fast-import: treat SIGUSR1 as a request to access objects early

[git] / fast-import.c

/*
(See Documentation/git-fast-import.txt for maintained documentation.)
Format of STDIN stream:

  stream ::= cmd*;

  cmd ::= new_blob
        | new_commit
        | new_tag
        | reset_branch
        | checkpoint
        | progress
        ;

  new_blob ::= 'blob' lf
    mark?
    file_content;
  file_content ::= data;

  new_commit ::= 'commit' sp ref_str lf
    mark?
    ('author' (sp name)? sp '<' email '>' sp when lf)?
    'committer' (sp name)? sp '<' email '>' sp when lf
    commit_msg
    ('from' sp committish lf)?
    ('merge' sp committish lf)*
    file_change*
    lf?;
  commit_msg ::= data;

  file_change ::= file_clr
    | file_del
    | file_rnm
    | file_cpy
    | file_obm
    | file_inm;
  file_clr ::= 'deleteall' lf;
  file_del ::= 'D' sp path_str lf;
  file_rnm ::= 'R' sp path_str sp path_str lf;
  file_cpy ::= 'C' sp path_str sp path_str lf;
  file_obm ::= 'M' sp mode sp (hexsha1 | idnum) sp path_str lf;
  file_inm ::= 'M' sp mode sp 'inline' sp path_str lf
    data;
  note_obm ::= 'N' sp (hexsha1 | idnum) sp committish lf;
  note_inm ::= 'N' sp 'inline' sp committish lf
    data;

  new_tag ::= 'tag' sp tag_str lf
    'from' sp committish lf
    ('tagger' (sp name)? sp '<' email '>' sp when lf)?
    tag_msg;
  tag_msg ::= data;

  reset_branch ::= 'reset' sp ref_str lf
    ('from' sp committish lf)?
    lf?;

  checkpoint ::= 'checkpoint' lf
    lf?;

  progress ::= 'progress' sp not_lf* lf
    lf?;

     # note: the first idnum in a stream should be 1 and subsequent
     # idnums should not have gaps between values as this will cause
     # the stream parser to reserve space for the gapped values.  An
     # idnum can be updated in the future to a new object by issuing
     # a new mark directive with the old idnum.
     #
  mark ::= 'mark' sp idnum lf;
  data ::= (delimited_data | exact_data)
    lf?;

    # note: delim may be any string but must not contain lf.
    # data_line may contain any data but must not be exactly
    # delim.
  delimited_data ::= 'data' sp '<<' delim lf
    (data_line lf)*
    delim lf;

     # note: declen indicates the length of binary_data in bytes.
     # declen does not include the lf preceding the binary data.
     #
  exact_data ::= 'data' sp declen lf
    binary_data;

     # note: quoted strings are C-style quoting supporting \c for
     # common escapes of 'c' (e..g \n, \t, \\, \") or \nnn where nnn
     # is the signed byte value in octal.  Note that the only
     # characters which must actually be escaped to protect the
     # stream formatting is: \, " and LF.  Otherwise these values
     # are UTF8.
     #
  committish  ::= (ref_str | hexsha1 | sha1exp_str | idnum);
  ref_str     ::= ref;
  sha1exp_str ::= sha1exp;
  tag_str     ::= tag;
  path_str    ::= path    | '"' quoted(path)    '"' ;
  mode        ::= '100644' | '644'
                | '100755' | '755'
                | '120000'
                ;

  declen ::= # unsigned 32 bit value, ascii base10 notation;
  bigint ::= # unsigned integer value, ascii base10 notation;
  binary_data ::= # file content, not interpreted;

  when         ::= raw_when | rfc2822_when;
  raw_when     ::= ts sp tz;
  rfc2822_when ::= # Valid RFC 2822 date and time;

  sp ::= # ASCII space character;
  lf ::= # ASCII newline (LF) character;

     # note: a colon (':') must precede the numerical value assigned to
     # an idnum.  This is to distinguish it from a ref or tag name as
     # GIT does not permit ':' in ref or tag strings.
     #
  idnum   ::= ':' bigint;
  path    ::= # GIT style file path, e.g. "a/b/c";
  ref     ::= # GIT ref name, e.g. "refs/heads/MOZ_GECKO_EXPERIMENT";
  tag     ::= # GIT tag name, e.g. "FIREFOX_1_5";
  sha1exp ::= # Any valid GIT SHA1 expression;
  hexsha1 ::= # SHA1 in hexadecimal format;

     # note: name and email are UTF8 strings, however name must not
     # contain '<' or lf and email must not contain any of the
     # following: '<', '>', lf.
     #
  name  ::= # valid GIT author/committer name;
  email ::= # valid GIT author/committer email;
  ts    ::= # time since the epoch in seconds, ascii base10 notation;
  tz    ::= # GIT style timezone;

     # note: comments may appear anywhere in the input, except
     # within a data command.  Any form of the data command
     # always escapes the related input from comment processing.
     #
     # In case it is not clear, the '#' that starts the comment
     # must be the first character on that line (an lf
     # preceded it).
     #
  comment ::= '#' not_lf* lf;
  not_lf  ::= # Any byte that is not ASCII newline (LF);
*/

#include "builtin.h"
#include "cache.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 "exec_cmd.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)

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

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_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 mem_pool
{
        struct mem_pool *next_pool;
        char *next_free;
        char *end;
        uintmax_t space[FLEX_ARRAY]; /* more */
};

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;
                unsigned char sha1[20];
        } 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 pack_id : PACK_ID_BITS;
        unsigned char sha1[20];
};

struct tag
{
        struct tag *next_tag;
        const char *name;
        unsigned int pack_id;
        unsigned char sha1[20];
};

struct hash_list
{
        struct hash_list *next;
        unsigned char sha1[20];
};

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

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

/* Configured limits on output */
static unsigned long max_depth = 10;
static off_t max_packsize;
static uintmax_t big_file_threshold = 512 * 1024 * 1024;
static int force_update;
static int pack_compression_level = Z_DEFAULT_COMPRESSION;
static int pack_compression_seen;

/* 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 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 size_t mem_pool_alloc = 2*1024*1024 - sizeof(struct mem_pool);
static size_t total_allocd;
static struct mem_pool *mem_pool;

/* 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 unsigned int pack_id;
static struct sha1file *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 object_entry *object_table[1 << 16];
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 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 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;

/* Signal handling */
static volatile sig_atomic_t checkpoint_requested;

static void parse_argv(void);

