULL;
                for (t = first_tag; t; t = t->next_tag) {
                        if (!strcmp(t->name, tag_name))
                                break;
                        prev = t;
                }
                if (t) {
                        if (prev)
                                prev->next_tag = t->next_tag;
                        else
                                first_tag = t->next_tag;
                        if (!t->next_tag)
                                last_tag = prev;
                        /* There is no mem_pool_free(t) function to call. */
                }
        }
        if (command_buf.len > 0)
                unread_command_buf = 1;
}

static void cat_blob_write(const char *buf, unsigned long size)
{
        if (write_in_full(cat_blob_fd, buf, size) < 0)
                die_errno("Write to frontend failed");
}

static void cat_blob(struct object_entry *oe, struct object_id *oid)
{
        struct strbuf line = STRBUF_INIT;
        unsigned long size;
        enum object_type type = 0;
        char *buf;

        if (!oe || oe->pack_id == MAX_PACK_ID) {
                buf = read_object_file(oid, &type, &size);
        } else {
                type = oe->type;
                buf = gfi_unpack_entry(oe, &size);
        }

        /*
         * Output based on batch_one_object() from cat-file.c.
         */
        if (type <= 0) {
                strbuf_reset(&line);
                strbuf_addf(&line, "%s missing\n", oid_to_hex(oid));
                cat_blob_write(line.buf, line.len);
                strbuf_release(&line);
                free(buf);
                return;
        }
        if (!buf)
                die("Can't read object %s", oid_to_hex(oid));
        if (type != OBJ_BLOB)
                die("Object %s is a %s but a blob was expected.",
                    oid_to_hex(oid), type_name(type));
        strbuf_reset(&line);
        strbuf_addf(&line, "%s %s %"PRIuMAX"\n", oid_to_hex(oid),
                    type_name(type), (uintmax_t)size);
        cat_blob_write(line.buf, line.len);
        strbuf_release(&line);
        cat_blob_write(buf, size);
        cat_blob_write("\n", 1);
        if (oe && oe->pack_id == pack_id) {
                last_blob.offset = oe->idx.offset;
                strbuf_attach(&last_blob.data, buf, size, size);
                last_blob.depth = oe->depth;
        } else
                free(buf);
}

static void parse_get_mark(const char *p)
{
        struct object_entry *oe;
        char output[GIT_MAX_HEXSZ + 2];

        /* get-mark SP <object> LF */
        if (*p != ':')
                die("Not a mark: %s", p);

        oe = find_mark(marks, parse_mark_ref_eol(p));
        if (!oe)
                die("Unknown mark: %s", command_buf.buf);

        xsnprintf(output, sizeof(output), "%s\n", oid_to_hex(&oe->idx.oid));
        cat_blob_write(output, the_hash_algo->hexsz + 1);
}

static void parse_cat_blob(const char *p)
{
        struct object_entry *oe;
        struct object_id oid;

        /* cat-blob SP <object> LF */
        if (*p == ':') {
                oe = find_mark(marks, parse_mark_ref_eol(p));
                if (!oe)
                        die("Unknown mark: %s", command_buf.buf);
                oidcpy(&oid, &oe->idx.oid);
        } else {
                if (parse_mapped_oid_hex(p, &oid, &p))
                        die("Invalid dataref: %s", command_buf.buf);
                if (*p)
                        die("Garbage after SHA1: %s", command_buf.buf);
                oe = find_object(&oid);
        }

        cat_blob(oe, &oid);
}

static struct object_entry *dereference(struct object_entry *oe,
                                        struct object_id *oid)
{
        unsigned long size;
        char *buf = NULL;
        const unsigned hexsz = the_hash_algo->hexsz;

        if (!oe) {
                enum object_type type = oid_object_info(the_repository, oid,
                                                        NULL);
                if (type < 0)
                        die("object not found: %s", oid_to_hex(oid));
                /* cache it! */
                oe = insert_object(oid);
                oe->type = type;
                oe->pack_id = MAX_PACK_ID;
                oe->idx.offset = 1;
        }
        switch (oe->type) {
        case OBJ_TREE:  /* easy case. */
                return oe;
        case OBJ_COMMIT:
        case OBJ_TAG:
                break;
        default:
                die("Not a tree-ish: %s", command_buf.buf);
        }

        if (oe->pack_id != MAX_PACK_ID) {       /* in a pack being written */
                buf = gfi_unpack_entry(oe, &size);
        } else {
                enum object_type unused;
                buf = read_object_file(oid, &unused, &size);
        }
        if (!buf)
                die("Can't load object %s", oid_to_hex(oid));

