/ext/zlib/zlib.c

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/*
 * zlib.c - An interface for zlib.
 *
 *   Copyright (C) UENO Katsuhiro 2000-2003
 *
 * $Id$
 */

#include <ruby.h>
#include <zlib.h>
#include <time.h>
#include <ruby/io.h>
#include <ruby/thread.h>

#ifdef HAVE_VALGRIND_MEMCHECK_H
# include <valgrind/memcheck.h>
# ifndef VALGRIND_MAKE_MEM_DEFINED
#  define VALGRIND_MAKE_MEM_DEFINED(p, n) VALGRIND_MAKE_READABLE((p), (n))
# endif
# ifndef VALGRIND_MAKE_MEM_UNDEFINED
#  define VALGRIND_MAKE_MEM_UNDEFINED(p, n) VALGRIND_MAKE_WRITABLE((p), (n))
# endif
#else
# define VALGRIND_MAKE_MEM_DEFINED(p, n) 0
# define VALGRIND_MAKE_MEM_UNDEFINED(p, n) 0
#endif

#define RUBY_ZLIB_VERSION "1.1.0"

#ifndef RB_PASS_CALLED_KEYWORDS
# define rb_class_new_instance_kw(argc, argv, klass, kw_splat) rb_class_new_instance(argc, argv, klass)
#endif

#ifndef GZIP_SUPPORT
#define GZIP_SUPPORT  1
#endif

/* from zutil.h */
#ifndef DEF_MEM_LEVEL
#if MAX_MEM_LEVEL >= 8
#define DEF_MEM_LEVEL  8
#else
#define DEF_MEM_LEVEL  MAX_MEM_LEVEL
#endif
#endif

#if SIZEOF_LONG > SIZEOF_INT
static inline uInt
max_uint(long n)
{
    if (n > UINT_MAX) n = UINT_MAX;
    return (uInt)n;
}
#define MAX_UINT(n) max_uint(n)
#else
#define MAX_UINT(n) (uInt)(n)
#endif

#define OPTHASH_GIVEN_P(opts) \
    (argc > 0 && !NIL_P((opts) = rb_check_hash_type(argv[argc-1])) && (--argc, 1))

static ID id_dictionaries, id_read, id_buffer;

/*--------- Prototypes --------*/

static NORETURN(void raise_zlib_error(int, const char*));
static VALUE rb_zlib_version(VALUE);
static VALUE do_checksum(int, VALUE*, uLong (*)(uLong, const Bytef*, uInt));
static VALUE rb_zlib_adler32(int, VALUE*, VALUE);
static VALUE rb_zlib_crc32(int, VALUE*, VALUE);
static VALUE rb_zlib_crc_table(VALUE);
static voidpf zlib_mem_alloc(voidpf, uInt, uInt);
static void zlib_mem_free(voidpf, voidpf);
static void finalizer_warn(const char*);

struct zstream;
struct zstream_funcs;
struct zstream_run_args;
static void zstream_init(struct zstream*, const struct zstream_funcs*);
static void zstream_expand_buffer(struct zstream*);
static void zstream_expand_buffer_into(struct zstream*, unsigned long);
static int zstream_expand_buffer_non_stream(struct zstream *z);
static void zstream_append_buffer(struct zstream*, const Bytef*, long);
static VALUE zstream_detach_buffer(struct zstream*);
static VALUE zstream_shift_buffer(struct zstream*, long);
static void zstream_buffer_ungets(struct zstream*, const Bytef*, unsigned long);
static void zstream_buffer_ungetbyte(struct zstream*, int);
static void zstream_append_input(struct zstream*, const Bytef*, long);
static void zstream_discard_input(struct zstream*, long);
static void zstream_reset_input(struct zstream*);
static void zstream_passthrough_input(struct zstream*);
static VALUE zstream_detach_input(struct zstream*);
static void zstream_reset(struct zstream*);
static VALUE zstream_end(struct zstream*);
static VALUE zstream_ensure_end(VALUE v);
static void zstream_run(struct zstream*, Bytef*, long, int);
static VALUE zstream_sync(struct zstream*, Bytef*, long);
static void zstream_mark(void*);
static void zstream_free(void*);
static VALUE zstream_new(VALUE, const struct zstream_funcs*);
static struct zstream *get_zstream(VALUE);
static void zstream_finalize(struct zstream*);

static VALUE rb_zstream_end(VALUE);
static VALUE rb_zstream_reset(VALUE);
static VALUE rb_zstream_finish(VALUE);
static VALUE rb_zstream_flush_next_in(VALUE);
static VALUE rb_zstream_flush_next_out(VALUE);
static VALUE rb_zstream_avail_out(VALUE);
static VALUE rb_zstream_set_avail_out(VALUE, VALUE);
static VALUE rb_zstream_avail_in(VALUE);
static VALUE rb_zstream_total_in(VALUE);
static VALUE rb_zstream_total_out(VALUE);
static VALUE rb_zstream_data_type(VALUE);
static VALUE rb_zstream_adler(VALUE);
static VALUE rb_zstream_finished_p(VALUE);
static VALUE rb_zstream_closed_p(VALUE);

static VALUE rb_deflate_s_allocate(VALUE);
static VALUE rb_deflate_initialize(int, VALUE*, VALUE);
static VALUE rb_deflate_init_copy(VALUE, VALUE);
static VALUE deflate_run(VALUE);
static VALUE rb_deflate_s_deflate(int, VALUE*, VALUE);
static void do_deflate(struct zstream*, VALUE, int);
static VALUE rb_deflate_deflate(int, VALUE*, VALUE);
static VALUE rb_deflate_addstr(VALUE, VALUE);
static VALUE rb_deflate_flush(int, VALUE*, VALUE);
static VALUE rb_deflate_params(VALUE, VALUE, VALUE);
static VALUE rb_deflate_set_dictionary(VALUE, VALUE);

static VALUE inflate_run(VALUE);
static VALUE rb_inflate_s_allocate(VALUE);
static VALUE rb_inflate_initialize(int, VALUE*, VALUE);
static VALUE rb_inflate_s_inflate(VALUE, VALUE);
static void do_inflate(struct zstream*, VALUE);
static VALUE rb_inflate_inflate(int, VALUE*, VALUE);
static VALUE rb_inflate_addstr(VALUE, VALUE);
static VALUE rb_inflate_sync(VALUE, VALUE);
static VALUE rb_inflate_sync_point_p(VALUE);
static VALUE rb_inflate_set_dictionary(VALUE, VALUE);

#if GZIP_SUPPORT
struct gzfile;
static void gzfile_mark(void*);
static void gzfile_free(void*);
static VALUE gzfile_new(VALUE, const struct zstream_funcs*, void (*) _((struct gzfile*)));
static void gzfile_reset(struct gzfile*);
static void gzfile_close(struct gzfile*, int);
static void gzfile_write_raw(struct gzfile*);
static VALUE gzfile_read_raw_partial(VALUE);
static VALUE gzfile_read_raw_rescue(VALUE,VALUE);
static VALUE gzfile_read_raw(struct gzfile*, VALUE outbuf);
static int gzfile_read_raw_ensure(struct gzfile*, long, VALUE outbuf);
static char *gzfile_read_raw_until_zero(struct gzfile*, long);
static unsigned int gzfile_get16(const unsigned char*);
static unsigned long gzfile_get32(const unsigned char*);
static void gzfile_set32(unsigned long n, unsigned char*);
static void gzfile_make_header(struct gzfile*);
static void gzfile_make_footer(struct gzfile*);
static void gzfile_read_header(struct gzfile*, VALUE outbuf);
static void gzfile_check_footer(struct gzfile*, VALUE outbuf);
static void gzfile_write(struct gzfile*, Bytef*, long);
static long gzfile_read_more(struct gzfile*, VALUE outbuf);
static void gzfile_calc_crc(struct gzfile*, VALUE);
static VALUE gzfile_read(struct gzfile*, long);
static VALUE gzfile_read_all(struct gzfile*);
static void gzfile_ungets(struct gzfile*, const Bytef*, long);
static void gzfile_ungetbyte(struct gzfile*, int);
static VALUE gzfile_writer_end_run(VALUE);
static void gzfile_writer_end(struct gzfile*);
static VALUE gzfile_reader_end_run(VALUE);
static void gzfile_reader_end(struct gzfile*);
static void gzfile_reader_rewind(struct gzfile*);
static VALUE gzfile_reader_get_unused(struct gzfile*);
static struct gzfile *get_gzfile(VALUE);
static VALUE gzfile_ensure_close(VALUE);
static VALUE rb_gzfile_s_wrap(int, VALUE*, VALUE);
static VALUE gzfile_s_open(int, VALUE*, VALUE, const char*);
NORETURN(static void gzfile_raise(struct gzfile *, VALUE, const char *));
static VALUE gzfile_error_inspect(VALUE);