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_sha1(b->branch_tree.versions[1].sha1))
                fputs(" dirty", rpt);
        fputc('\n', rpt);

        fprintf(rpt, "  tip commit  : %s\n", sha1_to_hex(b->sha1));
        fprintf(rpt, "  old tree    : %s\n", sha1_to_hex(b->branch_tree.versions[0].sha1));
        fprintf(rpt, "  cur tree    : %s\n", sha1_to_hex(b->branch_tree.versions[1].sha1));
        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 dump_marks_helper(FILE *, uintmax_t, struct mark_set *);

static void write_crash_report(const char *err)
{
        char *loc = git_path("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("can't write crash report %s: %s", loc, strerror(errno));
                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_LOCAL));
        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(sha1_to_hex(tg->sha1), 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
                dump_marks_helper(rpt, 0, marks);

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

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(unsigned char *sha1)
{
        struct object_entry *e;

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

        e = blocks->next_free++;
        hashcpy(e->idx.sha1, sha1);
        return e;
}

static struct object_entry *find_object(unsigned char *sha1)
{
        unsigned int h = sha1[0] << 8 | sha1[1];
        struct object_entry *e;
        for (e = object_table[h]; e; e = e->next)
                if (!hashcmp(sha1, e->idx.sha1))
                        return e;
        return NULL;
}

static struct object_entry *insert_object(unsigned char *sha1)
{
        unsigned int h = sha1[0] << 8 | sha1[1];
        struct object_entry *e = object_table[h];
        struct object_entry *p = NULL;

        while (e) {
                if (!hashcmp(sha1, e->idx.sha1))
                        return e;
                p = e;
                e = e->next;
        }

        e = new_object(sha1);
        e->next = NULL;
        e->idx.offset = 0;
        if (p)
                p->next = e;
        else
                object_table[h] = e;
        return e;
}

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 *pool_alloc(size_t len)
{
        struct mem_pool *p;
        void *r;

        /* round up to a 'uintmax_t' alignment */
        if (len & (sizeof(uintmax_t) - 1))
                len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));

        for (p = mem_pool; p; p = p->next_pool)
                if ((p->end - p->next_free >= len))
                        break;

        if (!p) {
                if (len >= (mem_pool_alloc/2)) {
                        total_allocd += len;
                        return xmalloc(len);
                }
                total_allocd += sizeof(struct mem_pool) + mem_pool_alloc;
                p = xmalloc(sizeof(struct mem_pool) + mem_pool_alloc);
                p->next_pool = mem_pool;
                p->next_free = (char *) p->space;
                p->end = p->next_free + mem_pool_alloc;
                mem_pool = p;
        }

        r = p->next_free;
        p->next_free += len;
        return r;
}

static void *pool_calloc(size_t count, size_t size)
{
        size_t len = count * size;
        void *r = pool_alloc(len);
        memset(r, 0, len);
        return r;
}

static char *pool_strdup(const char *s)
{
        char *r = pool_alloc(strlen(s) + 1);
        strcpy(r, s);
        return r;
}

static void insert_mark(uintmax_t idnum, struct object_entry *oe)
{
        struct mark_set *s = marks;
        while ((idnum >> s->shift) >= 1024) {
                s = pool_calloc(1, sizeof(struct mark_set));
                s->shift = marks->shift + 10;
                s->data.sets[0] = marks;
                marks = s;
        }
        while (s->shift) {
                uintmax_t i = idnum >> s->shift;
                idnum -= i << s->shift;
                if (!s->data.sets[i]) {
                        s->data.sets[i] = pool_calloc(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 struct object_entry *find_mark(uintmax_t idnum)
{
        uintmax_t orig_idnum = idnum;
        struct mark_set *s = marks;
        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 = pool_alloc(sizeof(struct atom_str) + len + 1);
        c->str_len = len;
        strncpy(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);
        switch (check_ref_format(name)) {
        case 0: break; /* its valid */
        case CHECK_REF_FORMAT_ONELEVEL:
                break; /* valid, but too few '/', allow anyway */
        default:
                die("Branch name doesn't conform to GIT standards: %s", name);
        }

        b = pool_calloc(1, sizeof(struct branch));
        b->name = pool_strdup(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 = pool_alloc(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;
        memcpy(r->entries,t->entries,t->entry_count*sizeof(t->entries[0]));
        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;
                total_allocd += n * sizeof(struct tree_entry);
                avail_tree_entry = e = xmalloc(n * sizeof(struct tree_entry));
                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_sha1(b->versions[1].sha1))
                        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)
{
        static char tmpfile[PATH_MAX];
        struct packed_git *p;
        struct pack_header hdr;
        int pack_fd;

        pack_fd = odb_mkstemp(tmpfile, sizeof(tmpfile),
                              "pack/tmp_pack_XXXXXX");
        p = xcalloc(1, sizeof(*p) + strlen(tmpfile) + 2);
        strcpy(p->pack_name, tmpfile);
        p->pack_fd = pack_fd;
        pack_file = sha1fd(pack_fd, p->pack_name);

        hdr.hdr_signature = htonl(PACK_SIGNATURE);
        hdr.hdr_version = htonl(2);
        hdr.hdr_entries = 0;
        sha1write(pack_file, &hdr, sizeof(hdr));

        pack_data = p;
        pack_size = sizeof(hdr);
        object_count = 0;

        all_packs = xrealloc(all_packs, sizeof(*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. */
        idx = xmalloc(object_count * sizeof(*idx));
        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_data->sha1);
        free(idx);
        return tmpfile;
}

static char *keep_pack(const char *curr_index_name)
{
        static char name[PATH_MAX];
        static const char *keep_msg = "fast-import";
        int keep_fd;

        keep_fd = odb_pack_keep(name, sizeof(name), pack_data->sha1);
        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");

        snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
                 get_object_directory(), sha1_to_hex(pack_data->sha1));
        if (move_temp_to_file(pack_data->pack_name, name))
                die("cannot store pack file");

        snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
                 get_object_directory(), sha1_to_hex(pack_data->sha1));
        if (move_temp_to_file(curr_index_name, name))
                die("cannot store index file");
        free((void *)curr_index_name);
        return name;
}

static void unkeep_all_packs(void)
{
        static char name[PATH_MAX];
        int k;

        for (k = 0; k < pack_id; k++) {
                struct packed_git *p = all_packs[k];
                snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
                         get_object_directory(), sha1_to_hex(p->sha1));
                unlink_or_warn(name);
        }
}

static void end_packfile(void)
{
        struct packed_git *old_p = pack_data, *new_p;

        clear_delta_base_cache();
        if (object_count) {
                unsigned char cur_pack_sha1[20];
                char *idx_name;
                int i;
                struct branch *b;
                struct tag *t;

                close_pack_windows(pack_data);
                sha1close(pack_file, cur_pack_sha1, 0);
                fixup_pack_header_footer(pack_data->pack_fd, pack_data->sha1,
                                    pack_data->pack_name, object_count,
                                    cur_pack_sha1, pack_size);
                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(new_p);

