Fix 'quickfix' on pack-objects.

[git.git] / index-pack.c

#include "cache.h"
#include "delta.h"
#include "pack.h"
#include "csum-file.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"

static const char index_pack_usage[] =
"git-index-pack [-v] [-o <index-file>] [{ ---keep | --keep=<msg> }] { <pack-file> | --stdin [--fix-thin] [<pack-file>] }";

struct object_entry
{
        off_t offset;
        unsigned long size;
        unsigned int hdr_size;
        uint32_t crc32;
        enum object_type type;
        enum object_type real_type;
        unsigned char sha1[20];
};

union delta_base {
        unsigned char sha1[20];
        off_t offset;
};

/*
 * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
 * to memcmp() only the first 20 bytes.
 */
#define UNION_BASE_SZ   20

struct delta_entry
{
        union delta_base base;
        int obj_no;
};

static struct object_entry *objects;
static struct delta_entry *deltas;
static int nr_objects;
static int nr_deltas;
static int nr_resolved_deltas;

static int from_stdin;
static int verbose;

static volatile sig_atomic_t progress_update;

static void progress_interval(int signum)
{
        progress_update = 1;
}

static void setup_progress_signal(void)
{
        struct sigaction sa;
        struct itimerval v;

        memset(&sa, 0, sizeof(sa));
        sa.sa_handler = progress_interval;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;
        sigaction(SIGALRM, &sa, NULL);

        v.it_interval.tv_sec = 1;
        v.it_interval.tv_usec = 0;
        v.it_value = v.it_interval;
        setitimer(ITIMER_REAL, &v, NULL);

}

static unsigned display_progress(unsigned n, unsigned total, unsigned last_pc)
{
        unsigned percent = n * 100 / total;
        if (percent != last_pc || progress_update) {
                fprintf(stderr, "%4u%% (%u/%u) done\r", percent, n, total);
                progress_update = 0;
        }
        return percent;
}

/* We always read in 4kB chunks. */
static unsigned char input_buffer[4096];
static unsigned int input_offset, input_len;
static off_t consumed_bytes;
static SHA_CTX input_ctx;
static uint32_t input_crc32;
static int input_fd, output_fd, pack_fd;

/* Discard current buffer used content. */
static void flush(void)
{
        if (input_offset) {
                if (output_fd >= 0)
                        write_or_die(output_fd, input_buffer, input_offset);
                SHA1_Update(&input_ctx, input_buffer, input_offset);
                memmove(input_buffer, input_buffer + input_offset, input_len);
                input_offset = 0;
        }
}

/*
 * Make sure at least "min" bytes are available in the buffer, and
 * return the pointer to the buffer.
 */
static void *fill(int min)
{
        if (min <= input_len)
                return input_buffer + input_offset;
        if (min > sizeof(input_buffer))
                die("cannot fill %d bytes", min);
        flush();
        do {
                int ret = xread(input_fd, input_buffer + input_len,
                                sizeof(input_buffer) - input_len);
                if (ret <= 0) {
                        if (!ret)
                                die("early EOF");
                        die("read error on input: %s", strerror(errno));
                }
                input_len += ret;
        } while (input_len < min);
        return input_buffer;
}

static void use(int bytes)
{
        if (bytes > input_len)
                die("used more bytes than were available");
        input_crc32 = crc32(input_crc32, input_buffer + input_offset, bytes);
        input_len -= bytes;
        input_offset += bytes;

        /* make sure off_t is sufficiently large not to wrap */
        if (consumed_bytes > consumed_bytes + bytes)
                die("pack too large for current definition of off_t");
        consumed_bytes += bytes;
}

static const char *open_pack_file(const char *pack_name)
{
        if (from_stdin) {
                input_fd = 0;
                if (!pack_name) {
                        static char tmpfile[PATH_MAX];
                        snprintf(tmpfile, sizeof(tmpfile),
                                 "%s/tmp_pack_XXXXXX", get_object_directory());
                        output_fd = mkstemp(tmpfile);
                        pack_name = xstrdup(tmpfile);
                } else
                        output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
                if (output_fd < 0)
                        die("unable to create %s: %s\n", pack_name, strerror(errno));
                pack_fd = output_fd;
        } else {
                input_fd = open(pack_name, O_RDONLY);
                if (input_fd < 0)
                        die("cannot open packfile '%s': %s",
                            pack_name, strerror(errno));
                output_fd = -1;
                pack_fd = input_fd;
        }
        SHA1_Init(&input_ctx);
        return pack_name;
}

static void parse_pack_header(void)
{
        struct pack_header *hdr = fill(sizeof(struct pack_header));