static VALUE rb_gzfile_to_io(VALUE);
static VALUE rb_gzfile_crc(VALUE);
static VALUE rb_gzfile_mtime(VALUE);
static VALUE rb_gzfile_level(VALUE);
static VALUE rb_gzfile_os_code(VALUE);
static VALUE rb_gzfile_orig_name(VALUE);
static VALUE rb_gzfile_comment(VALUE);
static VALUE rb_gzfile_lineno(VALUE);
static VALUE rb_gzfile_set_lineno(VALUE, VALUE);
static VALUE rb_gzfile_set_mtime(VALUE, VALUE);
static VALUE rb_gzfile_set_orig_name(VALUE, VALUE);
static VALUE rb_gzfile_set_comment(VALUE, VALUE);
static VALUE rb_gzfile_close(VALUE);
static VALUE rb_gzfile_finish(VALUE);
static VALUE rb_gzfile_closed_p(VALUE);
static VALUE rb_gzfile_eof_p(VALUE);
static VALUE rb_gzfile_sync(VALUE);
static VALUE rb_gzfile_set_sync(VALUE, VALUE);
static VALUE rb_gzfile_total_in(VALUE);
static VALUE rb_gzfile_total_out(VALUE);
static VALUE rb_gzfile_path(VALUE);

static VALUE rb_gzwriter_s_allocate(VALUE);
static VALUE rb_gzwriter_s_open(int, VALUE*, VALUE);
static VALUE rb_gzwriter_initialize(int, VALUE*, VALUE);
static VALUE rb_gzwriter_flush(int, VALUE*, VALUE);
static VALUE rb_gzwriter_write(int, VALUE*, VALUE);
static VALUE rb_gzwriter_putc(VALUE, VALUE);

static VALUE rb_gzreader_s_allocate(VALUE);
static VALUE rb_gzreader_s_open(int, VALUE*, VALUE);
static VALUE rb_gzreader_initialize(int, VALUE*, VALUE);
static VALUE rb_gzreader_rewind(VALUE);
static VALUE rb_gzreader_unused(VALUE);
static VALUE rb_gzreader_read(int, VALUE*, VALUE);
static VALUE rb_gzreader_getc(VALUE);
static VALUE rb_gzreader_readchar(VALUE);
static VALUE rb_gzreader_each_byte(VALUE);
static VALUE rb_gzreader_ungetc(VALUE, VALUE);
static VALUE rb_gzreader_ungetbyte(VALUE, VALUE);
static void gzreader_skip_linebreaks(struct gzfile*);
static VALUE gzreader_gets(int, VALUE*, VALUE);
static VALUE rb_gzreader_gets(int, VALUE*, VALUE);
static VALUE rb_gzreader_readline(int, VALUE*, VALUE);
static VALUE rb_gzreader_each(int, VALUE*, VALUE);
static VALUE rb_gzreader_readlines(int, VALUE*, VALUE);
#endif /* GZIP_SUPPORT */

/*
 * Document-module: Zlib
 *
 * This module provides access to the {zlib library}[http://zlib.net]. Zlib is
 * designed to be a portable, free, general-purpose, legally unencumbered --
 * that is, not covered by any patents -- lossless data-compression library
 * for use on virtually any computer hardware and operating system.
 *
 * The zlib compression library provides in-memory compression and
 * decompression functions, including integrity checks of the uncompressed
 * data.
 *
 * The zlib compressed data format is described in RFC 1950, which is a
 * wrapper around a deflate stream which is described in RFC 1951.
 *
 * The library also supports reading and writing files in gzip (.gz) format
 * with an interface similar to that of IO. The gzip format is described in
 * RFC 1952 which is also a wrapper around a deflate stream.
 *
 * The zlib format was designed to be compact and fast for use in memory and on
 * communications channels. The gzip format was designed for single-file
 * compression on file systems, has a larger header than zlib to maintain
 * directory information, and uses a different, slower check method than zlib.
 *
 * See your system's zlib.h for further information about zlib
 *
 * == Sample usage
 *
 * Using the wrapper to compress strings with default parameters is quite
 * simple:
 *
 *   require "zlib"
 *
 *   data_to_compress = File.read("don_quixote.txt")
 *
 *   puts "Input size: #{data_to_compress.size}"
 *   #=> Input size: 2347740
 *
 *   data_compressed = Zlib::Deflate.deflate(data_to_compress)
 *
 *   puts "Compressed size: #{data_compressed.size}"
 *   #=> Compressed size: 887238
 *
 *   uncompressed_data = Zlib::Inflate.inflate(data_compressed)
 *
 *   puts "Uncompressed data is: #{uncompressed_data}"
 *   #=> Uncompressed data is: The Project Gutenberg EBook of Don Quixote...
 *
 * == Class tree
 *
 * - Zlib::Deflate
 * - Zlib::Inflate
 * - Zlib::ZStream
 * - Zlib::Error
 *   - Zlib::StreamEnd
 *   - Zlib::NeedDict
 *   - Zlib::DataError
 *   - Zlib::StreamError
 *   - Zlib::MemError
 *   - Zlib::BufError
 *   - Zlib::VersionError
 *
 * (if you have GZIP_SUPPORT)
 * - Zlib::GzipReader
 * - Zlib::GzipWriter
 * - Zlib::GzipFile
 * - Zlib::GzipFile::Error
 *   - Zlib::GzipFile::LengthError
 *   - Zlib::GzipFile::CRCError
 *   - Zlib::GzipFile::NoFooter
 *
 */
void Init_zlib(void);

/*--------- Exceptions --------*/

static VALUE cZError, cStreamEnd, cNeedDict;
static VALUE cStreamError, cDataError, cMemError, cBufError, cVersionError;

static void
raise_zlib_error(int err, const char *msg)
{
    VALUE exc;

    if (!msg) {
	msg = zError(err);
    }

    switch(err) {
      case Z_STREAM_END:
	exc = rb_exc_new2(cStreamEnd, msg);
	break;
      case Z_NEED_DICT:
	exc = rb_exc_new2(cNeedDict, msg);
	break;
      case Z_STREAM_ERROR:
	exc = rb_exc_new2(cStreamError, msg);
	break;
      case Z_DATA_ERROR:
	exc = rb_exc_new2(cDataError, msg);
	break;
      case Z_BUF_ERROR:
	exc = rb_exc_new2(cBufError, msg);
	break;
      case Z_VERSION_ERROR:
	exc = rb_exc_new2(cVersionError, msg);
	break;
      case Z_MEM_ERROR:
	exc = rb_exc_new2(cMemError, msg);
	break;
      case Z_ERRNO:
	rb_sys_fail(msg);
	/* no return */
      default:
	exc = rb_exc_new_str(cZError,
			     rb_sprintf("unknown zlib error %d: %s", err, msg));
    }

    rb_exc_raise(exc);
}


/*--- Warning (in finalizer) ---*/

static void
finalizer_warn(const char *msg)
{
#if 0
    fprintf(stderr, "zlib(finalizer): %s\n", msg);
#endif
}