                /* 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", sha1_to_hex(b->sha1));
                                }
                        }
                        for (t = first_tag; t; t = t->next_tag) {
                                if (t->pack_id == pack_id)
                                        fprintf(pack_edges, " %s", sha1_to_hex(t->sha1));
                        }
                        fputc('\n', pack_edges);
                        fflush(pack_edges);
                }

                pack_id++;
        }
        else {
                close(old_p->pack_fd);
                unlink_or_warn(old_p->pack_name);
        }
        free(old_p);

        /* 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,
        unsigned char *sha1out,
        uintmax_t mark)
{
        void *out, *delta;
        struct object_entry *e;
        unsigned char hdr[96];
        unsigned char sha1[20];
        unsigned long hdrlen, deltalen;
        git_SHA_CTX c;
        z_stream s;

        hdrlen = sprintf((char *)hdr,"%s %lu", typename(type),
                (unsigned long)dat->len) + 1;
        git_SHA1_Init(&c);
        git_SHA1_Update(&c, hdr, hdrlen);
        git_SHA1_Update(&c, dat->buf, dat->len);
        git_SHA1_Final(sha1, &c);
        if (sha1out)
                hashcpy(sha1out, sha1);

        e = insert_object(sha1);
        if (mark)
                insert_mark(mark, e);
        if (e->idx.offset) {
                duplicate_count_by_type[type]++;
                return 1;
        } else if (find_sha1_pack(sha1, packed_git)) {
                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.buf && last->depth < max_depth && dat->len > 20) {
                delta = diff_delta(last->data.buf, last->data.len,
                        dat->buf, dat->len,
                        &deltalen, dat->len - 20);
        } else
                delta = NULL;

        memset(&s, 0, sizeof(s));
        deflateInit(&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 = deflateBound(&s, s.avail_in);
        s.next_out = out = xmalloc(s.avail_out);
        while (deflate(&s, Z_FINISH) == Z_OK)
                /* nothing */;
        deflateEnd(&s);

        /* Determine if we should auto-checkpoint. */
        if ((max_packsize && (pack_size + 60 + s.total_out) > max_packsize)
                || (pack_size + 60 + 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(delta);
                        delta = NULL;

                        memset(&s, 0, sizeof(s));
                        deflateInit(&s, pack_compression_level);
                        s.next_in = (void *)dat->buf;
                        s.avail_in = dat->len;
                        s.avail_out = deflateBound(&s, s.avail_in);
                        s.next_out = out = xrealloc(out, s.avail_out);
                        while (deflate(&s, Z_FINISH) == Z_OK)
                                /* nothing */;
                        deflateEnd(&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(OBJ_OFS_DELTA, deltalen, hdr);
                sha1write(pack_file, hdr, hdrlen);
                pack_size += hdrlen;

                hdr[pos] = ofs & 127;
                while (ofs >>= 7)
                        hdr[--pos] = 128 | (--ofs & 127);
                sha1write(pack_file, hdr + pos, sizeof(hdr) - pos);
                pack_size += sizeof(hdr) - pos;
        } else {
                e->depth = 0;
                hdrlen = encode_in_pack_object_header(type, dat->len, hdr);
                sha1write(pack_file, hdr, hdrlen);
                pack_size += hdrlen;
        }

        sha1write(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(off_t to, git_SHA_CTX *ctx)
{
        if (ftruncate(pack_data->pack_fd, to)
         || lseek(pack_data->pack_fd, to, SEEK_SET) != to)
                die_errno("cannot truncate pack to skip duplicate");
        pack_size = to;

        /* yes this is a layering violation */
        pack_file->total = to;
        pack_file->offset = 0;
        pack_file->ctx = *ctx;
}

static void stream_blob(uintmax_t len, unsigned char *sha1out, 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;
        unsigned char sha1[20];
        unsigned long hdrlen;
        off_t offset;
        git_SHA_CTX c;
        git_SHA_CTX pack_file_ctx;
        z_stream s;
        int status = Z_OK;

        /* Determine if we should auto-checkpoint. */
        if ((max_packsize && (pack_size + 60 + len) > max_packsize)
                || (pack_size + 60 + len) < pack_size)
                cycle_packfile();

        offset = pack_size;

        /* preserve the pack_file SHA1 ctx in case we have to truncate later */
        sha1flush(pack_file);
        pack_file_ctx = pack_file->ctx;

        hdrlen = snprintf((char *)out_buf, out_sz, "blob %" PRIuMAX, len) + 1;
        if (out_sz <= hdrlen)
                die("impossibly large object header");

        git_SHA1_Init(&c);
        git_SHA1_Update(&c, out_buf, hdrlen);

        crc32_begin(pack_file);

        memset(&s, 0, sizeof(s));
        deflateInit(&s, pack_compression_level);

        hdrlen = encode_in_pack_object_header(OBJ_BLOB, len, out_buf);
        if (out_sz <= hdrlen)
                die("impossibly large object header");

        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);

                        git_SHA1_Update(&c, in_buf, n);
                        s.next_in = in_buf;
                        s.avail_in = n;
                        len -= n;
                }

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

                if (!s.avail_out || status == Z_STREAM_END) {
                        size_t n = s.next_out - out_buf;
                        sha1write(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);
                }
        }
        deflateEnd(&s);
        git_SHA1_Final(sha1, &c);

        if (sha1out)
                hashcpy(sha1out, sha1);

        e = insert_object(sha1);

        if (mark)
                insert_mark(mark, e);

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

        } else if (find_sha1_pack(sha1, packed_git)) {
                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(offset, &pack_file_ctx);

        } 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 + 20)) {
                /* 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 + 20) 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);
                sha1flush(pack_file);

