/*

 * zlib wrappers to make sure we don't silently miss errors

 * at init time.

 */

#include "git-compat-util.h"

#include "git-zlib.h"

static const char *zerr_to_string(int status)

{

  switch (status) {

  case Z_MEM_ERROR:

    return "out of memory";

  case Z_VERSION_ERROR:

    return "wrong version";

  case Z_NEED_DICT:

    return "needs dictionary";

  case Z_DATA_ERROR:

    return "data stream error";

  case Z_STREAM_ERROR:

    return "stream consistency error";

  default:

    return "unknown error";

  }

}

/*

 * avail_in and avail_out in zlib are counted in uInt, which typically

 * limits the size of the buffer we can use to 4GB when interacting

 * with zlib in a single call to inflate/deflate.

 */

/* #define ZLIB_BUF_MAX ((uInt)-1) */

#define ZLIB_BUF_MAX ((uInt) 1024 * 1024 * 1024) /* 1GB */

static inline uInt zlib_buf_cap(unsigned long len)

{

  return (ZLIB_BUF_MAX < len) ? ZLIB_BUF_MAX : len;

}

static void zlib_pre_call(git_zstream *s)

{

  s->z.next_in = s->next_in;

  s->z.next_out = s->next_out;

  s->z.total_in = s->total_in;

  s->z.total_out = s->total_out;

  s->z.avail_in = zlib_buf_cap(s->avail_in);

  s->z.avail_out = zlib_buf_cap(s->avail_out);

}

static void zlib_post_call(git_zstream *s, int status)

{

  unsigned long bytes_consumed;

  unsigned long bytes_produced;

  bytes_consumed = s->z.next_in - s->next_in;

  bytes_produced = s->z.next_out - s->next_out;

  if (s->z.total_out != s->total_out + bytes_produced)

    BUG("total_out mismatch");

  /*

   * zlib does not update total_in when it returns Z_NEED_DICT,

   * causing a mismatch here. Skip the sanity check in that case.

   */

  if (status != Z_NEED_DICT &&

      s->z.total_in != s->total_in + bytes_consumed)

    BUG("total_in mismatch");

  s->total_out = s->z.total_out;

  s->total_in = s->z.total_in;

  /* zlib-ng marks `next_in` as `const`, so we have to cast it away. */

  s->next_in = (unsigned char *) s->z.next_in;

  s->next_out = s->z.next_out;

  s->avail_in -= bytes_consumed;

  s->avail_out -= bytes_produced;

}

void git_inflate_init(git_zstream *strm)

{

  int status;

  zlib_pre_call(strm);

  status = inflateInit(&strm->z);

  zlib_post_call(strm, status);

  if (status == Z_OK)

    return;

  die("inflateInit: %s (%s)", zerr_to_string(status),

      strm->z.msg ? strm->z.msg : "no message");

}

void git_inflate_init_gzip_only(git_zstream *strm)

{

  /*

   * Use default 15 bits, +16 is to accept only gzip and to

   * yield Z_DATA_ERROR when fed zlib format.

   */

  const int windowBits = 15 + 16;

  int status;

  zlib_pre_call(strm);

  status = inflateInit2(&strm->z, windowBits);

  zlib_post_call(strm, status);

  if (status == Z_OK)

    return;

  die("inflateInit2: %s (%s)", zerr_to_string(status),

      strm->z.msg ? strm->z.msg : "no message");

}

void git_inflate_end(git_zstream *strm)

{

  int status;

  zlib_pre_call(strm);

  status = inflateEnd(&strm->z);

  zlib_post_call(strm, status);

  if (status == Z_OK)

    return;

  error("inflateEnd: %s (%s)", zerr_to_string(status),

        strm->z.msg ? strm->z.msg : "no message");

}

int git_inflate(git_zstream *strm, int flush)

{

  int status;

  for (;;) {

    zlib_pre_call(strm);

    /* Never say Z_FINISH unless we are feeding everything */

    status = inflate(&strm->z,

         (strm->z.avail_in != strm->avail_in)

         ? 0 : flush);

    if (status == Z_MEM_ERROR)

      die("inflate: out of memory");

    zlib_post_call(strm, status);

    /*

     * Let zlib work another round, while we can still

     * make progress.

