class Zlib::GzipFile - Documentation for Ruby 4.0
Description: class Zlib::GzipFile: GzipFile is an abstract class for handling a gzip formatted compressed file. GzipWriter for writing.
Keywords: ruby,class,Zlib::GzipFile

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# class Zlib::GzipFile

`Zlib::GzipFile` is an abstract class for handling a gzip formatted compressed file. The operations are defined in the subclasses, `Zlib::GzipReader` for reading, and `Zlib::GzipWriter` for writing.

`GzipReader` should be used by associating an `IO`, or IO-like, object.

## Method Catalogue

- `::wrap`

- ::open (`Zlib::GzipReader::open` and `Zlib::GzipWriter::open`)

- `close`

- `closed?`

- `comment`

- comment= (`Zlib::GzipWriter#comment=`)

- `crc`

- eof? (`Zlib::GzipReader#eof?`)

- `finish`

- `level`

- lineno (`Zlib::GzipReader#lineno`)

- lineno= (`Zlib::GzipReader#lineno=`)

- `mtime`

- mtime= (`Zlib::GzipWriter#mtime=`)

- `orig_name`

- `orig_name` (`Zlib::GzipWriter#orig_name=`)

- `os_code`

- path (when the underlying `IO` supports path)

- `sync`

- `sync=`

- `to_io`

(due to internal structure, documentation may appear under `Zlib::GzipReader` or `Zlib::GzipWriter`)

### Public Class Methods

Zlib::GzipReader.wrap(io, ...) { |gz| ... }
Zlib::GzipWriter.wrap(io, ...) { |gz| ... }
Source

    static VALUE
    rb_gzfile_s_wrap(int argc, VALUE *argv, VALUE klass)
    {
        return gzfile_wrap(argc, argv, klass, 0);
    }

Creates a `GzipReader` or `GzipWriter` associated with `io`, passing in any necessary extra options, and executes the block with the newly created object just like `File.open`.

The `GzipFile` object will be closed automatically after executing the block. If you want to keep the associated `IO` object open, you may call `Zlib::GzipFile#finish` method in the block.

### Public Instance Methods

close ()
Source

    static VALUE
    rb_gzfile_close(VALUE obj)
    {
        struct gzfile *gz;
        VALUE io;

        TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, gz);
        if (!ZSTREAM_IS_READY(&gz->z)) {
            return Qnil;
        }
        io = gz->io;
        gzfile_close(gz, 1);
        return io;
    }

Closes the `GzipFile` object. This method calls close method of the associated `IO` object. Returns the associated `IO` object.

closed? ()
Source

    static VALUE
    rb_gzfile_closed_p(VALUE obj)
    {
        struct gzfile *gz;
        TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, gz);
        return NIL_P(gz->io) ? Qtrue : Qfalse;
    }

Same as `IO#closed?`

comment ()
Source

    static VALUE
    rb_gzfile_comment(VALUE obj)
    {
        VALUE str = get_gzfile(obj)->comment;
        if (!NIL_P(str)) {
            str = rb_str_dup(str);
        }
        return str;
    }

Returns comments recorded in the gzip file header, or nil if the comments is not present.

crc ()
Source

    static VALUE
    rb_gzfile_crc(VALUE obj)
    {
        return rb_uint2inum(get_gzfile(obj)->crc);
    }

Returns CRC value of the uncompressed data.

finish ()
Source

    static VALUE
    rb_gzfile_finish(VALUE obj)
    {
        struct gzfile *gz = get_gzfile(obj);
        VALUE io;

        io = gz->io;
        gzfile_close(gz, 0);
        return io;
    }

Closes the `GzipFile` object. Unlike `Zlib::GzipFile#close`, this method never calls the close method of the associated `IO` object. Returns the associated `IO` object.

level ()
Source

    static VALUE
    rb_gzfile_level(VALUE obj)
    {
        return INT2FIX(get_gzfile(obj)->level);
    }

Returns compression level.

mtime ()
Source

    static VALUE
    rb_gzfile_mtime(VALUE obj)
    {
        return rb_time_new(get_gzfile(obj)->mtime, (time_t)0);
    }

Returns last modification time recorded in the gzip file header.

orig_name ()
Source

    static VALUE
    rb_gzfile_orig_name(VALUE obj)
    {
        VALUE str = get_gzfile(obj)->orig_name;
        if (!NIL_P(str)) {
            str = rb_str_dup(str);
        }
        return str;
    }

Returns original filename recorded in the gzip file header, or `nil` if original filename is not present.

os_code ()
Source

    static VALUE
    rb_gzfile_os_code(VALUE obj)
    {
        return INT2FIX(get_gzfile(obj)->os_code);
    }

Returns OS code number recorded in the gzip file header.

sync ()
Source

    static VALUE
    rb_gzfile_sync(VALUE obj)
    {
        return (get_gzfile(obj)->z.flags & GZFILE_FLAG_SYNC) ? Qtrue : Qfalse;
    }

Same as `IO#sync`

sync = flag
Source

    static VALUE
    rb_gzfile_set_sync(VALUE obj, VALUE mode)
    {
        struct gzfile *gz = get_gzfile(obj);

        if (RTEST(mode)) {
            gz->z.flags |= GZFILE_FLAG_SYNC;
        }
        else {
            gz->z.flags &= ~GZFILE_FLAG_SYNC;
        }
        return mode;
    }

Same as `IO`. If flag is `true`, the associated `IO` object must respond to the `flush` method. While `sync` mode is `true`, the compression ratio decreases sharply.

to_io ()
Source

    static VALUE
    rb_gzfile_to_io(VALUE obj)
    {
        return get_gzfile(obj)->io;
    }

Same as `IO`.