                /* We have to offer 20 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 20 bytes within any window it maps.  But
                 * we don't actually create the footer here.
                 */
                p->pack_size = pack_size + 20;
        }
        return unpack_entry(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)
{
        unsigned char *sha1 = root->versions[1].sha1;
        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_sha1(sha1))
                return;

        myoe = find_object(sha1);
        if (myoe && myoe->pack_id != MAX_PACK_ID) {
                if (myoe->type != OBJ_TREE)
                        die("Not a tree: %s", sha1_to_hex(sha1));
                t->delta_depth = myoe->depth;
                buf = gfi_unpack_entry(myoe, &size);
                if (!buf)
                        die("Can't load tree %s", sha1_to_hex(sha1));
        } else {
                enum object_type type;
                buf = read_sha1_file(sha1, &type, &size);
                if (!buf || type != OBJ_TREE)
                        die("Can't load tree %s", sha1_to_hex(sha1));
        }

        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", sha1_to_hex(sha1));
                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].sha1, (unsigned char *)c);
                hashcpy(e->versions[1].sha1, (unsigned char *)c);
                c += 20;
        }
        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,sizeof(t->entries[0]),tecmp0);
        else
                qsort(t->entries,t->entry_count,sizeof(t->entries[0]),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,
                                        e->name->str_dat, '\0');
                strbuf_add(b, e->versions[v].sha1, 20);
        }
}

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

        if (!is_null_sha1(root->versions[1].sha1))
                return;

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

        le = find_object(root->versions[0].sha1);
        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].sha1, 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;
                        hashcpy(e->versions[0].sha1, e->versions[1].sha1);
                        t->entries[j++] = e;
                } else {
                        release_tree_entry(e);
                        del++;
                }
        }
        t->entry_count -= del;
}

static int tree_content_set(
        struct tree_entry *root,
        const char *p,
        const unsigned char *sha1,
        const uint16_t mode,
        struct tree_content *subtree)
{
        struct tree_content *t = root->tree;
        const char *slash1;
        unsigned int i, n;
        struct tree_entry *e;

        slash1 = strchr(p, '/');
        if (slash1)
                n = slash1 - p;
        else
                n = strlen(p);
        if (!slash1 && !n) {
                if (!S_ISDIR(mode))
                        die("Root cannot be a non-directory");
                hashcpy(root->versions[1].sha1, sha1);
                if (root->tree)
                        release_tree_content_recursive(root->tree);
                root->tree = subtree;
                return 1;
        }
        if (!n)
                die("Empty path component found in input");
        if (!slash1 && !S_ISDIR(mode) && subtree)
                die("Non-directories cannot have subtrees");

        for (i = 0; i < t->entry_count; i++) {
                e = t->entries[i];
                if (e->name->str_len == n && !strncmp(p, e->name->str_dat, n)) {
                        if (!slash1) {
                                if (!S_ISDIR(mode)
                                                && e->versions[1].mode == mode
                                                && !hashcmp(e->versions[1].sha1, sha1))
                                        return 0;
                                e->versions[1].mode = mode;
                                hashcpy(e->versions[1].sha1, sha1);
                                if (e->tree)
                                        release_tree_content_recursive(e->tree);
                                e->tree = subtree;
                                hashclr(root->versions[1].sha1);
                                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, sha1, mode, subtree)) {
                                hashclr(root->versions[1].sha1);
                                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;
        hashclr(e->versions[0].sha1);
        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, sha1, mode, subtree);
        } else {
                e->tree = subtree;
                e->versions[1].mode = mode;
                hashcpy(e->versions[1].sha1, sha1);
        }
        hashclr(root->versions[1].sha1);
        return 1;
}

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

        slash1 = strchr(p, '/');
        if (slash1)
                n = slash1 - p;
        else
                n = strlen(p);

        for (i = 0; i < t->entry_count; i++) {
                e = t->entries[i];
                if (e->name->str_len == n && !strncmp(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)) {
                                for (n = 0; n < e->tree->entry_count; n++) {
                                        if (e->tree->entries[n]->versions[1].mode) {
                                                hashclr(root->versions[1].sha1);
                                                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;
        hashclr(e->versions[1].sha1);
        hashclr(root->versions[1].sha1);
        return 1;
}

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

        slash1 = strchr(p, '/');
        if (slash1)
                n = slash1 - p;
        else
                n = strlen(p);

        for (i = 0; i < t->entry_count; i++) {
                e = t->entries[i];
                if (e->name->str_len == n && !strncmp(p, e->name->str_dat, n)) {
                        if (!slash1) {
                                memcpy(leaf, e, sizeof(*leaf));
                                if (e->tree && is_null_sha1(e->versions[1].sha1))
                                        leaf->tree = dup_tree_content(e->tree);
                                else
                                        leaf->tree = NULL;
                                return 1;
                        }
                        if (!S_ISDIR(e->versions[1].mode))
                                return 0;
                        if (!e->tree)
                                load_tree(e);
                        return tree_content_get(e, slash1 + 1, leaf);
                }
        }
        return 0;
}

static int update_branch(struct branch *b)
{
        static const char *msg = "fast-import";
        struct ref_lock *lock;
        unsigned char old_sha1[20];

        if (is_null_sha1(b->sha1))
                return 0;
        if (read_ref(b->name, old_sha1))
                hashclr(old_sha1);
        lock = lock_any_ref_for_update(b->name, old_sha1, 0);
        if (!lock)
                return error("Unable to lock %s", b->name);
        if (!force_update && !is_null_sha1(old_sha1)) {
                struct commit *old_cmit, *new_cmit;

                old_cmit = lookup_commit_reference_gently(old_sha1, 0);
                new_cmit = lookup_commit_reference_gently(b->sha1, 0);
                if (!old_cmit || !new_cmit) {
                        unlock_ref(lock);
                        return error("Branch %s is missing commits.", b->name);
                }

                if (!in_merge_bases(old_cmit, &new_cmit, 1)) {
                        unlock_ref(lock);
                        warning("Not updating %s"
                                " (new tip %s does not contain %s)",
                                b->name, sha1_to_hex(b->sha1), sha1_to_hex(old_sha1));
                        return -1;
                }
        }
        if (write_ref_sha1(lock, b->sha1, msg) < 0)
                return error("Unable to update %s", b->name);
        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 ref_lock *lock;
        char ref_name[PATH_MAX];

        for (t = first_tag; t; t = t->next_tag) {
                sprintf(ref_name, "tags/%s", t->name);
                lock = lock_ref_sha1(ref_name, NULL);
                if (!lock || write_ref_sha1(lock, t->sha1, msg) < 0)
                        failure |= error("Unable to update %s", ref_name);
        }
}

static void dump_marks_helper(FILE *f,
        uintmax_t base,
        struct mark_set *m)
{
        uintmax_t k;
        if (m->shift) {
                for (k = 0; k < 1024; k++) {
                        if (m->data.sets[k])
                                dump_marks_helper(f, base + (k << m->shift),
                                        m->data.sets[k]);
                }
        } else {
                for (k = 0; k < 1024; k++) {
                        if (m->data.marked[k])
                                fprintf(f, ":%" PRIuMAX " %s\n", base + k,
                                        sha1_to_hex(m->data.marked[k]->idx.sha1));
                }
        }
}

static void dump_marks(void)
{
        static struct lock_file mark_lock;
        int mark_fd;
        FILE *f;

        if (!export_marks_file)
                return;