        /* Peel one layer. */
        switch (oe->type) {
        case OBJ_TAG:
                if (size < hexsz + strlen("object ") ||
                    get_oid_hex(buf + strlen("object "), oid))
                        die("Invalid SHA1 in tag: %s", command_buf.buf);
                break;
        case OBJ_COMMIT:
                if (size < hexsz + strlen("tree ") ||
                    get_oid_hex(buf + strlen("tree "), oid))
                        die("Invalid SHA1 in commit: %s", command_buf.buf);
        }

        free(buf);
        return find_object(oid);
}

static void insert_mapped_mark(uintmax_t mark, void *object, void *cbp)
{
        struct object_id *fromoid = object;
        struct object_id *tooid = find_mark(cbp, mark);
        int ret;
        khiter_t it;

        it = kh_put_oid_map(sub_oid_map, *fromoid, &ret);
        /* We've already seen this object. */
        if (ret == 0)
                return;
        kh_value(sub_oid_map, it) = tooid;
}

static void build_mark_map_one(struct mark_set *from, struct mark_set *to)
{
        for_each_mark(from, 0, insert_mapped_mark, to);
}

static void build_mark_map(struct string_list *from, struct string_list *to)
{
        struct string_list_item *fromp, *top;

        sub_oid_map = kh_init_oid_map();

        for_each_string_list_item(fromp, from) {
                top = string_list_lookup(to, fromp->string);
                if (!fromp->util) {
                        die(_("Missing from marks for submodule '%s'"), fromp->string);
                } else if (!top || !top->util) {
                        die(_("Missing to marks for submodule '%s'"), fromp->string);
                }
                build_mark_map_one(fromp->util, top->util);
        }
}

static struct object_entry *parse_treeish_dataref(const char **p)
{
        struct object_id oid;
        struct object_entry *e;

        if (**p == ':') {       /* <mark> */
                e = find_mark(marks, parse_mark_ref_space(p));
                if (!e)
                        die("Unknown mark: %s", command_buf.buf);
                oidcpy(&oid, &e->idx.oid);
        } else {        /* <sha1> */
                if (parse_mapped_oid_hex(*p, &oid, p))
                        die("Invalid dataref: %s", command_buf.buf);
                e = find_object(&oid);
                if (*(*p)++ != ' ')
                        die("Missing space after tree-ish: %s", command_buf.buf);
        }

        while (!e || e->type != OBJ_TREE)
                e = dereference(e, &oid);
        return e;
}

static void print_ls(int mode, const unsigned char *hash, const char *path)
{
        static struct strbuf line = STRBUF_INIT;

        /* See show_tree(). */
        const char *type =
                S_ISGITLINK(mode) ? commit_type :
                S_ISDIR(mode) ? tree_type :
                blob_type;

        if (!mode) {
                /* missing SP path LF */
                strbuf_reset(&line);
                strbuf_addstr(&line, "missing ");
                quote_c_style(path, &line, NULL, 0);
                strbuf_addch(&line, '\n');
        } else {
                /* mode SP type SP object_name TAB path LF */
                strbuf_reset(&line);
                strbuf_addf(&line, "%06o %s %s\t",
                                mode & ~NO_DELTA, type, hash_to_hex(hash));
                quote_c_style(path, &line, NULL, 0);
                strbuf_addch(&line, '\n');
        }
        cat_blob_write(line.buf, line.len);
}

static void parse_ls(const char *p, struct branch *b)
{
        struct tree_entry *root = NULL;
        struct tree_entry leaf = {NULL};

