libarchive/archive_write_add_filter_gzip.c - third_party/libarchive - Git at Google

 /*-
  * Copyright (c) 2003-2007 Tim Kientzle
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "archive_platform.h"

 __FBSDID("$FreeBSD: head/lib/libarchive/archive_write_set_compression_gzip.c 201081 2009-12-28 02:04:42Z kientzle $");

 #ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
 #ifdef HAVE_STDLIB_H
 #include <stdlib.h>
 #endif
 #ifdef HAVE_STRING_H
 #include <string.h>
 #endif
 #include <time.h>
 #ifdef HAVE_ZLIB_H
 #include <zlib.h>
 #endif

 #include "archive.h"
 #include "archive_private.h"
 #include "archive_string.h"
 #include "archive_write_private.h"

 #if ARCHIVE_VERSION_NUMBER < 4000000
 int
 archive_write_set_compression_gzip(struct archive *a)
 {
 	__archive_write_filters_free(a);
 	return (archive_write_add_filter_gzip(a));
 }
 #endif

 /* Don't compile this if we don't have zlib. */

 struct private_data {
 	int		 compression_level;
 	int		 timestamp;
 #ifdef HAVE_ZLIB_H
 	z_stream	 stream;
 	int64_t		 total_in;
 	unsigned char	*compressed;
 	size_t		 compressed_buffer_size;
 	unsigned long	 crc;
 #else
 	struct archive_write_program_data *pdata;
 #endif
 };

 /*
  * Yuck.  zlib.h is not const-correct, so I need this one bit
  * of ugly hackery to convert a const * pointer to a non-const pointer.
  */
 #define	SET_NEXT_IN(st,src)					\
 	(st)->stream.next_in = (Bytef *)(uintptr_t)(const void *)(src)

 static int archive_compressor_gzip_options(struct archive_write_filter *,
 		    const char *, const char *);
 static int archive_compressor_gzip_open(struct archive_write_filter *);
 static int archive_compressor_gzip_write(struct archive_write_filter *,
 		    const void *, size_t);
 static int archive_compressor_gzip_close(struct archive_write_filter *);
 static int archive_compressor_gzip_free(struct archive_write_filter *);
 #ifdef HAVE_ZLIB_H
 static int drive_compressor(struct archive_write_filter *,
 		    struct private_data *, int finishing);
 #endif


 /*
  * Add a gzip compression filter to this write handle.
  */
 int
 archive_write_add_filter_gzip(struct archive *_a)
 {
 	struct archive_write *a = (struct archive_write *)_a;
 	struct archive_write_filter *f = __archive_write_allocate_filter(_a);
 	struct private_data *data;
 	archive_check_magic(&a->archive, ARCHIVE_WRITE_MAGIC,
 	    ARCHIVE_STATE_NEW, "archive_write_add_filter_gzip");

 	data = calloc(1, sizeof(*data));
 	if (data == NULL) {
 		archive_set_error(&a->archive, ENOMEM, "Out of memory");
 		return (ARCHIVE_FATAL);
 	}
 	f->data = data;
 	f->open = &archive_compressor_gzip_open;
 	f->options = &archive_compressor_gzip_options;
 	f->close = &archive_compressor_gzip_close;
 	f->free = &archive_compressor_gzip_free;
 	f->code = ARCHIVE_FILTER_GZIP;
 	f->name = "gzip";
 #ifdef HAVE_ZLIB_H
 	data->compression_level = Z_DEFAULT_COMPRESSION;
 	return (ARCHIVE_OK);
 #else
 	data->pdata = __archive_write_program_allocate("gzip");
 	if (data->pdata == NULL) {
 		free(data);
 		archive_set_error(&a->archive, ENOMEM, "Out of memory");
 		return (ARCHIVE_FATAL);
 	}
 	data->compression_level = 0;
 	archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
 	    "Using external gzip program");
 	return (ARCHIVE_WARN);
 #endif
 }

 static int
 archive_compressor_gzip_free(struct archive_write_filter *f)
 {
 	struct private_data *data = (struct private_data *)f->data;