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

        f = fdopen(mark_fd, "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;
        }

        /*
         * Since the lock file was fdopen()'ed, it should not be close()'ed.
         * Assign -1 to the lock file descriptor so that commit_lock_file()
         * won't try to close() it.
         */
        mark_lock.fd = -1;

        dump_marks_helper(f, 0, marks);
        if (ferror(f) || fclose(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;
        }

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

static void read_marks(void)
{
        char line[512];
        FILE *f = fopen(import_marks_file, "r");
        if (!f)
                die_errno("cannot read '%s'", import_marks_file);
        while (fgets(line, sizeof(line), f)) {
                uintmax_t mark;
                char *end;
                unsigned char sha1[20];
                struct object_entry *e;

                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_sha1(end + 1, sha1))
                        die("corrupt mark line: %s", line);
                e = find_object(sha1);
                if (!e) {
                        enum object_type type = sha1_object_info(sha1, NULL);
                        if (type < 0)
                                die("object not found: %s", sha1_to_hex(sha1));
                        e = insert_object(sha1);
                        e->type = type;
                        e->pack_id = MAX_PACK_ID;
                        e->idx.offset = 1; /* just not zero! */
                }
                insert_mark(mark, e);
        }
        fclose(f);
}


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

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

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

                        strbuf_detach(&command_buf, NULL);
                        stdin_eof = strbuf_getline(&command_buf, stdin, '\n');
                        if (stdin_eof)
                                return EOF;

                        if (!seen_data_command
                                && prefixcmp(command_buf.buf, "feature ")
                                && prefixcmp(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 = command_buf.buf;
                        rc->prev = cmd_tail;
                        rc->next = cmd_hist.prev;
                        rc->prev->next = rc;
                        cmd_tail = rc;
                }
        } while (command_buf.buf[0] == '#');

        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)
{
        if (!prefixcmp(command_buf.buf, "mark :")) {
                next_mark = strtoumax(command_buf.buf + 6, NULL, 10);
                read_next_command();
        }
        else
                next_mark = 0;
}

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

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

        if (!prefixcmp(command_buf.buf + 5, "<<")) {
                char *term = xstrdup(command_buf.buf + 5 + 2);
                size_t term_len = command_buf.len - 5 - 2;

                strbuf_detach(&command_buf, NULL);
                for (;;) {
                        if (strbuf_getline(&command_buf, stdin, '\n') == 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(command_buf.buf + 5, 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, char *result, int maxlen)
{
        const char *orig_src = src;
        char *endp;
        unsigned long num;

        errno = 0;

        num = strtoul(src, &endp, 10);
        /* NEEDSWORK: perhaps check for reasonable values? */
        if (errno || endp == src || *endp != ' ')
                return -1;

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

        num = strtoul(src + 1, &endp, 10);
        if (errno || endp == src + 1 || *endp || (endp - orig_src) >= maxlen ||
            1400 < num)
                return -1;

        strcpy(result, orig_src);
        return 0;
}

static char *parse_ident(const char *buf)
{
        const char *gt;
        size_t name_len;
        char *ident;

        gt = strrchr(buf, '>');
        if (!gt)
                die("Missing > in ident string: %s", buf);
        gt++;
        if (*gt != ' ')
                die("Missing space after > in ident string: %s", buf);
        gt++;
        name_len = gt - buf;
        ident = xmalloc(name_len + 24);
        strncpy(ident, buf, name_len);

        switch (whenspec) {
        case WHENSPEC_RAW:
                if (validate_raw_date(gt, ident + name_len, 24) < 0)
                        die("Invalid raw date \"%s\" in ident: %s", gt, buf);
                break;
        case WHENSPEC_RFC2822:
                if (parse_date(gt, ident + name_len, 24) < 0)
                        die("Invalid rfc2822 date \"%s\" in ident: %s", gt, buf);
                break;
        case WHENSPEC_NOW:
                if (strcmp("now", gt))
                        die("Date in ident must be 'now': %s", buf);
                datestamp(ident + name_len, 24);
                break;
        }

        return ident;
}

static void parse_and_store_blob(
        struct last_object *last,
        unsigned char *sha1out,
        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, sha1out, mark);
        else {
                if (last) {
                        strbuf_release(&last->data);
                        last->offset = 0;
                        last->depth = 0;
                }
                stream_blob(len, sha1out, mark);
                skip_optional_lf();
        }
}

static void parse_new_blob(void)
{
        read_next_command();
        parse_mark();
        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 >= 20)
                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, 40 - j);
        path[i + 40 - j] = '\0';
}

static uintmax_t do_change_note_fanout(
                struct tree_entry *orig_root, struct tree_entry *root,
                char *hex_sha1, unsigned int hex_sha1_len,
                char *fullpath, unsigned int fullpath_len,
                unsigned char fanout)
{
        struct tree_content *t = root->tree;
        struct tree_entry *e, leaf;
        unsigned int i, tmp_hex_sha1_len, tmp_fullpath_len;
        uintmax_t num_notes = 0;
        unsigned char sha1[20];
        char realpath[60];

        for (i = 0; t && i < t->entry_count; i++) {
                e = t->entries[i];
                tmp_hex_sha1_len = hex_sha1_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_sha1_len > 40 ||
                    e->name->str_len % 2)
                        continue;