        /* ls SP (<tree-ish> SP)? <path> */
        if (*p == '"') {
                if (!b)
                        die("Not in a commit: %s", command_buf.buf);
                root = &b->branch_tree;
        } else {
                struct object_entry *e = parse_treeish_dataref(&p);
                root = new_tree_entry();
                oidcpy(&root->versions[1].oid, &e->idx.oid);
                if (!is_null_oid(&root->versions[1].oid))
                        root->versions[1].mode = S_IFDIR;
                load_tree(root);
        }
        if (*p == '"') {
                static struct strbuf uq = STRBUF_INIT;
                const char *endp;
                strbuf_reset(&uq);
                if (unquote_c_style(&uq, p, &endp))
                        die("Invalid path: %s", command_buf.buf);
                if (*endp)
                        die("Garbage after path in: %s", command_buf.buf);
                p = uq.buf;
        }
        tree_content_get(root, p, &leaf, 1);
        /*
         * A directory in preparation would have a sha1 of zero
         * until it is saved.  Save, for simplicity.
         */
        if (S_ISDIR(leaf.versions[1].mode))
                store_tree(&leaf);

        print_ls(leaf.versions[1].mode, leaf.versions[1].oid.hash, p);
        if (leaf.tree)
                release_tree_content_recursive(leaf.tree);
        if (!b || root != &b->branch_tree)
                release_tree_entry(root);
}

static void checkpoint(void)
{
        checkpoint_requested = 0;
        if (object_count) {
                cycle_packfile();
        }
        dump_branches();
        dump_tags();
        dump_marks();
}

static void parse_checkpoint(void)
{
        checkpoint_requested = 1;
        skip_optional_lf();
}

static void parse_progress(void)
{
        fwrite(command_buf.buf, 1, command_buf.len, stdout);
        fputc('\n', stdout);
        fflush(stdout);
        skip_optional_lf();
}

static void parse_alias(void)
{
        struct object_entry *e;
        struct branch b;

        skip_optional_lf();
        read_next_command();

        /* mark ... */
        parse_mark();
        if (!next_mark)
                die(_("Expected 'mark' command, got %s"), command_buf.buf);

        /* to ... */
        memset(&b, 0, sizeof(b));
        if (!parse_objectish_with_prefix(&b, "to "))
                die(_("Expected 'to' command, got %s"), command_buf.buf);
        e = find_object(&b.oid);
        assert(e);
        insert_mark(&marks, next_mark, e);
}

static char* make_fast_import_path(const char *path)
{
        if (!relative_marks_paths || is_absolute_path(path))
                return xstrdup(path);
        return git_pathdup("info/fast-import/%s", path);
}

static void option_import_marks(const char *marks,
                                        int from_stream, int ignore_missing)
{
        if (import_marks_file) {
                if (from_stream)
                        die("Only one import-marks command allowed per stream");

                /* read previous mark file */
                if(!import_marks_file_from_stream)
                        read_marks();
        }

        import_marks_file = make_fast_import_path(marks);
        import_marks_file_from_stream = from_stream;
        import_marks_file_ignore_missing = ignore_missing;
}

static void option_date_format(const char *fmt)
{
        if (!strcmp(fmt, "raw"))
                whenspec = WHENSPEC_RAW;
        else if (!strcmp(fmt, "raw-permissive"))
                whenspec = WHENSPEC_RAW_PERMISSIVE;
        else if (!strcmp(fmt, "rfc2822"))
                whenspec = WHENSPEC_RFC2822;
        else if (!strcmp(fmt, "now"))
                whenspec = WHENSPEC_NOW;
        else
                die("unknown --date-format argument %s", fmt);
}

static unsigned long ulong_arg(const char *option, const char *arg)
{
        char *endptr;
        unsigned long rv = strtoul(arg, &endptr, 0);
        if (strchr(arg, '-') || endptr == arg || *endptr)
                die("%s: argument must be a non-negative integer", option);
        return rv;
}

static void option_depth(const char *depth)
{
        max_depth = ulong_arg("--depth", depth);
        if (max_depth > MAX_DEPTH)
                die("--depth cannot exceed %u", MAX_DEPTH);
}

static void option_active_branches(const char *branches)
{
        max_active_branches = ulong_arg("--active-branches", branches);
}

static void option_export_marks(const char *marks)
{
        export_marks_file = make_fast_import_path(marks);
}

static void option_cat_blob_fd(const char *fd)
{
        unsigned long n = ulong_arg("--cat-blob-fd", fd);
        if (n > (unsigned long) INT_MAX)
                die("--cat-blob-fd cannot exceed %d", INT_MAX);
        cat_blob_fd = (int) n;
}

static void option_export_pack_edges(const char *edges)
{
        if (pack_edges)
                fclose(pack_edges);
        pack_edges = xfopen(edges, "a");
}