 #ifdef HAVE_ZLIB_H
 	free(data->compressed);
 #else
 	__archive_write_program_free(data->pdata);
 #endif
 	free(data);
 	f->data = NULL;
 	return (ARCHIVE_OK);
 }

 /*
  * Set write options.
  */
 static int
 archive_compressor_gzip_options(struct archive_write_filter *f, const char *key,
     const char *value)
 {
 	struct private_data *data = (struct private_data *)f->data;

 	if (strcmp(key, "compression-level") == 0) {
 		if (value == NULL || !(value[0] >= '0' && value[0] <= '9') ||
 		    value[1] != '\0')
 			return (ARCHIVE_WARN);
 		data->compression_level = value[0] - '0';
 		return (ARCHIVE_OK);
 	}
 	if (strcmp(key, "timestamp") == 0) {
 		data->timestamp = (value == NULL)?-1:1;
 		return (ARCHIVE_OK);
 	}

 	/* Note: The "warn" return is just to inform the options
 	 * supervisor that we didn't handle it.  It will generate
 	 * a suitable error if no one used this option. */
 	return (ARCHIVE_WARN);
 }

 #ifdef HAVE_ZLIB_H
 /*
  * Setup callback.
  */
 static int
 archive_compressor_gzip_open(struct archive_write_filter *f)
 {
 	struct private_data *data = (struct private_data *)f->data;
 	int ret;

 	ret = __archive_write_open_filter(f->next_filter);
 	if (ret != ARCHIVE_OK)
 		return (ret);

 	if (data->compressed == NULL) {
 		size_t bs = 65536, bpb;
 		if (f->archive->magic == ARCHIVE_WRITE_MAGIC) {
 			/* Buffer size should be a multiple number of
 			 * the of bytes per block for performance. */
 			bpb = archive_write_get_bytes_per_block(f->archive);
 			if (bpb > bs)
 				bs = bpb;
 			else if (bpb != 0)
 				bs -= bs % bpb;
 		}
 		data->compressed_buffer_size = bs;
 		data->compressed
 		    = (unsigned char *)malloc(data->compressed_buffer_size);
 		if (data->compressed == NULL) {
 			archive_set_error(f->archive, ENOMEM,
 			    "Can't allocate data for compression buffer");
 			return (ARCHIVE_FATAL);
 		}
 	}

 	data->crc = crc32(0L, NULL, 0);
 	data->stream.next_out = data->compressed;
 	data->stream.avail_out = (uInt)data->compressed_buffer_size;

 	/* Prime output buffer with a gzip header. */
 	data->compressed[0] = 0x1f; /* GZip signature bytes */
 	data->compressed[1] = 0x8b;
 	data->compressed[2] = 0x08; /* "Deflate" compression */
 	data->compressed[3] = 0; /* No options */
 	if (data->timestamp >= 0) {
 		time_t t = time(NULL);
 		data->compressed[4] = (uint8_t)(t)&0xff;  /* Timestamp */
 		data->compressed[5] = (uint8_t)(t>>8)&0xff;
 		data->compressed[6] = (uint8_t)(t>>16)&0xff;
 		data->compressed[7] = (uint8_t)(t>>24)&0xff;
 	} else
 		memset(&data->compressed[4], 0, 4);
 	data->compressed[8] = 0; /* No deflate options */
 	data->compressed[9] = 3; /* OS=Unix */
 	data->stream.next_out += 10;
 	data->stream.avail_out -= 10;

 	f->write = archive_compressor_gzip_write;

 	/* Initialize compression library. */
 	ret = deflateInit2(&(data->stream),
 	    data->compression_level,
 	    Z_DEFLATED,
 	    -15 /* < 0 to suppress zlib header */,
 	    8,
 	    Z_DEFAULT_STRATEGY);

 	if (ret == Z_OK) {
 		f->data = data;
 		return (ARCHIVE_OK);
 	}

 	/* Library setup failed: clean up. */
 	archive_set_error(f->archive, ARCHIVE_ERRNO_MISC, "Internal error "
 	    "initializing compression library");