                /* This _may_ be a note entry, or a subdir containing notes */
                memcpy(hex_sha1 + hex_sha1_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_sha1_len == 40 && !get_sha1_hex(hex_sha1, sha1)) {
                        /* This is a note entry */
                        construct_path_with_fanout(hex_sha1, 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))
                                die("Failed to remove path %s", fullpath);
                        tree_content_set(orig_root, realpath,
                                leaf.versions[1].sha1,
                                leaf.versions[1].mode,
                                leaf.tree);
                } else if (S_ISDIR(e->versions[1].mode)) {
                        /* This is a subdir that may contain note entries */
                        if (!e->tree)
                                load_tree(e);
                        num_notes += do_change_note_fanout(orig_root, e,
                                hex_sha1, tmp_hex_sha1_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)
{
        char hex_sha1[40], path[60];
        return do_change_note_fanout(root, root, hex_sha1, 0, path, 0, fanout);
}

static void file_change_m(struct branch *b)
{
        const char *p = command_buf.buf + 2;
        static struct strbuf uq = STRBUF_INIT;
        const char *endp;
        struct object_entry *oe = oe;
        unsigned char sha1[20];
        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 == ':') {
                char *x;
                oe = find_mark(strtoumax(p + 1, &x, 10));
                hashcpy(sha1, oe->idx.sha1);
                p = x;
        } else if (!prefixcmp(p, "inline")) {
                inline_data = 1;
                p += 6;
        } else {
                if (get_sha1_hex(p, sha1))
                        die("Invalid SHA1: %s", command_buf.buf);
                oe = find_object(sha1);
                p += 40;
        }
        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;
        }

        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",
                                        typename(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;
                }
                read_next_command();
                parse_and_store_blob(&last_blob, sha1, 0);
        } else {
                enum object_type expected = S_ISDIR(mode) ?
                                                OBJ_TREE: OBJ_BLOB;
                enum object_type type = oe ? oe->type :
                                        sha1_object_info(sha1, 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",
                                typename(expected), typename(type),
                                command_buf.buf);
        }

        tree_content_set(&b->branch_tree, p, sha1, mode, NULL);
}

static void file_change_d(struct branch *b)
{
        const char *p = command_buf.buf + 2;
        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);
}

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

        s = command_buf.buf + 2;
        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);
        else
                tree_content_get(&b->branch_tree, s, &leaf);
        if (!leaf.versions[1].mode)
                die("Path %s not in branch", s);
        tree_content_set(&b->branch_tree, d,
                leaf.versions[1].sha1,
                leaf.versions[1].mode,
                leaf.tree);
}

static void note_change_n(struct branch *b, unsigned char old_fanout)
{
        const char *p = command_buf.buf + 2;
        static struct strbuf uq = STRBUF_INIT;
        struct object_entry *oe = oe;
        struct branch *s;
        unsigned char sha1[20], commit_sha1[20];
        char path[60];
        uint16_t inline_data = 0;
        unsigned char new_fanout;

        /* <dataref> or 'inline' */
        if (*p == ':') {
                char *x;
                oe = find_mark(strtoumax(p + 1, &x, 10));
                hashcpy(sha1, oe->idx.sha1);
                p = x;
        } else if (!prefixcmp(p, "inline")) {
                inline_data = 1;
                p += 6;
        } else {
                if (get_sha1_hex(p, sha1))
                        die("Invalid SHA1: %s", command_buf.buf);
                oe = find_object(sha1);
                p += 40;
        }
        if (*p++ != ' ')
                die("Missing space after SHA1: %s", command_buf.buf);

        /* <committish> */
        s = lookup_branch(p);
        if (s) {
                hashcpy(commit_sha1, s->sha1);
        } else if (*p == ':') {
                uintmax_t commit_mark = strtoumax(p + 1, NULL, 10);
                struct object_entry *commit_oe = find_mark(commit_mark);
                if (commit_oe->type != OBJ_COMMIT)
                        die("Mark :%" PRIuMAX " not a commit", commit_mark);
                hashcpy(commit_sha1, commit_oe->idx.sha1);
        } else if (!get_sha1(p, commit_sha1)) {
                unsigned long size;
                char *buf = read_object_with_reference(commit_sha1,
                        commit_type, &size, commit_sha1);
                if (!buf || size < 46)
                        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, sha1, 0);
        } else if (oe) {
                if (oe->type != OBJ_BLOB)
                        die("Not a blob (actually a %s): %s",
                                typename(oe->type), command_buf.buf);
        } else if (!is_null_sha1(sha1)) {
                enum object_type type = sha1_object_info(sha1, NULL);
                if (type < 0)
                        die("Blob not found: %s", command_buf.buf);
                if (type != OBJ_BLOB)
                        die("Not a blob (actually a %s): %s",
                            typename(type), command_buf.buf);
        }

        construct_path_with_fanout(sha1_to_hex(commit_sha1), old_fanout, path);
        if (tree_content_remove(&b->branch_tree, path, NULL))
                b->num_notes--;

        if (is_null_sha1(sha1))
                return; /* nothing to insert */

        b->num_notes++;
        new_fanout = convert_num_notes_to_fanout(b->num_notes);
        construct_path_with_fanout(sha1_to_hex(commit_sha1), new_fanout, path);
        tree_content_set(&b->branch_tree, path, sha1, S_IFREG | 0644, NULL);
}

static void file_change_deleteall(struct branch *b)
{
        release_tree_content_recursive(b->branch_tree.tree);
        hashclr(b->branch_tree.versions[0].sha1);
        hashclr(b->branch_tree.versions[1].sha1);
        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 < 46)
                die("Not a valid commit: %s", sha1_to_hex(b->sha1));
        if (memcmp("tree ", buf, 5)
                || get_sha1_hex(buf + 5, b->branch_tree.versions[1].sha1))
                die("The commit %s is corrupt", sha1_to_hex(b->sha1));
        hashcpy(b->branch_tree.versions[0].sha1,
                b->branch_tree.versions[1].sha1);
}

static void parse_from_existing(struct branch *b)
{
        if (is_null_sha1(b->sha1)) {
                hashclr(b->branch_tree.versions[0].sha1);
                hashclr(b->branch_tree.versions[1].sha1);
        } else {
                unsigned long size;
                char *buf;

                buf = read_object_with_reference(b->sha1,
                        commit_type, &size, b->sha1);
                parse_from_commit(b, buf, size);
                free(buf);
        }
}

