Class: Zlib::GzipReader

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, `GzipFile`
Instance Chain: self, Enumerable, `GzipFile`
Inherits:	Zlib::GzipFile `::Object` Zlib::GzipFile Zlib::GzipReader
Defined in:	ext/zlib/zlib.c, ext/zlib/zlib.c

Overview

GzipReader is the class for reading a gzipped file. GzipReader should be used as an IO, or -IO-like, object.

Zlib::GzipReader.open('hoge.gz') {|gz|
  print gz.read
}

File.open('hoge.gz') do |f|
  gz = Zlib::GzipReader.new(f)
  print gz.read
  gz.close
end

Method Catalogue

The following methods in GzipReader are just like their counterparts in IO, but they raise Error or GzipFile::Error exception if an error was found in the gzip file.

#each
#each_line
#each_byte
#gets
#getc
#lineno
#lineno=
#read
#readchar
#readline
#readlines
#ungetc

Be careful of the footer of the gzip file. A gzip file has the checksum of pre-compressed data in its footer. GzipReader checks all uncompressed data against that checksum at the following cases, and if it fails, raises GzipFile::NoFooter, GzipFile::CRCError, or GzipFile::LengthError exception.

When an reading request is received beyond the end of file (the end of compressed data). That is, when Zlib::GzipReader#read, Zlib::GzipReader#gets, or some other methods for reading returns nil.
When GzipFile#close method is called after the object reaches the end of file.
When #unused method is called after the object reaches the end of file.

The rest of the methods are adequately described in their own documentation.

Class Method Summary

.new(io, options = {}) constructor

Creates a GzipReader object associated with io.
.open(filename) {|gz| ... }

Opens a file specified by filename as a gzipped file, and returns a GzipReader object associated with that file.
.zcat(io, options = {}, &block) ⇒ nil

Decompresses all gzip data in the io, handling multiple gzip streams until the end of the io.

`GzipFile` - Inherited

.wrap

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.

Instance Attribute Summary

#eof (also: #eof?) readonly

Returns true or false whether the stream has reached the end.
#eof? readonly

Alias for #eof.
#lineno rw

The line number of the last row read from this file.
#lineno=(lineno) rw

Specify line number of the last row read from this file.

`GzipFile` - Inherited

#closed?	Same as `IO#closed?`
#sync	Same as `IO#sync`
#sync=	Same as IO.

Instance Method Summary

#each(*args) (also: #each_line)

See GzipReader documentation for a description.
#each_byte

See GzipReader documentation for a description.
#each_char

See GzipReader documentation for a description.
#each_line(*args)

Alias for #each.
#external_encoding

See GzipReader documentation for a description.
#getbyte

See GzipReader documentation for a description.
#getc

See GzipReader documentation for a description.
#gets(*args)

See GzipReader documentation for a description.
#pos (also: #tell)

Total number of output bytes output so far.
#read(*args)

See GzipReader documentation for a description.
#readbyte

See GzipReader documentation for a description.
#readchar

See GzipReader documentation for a description.
#readline(*args)

See GzipReader documentation for a description.
#readlines(*args)

See GzipReader documentation for a description.
#readpartial(maxlen [, outbuf]) ⇒ String, outbuf

Reads at most maxlen bytes from the gzipped stream but it blocks only if gzipreader has no data immediately available.
#rewind

Resets the position of the file pointer to the point created the GzipReader object.
#tell

Alias for #pos.
#ungetbyte(ch)

See GzipReader documentation for a description.
#ungetc(s)

See GzipReader documentation for a description.
#unused

Returns the rest of the data which had read for parsing gzip format, or nil if the whole gzip file is not parsed yet.

`GzipFile` - Inherited

#close	Closes the `GzipFile` object.
#comment	Returns comments recorded in the gzip file header, or nil if the comments is not present.
#crc	Returns CRC value of the uncompressed data.
#finish	Closes the `GzipFile` object.
#level	Returns compression level.
#mtime	Returns last modification time recorded in the gzip file header.
#orig_name	Returns original filename recorded in the gzip file header, or `nil` if original filename is not present.
#os_code	Returns OS code number recorded in the gzip file header.
#to_io	Same as IO.

Constructor Details

.new(io, options = {})

Creates a GzipReader object associated with io. The GzipReader object reads gzipped data from io, and parses/decompresses it. The io must have a #read method that behaves same as the IO#read.

The options hash may be used to set the encoding of the data. :external_encoding, :internal_encoding and :encoding may be set as in IO.new.