/*-------- module Zlib --------*/

/*
 * Document-method: Zlib.zlib_version
 *
 * Returns the string which represents the version of zlib library.
 */
static VALUE
rb_zlib_version(VALUE klass)
{
    return rb_str_new2(zlibVersion());
}

#if SIZEOF_LONG > SIZEOF_INT
static uLong
checksum_long(uLong (*func)(uLong, const Bytef*, uInt), uLong sum, const Bytef *ptr, long len)
{
    if (len > UINT_MAX) {
	do {
	    sum = func(sum, ptr, UINT_MAX);
	    ptr += UINT_MAX;
	    len -= UINT_MAX;
	} while (len >= UINT_MAX);
    }
    if (len > 0) sum = func(sum, ptr, (uInt)len);
    return sum;
}
#else
#define checksum_long(func, sum, ptr, len) (func)((sum), (ptr), (len))
#endif

static VALUE
do_checksum(int argc, VALUE *argv, uLong (*func)(uLong, const Bytef*, uInt))
{
    VALUE str, vsum;
    unsigned long sum;

    rb_scan_args(argc, argv, "02", &str, &vsum);

    if (!NIL_P(vsum)) {
	sum = NUM2ULONG(vsum);
    }
    else if (NIL_P(str)) {
	sum = 0;
    }
    else {
	sum = func(0, Z_NULL, 0);
    }

    if (NIL_P(str)) {
	sum = func(sum, Z_NULL, 0);
    }
    else if (rb_obj_is_kind_of(str, rb_cIO)) {
        VALUE buf;
        VALUE buflen = INT2NUM(8192);

        while (!NIL_P(buf = rb_funcall(str, id_read, 1, buflen))) {
            StringValue(buf);
            sum = checksum_long(func, sum, (Bytef*)RSTRING_PTR(buf), RSTRING_LEN(buf));
        }
    }
    else {
	StringValue(str);
	sum = checksum_long(func, sum, (Bytef*)RSTRING_PTR(str), RSTRING_LEN(str));
    }
    return rb_uint2inum(sum);
}

/*
 * Document-method: Zlib.adler32
 *
 * call-seq: Zlib.adler32(string, adler)
 *
 * Calculates Adler-32 checksum for +string+, and returns updated value of
 * +adler+. If +string+ is omitted, it returns the Adler-32 initial value. If
 * +adler+ is omitted, it assumes that the initial value is given to +adler+.
 * If +string+ is an IO instance, reads from the IO until the IO returns nil
 * and returns Adler-32 of all read data.
 *
 * Example usage:
 *
 *   require "zlib"
 *
 *   data = "foo"
 *   puts "Adler32 checksum: #{Zlib.adler32(data).to_s(16)}"
 *   #=> Adler32 checksum: 2820145
 *
 */
static VALUE
rb_zlib_adler32(int argc, VALUE *argv, VALUE klass)
{
    return do_checksum(argc, argv, adler32);
}

#ifdef HAVE_ADLER32_COMBINE
/*
 * Document-method: Zlib.adler32_combine
 *
 * call-seq: Zlib.adler32_combine(adler1, adler2, len2)
 *
 * Combine two Adler-32 check values in to one.  +alder1+ is the first Adler-32
 * value, +adler2+ is the second Adler-32 value.  +len2+ is the length of the
 * string used to generate +adler2+.
 *
 */
static VALUE
rb_zlib_adler32_combine(VALUE klass, VALUE adler1, VALUE adler2, VALUE len2)
{
    return ULONG2NUM(
	adler32_combine(NUM2ULONG(adler1), NUM2ULONG(adler2), NUM2LONG(len2)));
}
#else
#define rb_zlib_adler32_combine rb_f_notimplement
#endif

/*
 * Document-method: Zlib.crc32
 *
 * call-seq: Zlib.crc32(string, crc)
 *
 * Calculates CRC checksum for +string+, and returns updated value of +crc+. If
 * +string+ is omitted, it returns the CRC initial value. If +crc+ is omitted, it
 * assumes that the initial value is given to +crc+. If +string+ is an IO instance,
 * reads from the IO until the IO returns nil and returns CRC checksum of all read
 * data.
 *
 * FIXME: expression.
 */
static VALUE
rb_zlib_crc32(int argc, VALUE *argv, VALUE klass)
{
    return do_checksum(argc, argv, crc32);
}

#ifdef HAVE_CRC32_COMBINE
/*
 * Document-method: Zlib.crc32_combine
 *
 * call-seq: Zlib.crc32_combine(crc1, crc2, len2)
 *
 * Combine two CRC-32 check values in to one.  +crc1+ is the first CRC-32
 * value, +crc2+ is the second CRC-32 value.  +len2+ is the length of the
 * string used to generate +crc2+.
 *
 */
static VALUE
rb_zlib_crc32_combine(VALUE klass, VALUE crc1, VALUE crc2, VALUE len2)
{
    return ULONG2NUM(
	crc32_combine(NUM2ULONG(crc1), NUM2ULONG(crc2), NUM2LONG(len2)));
}
#else
#define rb_zlib_crc32_combine rb_f_notimplement
#endif

/*
 * Document-method: Zlib.crc_table
 *
 * Returns the table for calculating CRC checksum as an array.
 */
static VALUE
rb_zlib_crc_table(VALUE obj)
{
#if !defined(HAVE_TYPE_Z_CRC_T)
    /* z_crc_t is defined since zlib-1.2.7. */
    typedef unsigned long z_crc_t;
#endif
    const z_crc_t *crctbl;
    VALUE dst;
    int i;

    crctbl = get_crc_table();
    dst = rb_ary_new2(256);

    for (i = 0; i < 256; i++) {
	rb_ary_push(dst, rb_uint2inum(crctbl[i]));
    }
    return dst;
}



/*-------- zstream - internal APIs --------*/

struct zstream {
    unsigned long flags;
    VALUE buf;
    VALUE input;
    VALUE mutex;
    z_stream stream;
    const struct zstream_funcs {
	int (*reset)(z_streamp);
	int (*end)(z_streamp);
	int (*run)(z_streamp, int);
    } *func;
};

#define ZSTREAM_FLAG_READY      0x1
#define ZSTREAM_FLAG_IN_STREAM  0x2
#define ZSTREAM_FLAG_FINISHED   0x4
#define ZSTREAM_FLAG_CLOSING    0x8
#define ZSTREAM_FLAG_GZFILE     0x10 /* disallows yield from expand_buffer for
                                        gzip*/
#define ZSTREAM_REUSE_BUFFER    0x20
#define ZSTREAM_FLAG_UNUSED     0x40

#define ZSTREAM_READY(z)       ((z)->flags |= ZSTREAM_FLAG_READY)
#define ZSTREAM_IS_READY(z)    ((z)->flags & ZSTREAM_FLAG_READY)
#define ZSTREAM_IS_FINISHED(z) ((z)->flags & ZSTREAM_FLAG_FINISHED)
#define ZSTREAM_IS_CLOSING(z)  ((z)->flags & ZSTREAM_FLAG_CLOSING)
#define ZSTREAM_IS_GZFILE(z)   ((z)->flags & ZSTREAM_FLAG_GZFILE)
#define ZSTREAM_BUF_FILLED(z)  (NIL_P((z)->buf) ? 0 : RSTRING_LEN((z)->buf))