        /* Header consistency check */
        if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
                die("pack signature mismatch");
        if (!pack_version_ok(hdr->hdr_version))
                die("pack version %d unsupported", ntohl(hdr->hdr_version));

        nr_objects = ntohl(hdr->hdr_entries);
        use(sizeof(struct pack_header));
}

static void bad_object(unsigned long offset, const char *format,
                       ...) NORETURN __attribute__((format (printf, 2, 3)));

static void bad_object(unsigned long offset, const char *format, ...)
{
        va_list params;
        char buf[1024];

        va_start(params, format);
        vsnprintf(buf, sizeof(buf), format, params);
        va_end(params);
        die("pack has bad object at offset %lu: %s", offset, buf);
}

static void *unpack_entry_data(unsigned long offset, unsigned long size)
{
        z_stream stream;
        void *buf = xmalloc(size);

        memset(&stream, 0, sizeof(stream));
        stream.next_out = buf;
        stream.avail_out = size;
        stream.next_in = fill(1);
        stream.avail_in = input_len;
        inflateInit(&stream);

        for (;;) {
                int ret = inflate(&stream, 0);
                use(input_len - stream.avail_in);
                if (stream.total_out == size && ret == Z_STREAM_END)
                        break;
                if (ret != Z_OK)
                        bad_object(offset, "inflate returned %d", ret);
                stream.next_in = fill(1);
                stream.avail_in = input_len;
        }
        inflateEnd(&stream);
        return buf;
}

static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_base)
{
        unsigned char *p, c;
        unsigned long size;
        off_t base_offset;
        unsigned shift;
        void *data;

        obj->offset = consumed_bytes;
        input_crc32 = crc32(0, Z_NULL, 0);

        p = fill(1);
        c = *p;
        use(1);
        obj->type = (c >> 4) & 7;
        size = (c & 15);
        shift = 4;
        while (c & 0x80) {
                p = fill(1);
                c = *p;
                use(1);
                size += (c & 0x7fUL) << shift;
                shift += 7;
        }
        obj->size = size;

        switch (obj->type) {
        case OBJ_REF_DELTA:
                hashcpy(delta_base->sha1, fill(20));
                use(20);
                break;
        case OBJ_OFS_DELTA:
                memset(delta_base, 0, sizeof(*delta_base));
                p = fill(1);
                c = *p;
                use(1);
                base_offset = c & 127;
                while (c & 128) {
                        base_offset += 1;
                        if (!base_offset || MSB(base_offset, 7))
                                bad_object(obj->offset, "offset value overflow for delta base object");
                        p = fill(1);
                        c = *p;
                        use(1);
                        base_offset = (base_offset << 7) + (c & 127);
                }
                delta_base->offset = obj->offset - base_offset;
                if (delta_base->offset >= obj->offset)
                        bad_object(obj->offset, "delta base offset is out of bound");
                break;
        case OBJ_COMMIT:
        case OBJ_TREE:
        case OBJ_BLOB:
        case OBJ_TAG:
                break;
        default:
                bad_object(obj->offset, "unknown object type %d", obj->type);
        }
        obj->hdr_size = consumed_bytes - obj->offset;

        data = unpack_entry_data(obj->offset, obj->size);
        obj->crc32 = input_crc32;
        return data;
}

static void *get_data_from_pack(struct object_entry *obj)
{
        unsigned long from = obj[0].offset + obj[0].hdr_size;
        unsigned long len = obj[1].offset - from;
        unsigned long rdy = 0;
        unsigned char *src, *data;
        z_stream stream;
        int st;