static void option_rewrite_submodules(const char *arg, struct string_list *list)
{
        struct mark_set *ms;
        FILE *fp;
        char *s = xstrdup(arg);
        char *f = strchr(s, ':');
        if (!f)
                die(_("Expected format name:filename for submodule rewrite option"));
        *f = '\0';
        f++;
        ms = xcalloc(1, sizeof(*ms));

        fp = fopen(f, "r");
        if (!fp)
                die_errno("cannot read '%s'", f);
        read_mark_file(&ms, fp, insert_oid_entry);
        fclose(fp);

        string_list_insert(list, s)->util = ms;
}

static int parse_one_option(const char *option)
{
        if (skip_prefix(option, "max-pack-size=", &option)) {
                unsigned long v;
                if (!git_parse_ulong(option, &v))
                        return 0;
                if (v < 8192) {
                        warning("max-pack-size is now in bytes, assuming --max-pack-size=%lum", v);
                        v *= 1024 * 1024;
                } else if (v < 1024 * 1024) {
                        warning("minimum max-pack-size is 1 MiB");
                        v = 1024 * 1024;
                }
                max_packsize = v;
        } else if (skip_prefix(option, "big-file-threshold=", &option)) {
                unsigned long v;
                if (!git_parse_ulong(option, &v))
                        return 0;
                big_file_threshold = v;
        } else if (skip_prefix(option, "depth=", &option)) {
                option_depth(option);
        } else if (skip_prefix(option, "active-branches=", &option)) {
                option_active_branches(option);
        } else if (skip_prefix(option, "export-pack-edges=", &option)) {
                option_export_pack_edges(option);
        } else if (!strcmp(option, "quiet")) {
                show_stats = 0;
        } else if (!strcmp(option, "stats")) {
                show_stats = 1;
        } else if (!strcmp(option, "allow-unsafe-features")) {
                ; /* already handled during early option parsing */
        } else {
                return 0;
        }

        return 1;
}

static void check_unsafe_feature(const char *feature, int from_stream)
{
        if (from_stream && !allow_unsafe_features)
                die(_("feature '%s' forbidden in input without --allow-unsafe-features"),
                    feature);
}

static int parse_one_feature(const char *feature, int from_stream)
{
        const char *arg;

        if (skip_prefix(feature, "date-format=", &arg)) {
                option_date_format(arg);
        } else if (skip_prefix(feature, "import-marks=", &arg)) {
                check_unsafe_feature("import-marks", from_stream);
                option_import_marks(arg, from_stream, 0);
        } else if (skip_prefix(feature, "import-marks-if-exists=", &arg)) {
                check_unsafe_feature("import-marks-if-exists", from_stream);
                option_import_marks(arg, from_stream, 1);
        } else if (skip_prefix(feature, "export-marks=", &arg)) {
                check_unsafe_feature(feature, from_stream);
                option_export_marks(arg);
        } else if (!strcmp(feature, "alias")) {
                ; /* Don't die - this feature is supported */
        } else if (skip_prefix(feature, "rewrite-submodules-to=", &arg)) {
                option_rewrite_submodules(arg, &sub_marks_to);
        } else if (skip_prefix(feature, "rewrite-submodules-from=", &arg)) {
                option_rewrite_submodules(arg, &sub_marks_from);
        } else if (!strcmp(feature, "get-mark")) {
                ; /* Don't die - this feature is supported */
        } else if (!strcmp(feature, "cat-blob")) {
                ; /* Don't die - this feature is supported */
        } else if (!strcmp(feature, "relative-marks")) {
                relative_marks_paths = 1;
        } else if (!strcmp(feature, "no-relative-marks")) {
                relative_marks_paths = 0;
        } else if (!strcmp(feature, "done")) {
                require_explicit_termination = 1;
        } else if (!strcmp(feature, "force")) {
                force_update = 1;
        } else if (!strcmp(feature, "notes") || !strcmp(feature, "ls")) {
                ; /* do nothing; we have the feature */
        } else {
                return 0;
        }

        return 1;
}

static void parse_feature(const char *feature)
{
        if (seen_data_command)
                die("Got feature command '%s' after data command", feature);

        if (parse_one_feature(feature, 1))
                return;

        die("This version of fast-import does not support feature %s.", feature);
}

static void parse_option(const char *option)
{
        if (seen_data_command)
                die("Got option command '%s' after data command", option);