If the gzip file header is incorrect, raises an GzipFile::Error exception.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3963


static VALUE
rb_gzreader_initialize(int argc, VALUE *argv, VALUE obj)
{
    VALUE io, opt = Qnil;
    struct gzfile *gz;
    int err;

    TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, gz);
    rb_scan_args(argc, argv, "1:", &io, &opt);

    /* this is undocumented feature of zlib */
    err = inflateInit2(&gz->z.stream, -MAX_WBITS);
    if (err != Z_OK) {
	raise_zlib_error(err, gz->z.stream.msg);
    }
    gz->io = io;
    ZSTREAM_READY(&gz->z);
    gzfile_read_header(gz, Qnil);
    rb_gzfile_ecopts(gz, opt);

    if (rb_respond_to(io, id_path)) {
	/* File#path may raise IOError in case when a path is unavailable */
	rb_rescue2(gzfile_initialize_path_partial, obj, NULL, Qnil, rb_eIOError, (VALUE)0);
    }

    return obj;
}

Class Method Details

.open(filename) {|gz| ... }

Opens a file specified by filename as a gzipped file, and returns a GzipReader object associated with that file. Further details of this method are in .new and ZLib::GzipFile.wrap.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3886


static VALUE
rb_gzreader_s_open(int argc, VALUE *argv, VALUE klass)
{
    return gzfile_s_open(argc, argv, klass, "rb");
}

.zcat(io, options = {}, &block) ⇒ `nil` .zcat(io, options = {}) ⇒ `String`

Decompresses all gzip data in the io, handling multiple gzip streams until the end of the io. There should not be any non-gzip data after the gzip streams.

If a block is given, it is yielded strings of uncompressed data, and the method returns nil. If a block is not given, the method returns the concatenation of all uncompressed data in all gzip streams.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3908


static VALUE
rb_gzreader_s_zcat(int argc, VALUE *argv, VALUE klass)
{
    VALUE io, unused, obj, buf=0, tmpbuf;
    long pos;

    rb_check_arity(argc, 1, 2);
    io = argv[0];

    do {
        obj = rb_funcallv(klass, rb_intern("new"), argc, argv);
        if (rb_block_given_p()) {
           rb_gzreader_each(0, 0, obj);
        }
        else {
            if (!buf) {
                buf = rb_str_new(0, 0);
            }
            tmpbuf = gzfile_read_all(get_gzfile(obj), Qnil);
            rb_str_cat(buf, RSTRING_PTR(tmpbuf), RSTRING_LEN(tmpbuf));
        }

        rb_gzreader_read(0, 0, obj);
        pos = NUM2LONG(rb_funcall(io, rb_intern("pos"), 0));
        unused = rb_gzreader_unused(obj);
        rb_gzfile_finish(obj);
        if (!NIL_P(unused)) {
            pos -= NUM2LONG(rb_funcall(unused, rb_intern("length"), 0));
            rb_funcall(io, rb_intern("pos="), 1, LONG2NUM(pos));
        }
    } while (pos < NUM2LONG(rb_funcall(io, rb_intern("size"), 0)));

    if (rb_block_given_p()) {
        return Qnil;
    }
    return buf;
}

Instance Attribute Details

#eof (readonly) Also known as: #eof?

Returns true or false whether the stream has reached the end.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3513


static VALUE
rb_gzfile_eof_p(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    while (!ZSTREAM_IS_FINISHED(&gz->z) && ZSTREAM_BUF_FILLED(&gz->z) == 0) {
	gzfile_read_more(gz, Qnil);
    }
    return GZFILE_IS_FINISHED(gz) ? Qtrue : Qfalse;
}

#eof? (readonly)

Alias for #eof.

#lineno (rw)

The line number of the last row read from this file.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3352


static VALUE
rb_gzfile_lineno(VALUE obj)
{
    return INT2NUM(get_gzfile(obj)->lineno);
}

#lineno=(lineno) (rw)

Specify line number of the last row read from this file.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3363


static VALUE
rb_gzfile_set_lineno(VALUE obj, VALUE lineno)
{
    struct gzfile *gz = get_gzfile(obj);
    gz->lineno = NUM2INT(lineno);
    return lineno;
}

Instance Method Details

#each(*args) Also known as: #each_line

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4434


static VALUE
rb_gzreader_each(int argc, VALUE *argv, VALUE obj)
{
    VALUE str;

    RETURN_ENUMERATOR(obj, 0, 0);

    while (!NIL_P(str = gzreader_gets(argc, argv, obj))) {
	rb_yield(str);
    }
    return obj;
}

#each_byte

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4159


static VALUE
rb_gzreader_each_byte(VALUE obj)
{
    VALUE c;

    RETURN_ENUMERATOR(obj, 0, 0);

    while (!NIL_P(c = rb_gzreader_getbyte(obj))) {
	rb_yield(c);
    }
    return Qnil;
}

#each_char

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4141


static VALUE
rb_gzreader_each_char(VALUE obj)
{
    VALUE c;

    RETURN_ENUMERATOR(obj, 0, 0);

    while (!NIL_P(c = rb_gzreader_getc(obj))) {
	rb_yield(c);
    }
    return Qnil;
}

#each_line(*args)

Alias for #each.

