Class: Zlib::Inflate
Overview
Zlib:Inflate is the class for decompressing compressed data. Unlike Zlib::Deflate, an instance of this class is not able to duplicate (clone, dup) itself.
Class Method Summary collapse
-
.inflate ⇒ Object
call-seq: Zlib.inflate(string) Zlib::Inflate.inflate(string).
Instance Method Summary collapse
-
#<<(string) ⇒ Object
Inputs
stringinto the inflate stream just like Zlib::Inflate#inflate, but returns the Zlib::Inflate object itself. -
#add_dictionary ⇒ Object
call-seq: add_dictionary(string).
-
#inflate ⇒ Object
call-seq: inflate(deflate_string) -> String inflate(deflate_string) { |chunk| … } -> nil.
-
#initialize ⇒ Object
constructor
call-seq: Zlib::Inflate.new(window_bits = Zlib::MAX_WBITS).
-
#set_dictionary ⇒ Object
Sets the preset dictionary and returns
string. -
#sync(string) ⇒ Object
Inputs
stringinto the end of input buffer and skips data until a full flush point can be found. -
#sync_point? ⇒ Boolean
Quoted verbatim from original documentation:.
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 ⇒ Object
call-seq:
Zlib::Inflate.new(window_bits = Zlib::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 Zlib::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|
inflate = Zlib::Inflate.new(Zlib::MAX_WBITS + 32)
begin
open "uncompressed.file", "w+" do |uncompressed_io|
uncompressed_io << zi.inflate(compressed_io.read)
}
ensure
zi.close
end
end
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# File 'zlib.c', line 1865
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);
Data_Get_Struct(obj, struct zstream, z);
err = inflateInit2(&z->stream, ARG_WBITS(wbits));
if (err != Z_OK) {
raise_zlib_error(err, z->stream.msg);
}
ZSTREAM_READY(z);
return obj;
}
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Class Method Details
.inflate ⇒ Object
call-seq:
Zlib.inflate(string)
Zlib::Inflate.inflate(string)
Decompresses string. Raises a Zlib::NeedDict exception if a preset dictionary is needed for decompression.
This method is almost equivalent to the following code:
def inflate(string)
zstream = Zlib::Inflate.new
buf = zstream.inflate(string)
zstream.finish
zstream.close
buf
end
See also Zlib.deflate
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# File 'zlib.c', line 1918
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_end, (VALUE)&z);
OBJ_INFECT(dst, src);
return dst;
}
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Instance Method Details
#<<(string) ⇒ Object
Inputs string into the inflate stream just like Zlib::Inflate#inflate, but returns the Zlib::Inflate object itself. The output from the stream is preserved in output buffer.
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# File 'zlib.c', line 2047
static VALUE
rb_inflate_addstr(VALUE obj, VALUE src)
{
struct zstream *z = get_zstream(obj);
OBJ_INFECT(obj, src);
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 ⇒ 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 'zlib.c', line 1963
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;
}
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#inflate ⇒ 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 Zlib::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 Zlib::NeedDict exception if a preset dictionary is needed to decompress. Set the dictionary by Zlib::Inflate#set_dictionary and then call this method again with an empty string to flush the stream:
inflater = Zlib::Inflate.new
begin
out = inflater.inflate compressed
rescue Zlib::NeedDict
# ensure the dictionary matches the stream's required dictionary
raise unless inflater.adler == Zlib.adler32(dictionary)
inflater.set_dictionary dictionary
inflater.inflate ''
end
# ...
inflater.close
See also Zlib::Inflate.new
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# File 'zlib.c', line 2010
static VALUE
rb_inflate_inflate(VALUE obj, VALUE src)
{
struct zstream *z = get_zstream(obj);
VALUE dst;
OBJ_INFECT(obj, src);
if (ZSTREAM_IS_FINISHED(z)) {
if (NIL_P(src)) {
dst = zstream_detach_buffer(z);
}
else {
StringValue(src);
zstream_append_buffer2(z, src);
dst = rb_str_new(0, 0);
OBJ_INFECT(dst, obj);
}
}
else {
do_inflate(z, src);
dst = zstream_detach_buffer(z);
if (ZSTREAM_IS_FINISHED(z)) {
zstream_passthrough_input(z);
}
}
return dst;
}
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#set_dictionary ⇒ Object
Sets the preset dictionary and returns string. This method is available just only after a Zlib::NeedDict exception was raised. See zlib.h for details.
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# File 'zlib.c', line 2118
static VALUE
rb_inflate_set_dictionary(VALUE obj, VALUE dic)
{
struct zstream *z = get_zstream(obj);
VALUE src = dic;
int err;
OBJ_INFECT(obj, dic);
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;
}
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#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 'zlib.c', line 2078
static VALUE
rb_inflate_sync(VALUE obj, VALUE src)
{
struct zstream *z = get_zstream(obj);
OBJ_INFECT(obj, src);
StringValue(src);
return zstream_sync(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src));
}
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#sync_point? ⇒ Boolean
Quoted verbatim from original documentation:
What is this?
:)
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# File 'zlib.c', line 2095
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;
}
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