 	/* Override the error message if we know what really went wrong. */
 	switch (ret) {
 	case Z_STREAM_ERROR:
 		archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
 		    "Internal error initializing "
 		    "compression library: invalid setup parameter");
 		break;
 	case Z_MEM_ERROR:
 		archive_set_error(f->archive, ENOMEM,
 		    "Internal error initializing compression library");
 		break;
 	case Z_VERSION_ERROR:
 		archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
 		    "Internal error initializing "
 		    "compression library: invalid library version");
 		break;
 	}

 	return (ARCHIVE_FATAL);
 }

 /*
  * Write data to the compressed stream.
  */
 static int
 archive_compressor_gzip_write(struct archive_write_filter *f, const void *buff,
     size_t length)
 {
 	struct private_data *data = (struct private_data *)f->data;
 	int ret;

 	/* Update statistics */
 	data->crc = crc32(data->crc, (const Bytef *)buff, (uInt)length);
 	data->total_in += length;

 	/* Compress input data to output buffer */
 	SET_NEXT_IN(data, buff);
 	data->stream.avail_in = (uInt)length;
 	if ((ret = drive_compressor(f, data, 0)) != ARCHIVE_OK)
 		return (ret);

 	return (ARCHIVE_OK);
 }

 /*
  * Finish the compression...
  */
 static int
 archive_compressor_gzip_close(struct archive_write_filter *f)
 {
 	unsigned char trailer[8];
 	struct private_data *data = (struct private_data *)f->data;
 	int ret, r1;

 	/* Finish compression cycle */
 	ret = drive_compressor(f, data, 1);
 	if (ret == ARCHIVE_OK) {
 		/* Write the last compressed data. */
 		ret = __archive_write_filter(f->next_filter,
 		    data->compressed,
 		    data->compressed_buffer_size - data->stream.avail_out);
 	}
 	if (ret == ARCHIVE_OK) {
 		/* Build and write out 8-byte trailer. */
 		trailer[0] = (uint8_t)(data->crc)&0xff;
 		trailer[1] = (uint8_t)(data->crc >> 8)&0xff;
 		trailer[2] = (uint8_t)(data->crc >> 16)&0xff;
 		trailer[3] = (uint8_t)(data->crc >> 24)&0xff;
 		trailer[4] = (uint8_t)(data->total_in)&0xff;
 		trailer[5] = (uint8_t)(data->total_in >> 8)&0xff;
 		trailer[6] = (uint8_t)(data->total_in >> 16)&0xff;
 		trailer[7] = (uint8_t)(data->total_in >> 24)&0xff;
 		ret = __archive_write_filter(f->next_filter, trailer, 8);
 	}

 	switch (deflateEnd(&(data->stream))) {
 	case Z_OK:
 		break;
 	default:
 		archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
 		    "Failed to clean up compressor");
 		ret = ARCHIVE_FATAL;
 	}
 	r1 = __archive_write_close_filter(f->next_filter);
 	return (r1 < ret ? r1 : ret);
 }

 /*
  * Utility function to push input data through compressor,
  * writing full output blocks as necessary.
  *
  * Note that this handles both the regular write case (finishing ==
  * false) and the end-of-archive case (finishing == true).
  */
 static int
 drive_compressor(struct archive_write_filter *f,
     struct private_data *data, int finishing)
 {
 	int ret;

 	for (;;) {
 		if (data->stream.avail_out == 0) {
 			ret = __archive_write_filter(f->next_filter,
 			    data->compressed,
 			    data->compressed_buffer_size);
 			if (ret != ARCHIVE_OK)
 				return (ARCHIVE_FATAL);
 			data->stream.next_out = data->compressed;
 			data->stream.avail_out =
 			    (uInt)data->compressed_buffer_size;
 		}

