/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#include "zstream.h"

#include <zlib.h>

#include "str.h"

#define ZSTREAM_BUFFER_SIZE (1024 * 1024)

#define ZSTREAM_BUFFER_MIN_EXTRA 8

GIT_INLINE(int) zstream_seterr(git_zstream *zs)

{

  switch (zs->zerr) {

  case Z_OK:

  case Z_STREAM_END:

  case Z_BUF_ERROR: /* not fatal; we retry with a larger buffer */

    return 0;

  case Z_MEM_ERROR:

    git_error_set_oom();

    break;

  default:

    if (zs->z.msg)

      git_error_set_str(GIT_ERROR_ZLIB, zs->z.msg);

    else

      git_error_set(GIT_ERROR_ZLIB, "unknown compression error");

  }

  return -1;

}

int git_zstream_init(git_zstream *zstream, git_zstream_t type)

{

  zstream->type = type;

  if (zstream->type == GIT_ZSTREAM_INFLATE)

    zstream->zerr = inflateInit(&zstream->z);

  else

    zstream->zerr = deflateInit(&zstream->z, Z_DEFAULT_COMPRESSION);

  return zstream_seterr(zstream);

}

void git_zstream_free(git_zstream *zstream)

{

  if (zstream->type == GIT_ZSTREAM_INFLATE)

    inflateEnd(&zstream->z);

  else

    deflateEnd(&zstream->z);

}

void git_zstream_reset(git_zstream *zstream)

{

  if (zstream->type == GIT_ZSTREAM_INFLATE)

    inflateReset(&zstream->z);

  else

    deflateReset(&zstream->z);

  zstream->in = NULL;

  zstream->in_len = 0;

  zstream->zerr = Z_STREAM_END;

}

int git_zstream_set_input(git_zstream *zstream, const void *in, size_t in_len)

{

  zstream->in = in;

  zstream->in_len = in_len;

  zstream->zerr = Z_OK;

  return 0;

}

bool git_zstream_done(git_zstream *zstream)

{

  return (!zstream->in_len && zstream->zerr == Z_STREAM_END);

}

bool git_zstream_eos(git_zstream *zstream)

{

  return zstream->zerr == Z_STREAM_END;

}

size_t git_zstream_suggest_output_len(git_zstream *zstream)

{

  if (zstream->in_len > ZSTREAM_BUFFER_SIZE)

    return ZSTREAM_BUFFER_SIZE;

  else if (zstream->in_len > ZSTREAM_BUFFER_MIN_EXTRA)

    return zstream->in_len;

  else

    return ZSTREAM_BUFFER_MIN_EXTRA;

}

int git_zstream_get_output_chunk(

  void *out, size_t *out_len, git_zstream *zstream)

{

  size_t in_queued, in_used, out_queued;

  /* set up input data */

  zstream->z.next_in = (Bytef *)zstream->in;

  /* feed as much data to zlib as it can consume, at most UINT_MAX */

  if (zstream->in_len > UINT_MAX) {

    zstream->z.avail_in = UINT_MAX;

    zstream->flush = Z_NO_FLUSH;

  } else {

    zstream->z.avail_in = (uInt)zstream->in_len;

    zstream->flush = Z_FINISH;

  }

  in_queued = (size_t)zstream->z.avail_in;

  /* set up output data */

  zstream->z.next_out = out;

  zstream->z.avail_out = (uInt)*out_len;

  if ((size_t)zstream->z.avail_out != *out_len)

    zstream->z.avail_out = UINT_MAX;

  out_queued = (size_t)zstream->z.avail_out;

  /* compress next chunk */

  if (zstream->type == GIT_ZSTREAM_INFLATE)

    zstream->zerr = inflate(&zstream->z, zstream->flush);

  else

    zstream->zerr = deflate(&zstream->z, zstream->flush);

  if (zstream_seterr(zstream))

    return -1;

  in_used = (in_queued - zstream->z.avail_in);

  zstream->in_len -= in_used;

  zstream->in += in_used;

  *out_len = (out_queued - zstream->z.avail_out);

  return 0;

}

int git_zstream_get_output(void *out, size_t *out_len, git_zstream *zstream)

{

  size_t out_remain = *out_len;

  if (zstream->in_len && zstream->zerr == Z_STREAM_END) {

    git_error_set(GIT_ERROR_ZLIB, "zlib input had trailing garbage");

    return -1;

  }

  while (out_remain > 0 && zstream->zerr != Z_STREAM_END) {

    size_t out_written = out_remain;

    if (git_zstream_get_output_chunk(out, &out_written, zstream) < 0)

      return -1;

    out_remain -= out_written;

    out = ((char *)out) + out_written;

  }

  /* either we finished the input or we did not flush the data */

  GIT_ASSERT(zstream->in_len > 0 || zstream->flush == Z_FINISH);

  /* set out_size to number of bytes actually written to output */

  *out_len = *out_len - out_remain;

  return 0;

}

static int zstream_buf(git_str *out, const void *in, size_t in_len, git_zstream_t type)

{

  git_zstream zs = GIT_ZSTREAM_INIT;

  int error = 0;

  if ((error = git_zstream_init(&zs, type)) < 0)

    return error;

  if ((error = git_zstream_set_input(&zs, in, in_len)) < 0)

    goto done;

  while (!git_zstream_done(&zs)) {

    size_t step = git_zstream_suggest_output_len(&zs), written;

    if ((error = git_str_grow_by(out, step)) < 0)

      goto done;

    written = out->asize - out->size;

    if ((error = git_zstream_get_output(

        out->ptr + out->size, &written, &zs)) < 0)

      goto done;

    out->size += written;

  }

  /* NULL terminate for consistency if possible */

  if (out->size < out->asize)

    out->ptr[out->size] = '\0';

done:

  git_zstream_free(&zs);

  return error;

}

int git_zstream_deflatebuf(git_str *out, const void *in, size_t in_len)

{

  return zstream_buf(out, in, in_len, GIT_ZSTREAM_DEFLATE);

}

int git_zstream_inflatebuf(git_str *out, const void *in, size_t in_len)

{

  return zstream_buf(out, in, in_len, GIT_ZSTREAM_INFLATE);

}