        src = xmalloc(len);
        data = src;
        do {
                ssize_t n = pread(pack_fd, data + rdy, len - rdy, from + rdy);
                if (n <= 0)
                        die("cannot pread pack file: %s", strerror(errno));
                rdy += n;
        } while (rdy < len);
        data = xmalloc(obj->size);
        memset(&stream, 0, sizeof(stream));
        stream.next_out = data;
        stream.avail_out = obj->size;
        stream.next_in = src;
        stream.avail_in = len;
        inflateInit(&stream);
        while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
        inflateEnd(&stream);
        if (st != Z_STREAM_END || stream.total_out != obj->size)
                die("serious inflate inconsistency");
        free(src);
        return data;
}

static int find_delta(const union delta_base *base)
{
        int first = 0, last = nr_deltas;

        while (first < last) {
                int next = (first + last) / 2;
                struct delta_entry *delta = &deltas[next];
                int cmp;

                cmp = memcmp(base, &delta->base, UNION_BASE_SZ);
                if (!cmp)
                        return next;
                if (cmp < 0) {
                        last = next;
                        continue;
                }
                first = next+1;
        }
        return -first-1;
}

static int find_delta_children(const union delta_base *base,
                               int *first_index, int *last_index)
{
        int first = find_delta(base);
        int last = first;
        int end = nr_deltas - 1;

        if (first < 0)
                return -1;
        while (first > 0 && !memcmp(&deltas[first - 1].base, base, UNION_BASE_SZ))
                --first;
        while (last < end && !memcmp(&deltas[last + 1].base, base, UNION_BASE_SZ))
                ++last;
        *first_index = first;
        *last_index = last;
        return 0;
}

static void sha1_object(const void *data, unsigned long size,
                        enum object_type type, unsigned char *sha1)
{
        hash_sha1_file(data, size, typename(type), sha1);
        if (has_sha1_file(sha1)) {
                void *has_data;
                enum object_type has_type;
                unsigned long has_size;
                has_data = read_sha1_file(sha1, &has_type, &has_size);
                if (!has_data)
                        die("cannot read existing object %s", sha1_to_hex(sha1));
                if (size != has_size || type != has_type ||
                    memcmp(data, has_data, size) != 0)
                        die("SHA1 COLLISION FOUND WITH %s !", sha1_to_hex(sha1));
                free(has_data);
        }
}

static void resolve_delta(struct object_entry *delta_obj, void *base_data,
                          unsigned long base_size, enum object_type type)
{
        void *delta_data;
        unsigned long delta_size;
        void *result;
        unsigned long result_size;
        union delta_base delta_base;
        int j, first, last;

        delta_obj->real_type = type;
        delta_data = get_data_from_pack(delta_obj);
        delta_size = delta_obj->size;
        result = patch_delta(base_data, base_size, delta_data, delta_size,
                             &result_size);
        free(delta_data);
        if (!result)
                bad_object(delta_obj->offset, "failed to apply delta");
        sha1_object(result, result_size, type, delta_obj->sha1);
        nr_resolved_deltas++;

        hashcpy(delta_base.sha1, delta_obj->sha1);
        if (!find_delta_children(&delta_base, &first, &last)) {
                for (j = first; j <= last; j++) {
                        struct object_entry *child = objects + deltas[j].obj_no;
                        if (child->real_type == OBJ_REF_DELTA)
                                resolve_delta(child, result, result_size, type);
                }
        }

        memset(&delta_base, 0, sizeof(delta_base));
        delta_base.offset = delta_obj->offset;
        if (!find_delta_children(&delta_base, &first, &last)) {
                for (j = first; j <= last; j++) {
                        struct object_entry *child = objects + deltas[j].obj_no;
                        if (child->real_type == OBJ_OFS_DELTA)
                                resolve_delta(child, result, result_size, type);
                }
        }

        free(result);
}

static int compare_delta_entry(const void *a, const void *b)
{
        const struct delta_entry *delta_a = a;
        const struct delta_entry *delta_b = b;
        return memcmp(&delta_a->base, &delta_b->base, UNION_BASE_SZ);
}