 		/* If there's nothing to do, we're done. */
 		if (!finishing && data->stream.avail_in == 0)
 			return (ARCHIVE_OK);

 		ret = deflate(&(data->stream),
 		    finishing ? Z_FINISH : Z_NO_FLUSH );

 		switch (ret) {
 		case Z_OK:
 			/* In non-finishing case, check if compressor
 			 * consumed everything */
 			if (!finishing && data->stream.avail_in == 0)
 				return (ARCHIVE_OK);
 			/* In finishing case, this return always means
 			 * there's more work */
 			break;
 		case Z_STREAM_END:
 			/* This return can only occur in finishing case. */
 			return (ARCHIVE_OK);
 		default:
 			/* Any other return value indicates an error. */
 			archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
 			    "GZip compression failed:"
 			    " deflate() call returned status %d",
 			    ret);
 			return (ARCHIVE_FATAL);
 		}
 	}
 }

 #else /* HAVE_ZLIB_H */

 static int
 archive_compressor_gzip_open(struct archive_write_filter *f)
 {
 	struct private_data *data = (struct private_data *)f->data;
 	struct archive_string as;
 	int r;

 	archive_string_init(&as);
 	archive_strcpy(&as, "gzip");

 	/* Specify compression level. */
 	if (data->compression_level > 0) {
 		archive_strcat(&as, " -");
 		archive_strappend_char(&as, '0' + data->compression_level);
 	}
 	if (data->timestamp < 0)
 		/* Do not save timestamp. */
 		archive_strcat(&as, " -n");
 	else if (data->timestamp > 0)
 		/* Save timestamp. */
 		archive_strcat(&as, " -N");

 	f->write = archive_compressor_gzip_write;
 	r = __archive_write_program_open(f, data->pdata, as.s);
 	archive_string_free(&as);
 	return (r);
 }

 static int
 archive_compressor_gzip_write(struct archive_write_filter *f, const void *buff,
     size_t length)
 {
 	struct private_data *data = (struct private_data *)f->data;

 	return __archive_write_program_write(f, data->pdata, buff, length);
 }

 static int
 archive_compressor_gzip_close(struct archive_write_filter *f)
 {
 	struct private_data *data = (struct private_data *)f->data;

 	return __archive_write_program_close(f, data->pdata);
 }

 #endif /* HAVE_ZLIB_H */
	/*-
	* Copyright (c) 2003-2007 Tim Kientzle
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "archive_platform.h"

	__FBSDID("$FreeBSD: head/lib/libarchive/archive_write_set_compression_gzip.c 201081 2009-12-28 02:04:42Z kientzle $");

	#ifdef HAVE_ERRNO_H
	#include <errno.h>
	#endif
	#ifdef HAVE_STDLIB_H
	#include <stdlib.h>
	#endif
	#ifdef HAVE_STRING_H
	#include <string.h>
	#endif
	#include <time.h>
	#ifdef HAVE_ZLIB_H
	#include <zlib.h>
	#endif

	#include "archive.h"
	#include "archive_private.h"
	#include "archive_string.h"
	#include "archive_write_private.h"

	#if ARCHIVE_VERSION_NUMBER < 4000000
	int
	archive_write_set_compression_gzip(struct archive *a)
	{
	__archive_write_filters_free(a);
	return (archive_write_add_filter_gzip(a));
	}
	#endif

	/* Don't compile this if we don't have zlib. */

	struct private_data {
	int compression_level;
	int timestamp;
	#ifdef HAVE_ZLIB_H
	z_stream stream;
	int64_t total_in;
	unsigned char *compressed;
	size_t compressed_buffer_size;
	unsigned long crc;
	#else
	struct archive_write_program_data *pdata;
	#endif
	};