        if (parse_one_option(option))
                return;

        die("This version of fast-import does not support option: %s", option);
}

static void git_pack_config(void)
{
        int indexversion_value;
        int limit;
        unsigned long packsizelimit_value;

        if (!git_config_get_ulong("pack.depth", &max_depth)) {
                if (max_depth > MAX_DEPTH)
                        max_depth = MAX_DEPTH;
        }
        if (!git_config_get_int("pack.indexversion", &indexversion_value)) {
                pack_idx_opts.version = indexversion_value;
                if (pack_idx_opts.version > 2)
                        git_die_config("pack.indexversion",
                                        "bad pack.indexversion=%"PRIu32, pack_idx_opts.version);
        }
        if (!git_config_get_ulong("pack.packsizelimit", &packsizelimit_value))
                max_packsize = packsizelimit_value;

        if (!git_config_get_int("fastimport.unpacklimit", &limit))
                unpack_limit = limit;
        else if (!git_config_get_int("transfer.unpacklimit", &limit))
                unpack_limit = limit;

        git_config(git_default_config, NULL);
}

static const char fast_import_usage[] =
"git fast-import [--date-format=<f>] [--max-pack-size=<n>] [--big-file-threshold=<n>] [--depth=<n>] [--active-branches=<n>] [--export-marks=<marks.file>]";

static void parse_argv(void)
{
        unsigned int i;

        for (i = 1; i < global_argc; i++) {
                const char *a = global_argv[i];

                if (*a != '-' || !strcmp(a, "--"))
                        break;

                if (!skip_prefix(a, "--", &a))
                        die("unknown option %s", a);

                if (parse_one_option(a))
                        continue;

                if (parse_one_feature(a, 0))
                        continue;

                if (skip_prefix(a, "cat-blob-fd=", &a)) {
                        option_cat_blob_fd(a);
                        continue;
                }

                die("unknown option --%s", a);
        }
        if (i != global_argc)
                usage(fast_import_usage);

        seen_data_command = 1;
        if (import_marks_file)
                read_marks();
        build_mark_map(&sub_marks_from, &sub_marks_to);
}

int cmd_fast_import(int argc, const char **argv, const char *prefix)
{
        unsigned int i;

        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage(fast_import_usage);

        reset_pack_idx_option(&pack_idx_opts);
        git_pack_config();

        alloc_objects(object_entry_alloc);
        strbuf_init(&command_buf, 0);
        atom_table = xcalloc(atom_table_sz, sizeof(struct atom_str*));
        branch_table = xcalloc(branch_table_sz, sizeof(struct branch*));
        avail_tree_table = xcalloc(avail_tree_table_sz, sizeof(struct avail_tree_content*));
        marks = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct mark_set));

        hashmap_init(&object_table, object_entry_hashcmp, NULL, 0);

        /*
         * We don't parse most options until after we've seen the set of
         * "feature" lines at the start of the stream (which allows the command
         * line to override stream data). But we must do an early parse of any
         * command-line options that impact how we interpret the feature lines.
         */
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (*arg != '-' || !strcmp(arg, "--"))
                        break;
                if (!strcmp(arg, "--allow-unsafe-features"))
                        allow_unsafe_features = 1;
        }

        global_argc = argc;
        global_argv = argv;

        rc_free = mem_pool_alloc(&fi_mem_pool, cmd_save * sizeof(*rc_free));
        for (i = 0; i < (cmd_save - 1); i++)
                rc_free[i].next = &rc_free[i + 1];
        rc_free[cmd_save - 1].next = NULL;

