Class: Zstdlib::Inflate

Inherits:
ZStream show all
Defined in:
ext/zstdlib/ruby/zlib-3.0/zstdlib.c,
ext/zstdlib/ruby/zlib-3.0/zstdlib.c,
ext/zstdlib/ruby/zlib-2.7/zstdlib.c,
ext/zstdlib/ruby/zlib-2.7/zstdlib.c,
ext/zstdlib/ruby/zlib-2.6/zstdlib.c,
ext/zstdlib/ruby/zlib-2.6/zstdlib.c,
ext/zstdlib/ruby/zlib-2.5/zstdlib.c,
ext/zstdlib/ruby/zlib-2.5/zstdlib.c,
ext/zstdlib/ruby/zlib-2.4/zstdlib.c,
ext/zstdlib/ruby/zlib-2.4/zstdlib.c,
ext/zstdlib/ruby/zlib-2.3/zstdlib.c,
ext/zstdlib/ruby/zlib-2.3/zstdlib.c,
ext/zstdlib/ruby/zlib-2.2/zstdlib.c,
ext/zstdlib/ruby/zlib-2.2/zstdlib.c

Overview

Zlib:Inflate is the class for decompressing compressed data. Unlike Zstdlib::Deflate, an instance of this class is not able to duplicate (clone, dup) itself.

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from ZStream

#adler, #avail_in, #avail_out, #avail_out=, #close, #closed?, #data_type, #end, #ended?, #finish, #finished?, #flush_next_in, #flush_next_out, #reset, #stream_end?, #total_in, #total_out

Constructor Details

#initialize(*args) ⇒ Object

call-seq: Zstdlib::Inflate.new(window_bits = Zstdlib::MAX_WBITS)

Creates a new inflate stream for decompression. +window_bits+ sets the size of the history buffer and can have the following values:

0:: Have inflate use the window size from the zlib header of the compressed stream.

(8..15):: Overrides the window size of the inflate header in the compressed stream. The window size must be greater than or equal to the window size of the compressed stream.

Greater than 15:: Add 32 to window_bits to enable zlib and gzip decoding with automatic header detection, or add 16 to decode only the gzip format (a Zstdlib::DataError will be raised for a non-gzip stream).

(-8..-15):: Enables raw deflate mode which will not generate a check value, and will not look for any check values for comparison at the end of the stream.

This is for use with other formats that use the deflate compressed data format such as zip which provide their own check values.

== Example

open "compressed.file" do |compressed_io| zi = Zstdlib::Inflate.new(Zstdlib::MAX_WBITS + 32)

begin
  open "uncompressed.file", "w+" do |uncompressed_io|
    uncompressed_io << zi.inflate(compressed_io.read)
  end
ensure
  zi.close
end

end



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 1934

static VALUE
rb_inflate_initialize(int argc, VALUE *argv, VALUE obj)
{
    struct zstream *z;
    VALUE wbits;
    int err;

    rb_scan_args(argc, argv, "01", &wbits);
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);

    err = inflateInit2(&z->stream, ARG_WBITS(wbits));
    if (err != Z_OK) {
	raise_zlib_error(err, z->stream.msg);
    }
    ZSTREAM_READY(z);

    return obj;
}

Class Method Details

.inflate(src) ⇒ Object

call-seq: Zstdlib.inflate(string) Zstdlib::Inflate.inflate(string)

Decompresses +string+. Raises a Zstdlib::NeedDict exception if a preset dictionary is needed for decompression.

This method is almost equivalent to the following code:

def inflate(string) zstream = Zstdlib::Inflate.new buf = zstream.inflate(string) zstream.finish zstream.close buf end

See also Zstdlib.deflate



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 1987

static VALUE
rb_inflate_s_inflate(VALUE obj, VALUE src)
{
    struct zstream z;
    VALUE dst, args[2];
    int err;

    StringValue(src);
    zstream_init_inflate(&z);
    err = inflateInit(&z.stream);
    if (err != Z_OK) {
	raise_zlib_error(err, z.stream.msg);
    }
    ZSTREAM_READY(&z);

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

    return dst;
}

Instance Method Details

#<<(string) ⇒ Object

Inputs +string+ into the inflate stream just like Zstdlib::Inflate#inflate, but returns the Zstdlib::Inflate object itself. The output from the stream is preserved in output buffer.



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 2153

static VALUE
rb_inflate_addstr(VALUE obj, VALUE src)
{
    struct zstream *z = get_zstream(obj);

    if (ZSTREAM_IS_FINISHED(z)) {
	if (!NIL_P(src)) {
	    StringValue(src);
	    zstream_append_buffer2(z, src);
	}
    }
    else {
	do_inflate(z, src);
	if (ZSTREAM_IS_FINISHED(z)) {
	    zstream_passthrough_input(z);
	}
    }

    return obj;
}

#add_dictionary(dictionary) ⇒ Object

call-seq: add_dictionary(string)

Provide the inflate stream with a dictionary that may be required in the future. Multiple dictionaries may be provided. The inflate stream will automatically choose the correct user-provided dictionary based on the stream's required dictionary.