/* Parse all objects and return the pack content SHA1 hash */
static void parse_pack_objects(unsigned char *sha1)
{
        int i, percent = -1;
        struct delta_entry *delta = deltas;
        void *data;
        struct stat st;

        /*
         * First pass:
         * - find locations of all objects;
         * - calculate SHA1 of all non-delta objects;
         * - remember base (SHA1 or offset) for all deltas.
         */
        if (verbose)
                fprintf(stderr, "Indexing %d objects.\n", nr_objects);
        for (i = 0; i < nr_objects; i++) {
                struct object_entry *obj = &objects[i];
                data = unpack_raw_entry(obj, &delta->base);
                obj->real_type = obj->type;
                if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
                        nr_deltas++;
                        delta->obj_no = i;
                        delta++;
                } else
                        sha1_object(data, obj->size, obj->type, obj->sha1);
                free(data);
                if (verbose)
                        percent = display_progress(i+1, nr_objects, percent);
        }
        objects[i].offset = consumed_bytes;
        if (verbose)
                fputc('\n', stderr);

        /* Check pack integrity */
        flush();
        SHA1_Final(sha1, &input_ctx);
        if (hashcmp(fill(20), sha1))
                die("pack is corrupted (SHA1 mismatch)");
        use(20);

        /* If input_fd is a file, we should have reached its end now. */
        if (fstat(input_fd, &st))
                die("cannot fstat packfile: %s", strerror(errno));
        if (S_ISREG(st.st_mode) &&
                        lseek(input_fd, 0, SEEK_CUR) - input_len != st.st_size)
                die("pack has junk at the end");

        if (!nr_deltas)
                return;

        /* Sort deltas by base SHA1/offset for fast searching */
        qsort(deltas, nr_deltas, sizeof(struct delta_entry),
              compare_delta_entry);

        /*
         * Second pass:
         * - for all non-delta objects, look if it is used as a base for
         *   deltas;
         * - if used as a base, uncompress the object and apply all deltas,
         *   recursively checking if the resulting object is used as a base
         *   for some more deltas.
         */
        if (verbose)
                fprintf(stderr, "Resolving %d deltas.\n", nr_deltas);
        for (i = 0; i < nr_objects; i++) {
                struct object_entry *obj = &objects[i];
                union delta_base base;
                int j, ref, ref_first, ref_last, ofs, ofs_first, ofs_last;

                if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
                        continue;
                hashcpy(base.sha1, obj->sha1);
                ref = !find_delta_children(&base, &ref_first, &ref_last);
                memset(&base, 0, sizeof(base));
                base.offset = obj->offset;
                ofs = !find_delta_children(&base, &ofs_first, &ofs_last);
                if (!ref && !ofs)
                        continue;
                data = get_data_from_pack(obj);
                if (ref)
                        for (j = ref_first; j <= ref_last; j++) {
                                struct object_entry *child = objects + deltas[j].obj_no;
                                if (child->real_type == OBJ_REF_DELTA)
                                        resolve_delta(child, data,
                                                      obj->size, obj->type);
                        }
                if (ofs)
                        for (j = ofs_first; j <= ofs_last; j++) {
                                struct object_entry *child = objects + deltas[j].obj_no;
                                if (child->real_type == OBJ_OFS_DELTA)
                                        resolve_delta(child, data,
                                                      obj->size, obj->type);
                        }
                free(data);
                if (verbose)
                        percent = display_progress(nr_resolved_deltas,
                                                   nr_deltas, percent);
        }
        if (verbose && nr_resolved_deltas == nr_deltas)
                fputc('\n', stderr);
}

static int write_compressed(int fd, void *in, unsigned int size, uint32_t *obj_crc)
{
        z_stream stream;
        unsigned long maxsize;
        void *out;

        memset(&stream, 0, sizeof(stream));
        deflateInit(&stream, zlib_compression_level);
        maxsize = deflateBound(&stream, size);
        out = xmalloc(maxsize);