	/*
	* Yuck. zlib.h is not const-correct, so I need this one bit
	* of ugly hackery to convert a const * pointer to a non-const pointer.
	*/
	#define SET_NEXT_IN(st,src) \
	(st)->stream.next_in = (Bytef )(uintptr_t)(const void )(src)

	static int archive_compressor_gzip_options(struct archive_write_filter *,
	const char , const char );
	static int archive_compressor_gzip_open(struct archive_write_filter *);
	static int archive_compressor_gzip_write(struct archive_write_filter *,
	const void *, size_t);
	static int archive_compressor_gzip_close(struct archive_write_filter *);
	static int archive_compressor_gzip_free(struct archive_write_filter *);
	#ifdef HAVE_ZLIB_H
	static int drive_compressor(struct archive_write_filter *,
	struct private_data *, int finishing);
	#endif


	/*
	* Add a gzip compression filter to this write handle.
	*/
	int
	archive_write_add_filter_gzip(struct archive *_a)
	{
	struct archive_write a = (struct archive_write )_a;
	struct archive_write_filter *f = __archive_write_allocate_filter(_a);
	struct private_data *data;
	archive_check_magic(&a->archive, ARCHIVE_WRITE_MAGIC,
	ARCHIVE_STATE_NEW, "archive_write_add_filter_gzip");

	data = calloc(1, sizeof(*data));
	if (data == NULL) {
	archive_set_error(&a->archive, ENOMEM, "Out of memory");
	return (ARCHIVE_FATAL);
	}
	f->data = data;
	f->open = &archive_compressor_gzip_open;
	f->options = &archive_compressor_gzip_options;
	f->close = &archive_compressor_gzip_close;
	f->free = &archive_compressor_gzip_free;
	f->code = ARCHIVE_FILTER_GZIP;
	f->name = "gzip";
	#ifdef HAVE_ZLIB_H
	data->compression_level = Z_DEFAULT_COMPRESSION;
	return (ARCHIVE_OK);
	#else
	data->pdata = __archive_write_program_allocate("gzip");
	if (data->pdata == NULL) {
	free(data);
	archive_set_error(&a->archive, ENOMEM, "Out of memory");
	return (ARCHIVE_FATAL);
	}
	data->compression_level = 0;
	archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
	"Using external gzip program");
	return (ARCHIVE_WARN);
	#endif
	}

	static int
	archive_compressor_gzip_free(struct archive_write_filter *f)
	{
	struct private_data data = (struct private_data )f->data;

	#ifdef HAVE_ZLIB_H
	free(data->compressed);
	#else
	__archive_write_program_free(data->pdata);
	#endif
	free(data);
	f->data = NULL;
	return (ARCHIVE_OK);
	}

	/*
	* Set write options.
	*/
	static int
	archive_compressor_gzip_options(struct archive_write_filter f, const char key,
	const char *value)
	{
	struct private_data data = (struct private_data )f->data;

	if (strcmp(key, "compression-level") == 0) {
	if (value == NULL \|\| !(value[0] >= '0' && value[0] <= '9') \|\|
	value[1] != '\0')
	return (ARCHIVE_WARN);
	data->compression_level = value[0] - '0';
	return (ARCHIVE_OK);
	}
	if (strcmp(key, "timestamp") == 0) {
	data->timestamp = (value == NULL)?-1:1;
	return (ARCHIVE_OK);
	}

	/* Note: The "warn" return is just to inform the options
	* supervisor that we didn't handle it. It will generate
	* a suitable error if no one used this option. */
	return (ARCHIVE_WARN);
	}

	#ifdef HAVE_ZLIB_H
	/*
	* Setup callback.
	*/
	static int
	archive_compressor_gzip_open(struct archive_write_filter *f)
	{
	struct private_data data = (struct private_data )f->data;
	int ret;

	ret = __archive_write_open_filter(f->next_filter);
	if (ret != ARCHIVE_OK)
	return (ret);