#define ZSTREAM_REUSE_BUFFER_P(z)     ((z)->flags & ZSTREAM_REUSE_BUFFER)

#define ZSTREAM_EXPAND_BUFFER_OK          0

/* I think that more better value should be found,
   but I gave up finding it. B) */
#define ZSTREAM_INITIAL_BUFSIZE       1024
/* Allow a quick return when the thread is interrupted */
#define ZSTREAM_AVAIL_OUT_STEP_MAX   16384
#define ZSTREAM_AVAIL_OUT_STEP_MIN    2048

static const struct zstream_funcs deflate_funcs = {
    deflateReset, deflateEnd, deflate,
};

static const struct zstream_funcs inflate_funcs = {
    inflateReset, inflateEnd, inflate,
};

struct zstream_run_args {
    struct zstream * z;
    int flush;         /* stream flush value for inflate() or deflate() */
    int interrupt;     /* stop processing the stream and return to ruby */
    int jump_state;    /* for buffer expansion block break or exception */
    int stream_output; /* for streaming zlib processing */
};

static voidpf
zlib_mem_alloc(voidpf opaque, uInt items, uInt size)
{
    voidpf p = xmalloc2(items, size);
    /* zlib FAQ: Valgrind (or some similar memory access checker) says that
       deflate is performing a conditional jump that depends on an
       uninitialized value.  Isn't that a bug?
       http://www.zlib.net/zlib_faq.html#faq36 */
    (void)VALGRIND_MAKE_MEM_DEFINED(p, items * size);
    return p;
}

static void
zlib_mem_free(voidpf opaque, voidpf address)
{
    xfree(address);
}

static void
zstream_init(struct zstream *z, const struct zstream_funcs *func)
{
    z->flags = 0;
    z->buf = Qnil;
    z->input = Qnil;
    z->mutex = rb_mutex_new();
    z->stream.zalloc = zlib_mem_alloc;
    z->stream.zfree = zlib_mem_free;
    z->stream.opaque = Z_NULL;
    z->stream.msg = Z_NULL;
    z->stream.next_in = Z_NULL;
    z->stream.avail_in = 0;
    z->stream.next_out = Z_NULL;
    z->stream.avail_out = 0;
    z->func = func;
}

#define zstream_init_deflate(z)   zstream_init((z), &deflate_funcs)
#define zstream_init_inflate(z)   zstream_init((z), &inflate_funcs)

static void
zstream_expand_buffer(struct zstream *z)
{
    if (NIL_P(z->buf)) {
	zstream_expand_buffer_into(z, ZSTREAM_INITIAL_BUFSIZE);
	return;
    }

    if (!ZSTREAM_IS_GZFILE(z) && rb_block_given_p()) {
	long buf_filled = ZSTREAM_BUF_FILLED(z);
	if (buf_filled >= ZSTREAM_AVAIL_OUT_STEP_MAX) {
	    int state = 0;

            if (!ZSTREAM_REUSE_BUFFER_P(z)) {
	        rb_obj_reveal(z->buf, rb_cString);
            }

            rb_mutex_unlock(z->mutex);
	    rb_protect(rb_yield, z->buf, &state);
            rb_mutex_lock(z->mutex);

            if (ZSTREAM_REUSE_BUFFER_P(z)) {
                rb_str_modify(z->buf);
                rb_str_set_len(z->buf, 0);
            }
            else {
                z->buf = Qnil;
            }
	    zstream_expand_buffer_into(z, ZSTREAM_AVAIL_OUT_STEP_MAX);

	    if (state)
		rb_jump_tag(state);

	    return;
	}
	else {
	    zstream_expand_buffer_into(z,
				       ZSTREAM_AVAIL_OUT_STEP_MAX - buf_filled);
	}
    }
    else {
	zstream_expand_buffer_non_stream(z);
    }
}

static void
zstream_expand_buffer_into(struct zstream *z, unsigned long size)
{
    if (NIL_P(z->buf)) {
	/* I uses rb_str_new here not rb_str_buf_new because
	   rb_str_buf_new makes a zero-length string. */
	z->buf = rb_str_buf_new(size);
	z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf);
	z->stream.avail_out = MAX_UINT(size);
	rb_obj_hide(z->buf);
    }
    else if (z->stream.avail_out != size) {
	rb_str_modify_expand(z->buf, size);
	z->stream.next_out = (Bytef*)RSTRING_END(z->buf);
	z->stream.avail_out = MAX_UINT(size);
    }
}

static void *
zstream_expand_buffer_protect(void *ptr)
{
    struct zstream *z = (struct zstream *)ptr;
    int state = 0;

    rb_protect((VALUE (*)(VALUE))zstream_expand_buffer, (VALUE)z, &state);

    return (void *)(VALUE)state;
}

static int
zstream_expand_buffer_non_stream(struct zstream *z)
{
    long inc, len = ZSTREAM_BUF_FILLED(z);

    if (rb_str_capacity(z->buf) - len >= ZSTREAM_AVAIL_OUT_STEP_MAX) {
	z->stream.avail_out = ZSTREAM_AVAIL_OUT_STEP_MAX;
    }
    else {
	inc = len / 2;
	if (inc < ZSTREAM_AVAIL_OUT_STEP_MIN) {
	    inc = ZSTREAM_AVAIL_OUT_STEP_MIN;
	}

	rb_str_modify_expand(z->buf, inc);
	z->stream.avail_out = (inc < ZSTREAM_AVAIL_OUT_STEP_MAX) ?
	    (int)inc : ZSTREAM_AVAIL_OUT_STEP_MAX;
    }
    z->stream.next_out = (Bytef*)RSTRING_END(z->buf);

    return ZSTREAM_EXPAND_BUFFER_OK;
}

static void
zstream_append_buffer(struct zstream *z, const Bytef *src, long len)
{
    if (NIL_P(z->buf)) {
	z->buf = rb_str_buf_new(len);
	rb_str_buf_cat(z->buf, (const char*)src, len);
	z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf);
	z->stream.avail_out = 0;
	rb_obj_hide(z->buf);
	return;
    }

    if ((long)rb_str_capacity(z->buf) < ZSTREAM_BUF_FILLED(z) + len) {
	rb_str_modify_expand(z->buf, len);
	z->stream.avail_out = 0;
    }
    else {
	if (z->stream.avail_out >= (uInt)len) {
	    z->stream.avail_out -= (uInt)len;
	}
	else {
	    z->stream.avail_out = 0;
	}
    }
    rb_str_cat(z->buf, (const char *)src, len);
    z->stream.next_out = (Bytef*)RSTRING_END(z->buf);
}