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 2031

static VALUE
rb_inflate_add_dictionary(VALUE obj, VALUE dictionary)
{
    VALUE dictionaries = rb_ivar_get(obj, id_dictionaries);
    VALUE checksum = do_checksum(1, &dictionary, adler32);

    rb_hash_aset(dictionaries, checksum, dictionary);

    return obj;
}

#inflate(src) ⇒ Object

call-seq: inflate(deflate_string) -> String inflate(deflate_string) { |chunk| ... } -> nil

Inputs +deflate_string+ into the inflate stream and returns the output from the stream. Calling this method, both the input and the output buffer of the stream are flushed. If string is +nil+, this method finishes the stream, just like Zstdlib::ZStream#finish.

If a block is given consecutive inflated chunks from the +deflate_string+ are yielded to the block and +nil+ is returned.

Raises a Zstdlib::NeedDict exception if a preset dictionary is needed to decompress. Set the dictionary by Zstdlib::Inflate#set_dictionary and then call this method again with an empty string to flush the stream:

inflater = Zstdlib::Inflate.new

begin out = inflater.inflate compressed rescue Zstdlib::NeedDict # ensure the dictionary matches the stream's required dictionary raise unless inflater.adler == Zstdlib.adler32(dictionary)

inflater.set_dictionary dictionary
inflater.inflate ''

end

# ...

inflater.close

See also Zstdlib::Inflate.new



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 2088

static VALUE
rb_inflate_inflate(int argc, VALUE* argv, VALUE obj)
{
    struct zstream *z = get_zstream(obj);
    VALUE dst, src, opts, buffer = Qnil;

    if (OPTHASH_GIVEN_P(opts)) {
        VALUE buf;
        rb_get_kwargs(opts, &id_buffer, 0, 1, &buf);
        if (buf != Qundef && buf != Qnil) {
            buffer = StringValue(buf);
        }
    }
    if (buffer != Qnil) {
        if (!(ZSTREAM_REUSE_BUFFER_P(z) && z->buf == buffer)) {
            long len = RSTRING_LEN(buffer);
            if (len >= ZSTREAM_AVAIL_OUT_STEP_MAX) {
                rb_str_modify(buffer);
            }
            else {
                len = ZSTREAM_AVAIL_OUT_STEP_MAX - len;
                rb_str_modify_expand(buffer, len);
            }
            rb_str_set_len(buffer, 0);
            z->flags |= ZSTREAM_REUSE_BUFFER;
            z->buf = buffer;
        }
    } else if (ZSTREAM_REUSE_BUFFER_P(z)) {
        z->flags &= ~ZSTREAM_REUSE_BUFFER;
        z->buf = Qnil;
    }
    rb_scan_args(argc, argv, "10", &src);

    if (ZSTREAM_IS_FINISHED(z)) {
	if (NIL_P(src)) {
	    dst = zstream_detach_buffer(z);
	}
	else {
	    StringValue(src);
	    zstream_append_buffer2(z, src);
	    if (ZSTREAM_REUSE_BUFFER_P(z)) {
                dst = rb_str_resize(buffer, 0);
            } else {
                dst = rb_str_new(0, 0);
            }
	}
    }
    else {
	do_inflate(z, src);
	dst = zstream_detach_buffer(z);
	if (ZSTREAM_IS_FINISHED(z)) {
	    zstream_passthrough_input(z);
	}
    }

    return dst;
}

#set_dictionary(dic) ⇒ Object

Sets the preset dictionary and returns +string+. This method is available just only after a Zstdlib::NeedDict exception was raised. See zlib.h for details.



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 2221

static VALUE
rb_inflate_set_dictionary(VALUE obj, VALUE dic)
{
    struct zstream *z = get_zstream(obj);
    VALUE src = dic;
    int err;

    StringValue(src);
    err = inflateSetDictionary(&z->stream,
			       (Bytef*)RSTRING_PTR(src), RSTRING_LENINT(src));
    if (err != Z_OK) {
	raise_zlib_error(err, z->stream.msg);
    }

    return dic;
}

#sync(string) ⇒ Object

Inputs +string+ into the end of input buffer and skips data until a full flush point can be found. If the point is found in the buffer, this method flushes the buffer and returns false. Otherwise it returns +true+ and the following data of full flush point is preserved in the buffer.



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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 2182

static VALUE
rb_inflate_sync(VALUE obj, VALUE src)
{
    struct zstream *z = get_zstream(obj);

    StringValue(src);
    return zstream_sync(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src));
}

#sync_point? ⇒ Boolean

Quoted verbatim from original documentation:

What is this?

:)

Returns:

  • (Boolean) 


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# File 'ext/zstdlib/ruby/zlib-3.0/zstdlib.c', line 2198

static VALUE
rb_inflate_sync_point_p(VALUE obj)
{
    struct zstream *z = get_zstream(obj);
    int err;

    err = inflateSyncPoint(&z->stream);
    if (err == 1) {
	return Qtrue;
    }
    if (err != Z_OK) {
	raise_zlib_error(err, z->stream.msg);
    }
    return Qfalse;
}