#include "git-compat-util.h"

#include "gettext.h"

#include "pack-mtimes.h"

#include "object-file.h"

#include "object-store-ll.h"

#include "packfile.h"

#include "strbuf.h"

static char *pack_mtimes_filename(struct packed_git *p)

{

  size_t len;

  if (!strip_suffix(p->pack_name, ".pack", &len))

    BUG("pack_name does not end in .pack");

  return xstrfmt("%.*s.mtimes", (int)len, p->pack_name);

}

#define MTIMES_HEADER_SIZE (12)

struct mtimes_header {

  uint32_t signature;

  uint32_t version;

  uint32_t hash_id;

};

static int load_pack_mtimes_file(char *mtimes_file,

         uint32_t num_objects,

         const uint32_t **data_p, size_t *len_p)

{

  int fd, ret = 0;

  struct stat st;

  uint32_t *data = NULL;

  size_t mtimes_size, expected_size;

  struct mtimes_header header;

  fd = git_open(mtimes_file);

  if (fd < 0) {

    ret = -1;

    goto cleanup;

  }

  if (fstat(fd, &st)) {

    ret = error_errno(_("failed to read %s"), mtimes_file);

    goto cleanup;

  }

  mtimes_size = xsize_t(st.st_size);

  if (mtimes_size < MTIMES_HEADER_SIZE) {

    ret = error(_("mtimes file %s is too small"), mtimes_file);

    goto cleanup;

  }

  data = xmmap(NULL, mtimes_size, PROT_READ, MAP_PRIVATE, fd, 0);

  header.signature = ntohl(data[0]);

  header.version = ntohl(data[1]);

  header.hash_id = ntohl(data[2]);

  if (header.signature != MTIMES_SIGNATURE) {

    ret = error(_("mtimes file %s has unknown signature"), mtimes_file);

    goto cleanup;

  }

  if (header.version != 1) {

    ret = error(_("mtimes file %s has unsupported version %"PRIu32),

          mtimes_file, header.version);

    goto cleanup;

  }

  if (!(header.hash_id == 1 || header.hash_id == 2)) {

    ret = error(_("mtimes file %s has unsupported hash id %"PRIu32),

          mtimes_file, header.hash_id);

    goto cleanup;

  }

  expected_size = MTIMES_HEADER_SIZE;

  expected_size = st_add(expected_size, st_mult(sizeof(uint32_t), num_objects));

  expected_size = st_add(expected_size, 2 * (header.hash_id == 1 ? GIT_SHA1_RAWSZ : GIT_SHA256_RAWSZ));

  if (mtimes_size != expected_size) {

    ret = error(_("mtimes file %s is corrupt"), mtimes_file);

    goto cleanup;

  }

cleanup:

  if (ret) {

    if (data)

      munmap(data, mtimes_size);

  } else {

    *len_p = mtimes_size;

    *data_p = data;

  }

  if (fd >= 0)

    close(fd);

  return ret;

}

int load_pack_mtimes(struct packed_git *p)

{

  char *mtimes_name = NULL;

  int ret = 0;

  if (!p->is_cruft)

    return ret; /* not a cruft pack */

  if (p->mtimes_map)

    return ret; /* already loaded */

  ret = open_pack_index(p);

  if (ret < 0)

    goto cleanup;

  mtimes_name = pack_mtimes_filename(p);

  ret = load_pack_mtimes_file(mtimes_name,

            p->num_objects,

            &p->mtimes_map,

            &p->mtimes_size);

cleanup:

  free(mtimes_name);

  return ret;

}

uint32_t nth_packed_mtime(struct packed_git *p, uint32_t pos)

{

  if (!p->mtimes_map)

    BUG("pack .mtimes file not loaded for %s", p->pack_name);

  if (p->num_objects <= pos)

    BUG("pack .mtimes out-of-bounds (%"PRIu32" vs %"PRIu32")",

        pos, p->num_objects);

  return get_be32(p->mtimes_map + pos + 3);

}