	if (data->compressed == NULL) {
	size_t bs = 65536, bpb;
	if (f->archive->magic == ARCHIVE_WRITE_MAGIC) {
	/* Buffer size should be a multiple number of
	* the of bytes per block for performance. */
	bpb = archive_write_get_bytes_per_block(f->archive);
	if (bpb > bs)
	bs = bpb;
	else if (bpb != 0)
	bs -= bs % bpb;
	}
	data->compressed_buffer_size = bs;
	data->compressed
	= (unsigned char *)malloc(data->compressed_buffer_size);
	if (data->compressed == NULL) {
	archive_set_error(f->archive, ENOMEM,
	"Can't allocate data for compression buffer");
	return (ARCHIVE_FATAL);
	}
	}

	data->crc = crc32(0L, NULL, 0);
	data->stream.next_out = data->compressed;
	data->stream.avail_out = (uInt)data->compressed_buffer_size;

	/* Prime output buffer with a gzip header. */
	data->compressed[0] = 0x1f; /* GZip signature bytes */
	data->compressed[1] = 0x8b;
	data->compressed[2] = 0x08; /* "Deflate" compression */
	data->compressed[3] = 0; /* No options */
	if (data->timestamp >= 0) {
	time_t t = time(NULL);
	data->compressed[4] = (uint8_t)(t)&0xff; /* Timestamp */
	data->compressed[5] = (uint8_t)(t>>8)&0xff;
	data->compressed[6] = (uint8_t)(t>>16)&0xff;
	data->compressed[7] = (uint8_t)(t>>24)&0xff;
	} else
	memset(&data->compressed[4], 0, 4);
	data->compressed[8] = 0; /* No deflate options */
	data->compressed[9] = 3; /* OS=Unix */
	data->stream.next_out += 10;
	data->stream.avail_out -= 10;

	f->write = archive_compressor_gzip_write;

	/* Initialize compression library. */
	ret = deflateInit2(&(data->stream),
	data->compression_level,
	Z_DEFLATED,
	-15 /* < 0 to suppress zlib header */,
	8,
	Z_DEFAULT_STRATEGY);

	if (ret == Z_OK) {
	f->data = data;
	return (ARCHIVE_OK);
	}

	/* Library setup failed: clean up. */
	archive_set_error(f->archive, ARCHIVE_ERRNO_MISC, "Internal error "
	"initializing compression library");

	/* Override the error message if we know what really went wrong. */
	switch (ret) {
	case Z_STREAM_ERROR:
	archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
	"Internal error initializing "
	"compression library: invalid setup parameter");
	break;
	case Z_MEM_ERROR:
	archive_set_error(f->archive, ENOMEM,
	"Internal error initializing compression library");
	break;
	case Z_VERSION_ERROR:
	archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
	"Internal error initializing "
	"compression library: invalid library version");
	break;
	}

	return (ARCHIVE_FATAL);
	}

	/*
	* Write data to the compressed stream.
	*/
	static int
	archive_compressor_gzip_write(struct archive_write_filter f, const void buff,
	size_t length)
	{
	struct private_data data = (struct private_data )f->data;
	int ret;

	/* Update statistics */
	data->crc = crc32(data->crc, (const Bytef *)buff, (uInt)length);
	data->total_in += length;

	/* Compress input data to output buffer */
	SET_NEXT_IN(data, buff);
	data->stream.avail_in = (uInt)length;
	if ((ret = drive_compressor(f, data, 0)) != ARCHIVE_OK)
	return (ret);

	return (ARCHIVE_OK);
	}

	/*
	* Finish the compression...
	*/
	static int
	archive_compressor_gzip_close(struct archive_write_filter *f)
	{
	unsigned char trailer[8];
	struct private_data data = (struct private_data )f->data;
	int ret, r1;

