thodg/libgit2/src/util/zstream.c

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• Hash : c3b7ace9
  Author :
  Date : 2021-11-14T16:43:53
  

  refactor: make util an object library Instead of simply including the utility files directly, make them a cmake object library for easy reusability between other projects within libgit2. Now the top-level `src` is responsible for platform selection, while the next-level `libgit2` and `util` configurations are responsible for identifying what objects they include.

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• src/util/zstream.c

• /*
   * 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);
  }
  

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