#define zstream_append_buffer2(z,v) \
    zstream_append_buffer((z),(Bytef*)RSTRING_PTR(v),RSTRING_LEN(v))

static VALUE
zstream_detach_buffer(struct zstream *z)
{
    VALUE dst;

    if (!ZSTREAM_IS_FINISHED(z) && !ZSTREAM_IS_GZFILE(z) &&
	    rb_block_given_p()) {
	/* prevent tiny yields mid-stream, save for next
	 * zstream_expand_buffer() or stream end */
	return Qnil;
    }

    if (NIL_P(z->buf)) {
	dst = rb_str_new(0, 0);
    }
    else {
	dst = z->buf;
        if (!ZSTREAM_REUSE_BUFFER_P(z)) {
	    rb_obj_reveal(dst, rb_cString);
        }
    }

    z->buf = Qnil;
    z->stream.next_out = 0;
    z->stream.avail_out = 0;

    if (!ZSTREAM_IS_GZFILE(z) && rb_block_given_p()) {
	rb_yield(dst);
	dst = Qnil;
    }

    return dst;
}

static VALUE
zstream_shift_buffer(struct zstream *z, long len)
{
    VALUE dst;
    char *bufptr;
    long buflen = ZSTREAM_BUF_FILLED(z);

    if (buflen <= len) {
	return zstream_detach_buffer(z);
    }

    bufptr = RSTRING_PTR(z->buf);
    dst = rb_str_new(bufptr, len);
    buflen -= len;
    memmove(bufptr, bufptr + len, buflen);
    rb_str_set_len(z->buf, buflen);
    z->stream.next_out = (Bytef*)RSTRING_END(z->buf);
    buflen = (long)rb_str_capacity(z->buf) - ZSTREAM_BUF_FILLED(z);
    if (buflen > ZSTREAM_AVAIL_OUT_STEP_MAX) {
	buflen = ZSTREAM_AVAIL_OUT_STEP_MAX;
    }
    z->stream.avail_out = (uInt)buflen;

    return dst;
}

static void
zstream_buffer_ungets(struct zstream *z, const Bytef *b, unsigned long len)
{
    char *bufptr;
    long filled;

    if (NIL_P(z->buf) || (long)rb_str_capacity(z->buf) <= ZSTREAM_BUF_FILLED(z)) {
	zstream_expand_buffer_into(z, len);
    }

    RSTRING_GETMEM(z->buf, bufptr, filled);
    memmove(bufptr + len, bufptr, filled);
    memmove(bufptr, b, len);
    rb_str_set_len(z->buf, filled + len);
    if (z->stream.avail_out > 0) {
	if (len > z->stream.avail_out) len = z->stream.avail_out;
	z->stream.next_out+=len;
	z->stream.avail_out-=(uInt)len;
    }
}

static void
zstream_buffer_ungetbyte(struct zstream *z, int c)
{
    Bytef cc = (Bytef)c;
    zstream_buffer_ungets(z, &cc, 1);
}

static void
zstream_append_input(struct zstream *z, const Bytef *src, long len)
{
    if (len <= 0) return;

    if (NIL_P(z->input)) {
	z->input = rb_str_buf_new(len);
	rb_str_buf_cat(z->input, (const char*)src, len);
	rb_obj_hide(z->input);
    }
    else {
	rb_str_buf_cat(z->input, (const char*)src, len);
    }
}

#define zstream_append_input2(z,v)\
    RB_GC_GUARD(v),\
    zstream_append_input((z), (Bytef*)RSTRING_PTR(v), RSTRING_LEN(v))

static void
zstream_discard_input(struct zstream *z, long len)
{
    if (NIL_P(z->input)) {
    }
    else if (RBASIC_CLASS(z->input) == 0) {
	/* hidden, we created z->input and have complete control */
	char *ptr;
	long oldlen, newlen;

	RSTRING_GETMEM(z->input, ptr, oldlen);
	newlen = oldlen - len;
	if (newlen > 0) {
	    memmove(ptr, ptr + len, newlen);
	}
	if (newlen < 0) {
	    newlen = 0;
	}
	rb_str_resize(z->input, newlen);
	if (newlen == 0) {
	    rb_gc_force_recycle(z->input);
	    z->input = Qnil;
	}
	else {
	    rb_str_set_len(z->input, newlen);
	}
    }
    else { /* do not mangle user-provided data */
	if (RSTRING_LEN(z->input) <= len) {
	    z->input = Qnil;
	}
	else {
	    z->input = rb_str_substr(z->input, len,
				     RSTRING_LEN(z->input) - len);
	}
    }
}

static void
zstream_reset_input(struct zstream *z)
{
    if (!NIL_P(z->input) && RBASIC_CLASS(z->input) == 0) {
	rb_str_resize(z->input, 0);
    }
    else {
	z->input = Qnil;
    }
}

static void
zstream_passthrough_input(struct zstream *z)
{
    if (!NIL_P(z->input)) {
	zstream_append_buffer2(z, z->input);
	z->input = Qnil;
    }
}

static VALUE
zstream_detach_input(struct zstream *z)
{
    VALUE dst;

    if (NIL_P(z->input)) {
	dst = rb_str_new(0, 0);
    }
    else {
	dst = z->input;
	rb_obj_reveal(dst, rb_cString);
    }
    z->input = Qnil;
    return dst;
}

static void
zstream_reset(struct zstream *z)
{
    int err;

    err = z->func->reset(&z->stream);
    if (err != Z_OK) {
	raise_zlib_error(err, z->stream.msg);
    }
    z->flags = ZSTREAM_FLAG_READY;
    z->buf = Qnil;
    z->stream.next_out = 0;
    z->stream.avail_out = 0;
    zstream_reset_input(z);
}

static VALUE
zstream_end(struct zstream *z)
{
    int err;

    if (!ZSTREAM_IS_READY(z)) {
	rb_warning("attempt to close uninitialized zstream; ignored.");
	return Qnil;
    }
    if (z->flags & ZSTREAM_FLAG_IN_STREAM) {
	rb_warning("attempt to close unfinished zstream; reset forced.");
	zstream_reset(z);
    }

    zstream_reset_input(z);
    err = z->func->end(&z->stream);
    if (err != Z_OK) {
	raise_zlib_error(err, z->stream.msg);
    }
    z->flags = 0;
    return Qnil;
}

static VALUE
zstream_ensure_end(VALUE v)
{
    return zstream_end((struct zstream *)v);
}

static void *
zstream_run_func(void *ptr)
{
    struct zstream_run_args *args = (struct zstream_run_args *)ptr;
    int err, state, flush = args->flush;
    struct zstream *z = args->z;
    uInt n;

    err = Z_OK;
    while (!args->interrupt) {
	n = z->stream.avail_out;
	err = z->func->run(&z->stream, flush);
	rb_str_set_len(z->buf, ZSTREAM_BUF_FILLED(z) + (n - z->stream.avail_out));

	if (err == Z_STREAM_END) {
	    z->flags &= ~ZSTREAM_FLAG_IN_STREAM;
	    z->flags |= ZSTREAM_FLAG_FINISHED;
	    break;
	}

	if (err != Z_OK && err != Z_BUF_ERROR)
	    break;

	if (z->stream.avail_out > 0) {
	    z->flags |= ZSTREAM_FLAG_IN_STREAM;
	    break;
	}

	if (z->stream.avail_in == 0 && z->func == &inflate_funcs) {
	    /* break here because inflate() return Z_BUF_ERROR when avail_in == 0. */
	    /* but deflate() could be called with avail_in == 0 (there's hidden buffer
	       in zstream->state) */
	    z->flags |= ZSTREAM_FLAG_IN_STREAM;
	    break;
	}

	if (args->stream_output) {
	    state = (int)(VALUE)rb_thread_call_with_gvl(zstream_expand_buffer_protect,
							(void *)z);
	}
	else {
	    state = zstream_expand_buffer_non_stream(z);
	}

	if (state) {
	    err = Z_OK; /* buffer expanded but stream processing was stopped */
	    args->jump_state = state;
	    break;
	}
    }

    return (void *)(VALUE)err;
}

/*
 * There is no safe way to interrupt z->run->func().
 * async-signal-safe
 */
static void
zstream_unblock_func(void *ptr)
{
    struct zstream_run_args *args = (struct zstream_run_args *)ptr;

    args->interrupt = 1;
}

static void
zstream_run0(struct zstream *z, Bytef *src, long len, int flush)
{
    struct zstream_run_args args;
    int err;
    VALUE old_input = Qnil;

    args.z = z;
    args.flush = flush;
    args.interrupt = 0;
    args.jump_state = 0;
    args.stream_output = !ZSTREAM_IS_GZFILE(z) && rb_block_given_p();

    if (NIL_P(z->input) && len == 0) {
	z->stream.next_in = (Bytef*)"";
	z->stream.avail_in = 0;
    }
    else {
	zstream_append_input(z, src, len);
	/* keep reference to `z->input' so as not to be garbage collected
	   after zstream_reset_input() and prevent `z->stream.next_in'
	   from dangling. */
	old_input = zstream_detach_input(z);
	rb_obj_hide(old_input); /* for GVL release and later recycle */
	z->stream.next_in = (Bytef*)RSTRING_PTR(old_input);
	z->stream.avail_in = MAX_UINT(RSTRING_LEN(old_input));
    }

    if (z->stream.avail_out == 0) {
	zstream_expand_buffer(z);
    }

loop:
#ifndef RB_NOGVL_UBF_ASYNC_SAFE
    err = (int)(VALUE)rb_thread_call_without_gvl(zstream_run_func, (void *)&args,
						 zstream_unblock_func, (void *)&args);
#else
    err = (int)(VALUE)rb_nogvl(zstream_run_func, (void *)&args,
                               zstream_unblock_func, (void *)&args,
                               RB_NOGVL_UBF_ASYNC_SAFE);
#endif