        start_packfile();
        set_die_routine(die_nicely);
        set_checkpoint_signal();
        while (read_next_command() != EOF) {
                const char *v;
                if (!strcmp("blob", command_buf.buf))
                        parse_new_blob();
                else if (skip_prefix(command_buf.buf, "commit ", &v))
                        parse_new_commit(v);
                else if (skip_prefix(command_buf.buf, "tag ", &v))
                        parse_new_tag(v);
                else if (skip_prefix(command_buf.buf, "reset ", &v))
                        parse_reset_branch(v);
                else if (skip_prefix(command_buf.buf, "ls ", &v))
                        parse_ls(v, NULL);
                else if (skip_prefix(command_buf.buf, "cat-blob ", &v))
                        parse_cat_blob(v);
                else if (skip_prefix(command_buf.buf, "get-mark ", &v))
                        parse_get_mark(v);
                else if (!strcmp("checkpoint", command_buf.buf))
                        parse_checkpoint();
                else if (!strcmp("done", command_buf.buf))
                        break;
                else if (!strcmp("alias", command_buf.buf))
                        parse_alias();
                else if (starts_with(command_buf.buf, "progress "))
                        parse_progress();
                else if (skip_prefix(command_buf.buf, "feature ", &v))
                        parse_feature(v);
                else if (skip_prefix(command_buf.buf, "option git ", &v))
                        parse_option(v);
                else if (starts_with(command_buf.buf, "option "))
                        /* ignore non-git options*/;
                else
                        die("Unsupported command: %s", command_buf.buf);

                if (checkpoint_requested)
                        checkpoint();
        }

        /* argv hasn't been parsed yet, do so */
        if (!seen_data_command)
                parse_argv();

        if (require_explicit_termination && feof(stdin))
                die("stream ends early");

        end_packfile();

        dump_branches();
        dump_tags();
        unkeep_all_packs();
        dump_marks();

        if (pack_edges)
                fclose(pack_edges);

        if (show_stats) {
                uintmax_t total_count = 0, duplicate_count = 0;
                for (i = 0; i < ARRAY_SIZE(object_count_by_type); i++)
                        total_count += object_count_by_type[i];
                for (i = 0; i < ARRAY_SIZE(duplicate_count_by_type); i++)
                        duplicate_count += duplicate_count_by_type[i];

                fprintf(stderr, "%s statistics:\n", argv[0]);
                fprintf(stderr, "---------------------------------------------------------------------\n");
                fprintf(stderr, "Alloc'd objects: %10" PRIuMAX "\n", alloc_count);
                fprintf(stderr, "Total objects:   %10" PRIuMAX " (%10" PRIuMAX " duplicates                  )\n", total_count, duplicate_count);
                fprintf(stderr, "      blobs  :   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas of %10" PRIuMAX" attempts)\n", object_count_by_type[OBJ_BLOB], duplicate_count_by_type[OBJ_BLOB], delta_count_by_type[OBJ_BLOB], delta_count_attempts_by_type[OBJ_BLOB]);
                fprintf(stderr, "      trees  :   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas of %10" PRIuMAX" attempts)\n", object_count_by_type[OBJ_TREE], duplicate_count_by_type[OBJ_TREE], delta_count_by_type[OBJ_TREE], delta_count_attempts_by_type[OBJ_TREE]);
                fprintf(stderr, "      commits:   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas of %10" PRIuMAX" attempts)\n", object_count_by_type[OBJ_COMMIT], duplicate_count_by_type[OBJ_COMMIT], delta_count_by_type[OBJ_COMMIT], delta_count_attempts_by_type[OBJ_COMMIT]);
                fprintf(stderr, "      tags   :   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas of %10" PRIuMAX" attempts)\n", object_count_by_type[OBJ_TAG], duplicate_count_by_type[OBJ_TAG], delta_count_by_type[OBJ_TAG], delta_count_attempts_by_type[OBJ_TAG]);
                fprintf(stderr, "Total branches:  %10lu (%10lu loads     )\n", branch_count, branch_load_count);
                fprintf(stderr, "      marks:     %10" PRIuMAX " (%10" PRIuMAX " unique    )\n", (((uintmax_t)1) << marks->shift) * 1024, marks_set_count);
                fprintf(stderr, "      atoms:     %10u\n", atom_cnt);
                fprintf(stderr, "Memory total:    %10" PRIuMAX " KiB\n", (tree_entry_allocd + fi_mem_pool.pool_alloc + alloc_count*sizeof(struct object_entry))/1024);
                fprintf(stderr, "       pools:    %10lu KiB\n", (unsigned long)((tree_entry_allocd + fi_mem_pool.pool_alloc) /1024));
                fprintf(stderr, "     objects:    %10" PRIuMAX " KiB\n", (alloc_count*sizeof(struct object_entry))/1024);
                fprintf(stderr, "---------------------------------------------------------------------\n");
                pack_report();
                fprintf(stderr, "---------------------------------------------------------------------\n");
                fprintf(stderr, "\n");
        }

        return failure ? 1 : 0;
}