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

        if (prefixcmp(command_buf.buf, "from "))
                return 0;

        if (b->branch_tree.tree) {
                release_tree_content_recursive(b->branch_tree.tree);
                b->branch_tree.tree = NULL;
        }

        from = strchr(command_buf.buf, ' ') + 1;
        s = lookup_branch(from);
        if (b == s)
                die("Can't create a branch from itself: %s", b->name);
        else if (s) {
                unsigned char *t = s->branch_tree.versions[1].sha1;
                hashcpy(b->sha1, s->sha1);
                hashcpy(b->branch_tree.versions[0].sha1, t);
                hashcpy(b->branch_tree.versions[1].sha1, t);
        } else if (*from == ':') {
                uintmax_t idnum = strtoumax(from + 1, NULL, 10);
                struct object_entry *oe = find_mark(idnum);
                if (oe->type != OBJ_COMMIT)
                        die("Mark :%" PRIuMAX " not a commit", idnum);
                hashcpy(b->sha1, oe->idx.sha1);
                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_sha1(from, b->sha1))
                parse_from_existing(b);
        else
                die("Invalid ref name or SHA1 expression: %s", from);

        read_next_command();
        return 1;
}

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

        *count = 0;
        while (!prefixcmp(command_buf.buf, "merge ")) {
                from = strchr(command_buf.buf, ' ') + 1;
                n = xmalloc(sizeof(*n));
                s = lookup_branch(from);
                if (s)
                        hashcpy(n->sha1, s->sha1);
                else if (*from == ':') {
                        uintmax_t idnum = strtoumax(from + 1, NULL, 10);
                        struct object_entry *oe = find_mark(idnum);
                        if (oe->type != OBJ_COMMIT)
                                die("Mark :%" PRIuMAX " not a commit", idnum);
                        hashcpy(n->sha1, oe->idx.sha1);
                } else if (!get_sha1(from, n->sha1)) {
                        unsigned long size;
                        char *buf = read_object_with_reference(n->sha1,
                                commit_type, &size, n->sha1);
                        if (!buf || size < 46)
                                die("Not a valid commit: %s", from);
                        free(buf);
                } else
                        die("Invalid ref name or SHA1 expression: %s", from);

                n->next = NULL;
                if (list)
                        e->next = n;
                else
                        list = n;
                e = n;
                (*count)++;
                read_next_command();
        }
        return list;
}

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

        /* Obtain the branch name from the rest of our command */
        sp = strchr(command_buf.buf, ' ') + 1;
        b = lookup_branch(sp);
        if (!b)
                b = new_branch(sp);

        read_next_command();
        parse_mark();
        if (!prefixcmp(command_buf.buf, "author ")) {
                author = parse_ident(command_buf.buf + 7);
                read_next_command();
        }
        if (!prefixcmp(command_buf.buf, "committer ")) {
                committer = parse_ident(command_buf.buf + 10);
                read_next_command();
        }
        if (!committer)
                die("Expected committer but didn't get one");
        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 (!prefixcmp(command_buf.buf, "M "))
                        file_change_m(b);
                else if (!prefixcmp(command_buf.buf, "D "))
                        file_change_d(b);
                else if (!prefixcmp(command_buf.buf, "R "))
                        file_change_cr(b, 1);
                else if (!prefixcmp(command_buf.buf, "C "))
                        file_change_cr(b, 0);
                else if (!prefixcmp(command_buf.buf, "N "))
                        note_change_n(b, prev_fanout);
                else if (!strcmp("deleteall", command_buf.buf))
                        file_change_deleteall(b);
                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);
        hashcpy(b->branch_tree.versions[0].sha1,
                b->branch_tree.versions[1].sha1);

        strbuf_reset(&new_data);
        strbuf_addf(&new_data, "tree %s\n",
                sha1_to_hex(b->branch_tree.versions[1].sha1));
        if (!is_null_sha1(b->sha1))
                strbuf_addf(&new_data, "parent %s\n", sha1_to_hex(b->sha1));
        while (merge_list) {
                struct hash_list *next = merge_list->next;
                strbuf_addf(&new_data, "parent %s\n", sha1_to_hex(merge_list->sha1));
                free(merge_list);
                merge_list = next;
        }
        strbuf_addf(&new_data,
                "author %s\n"
                "committer %s\n"
                "\n",
                author ? author : committer, committer);
        strbuf_addbuf(&new_data, &msg);
        free(author);
        free(committer);

        if (!store_object(OBJ_COMMIT, &new_data, NULL, b->sha1, next_mark))
                b->pack_id = pack_id;
        b->last_commit = object_count_by_type[OBJ_COMMIT];
}

static void parse_new_tag(void)
{
        static struct strbuf msg = STRBUF_INIT;
        char *sp;
        const char *from;
        char *tagger;
        struct branch *s;
        struct tag *t;
        uintmax_t from_mark = 0;
        unsigned char sha1[20];
        enum object_type type;

        /* Obtain the new tag name from the rest of our command */
        sp = strchr(command_buf.buf, ' ') + 1;
        t = pool_alloc(sizeof(struct tag));
        t->next_tag = NULL;
        t->name = pool_strdup(sp);
        if (last_tag)
                last_tag->next_tag = t;
        else
                first_tag = t;
        last_tag = t;
        read_next_command();

        /* from ... */
        if (prefixcmp(command_buf.buf, "from "))
                die("Expected from command, got %s", command_buf.buf);
        from = strchr(command_buf.buf, ' ') + 1;
        s = lookup_branch(from);
        if (s) {
                hashcpy(sha1, s->sha1);
                type = OBJ_COMMIT;
        } else if (*from == ':') {
                struct object_entry *oe;
                from_mark = strtoumax(from + 1, NULL, 10);
                oe = find_mark(from_mark);
                type = oe->type;
                hashcpy(sha1, oe->idx.sha1);
        } else if (!get_sha1(from, sha1)) {
                unsigned long size;
                char *buf;

                buf = read_sha1_file(sha1, &type, &size);
                if (!buf || size < 46)
                        die("Not a valid commit: %s", from);
                free(buf);
        } else
                die("Invalid ref name or SHA1 expression: %s", from);
        read_next_command();

        /* tagger ... */
        if (!prefixcmp(command_buf.buf, "tagger ")) {
                tagger = parse_ident(command_buf.buf + 7);
                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",
                    sha1_to_hex(sha1), typename(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->sha1, 0))
                t->pack_id = MAX_PACK_ID;
        else
                t->pack_id = pack_id;
}

static void parse_reset_branch(void)
{
        struct branch *b;
        char *sp;

        /* Obtain the branch name from the rest of our command */
        sp = strchr(command_buf.buf, ' ') + 1;
        b = lookup_branch(sp);
        if (b) {
                hashclr(b->sha1);
                hashclr(b->branch_tree.versions[0].sha1);
                hashclr(b->branch_tree.versions[1].sha1);
                if (b->branch_tree.tree) {
                        release_tree_content_recursive(b->branch_tree.tree);
                        b->branch_tree.tree = NULL;
                }
        }
        else
                b = new_branch(sp);
        read_next_command();
        parse_from(b);
        if (command_buf.len > 0)
                unread_command_buf = 1;
}