    /* retry if no exception is thrown */
    if (err == Z_OK && args.interrupt) {
       args.interrupt = 0;
       goto loop;
    }

    if (flush != Z_FINISH && err == Z_BUF_ERROR
	    && z->stream.avail_out > 0) {
	z->flags |= ZSTREAM_FLAG_IN_STREAM;
    }

    zstream_reset_input(z);

    if (err != Z_OK && err != Z_STREAM_END) {
	if (z->stream.avail_in > 0) {
	    zstream_append_input(z, z->stream.next_in, z->stream.avail_in);
	}
	if (err == Z_NEED_DICT) {
	    VALUE self = (VALUE)z->stream.opaque;
	    if (self) {
		VALUE dicts = rb_ivar_get(self, id_dictionaries);
		VALUE dict = rb_hash_aref(dicts, rb_uint2inum(z->stream.adler));
		if (!NIL_P(dict)) {
		    rb_inflate_set_dictionary(self, dict);
		    goto loop;
		}
	    }
	}
	raise_zlib_error(err, z->stream.msg);
    }

    if (z->stream.avail_in > 0) {
	zstream_append_input(z, z->stream.next_in, z->stream.avail_in);
    }
    if (!NIL_P(old_input)) {
	rb_str_resize(old_input, 0);
	rb_gc_force_recycle(old_input);
    }

    if (args.jump_state)
	rb_jump_tag(args.jump_state);
}

struct zstream_run_synchronized_args {
    struct zstream *z;
    Bytef *src;
    long len;
    int flush;
};

static VALUE
zstream_run_synchronized(VALUE value_arg)
{
    struct zstream_run_synchronized_args *run_args = (struct zstream_run_synchronized_args *)value_arg;
    zstream_run0(run_args->z, run_args->src, run_args->len, run_args->flush);
    return Qnil;
}

static void
zstream_run(struct zstream *z, Bytef *src, long len, int flush)
{
    struct zstream_run_synchronized_args run_args;
    run_args.z = z;
    run_args.src = src;
    run_args.len = len;
    run_args.flush = flush;
    rb_mutex_synchronize(z->mutex, zstream_run_synchronized, (VALUE)&run_args);
}

static VALUE
zstream_sync(struct zstream *z, Bytef *src, long len)
{
    /* VALUE rest; */
    int err;

    if (!NIL_P(z->input)) {
	z->stream.next_in = (Bytef*)RSTRING_PTR(z->input);
	z->stream.avail_in = MAX_UINT(RSTRING_LEN(z->input));
	err = inflateSync(&z->stream);
	if (err == Z_OK) {
	    zstream_discard_input(z,
				  RSTRING_LEN(z->input) - z->stream.avail_in);
	    zstream_append_input(z, src, len);
	    return Qtrue;
	}
	zstream_reset_input(z);
	if (err != Z_DATA_ERROR) {
	    /* rest = rb_str_new((char*)z->stream.next_in, z->stream.avail_in); */
	    raise_zlib_error(err, z->stream.msg);
	}
    }

    if (len <= 0) return Qfalse;

    z->stream.next_in = src;
    z->stream.avail_in = MAX_UINT(len);
    err = inflateSync(&z->stream);
    if (err == Z_OK) {
	zstream_append_input(z, z->stream.next_in, z->stream.avail_in);
	return Qtrue;
    }
    if (err != Z_DATA_ERROR) {
	/* rest = rb_str_new((char*)z->stream.next_in, z->stream.avail_in); */
	raise_zlib_error(err, z->stream.msg);
    }
    return Qfalse;
}

static void
zstream_mark(void *p)
{
    struct zstream *z = p;
    rb_gc_mark(z->buf);
    rb_gc_mark(z->input);
    rb_gc_mark(z->mutex);
}

static void
zstream_finalize(struct zstream *z)
{
    int err = z->func->end(&z->stream);
    if (err == Z_STREAM_ERROR)
	finalizer_warn("the stream state was inconsistent.");
    if (err == Z_DATA_ERROR)
	finalizer_warn("the stream was freed prematurely.");
}

static void
zstream_free(void *p)
{
    struct zstream *z = p;

    if (ZSTREAM_IS_READY(z)) {
	zstream_finalize(z);
    }
    xfree(z);
}

static size_t
zstream_memsize(const void *p)
{
    /* n.b. this does not track memory managed via zalloc/zfree callbacks */
    return sizeof(struct zstream);
}

static const rb_data_type_t zstream_data_type = {
    "zstream",
    { zstream_mark, zstream_free, zstream_memsize, },
     0, 0, RUBY_TYPED_FREE_IMMEDIATELY
};

static VALUE
zstream_new(VALUE klass, const struct zstream_funcs *funcs)
{
    VALUE obj;
    struct zstream *z;

    obj = TypedData_Make_Struct(klass, struct zstream, &zstream_data_type, z);
    zstream_init(z, funcs);
    z->stream.opaque = (voidpf)obj;
    return obj;
}

#define zstream_deflate_new(klass)  zstream_new((klass), &deflate_funcs)
#define zstream_inflate_new(klass)  zstream_new((klass), &inflate_funcs)

static struct zstream *
get_zstream(VALUE obj)
{
    struct zstream *z;

    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    if (!ZSTREAM_IS_READY(z)) {
	rb_raise(cZError, "stream is not ready");
    }
    return z;
}


/* ------------------------------------------------------------------------- */

/*
 * Document-class: Zlib::ZStream
 *
 * Zlib::ZStream is the abstract class for the stream which handles the
 * compressed data. The operations are defined in the subclasses:
 * Zlib::Deflate for compression, and Zlib::Inflate for decompression.
 *
 * An instance of Zlib::ZStream has one stream (struct zstream in the source)
 * and two variable-length buffers which associated to the input (next_in) of
 * the stream and the output (next_out) of the stream. In this document,
 * "input buffer" means the buffer for input, and "output buffer" means the
 * buffer for output.
 *
 * Data input into an instance of Zlib::ZStream are temporally stored into
 * the end of input buffer, and then data in input buffer are processed from
 * the beginning of the buffer until no more output from the stream is
 * produced (i.e. until avail_out > 0 after processing).  During processing,
 * output buffer is allocated and expanded automatically to hold all output
 * data.
 *
 * Some particular instance methods consume the data in output buffer and
 * return them as a String.
 *
 * Here is an ascii art for describing above:
 *
 *    +================ an instance of Zlib::ZStream ================+
 *    ||                                                            ||
 *    ||     +--------+          +-------+          +--------+      ||
 *    ||  +--| output |<---------|zstream|<---------| input  |<--+  ||
 *    ||  |  | buffer |  next_out+-------+next_in   | buffer |   |  ||
 *    ||  |  +--------+                             +--------+   |  ||
 *    ||  |                                                      |  ||
 *    +===|======================================================|===+
 *        |                                                      |
 *        v                                                      |
 *    "output data"                                         "input data"
 *
 * If an error occurs during processing input buffer, an exception which is a
 * subclass of Zlib::Error is raised.  At that time, both input and output
 * buffer keep their conditions at the time when the error occurs.
 *
 * == Method Catalogue
 *
 * Many of the methods in this class are fairly low-level and unlikely to be
 * of interest to users.  In fact, users are unlikely to use this class
 * directly; rather they will be interested in Zlib::Inflate and
 * Zlib::Deflate.
 *
 * The higher level methods are listed below.
 *
 * - #total_in
 * - #total_out
 * - #data_type
 * - #adler
 * - #reset
 * - #finish
 * - #finished?
 * - #close
 * - #closed?
 */

