thodg/libgit2/src/zstream.c

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• Hash : b7d36ef4
  Author :
  Date : 2017-12-12T12:24:11
  

  zstream: treat `Z_BUF_ERROR` as non-fatal zlib will return `Z_BUF_ERROR` whenever there is more input to inflate or deflate than there is output to store the result. This is normal for us as we iterate through the input, particularly with very large input buffers.

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• src/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 "buffer.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:
  		giterr_set_oom();
  		break;
  	default:
  		if (zs->z.msg)
  			giterr_set_str(GITERR_ZLIB, zs->z.msg);
  		else
  			giterr_set(GITERR_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);
  }
  
  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(void *out, size_t *out_len, git_zstream *zstream)
  {
  	int zflush = Z_FINISH;
  	size_t out_remain = *out_len;
  
  	if (zstream->in_len && zstream->zerr == Z_STREAM_END) {
  		giterr_set(GITERR_ZLIB, "zlib input had trailing garbage");
  		return -1;
  	}
  
  	while (out_remain > 0 && zstream->zerr != Z_STREAM_END) {
  		size_t out_queued, in_queued, out_used, in_used;
  
  		/* set up in data */
  		zstream->z.next_in  = (Bytef *)zstream->in;
  		zstream->z.avail_in = (uInt)zstream->in_len;
  		if ((size_t)zstream->z.avail_in != zstream->in_len) {
  			zstream->z.avail_in = INT_MAX;
  			zflush = Z_NO_FLUSH;
  		} else {
  			zflush = Z_FINISH;
  		}
  		in_queued = (size_t)zstream->z.avail_in;
  
  		/* set up out data */
  		zstream->z.next_out = out;
  		zstream->z.avail_out = (uInt)out_remain;
  		if ((size_t)zstream->z.avail_out != out_remain)
  			zstream->z.avail_out = INT_MAX;
  		out_queued = (size_t)zstream->z.avail_out;
  
  		/* compress next chunk */
  		if (zstream->type == GIT_ZSTREAM_INFLATE)
  			zstream->zerr = inflate(&zstream->z, zflush);
  		else
  			zstream->zerr = deflate(&zstream->z, zflush);
  
  		if (zstream_seterr(zstream))
  			return -1;
  
  		out_used = (out_queued - zstream->z.avail_out);
  		out_remain -= out_used;
  		out = ((char *)out) + out_used;
  
  		in_used = (in_queued - zstream->z.avail_in);
  		zstream->in_len -= in_used;
  		zstream->in += in_used;
  	}
  
  	/* either we finished the input or we did not flush the data */
  	assert(zstream->in_len > 0 || zflush == 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_buf *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_buf_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_buf *out, const void *in, size_t in_len)
  {
  	return zstream_buf(out, in, in_len, GIT_ZSTREAM_DEFLATE);
  }
  
  int git_zstream_inflatebuf(git_buf *out, const void *in, size_t in_len)
  {
  	return zstream_buf(out, in, in_len, GIT_ZSTREAM_INFLATE);
  }
  

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