        /* Compress it */
        stream.next_in = in;
        stream.avail_in = size;
        stream.next_out = out;
        stream.avail_out = maxsize;
        while (deflate(&stream, Z_FINISH) == Z_OK);
        deflateEnd(&stream);

        size = stream.total_out;
        write_or_die(fd, out, size);
        *obj_crc = crc32(*obj_crc, out, size);
        free(out);
        return size;
}

static void append_obj_to_pack(const unsigned char *sha1, void *buf,
                               unsigned long size, enum object_type type)
{
        struct object_entry *obj = &objects[nr_objects++];
        unsigned char header[10];
        unsigned long s = size;
        int n = 0;
        unsigned char c = (type << 4) | (s & 15);
        s >>= 4;
        while (s) {
                header[n++] = c | 0x80;
                c = s & 0x7f;
                s >>= 7;
        }
        header[n++] = c;
        write_or_die(output_fd, header, n);
        obj[0].crc32 = crc32(0, Z_NULL, 0);
        obj[0].crc32 = crc32(obj[0].crc32, header, n);
        obj[1].offset = obj[0].offset + n;
        obj[1].offset += write_compressed(output_fd, buf, size, &obj[0].crc32);
        hashcpy(obj->sha1, sha1);
}

static int delta_pos_compare(const void *_a, const void *_b)
{
        struct delta_entry *a = *(struct delta_entry **)_a;
        struct delta_entry *b = *(struct delta_entry **)_b;
        return a->obj_no - b->obj_no;
}

static void fix_unresolved_deltas(int nr_unresolved)
{
        struct delta_entry **sorted_by_pos;
        int i, n = 0, percent = -1;

        /*
         * Since many unresolved deltas may well be themselves base objects
         * for more unresolved deltas, we really want to include the
         * smallest number of base objects that would cover as much delta
         * as possible by picking the
         * trunc deltas first, allowing for other deltas to resolve without
         * additional base objects.  Since most base objects are to be found
         * before deltas depending on them, a good heuristic is to start
         * resolving deltas in the same order as their position in the pack.
         */
        sorted_by_pos = xmalloc(nr_unresolved * sizeof(*sorted_by_pos));
        for (i = 0; i < nr_deltas; i++) {
                if (objects[deltas[i].obj_no].real_type != OBJ_REF_DELTA)
                        continue;
                sorted_by_pos[n++] = &deltas[i];
        }
        qsort(sorted_by_pos, n, sizeof(*sorted_by_pos), delta_pos_compare);

        for (i = 0; i < n; i++) {
                struct delta_entry *d = sorted_by_pos[i];
                void *data;
                unsigned long size;
                enum object_type type;
                int j, first, last;

                if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
                        continue;
                data = read_sha1_file(d->base.sha1, &type, &size);
                if (!data)
                        continue;

                find_delta_children(&d->base, &first, &last);
                for (j = first; j <= last; j++) {
                        struct object_entry *child = objects + deltas[j].obj_no;
                        if (child->real_type == OBJ_REF_DELTA)
                                resolve_delta(child, data, size, type);
                }

                if (check_sha1_signature(d->base.sha1, data, size, typename(type)))
                        die("local object %s is corrupt", sha1_to_hex(d->base.sha1));
                append_obj_to_pack(d->base.sha1, data, size, type);
                free(data);
                if (verbose)
                        percent = display_progress(nr_resolved_deltas,
                                                   nr_deltas, percent);
        }
        free(sorted_by_pos);
        if (verbose)
                fputc('\n', stderr);
}

static void readjust_pack_header_and_sha1(unsigned char *sha1)
{
        struct pack_header hdr;
        SHA_CTX ctx;
        int size;

        /* Rewrite pack header with updated object number */
        if (lseek(output_fd, 0, SEEK_SET) != 0)
                die("cannot seek back: %s", strerror(errno));
        if (read_in_full(output_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
                die("cannot read pack header back: %s", strerror(errno));
        hdr.hdr_entries = htonl(nr_objects);
        if (lseek(output_fd, 0, SEEK_SET) != 0)
                die("cannot seek back: %s", strerror(errno));
        write_or_die(output_fd, &hdr, sizeof(hdr));
        if (lseek(output_fd, 0, SEEK_SET) != 0)
                die("cannot seek back: %s", strerror(errno));