/*
 * Closes the stream. All operations on the closed stream will raise an
 * exception.
 */
static VALUE
rb_zstream_end(VALUE obj)
{
    zstream_end(get_zstream(obj));
    return Qnil;
}

/*
 * Resets and initializes the stream. All data in both input and output buffer
 * are discarded.
 */
static VALUE
rb_zstream_reset(VALUE obj)
{
    zstream_reset(get_zstream(obj));
    return Qnil;
}

/*
 * call-seq:
 *   finish                 -> String
 *   finish { |chunk| ... } -> nil
 *
 * Finishes the stream and flushes output buffer.  If a block is given each
 * chunk is yielded to the block until the input buffer has been flushed to
 * the output buffer.
 */
static VALUE
rb_zstream_finish(VALUE obj)
{
    struct zstream *z = get_zstream(obj);

    zstream_run(z, (Bytef*)"", 0, Z_FINISH);

    return zstream_detach_buffer(z);
}

/*
 * call-seq:
 *   flush_next_in -> input
 *
 */
static VALUE
rb_zstream_flush_next_in(VALUE obj)
{
    struct zstream *z;
    VALUE dst;

    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    dst = zstream_detach_input(z);
    return dst;
}

/*
 * call-seq:
 *   flush_next_out                 -> String
 *   flush_next_out { |chunk| ... } -> nil
 *
 * Flushes output buffer and returns all data in that buffer.  If a block is
 * given each chunk is yielded to the block until the current output buffer
 * has been flushed.
 */
static VALUE
rb_zstream_flush_next_out(VALUE obj)
{
    struct zstream *z;

    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);

    return zstream_detach_buffer(z);
}

/*
 * Returns number of bytes of free spaces in output buffer.  Because the free
 * space is allocated automatically, this method returns 0 normally.
 */
static VALUE
rb_zstream_avail_out(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return rb_uint2inum(z->stream.avail_out);
}

/*
 * Allocates +size+ bytes of free space in the output buffer. If there are more
 * than +size+ bytes already in the buffer, the buffer is truncated. Because
 * free space is allocated automatically, you usually don't need to use this
 * method.
 */
static VALUE
rb_zstream_set_avail_out(VALUE obj, VALUE size)
{
    struct zstream *z = get_zstream(obj);

    zstream_expand_buffer_into(z, FIX2INT(size));
    return size;
}

/*
 * Returns bytes of data in the input buffer. Normally, returns 0.
 */
static VALUE
rb_zstream_avail_in(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return INT2FIX(NIL_P(z->input) ? 0 : (int)(RSTRING_LEN(z->input)));
}

/*
 * Returns the total bytes of the input data to the stream.  FIXME
 */
static VALUE
rb_zstream_total_in(VALUE obj)
{
    return rb_uint2inum(get_zstream(obj)->stream.total_in);
}

/*
 * Returns the total bytes of the output data from the stream.  FIXME
 */
static VALUE
rb_zstream_total_out(VALUE obj)
{
    return rb_uint2inum(get_zstream(obj)->stream.total_out);
}

/*
 * Guesses the type of the data which have been inputed into the stream. The
 * returned value is either <tt>BINARY</tt>, <tt>ASCII</tt>, or
 * <tt>UNKNOWN</tt>.
 */
static VALUE
rb_zstream_data_type(VALUE obj)
{
    return INT2FIX(get_zstream(obj)->stream.data_type);
}

/*
 * Returns the adler-32 checksum.
 */
static VALUE
rb_zstream_adler(VALUE obj)
{
    return rb_uint2inum(get_zstream(obj)->stream.adler);
}

/*
 * Returns true if the stream is finished.
 */
static VALUE
rb_zstream_finished_p(VALUE obj)
{
    return ZSTREAM_IS_FINISHED(get_zstream(obj)) ? Qtrue : Qfalse;
}

/*
 * Returns true if the stream is closed.
 */
static VALUE
rb_zstream_closed_p(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return ZSTREAM_IS_READY(z) ? Qfalse : Qtrue;
}


/* ------------------------------------------------------------------------- */

/*
 * Document-class: Zlib::Deflate
 *
 * Zlib::Deflate is the class for compressing data.  See Zlib::ZStream for more
 * information.
 */

#define FIXNUMARG(val, ifnil) \
    (NIL_P((val)) ? (ifnil) \
    : (FIX2INT((val))))

#define ARG_LEVEL(val)     FIXNUMARG((val), Z_DEFAULT_COMPRESSION)
#define ARG_WBITS(val)     FIXNUMARG((val), MAX_WBITS)
#define ARG_MEMLEVEL(val)  FIXNUMARG((val), DEF_MEM_LEVEL)
#define ARG_STRATEGY(val)  FIXNUMARG((val), Z_DEFAULT_STRATEGY)
#define ARG_FLUSH(val)     FIXNUMARG((val), Z_NO_FLUSH)


static VALUE
rb_deflate_s_allocate(VALUE klass)
{
    return zstream_deflate_new(klass);
}

/*
 * Document-method: Zlib::Deflate.new
 *
 * call-seq:
 *   Zlib::Deflate.new(level=DEFAULT_COMPRESSION, window_bits=MAX_WBITS, mem_level=DEF_MEM_LEVEL, strategy=DEFAULT_STRATEGY)
 *
 * Creates a new deflate stream for compression. If a given argument is nil,
 * the default value of that argument is used.
 *
 * The +level+ sets the compression level for the deflate stream between 0 (no
 * compression) and 9 (best compression). The following constants have been
 * defined to make code more readable:
 *
 * * Zlib::DEFAULT_COMPRESSION
 * * Zlib::NO_COMPRESSION
 * * Zlib::BEST_SPEED
 * * Zlib::BEST_COMPRESSION
 *
 * See http://www.zlib.net/manual.html#Constants for further information.
 *
 * The +window_bits+ sets the size of the history buffer and should be between
 * 8 and 15.  Larger values of this parameter result in better compression at
 * the expense of memory usage.
 *
 * The +mem_level+ specifies how much memory should be allocated for the
 * internal compression state.  1 uses minimum memory but is slow and reduces
 * compression ratio while 9 uses maximum memory for optimal speed.  The
 * default value is 8. Two constants are defined:
 *
 * * Zlib::DEF_MEM_LEVEL
 * * Zlib::MAX_MEM_LEVEL
 *
 * The +strategy+ sets the deflate compression strategy.  The following
 * strategies are available:
 *
 * Zlib::DEFAULT_STRATEGY:: For normal data
 * Zlib::FILTERED:: For data produced by a filter or predictor
 * Zlib::FIXED:: Prevents dynamic Huffman codes
 * Zlib::HUFFMAN_ONLY:: Prevents string matching
 * Zlib::RLE:: Designed for better compression of PNG image data
 *
 * See the constants for further description.
 *
 * == Examples
 *
 * === Basic
 *
 *   open "compressed.file", "w+" do |io|
 *     io << Zlib::Deflate.new.deflate(File.read("big.file"))
 *   end
 *
 * === Custom compression
 *
 *   open "compressed.file", "w+" do |compressed_io|
 *     deflate = Zlib::Deflate.new(Zlib::BEST_COMPRESSION,
 *                                 Zlib::MAX_WBITS,
 *                                 Zlib::MAX_MEM_LEVEL,
 *                                 Zlib::HUFFMAN_ONLY)
 *
 *     begin
 *       open "big.file" do |big_io|
 *         until big_io.eof? do
 *           compressed_io << zd.deflate(big_io.read(16384))
 *         end
 *       end
 *     ensure
 *       deflate.close
 *     end
 *   end
 *
 * While this example will work, for best optimization review the flags for
 * your specific time, memory usage and output space requirements.
 */
static VALUE
rb_deflate_initialize(int argc, VALUE *argv, VALUE obj)
{
    struct zstream *z;
    VALUE level, wbits, memlevel, strategy;
    int err;