     */

    if ((strm->avail_out && !strm->z.avail_out) &&

        (status == Z_OK || status == Z_BUF_ERROR))

      continue;

    break;

  }

  switch (status) {

  /* Z_BUF_ERROR: normal, needs more space in the output buffer */

  case Z_BUF_ERROR:

  case Z_OK:

  case Z_STREAM_END:

    return status;

  default:

    break;

  }

  error("inflate: %s (%s)", zerr_to_string(status),

        strm->z.msg ? strm->z.msg : "no message");

  return status;

}

unsigned long git_deflate_bound(git_zstream *strm, unsigned long size)

{

  return deflateBound(&strm->z, size);

}

void git_deflate_init(git_zstream *strm, int level)

{

  int status;

  memset(strm, 0, sizeof(*strm));

  zlib_pre_call(strm);

  status = deflateInit(&strm->z, level);

  zlib_post_call(strm, status);

  if (status == Z_OK)

    return;

  die("deflateInit: %s (%s)", zerr_to_string(status),

      strm->z.msg ? strm->z.msg : "no message");

}

static void do_git_deflate_init(git_zstream *strm, int level, int windowBits)

{

  int status;

  memset(strm, 0, sizeof(*strm));

  zlib_pre_call(strm);

  status = deflateInit2(&strm->z, level,

          Z_DEFLATED, windowBits,

          8, Z_DEFAULT_STRATEGY);

  zlib_post_call(strm, status);

  if (status == Z_OK)

    return;

  die("deflateInit2: %s (%s)", zerr_to_string(status),

      strm->z.msg ? strm->z.msg : "no message");

}

void git_deflate_init_gzip(git_zstream *strm, int level)

{

  /*

   * Use default 15 bits, +16 is to generate gzip header/trailer

   * instead of the zlib wrapper.

   */

  do_git_deflate_init(strm, level, 15 + 16);

}

void git_deflate_init_raw(git_zstream *strm, int level)

{

  /*

   * Use default 15 bits, negate the value to get raw compressed

   * data without zlib header and trailer.

   */

  do_git_deflate_init(strm, level, -15);

}

int git_deflate_abort(git_zstream *strm)

{

  int status;

  zlib_pre_call(strm);

  status = deflateEnd(&strm->z);

  zlib_post_call(strm, status);

  return status;

}

void git_deflate_end(git_zstream *strm)

{

  int status = git_deflate_abort(strm);

  if (status == Z_OK)

    return;

  error("deflateEnd: %s (%s)", zerr_to_string(status),

        strm->z.msg ? strm->z.msg : "no message");

}

int git_deflate_end_gently(git_zstream *strm)

{

  int status;

  zlib_pre_call(strm);

  status = deflateEnd(&strm->z);

  zlib_post_call(strm, status);

  return status;

}

int git_deflate(git_zstream *strm, int flush)

{

  int status;

  for (;;) {

    zlib_pre_call(strm);

    /* Never say Z_FINISH unless we are feeding everything */

    status = deflate(&strm->z,

         (strm->z.avail_in != strm->avail_in)

         ? 0 : flush);

    if (status == Z_MEM_ERROR)

      die("deflate: out of memory");

    zlib_post_call(strm, status);

    /*

     * Let zlib work another round, while we can still

     * make progress.

     */

    if ((strm->avail_out && !strm->z.avail_out) &&

        (status == Z_OK || status == Z_BUF_ERROR))

      continue;

    break;

  }

  switch (status) {

  /* Z_BUF_ERROR: normal, needs more space in the output buffer */

  case Z_BUF_ERROR:

  case Z_OK:

  case Z_STREAM_END:

    return status;

  default:

    break;

  }

  error("deflate: %s (%s)", zerr_to_string(status),

        strm->z.msg ? strm->z.msg : "no message");

  return status;

}