        /* Recompute and store the new pack's SHA1 */
        SHA1_Init(&ctx);
        do {
                unsigned char *buf[4096];
                size = xread(output_fd, buf, sizeof(buf));
                if (size < 0)
                        die("cannot read pack data back: %s", strerror(errno));
                SHA1_Update(&ctx, buf, size);
        } while (size > 0);
        SHA1_Final(sha1, &ctx);
        write_or_die(output_fd, sha1, 20);
}

static uint32_t index_default_version = 1;
static uint32_t index_off32_limit = 0x7fffffff;

static int sha1_compare(const void *_a, const void *_b)
{
        struct object_entry *a = *(struct object_entry **)_a;
        struct object_entry *b = *(struct object_entry **)_b;
        return hashcmp(a->sha1, b->sha1);
}

/*
 * On entry *sha1 contains the pack content SHA1 hash, on exit it is
 * the SHA1 hash of sorted object names.
 */
static const char *write_index_file(const char *index_name, unsigned char *sha1)
{
        struct sha1file *f;
        struct object_entry **sorted_by_sha, **list, **last;
        uint32_t array[256];
        int i, fd;
        SHA_CTX ctx;
        uint32_t index_version;

        if (nr_objects) {
                sorted_by_sha =
                        xcalloc(nr_objects, sizeof(struct object_entry *));
                list = sorted_by_sha;
                last = sorted_by_sha + nr_objects;
                for (i = 0; i < nr_objects; ++i)
                        sorted_by_sha[i] = &objects[i];
                qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
                      sha1_compare);
        }
        else
                sorted_by_sha = list = last = NULL;

        if (!index_name) {
                static char tmpfile[PATH_MAX];
                snprintf(tmpfile, sizeof(tmpfile),
                         "%s/tmp_idx_XXXXXX", get_object_directory());
                fd = mkstemp(tmpfile);
                index_name = xstrdup(tmpfile);
        } else {
                unlink(index_name);
                fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
        }
        if (fd < 0)
                die("unable to create %s: %s", index_name, strerror(errno));
        f = sha1fd(fd, index_name);

        /* if last object's offset is >= 2^31 we should use index V2 */
        index_version = (objects[nr_objects-1].offset >> 31) ? 2 : index_default_version;

        /* index versions 2 and above need a header */
        if (index_version >= 2) {
                struct pack_idx_header hdr;
                hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
                hdr.idx_version = htonl(index_version);
                sha1write(f, &hdr, sizeof(hdr));
        }

        /*
         * Write the first-level table (the list is sorted,
         * but we use a 256-entry lookup to be able to avoid
         * having to do eight extra binary search iterations).
         */
        for (i = 0; i < 256; i++) {
                struct object_entry **next = list;
                while (next < last) {
                        struct object_entry *obj = *next;
                        if (obj->sha1[0] != i)
                                break;
                        next++;
                }
                array[i] = htonl(next - sorted_by_sha);
                list = next;
        }
        sha1write(f, array, 256 * 4);

        /* compute the SHA1 hash of sorted object names. */
        SHA1_Init(&ctx);

        /*
         * Write the actual SHA1 entries..
         */
        list = sorted_by_sha;
        for (i = 0; i < nr_objects; i++) {
                struct object_entry *obj = *list++;
                if (index_version < 2) {
                        uint32_t offset = htonl(obj->offset);
                        sha1write(f, &offset, 4);
                }
                sha1write(f, obj->sha1, 20);
                SHA1_Update(&ctx, obj->sha1, 20);
        }

        if (index_version >= 2) {
                unsigned int nr_large_offset = 0;

                /* write the crc32 table */
                list = sorted_by_sha;
                for (i = 0; i < nr_objects; i++) {
                        struct object_entry *obj = *list++;
                        uint32_t crc32_val = htonl(obj->crc32);
                        sha1write(f, &crc32_val, 4);
                }