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 char* make_fast_import_path(const char *path)
{
        struct strbuf abs_path = STRBUF_INIT;

        if (!relative_marks_paths || is_absolute_path(path))
                return xstrdup(path);
        strbuf_addf(&abs_path, "%s/info/fast-import/%s", get_git_dir(), path);
        return strbuf_detach(&abs_path, NULL);
}

static void option_import_marks(const char *marks, int from_stream)
{
        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);
        safe_create_leading_directories_const(import_marks_file);
        import_marks_file_from_stream = from_stream;
}

static void option_date_format(const char *fmt)
{
        if (!strcmp(fmt, "raw"))
                whenspec = WHENSPEC_RAW;
        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 void option_depth(const char *depth)
{
        max_depth = strtoul(depth, NULL, 0);
        if (max_depth > MAX_DEPTH)
                die("--depth cannot exceed %u", MAX_DEPTH);
}

static void option_active_branches(const char *branches)
{
        max_active_branches = strtoul(branches, NULL, 0);
}

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

static void option_export_pack_edges(const char *edges)
{
        if (pack_edges)
                fclose(pack_edges);
        pack_edges = fopen(edges, "a");
        if (!pack_edges)
                die_errno("Cannot open '%s'", edges);
}

static int parse_one_option(const char *option)
{
        if (!prefixcmp(option, "max-pack-size=")) {
                unsigned long v;
                if (!git_parse_ulong(option + 14, &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 (!prefixcmp(option, "big-file-threshold=")) {
                unsigned long v;
                if (!git_parse_ulong(option + 19, &v))
                        return 0;
                big_file_threshold = v;
        } else if (!prefixcmp(option, "depth=")) {
                option_depth(option + 6);
        } else if (!prefixcmp(option, "active-branches=")) {
                option_active_branches(option + 16);
        } else if (!prefixcmp(option, "export-pack-edges=")) {
                option_export_pack_edges(option + 18);
        } else if (!prefixcmp(option, "quiet")) {
                show_stats = 0;
        } else if (!prefixcmp(option, "stats")) {
                show_stats = 1;
        } else {
                return 0;
        }

        return 1;
}

static int parse_one_feature(const char *feature, int from_stream)
{
        if (!prefixcmp(feature, "date-format=")) {
                option_date_format(feature + 12);
        } else if (!prefixcmp(feature, "import-marks=")) {
                option_import_marks(feature + 13, from_stream);
        } else if (!prefixcmp(feature, "export-marks=")) {
                option_export_marks(feature + 13);
        } else if (!prefixcmp(feature, "relative-marks")) {
                relative_marks_paths = 1;
        } else if (!prefixcmp(feature, "no-relative-marks")) {
                relative_marks_paths = 0;
        } else if (!prefixcmp(feature, "force")) {
                force_update = 1;
        } else {
                return 0;
        }

        return 1;
}

static void parse_feature(void)
{
        char *feature = command_buf.buf + 8;

        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(void)
{
        char *option = command_buf.buf + 11;

        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 int git_pack_config(const char *k, const char *v, void *cb)
{
        if (!strcmp(k, "pack.depth")) {
                max_depth = git_config_int(k, v);
                if (max_depth > MAX_DEPTH)
                        max_depth = MAX_DEPTH;
                return 0;
        }
        if (!strcmp(k, "pack.compression")) {
                int level = git_config_int(k, v);
                if (level == -1)
                        level = Z_DEFAULT_COMPRESSION;
                else if (level < 0 || level > Z_BEST_COMPRESSION)
                        die("bad pack compression level %d", level);
                pack_compression_level = level;
                pack_compression_seen = 1;
                return 0;
        }
        if (!strcmp(k, "pack.indexversion")) {
                pack_idx_default_version = git_config_int(k, v);
                if (pack_idx_default_version > 2)
                        die("bad pack.indexversion=%"PRIu32,
                            pack_idx_default_version);
                return 0;
        }
        if (!strcmp(k, "pack.packsizelimit")) {
                max_packsize = git_config_ulong(k, v);
                return 0;
        }
        if (!strcmp(k, "core.bigfilethreshold")) {
                long n = git_config_int(k, v);
                big_file_threshold = 0 < n ? n : 0;
        }
        return git_default_config(k, v, cb);
}

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 (parse_one_option(a + 2))
                        continue;

                if (parse_one_feature(a + 2, 0))
                        continue;

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

        seen_data_command = 1;
        if (import_marks_file)
                read_marks();
}

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

        git_extract_argv0_path(argv[0]);

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

        setup_git_directory();
        git_config(git_pack_config, NULL);
        if (!pack_compression_seen && core_compression_seen)
                pack_compression_level = core_compression_level;

        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 = pool_calloc(1, sizeof(struct mark_set));

        global_argc = argc;
        global_argv = argv;

        rc_free = pool_alloc(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;

        prepare_packed_git();
        start_packfile();
        set_die_routine(die_nicely);
        set_checkpoint_signal();
        while (read_next_command() != EOF) {
                if (!strcmp("blob", command_buf.buf))
                        parse_new_blob();
                else if (!prefixcmp(command_buf.buf, "commit "))
                        parse_new_commit();
                else if (!prefixcmp(command_buf.buf, "tag "))
                        parse_new_tag();
                else if (!prefixcmp(command_buf.buf, "reset "))
                        parse_reset_branch();
                else if (!strcmp("checkpoint", command_buf.buf))
                        parse_checkpoint();
                else if (!prefixcmp(command_buf.buf, "progress "))
                        parse_progress();
                else if (!prefixcmp(command_buf.buf, "feature "))
                        parse_feature();
                else if (!prefixcmp(command_buf.buf, "option git "))
                        parse_option();
                else if (!prefixcmp(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();

        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)\n", object_count_by_type[OBJ_BLOB], duplicate_count_by_type[OBJ_BLOB], delta_count_by_type[OBJ_BLOB]);
                fprintf(stderr, "      trees  :   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas)\n", object_count_by_type[OBJ_TREE], duplicate_count_by_type[OBJ_TREE], delta_count_by_type[OBJ_TREE]);
                fprintf(stderr, "      commits:   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas)\n", object_count_by_type[OBJ_COMMIT], duplicate_count_by_type[OBJ_COMMIT], delta_count_by_type[OBJ_COMMIT]);
                fprintf(stderr, "      tags   :   %10" PRIuMAX " (%10" PRIuMAX " duplicates %10" PRIuMAX " deltas)\n", object_count_by_type[OBJ_TAG], duplicate_count_by_type[OBJ_TAG], delta_count_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", (total_allocd + alloc_count*sizeof(struct object_entry))/1024);
                fprintf(stderr, "       pools:    %10lu KiB\n", (unsigned long)(total_allocd/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;
}