    rb_scan_args(argc, argv, "04", &level, &wbits, &memlevel, &strategy);
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);

    err = deflateInit2(&z->stream, ARG_LEVEL(level), Z_DEFLATED,
		       ARG_WBITS(wbits), ARG_MEMLEVEL(memlevel),
		       ARG_STRATEGY(strategy));
    if (err != Z_OK) {
	raise_zlib_error(err, z->stream.msg);
    }
    ZSTREAM_READY(z);

    return obj;
}

/*
 * Document-method: Zlib::Deflate#initialize_copy
 *
 * Duplicates the deflate stream.
 */
static VALUE
rb_deflate_init_copy(VALUE self, VALUE orig)
{
    struct zstream *z1, *z2;
    int err;

    TypedData_Get_Struct(self, struct zstream, &zstream_data_type, z1);
    z2 = get_zstream(orig);

    if (z1 == z2) return self;
    err = deflateCopy(&z1->stream, &z2->stream);
    if (err != Z_OK) {
	raise_zlib_error(err, 0);
    }
    z1->input = NIL_P(z2->input) ? Qnil : rb_str_dup(z2->input);
    z1->buf   = NIL_P(z2->buf)   ? Qnil : rb_str_dup(z2->buf);
    z1->flags = z2->flags;

    return self;
}

static VALUE
deflate_run(VALUE args)
{
    struct zstream *z = (struct zstream*)((VALUE*)args)[0];
    VALUE src = ((VALUE*)args)[1];

    zstream_run(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src), Z_FINISH);
    return zstream_detach_buffer(z);
}

/*
 * Document-method: Zlib::Deflate.deflate
 *
 * call-seq:
 *   Zlib.deflate(string[, level])
 *   Zlib::Deflate.deflate(string[, level])
 *
 * Compresses the given +string+. Valid values of level are
 * Zlib::NO_COMPRESSION, Zlib::BEST_SPEED, Zlib::BEST_COMPRESSION,
 * Zlib::DEFAULT_COMPRESSION, or an integer from 0 to 9.
 *
 * This method is almost equivalent to the following code:
 *
 *   def deflate(string, level)
 *     z = Zlib::Deflate.new(level)
 *     dst = z.deflate(string, Zlib::FINISH)
 *     z.close
 *     dst
 *   end
 *
 * See also Zlib.inflate
 *
 */
static VALUE
rb_deflate_s_deflate(int argc, VALUE *argv, VALUE klass)
{
    struct zstream z;
    VALUE src, level, dst, args[2];
    int err, lev;

    rb_scan_args(argc, argv, "11", &src, &level);

    lev = ARG_LEVEL(level);
    StringValue(src);
    zstream_init_deflate(&z);
    err = deflateInit(&z.stream, lev);
    if (err != Z_OK) {
	raise_zlib_error(err, z.stream.msg);
    }
    ZSTREAM_READY(&z);

    args[0] = (VALUE)&z;
    args[1] = src;
    dst = rb_ensure(deflate_run, (VALUE)args, zstream_ensure_end, (VALUE)&z);

    return dst;
}

static void
do_deflate(struct zstream *z, VALUE src, int flush)
{
    if (NIL_P(src)) {
	zstream_run(z, (Bytef*)"", 0, Z_FINISH);
	return;
    }
    StringValue(src);
    if (flush != Z_NO_FLUSH || RSTRING_LEN(src) > 0) { /* prevent BUF_ERROR */
	zstream_run(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src), flush);
    }
}

/*
 * Document-method: Zlib::Deflate#deflate
 *
 * call-seq:
 *   z.deflate(string, flush = Zlib::NO_FLUSH)                 -> String
 *   z.deflate(string, flush = Zlib::NO_FLUSH) { |chunk| ... } -> nil
 *
 * Inputs +string+ into the deflate stream and returns the output from the
 * stream.  On calling this method, both the input and the output buffers of
 * the stream are flushed.  If +string+ is nil, this method finishes the
 * stream, just like Zlib::ZStream#finish.
 *
 * If a block is given consecutive deflated chunks from the +string+ are
 * yielded to the block and +nil+ is returned.
 *
 * The +flush+ parameter specifies the flush mode.  The following constants
 * may be used:
 *
 * Zlib::NO_FLUSH:: The default
 * Zlib::SYNC_FLUSH:: Flushes the output to a byte boundary
 * Zlib::FULL_FLUSH:: SYNC_FLUSH + resets the compression state
 * Zlib::FINISH:: Pending input is processed, pending output is flushed.
 *
 * See the constants for further description.
 *
 */
static VALUE
rb_deflate_deflate(int argc, VALUE *argv, VALUE obj)
{
    struct zstream *z = get_zstream(obj);
    VALUE src, flush;

    rb_scan_args(argc, argv, "11", &src, &flush);
    do_deflate(z, src, ARG_FLUSH(flush));

    return zstream_detach_buffer(z);
}

/*
 * Document-method: Zlib::Deflate#<<
 *
 * call-seq: << string
 *
 * Inputs +string+ into the deflate stream just like Zlib::Deflate#deflate, but
 * returns the Zlib::Deflate object itself.  The output from the stream is
 * preserved in output buffer.
 */
static VALUE
rb_deflate_addstr(VALUE obj, VALUE src)
{
    do_deflate(get_zstream(obj), src, Z_NO_FLUSH);
    return obj;
}

/*
 * Document-method: Zlib::Deflate#flush
 *
 * call-seq:
 *   flush(flush = Zlib::SYNC_FLUSH)                 -> String
 *   flush(flush = Zlib::SYNC_FLUSH) { |chunk| ... } -> nil
 *
 * This method is equivalent to <tt>deflate('', flush)</tt>. This method is
 * just provided to improve the readability of your Ruby program.  If a block
 * is given chunks of deflate output are yielded to the block until the buffer
 * is flushed.
 *
 * See Zlib::Deflate#deflate for detail on the +flush+ constants NO_FLUSH,
 * SYNC_FLUSH, FULL_FLUSH and FINISH.
 */
static VALUE
rb_deflate_flush(int argc, VALUE *argv, VALUE obj)
{
    struct zstream *z = get_zstream(obj);
    VALUE v_flush;
    int flush;

    rb_scan_args(argc, argv, "01", &v_flush);
    flush = FIXNUMARG(v_flush, Z_SYNC_FLUSH);
    if (flush != Z_NO_FLUSH) {  /* prevent Z_BUF_ERROR */
	zstream_run(z, (Bytef*)"", 0, flush);
    }

    return zstream_detach_buffer(z);
}

/*
 * Document-method: Zlib::Deflate.params
 *
 * call-seq: params(level, strategy)
 *
 * Changes the parameters of the deflate str…