                /* write the 32-bit offset table */
                list = sorted_by_sha;
                for (i = 0; i < nr_objects; i++) {
                        struct object_entry *obj = *list++;
                        uint32_t offset = (obj->offset <= index_off32_limit) ?
                                obj->offset : (0x80000000 | nr_large_offset++);
                        offset = htonl(offset);
                        sha1write(f, &offset, 4);
                }

                /* write the large offset table */
                list = sorted_by_sha;
                while (nr_large_offset) {
                        struct object_entry *obj = *list++;
                        uint64_t offset = obj->offset;
                        if (offset > index_off32_limit) {
                                uint32_t split[2];
                                split[0]        = htonl(offset >> 32);
                                split[1] = htonl(offset & 0xffffffff);
                                sha1write(f, split, 8);
                                nr_large_offset--;
                        }
                }
        }

        sha1write(f, sha1, 20);
        sha1close(f, NULL, 1);
        free(sorted_by_sha);
        SHA1_Final(sha1, &ctx);
        return index_name;
}

static void final(const char *final_pack_name, const char *curr_pack_name,
                  const char *final_index_name, const char *curr_index_name,
                  const char *keep_name, const char *keep_msg,
                  unsigned char *sha1)
{
        const char *report = "pack";
        char name[PATH_MAX];
        int err;

        if (!from_stdin) {
                close(input_fd);
        } else {
                err = close(output_fd);
                if (err)
                        die("error while closing pack file: %s", strerror(errno));
                chmod(curr_pack_name, 0444);
        }

        if (keep_msg) {
                int keep_fd, keep_msg_len = strlen(keep_msg);
                if (!keep_name) {
                        snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
                                 get_object_directory(), sha1_to_hex(sha1));
                        keep_name = name;
                }
                keep_fd = open(keep_name, O_RDWR|O_CREAT|O_EXCL, 0600);
                if (keep_fd < 0) {
                        if (errno != EEXIST)
                                die("cannot write keep file");
                } else {
                        if (keep_msg_len > 0) {
                                write_or_die(keep_fd, keep_msg, keep_msg_len);
                                write_or_die(keep_fd, "\n", 1);
                        }
                        close(keep_fd);
                        report = "keep";
                }
        }

        if (final_pack_name != curr_pack_name) {
                if (!final_pack_name) {
                        snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
                                 get_object_directory(), sha1_to_hex(sha1));
                        final_pack_name = name;
                }
                if (move_temp_to_file(curr_pack_name, final_pack_name))
                        die("cannot store pack file");
        }

        chmod(curr_index_name, 0444);
        if (final_index_name != curr_index_name) {
                if (!final_index_name) {
                        snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
                                 get_object_directory(), sha1_to_hex(sha1));
                        final_index_name = name;
                }
                if (move_temp_to_file(curr_index_name, final_index_name))
                        die("cannot store index file");
        }

        if (!from_stdin) {
                printf("%s\n", sha1_to_hex(sha1));
        } else {
                char buf[48];
                int len = snprintf(buf, sizeof(buf), "%s\t%s\n",
                                   report, sha1_to_hex(sha1));
                write_or_die(1, buf, len);

                /*
                 * Let's just mimic git-unpack-objects here and write
                 * the last part of the input buffer to stdout.
                 */
                while (input_len) {
                        err = xwrite(1, input_buffer + input_offset, input_len);
                        if (err <= 0)
                                break;
                        input_len -= err;
                        input_offset += err;
                }
        }
}

int main(int argc, char **argv)
{
        int i, fix_thin_pack = 0;
        const char *curr_pack, *pack_name = NULL;
        const char *curr_index, *index_name = NULL;
        const char *keep_name = NULL, *keep_msg = NULL;
        char *index_name_buf = NULL, *keep_name_buf = NULL;
        unsigned char sha1[20];