	/* Finish compression cycle */
	ret = drive_compressor(f, data, 1);
	if (ret == ARCHIVE_OK) {
	/* Write the last compressed data. */
	ret = __archive_write_filter(f->next_filter,
	data->compressed,
	data->compressed_buffer_size - data->stream.avail_out);
	}
	if (ret == ARCHIVE_OK) {
	/* Build and write out 8-byte trailer. */
	trailer[0] = (uint8_t)(data->crc)&0xff;
	trailer[1] = (uint8_t)(data->crc >> 8)&0xff;
	trailer[2] = (uint8_t)(data->crc >> 16)&0xff;
	trailer[3] = (uint8_t)(data->crc >> 24)&0xff;
	trailer[4] = (uint8_t)(data->total_in)&0xff;
	trailer[5] = (uint8_t)(data->total_in >> 8)&0xff;
	trailer[6] = (uint8_t)(data->total_in >> 16)&0xff;
	trailer[7] = (uint8_t)(data->total_in >> 24)&0xff;
	ret = __archive_write_filter(f->next_filter, trailer, 8);
	}

	switch (deflateEnd(&(data->stream))) {
	case Z_OK:
	break;
	default:
	archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
	"Failed to clean up compressor");
	ret = ARCHIVE_FATAL;
	}
	r1 = __archive_write_close_filter(f->next_filter);
	return (r1 < ret ? r1 : ret);
	}

	/*
	* Utility function to push input data through compressor,
	* writing full output blocks as necessary.
	*
	* Note that this handles both the regular write case (finishing ==
	* false) and the end-of-archive case (finishing == true).
	*/
	static int
	drive_compressor(struct archive_write_filter *f,
	struct private_data *data, int finishing)
	{
	int ret;

	for (;;) {
	if (data->stream.avail_out == 0) {
	ret = __archive_write_filter(f->next_filter,
	data->compressed,
	data->compressed_buffer_size);
	if (ret != ARCHIVE_OK)
	return (ARCHIVE_FATAL);
	data->stream.next_out = data->compressed;
	data->stream.avail_out =
	(uInt)data->compressed_buffer_size;
	}

	/* If there's nothing to do, we're done. */
	if (!finishing && data->stream.avail_in == 0)
	return (ARCHIVE_OK);

	ret = deflate(&(data->stream),
	finishing ? Z_FINISH : Z_NO_FLUSH );

	switch (ret) {
	case Z_OK:
	/* In non-finishing case, check if compressor
	* consumed everything */
	if (!finishing && data->stream.avail_in == 0)
	return (ARCHIVE_OK);
	/* In finishing case, this return always means
	* there's more work */
	break;
	case Z_STREAM_END:
	/* This return can only occur in finishing case. */
	return (ARCHIVE_OK);
	default:
	/* Any other return value indicates an error. */
	archive_set_error(f->archive, ARCHIVE_ERRNO_MISC,
	"GZip compression failed:"
	" deflate() call returned status %d",
	ret);
	return (ARCHIVE_FATAL);
	}
	}
	}

	#else /* HAVE_ZLIB_H */

	static int
	archive_compressor_gzip_open(struct archive_write_filter *f)
	{
	struct private_data data = (struct private_data )f->data;
	struct archive_string as;
	int r;

	archive_string_init(&as);
	archive_strcpy(&as, "gzip");

	/* Specify compression level. */
	if (data->compression_level > 0) {
	archive_strcat(&as, " -");
	archive_strappend_char(&as, '0' + data->compression_level);
	}
	if (data->timestamp < 0)
	/* Do not save timestamp. */
	archive_strcat(&as, " -n");
	else if (data->timestamp > 0)
	/* Save timestamp. */
	archive_strcat(&as, " -N");

	f->write = archive_compressor_gzip_write;
	r = __archive_write_program_open(f, data->pdata, as.s);
	archive_string_free(&as);
	return (r);
	}

	static int
	archive_compressor_gzip_write(struct archive_write_filter f, const void buff,
	size_t length)
	{
	struct private_data data = (struct private_data )f->data;

	return __archive_write_program_write(f, data->pdata, buff, length);
	}

	static int
	archive_compressor_gzip_close(struct archive_write_filter *f)
	{
	struct private_data data = (struct private_data )f->data;

	return __archive_write_program_close(f, data->pdata);
	}

	#endif /* HAVE_ZLIB_H */