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];

                if (*arg == '-') {
                        if (!strcmp(arg, "--stdin")) {
                                from_stdin = 1;
                        } else if (!strcmp(arg, "--fix-thin")) {
                                fix_thin_pack = 1;
                        } else if (!strcmp(arg, "--keep")) {
                                keep_msg = "";
                        } else if (!prefixcmp(arg, "--keep=")) {
                                keep_msg = arg + 7;
                        } else if (!prefixcmp(arg, "--pack_header=")) {
                                struct pack_header *hdr;
                                char *c;

                                hdr = (struct pack_header *)input_buffer;
                                hdr->hdr_signature = htonl(PACK_SIGNATURE);
                                hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
                                if (*c != ',')
                                        die("bad %s", arg);
                                hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
                                if (*c)
                                        die("bad %s", arg);
                                input_len = sizeof(*hdr);
                        } else if (!strcmp(arg, "-v")) {
                                verbose = 1;
                        } else if (!strcmp(arg, "-o")) {
                                if (index_name || (i+1) >= argc)
                                        usage(index_pack_usage);
                                index_name = argv[++i];
                        } else if (!prefixcmp(arg, "--index-version=")) {
                                char *c;
                                index_default_version = strtoul(arg + 16, &c, 10);
                                if (index_default_version > 2)
                                        die("bad %s", arg);
                                if (*c == ',')
                                        index_off32_limit = strtoul(c+1, &c, 0);
                                if (*c || index_off32_limit & 0x80000000)
                                        die("bad %s", arg);
                        } else
                                usage(index_pack_usage);
                        continue;
                }

                if (pack_name)
                        usage(index_pack_usage);
                pack_name = arg;
        }

        if (!pack_name && !from_stdin)
                usage(index_pack_usage);
        if (fix_thin_pack && !from_stdin)
                die("--fix-thin cannot be used without --stdin");
        if (!index_name && pack_name) {
                int len = strlen(pack_name);
                if (!has_extension(pack_name, ".pack"))
                        die("packfile name '%s' does not end with '.pack'",
                            pack_name);
                index_name_buf = xmalloc(len);
                memcpy(index_name_buf, pack_name, len - 5);
                strcpy(index_name_buf + len - 5, ".idx");
                index_name = index_name_buf;
        }
        if (keep_msg && !keep_name && pack_name) {
                int len = strlen(pack_name);
                if (!has_extension(pack_name, ".pack"))
                        die("packfile name '%s' does not end with '.pack'",
                            pack_name);
                keep_name_buf = xmalloc(len);
                memcpy(keep_name_buf, pack_name, len - 5);
                strcpy(keep_name_buf + len - 5, ".keep");
                keep_name = keep_name_buf;
        }

        curr_pack = open_pack_file(pack_name);
        parse_pack_header();
        objects = xmalloc((nr_objects + 1) * sizeof(struct object_entry));
        deltas = xmalloc(nr_objects * sizeof(struct delta_entry));
        if (verbose)
                setup_progress_signal();
        parse_pack_objects(sha1);
        if (nr_deltas != nr_resolved_deltas) {
                if (fix_thin_pack) {
                        int nr_unresolved = nr_deltas - nr_resolved_deltas;
                        int nr_objects_initial = nr_objects;
                        if (nr_unresolved <= 0)
                                die("confusion beyond insanity");
                        objects = xrealloc(objects,
                                           (nr_objects + nr_unresolved + 1)
                                           * sizeof(*objects));
                        fix_unresolved_deltas(nr_unresolved);
                        if (verbose)
                                fprintf(stderr, "%d objects were added to complete this thin pack.\n",
                                        nr_objects - nr_objects_initial);
                        readjust_pack_header_and_sha1(sha1);
                }
                if (nr_deltas != nr_resolved_deltas)
                        die("pack has %d unresolved deltas",
                            nr_deltas - nr_resolved_deltas);
        } else {
                /* Flush remaining pack final 20-byte SHA1. */
                flush();
        }
        free(deltas);
        curr_index = write_index_file(index_name, sha1);
        final(pack_name, curr_pack,
                index_name, curr_index,
                keep_name, keep_msg,
                sha1);
        free(objects);
        free(index_name_buf);
        free(keep_name_buf);

        return 0;
}