#external_encoding

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4468


static VALUE
rb_gzreader_external_encoding(VALUE self)
{
    return rb_enc_from_encoding(get_gzfile(self)->enc);
}

#getbyte

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4107


static VALUE
rb_gzreader_getbyte(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE dst;

    dst = gzfile_read(gz, 1, Qnil);
    if (!NIL_P(dst)) {
	dst = INT2FIX((unsigned int)(RSTRING_PTR(dst)[0]) & 0xff);
    }
    return dst;
}

#getc

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4078


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

    return gzfile_getc(gz);
}

#gets(*args)

See GzipReader documentation for a description. However, note that this method can return nil even if #eof? returns false, unlike the behavior of File#gets.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4402


static VALUE
rb_gzreader_gets(int argc, VALUE *argv, VALUE obj)
{
    VALUE dst;
    dst = gzreader_gets(argc, argv, obj);
    if (!NIL_P(dst)) {
	rb_lastline_set(dst);
    }
    return dst;
}

#pos Also known as: #tell

Total number of output bytes output so far.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3574


static VALUE
rb_gzfile_total_out(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    uLong total_out = gz->z.stream.total_out;
    long buf_filled = ZSTREAM_BUF_FILLED(&gz->z);

    if (total_out >= (uLong)buf_filled) {
        return rb_uint2inum(total_out - buf_filled);
    } else {
        return LONG2FIX(-(buf_filled - (long)total_out));
    }
}

#read(*args)

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4024


static VALUE
rb_gzreader_read(int argc, VALUE *argv, VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE vlen, outbuf;
    long len;

    rb_scan_args(argc, argv, "02", &vlen, &outbuf);
    if (NIL_P(vlen)) {
	return gzfile_read_all(gz, outbuf);
    }

    len = NUM2INT(vlen);
    if (len < 0) {
	rb_raise(rb_eArgError, "negative length %ld given", len);
    }
    return gzfile_read(gz, len, outbuf);
}

#readbyte

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4125


static VALUE
rb_gzreader_readbyte(VALUE obj)
{
    VALUE dst;
    dst = rb_gzreader_getbyte(obj);
    if (NIL_P(dst)) {
	rb_raise(rb_eEOFError, "end of file reached");
    }
    return dst;
}

#readchar

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4091


static VALUE
rb_gzreader_readchar(VALUE obj)
{
    VALUE dst;
    dst = rb_gzreader_getc(obj);
    if (NIL_P(dst)) {
	rb_raise(rb_eEOFError, "end of file reached");
    }
    return dst;
}

#readline(*args)

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4418


static VALUE
rb_gzreader_readline(int argc, VALUE *argv, VALUE obj)
{
    VALUE dst;
    dst = rb_gzreader_gets(argc, argv, obj);
    if (NIL_P(dst)) {
	rb_raise(rb_eEOFError, "end of file reached");
    }
    return dst;
}

#readlines(*args)

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4452


static VALUE
rb_gzreader_readlines(int argc, VALUE *argv, VALUE obj)
{
    VALUE str, dst;
    dst = rb_ary_new();
    while (!NIL_P(str = gzreader_gets(argc, argv, obj))) {
	rb_ary_push(dst, str);
    }
    return dst;
}

#readpartial(maxlen [, outbuf]) ⇒ `String`, `outbuf`

Reads at most maxlen bytes from the gzipped stream but it blocks only if gzipreader has no data immediately available. If the optional outbuf argument is present, it must reference a String, which will receive the data. It raises EOFError on end of file.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4055


static VALUE
rb_gzreader_readpartial(int argc, VALUE *argv, VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE vlen, outbuf;
    long len;

    rb_scan_args(argc, argv, "11", &vlen, &outbuf);

    len = NUM2INT(vlen);
    if (len < 0) {
	rb_raise(rb_eArgError, "negative length %ld given", len);
    }
    if (!NIL_P(outbuf))
        Check_Type(outbuf, T_STRING);
    return gzfile_readpartial(gz, len, outbuf);
}

#rewind

Resets the position of the file pointer to the point created the GzipReader object. The associated IO object needs to respond to the seek method.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 3997


static VALUE
rb_gzreader_rewind(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    gzfile_reader_rewind(gz);
    return INT2FIX(0);
}

#tell

Alias for #pos.

#ungetbyte(ch)

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4199


static VALUE
rb_gzreader_ungetbyte(VALUE obj, VALUE ch)
{
    struct gzfile *gz = get_gzfile(obj);
    gzfile_ungetbyte(gz, NUM2CHR(ch));
    return Qnil;
}

#ungetc(s)

See GzipReader documentation for a description.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4177


static VALUE
rb_gzreader_ungetc(VALUE obj, VALUE s)
{
    struct gzfile *gz;

    if (FIXNUM_P(s))
	return rb_gzreader_ungetbyte(obj, s);
    gz = get_gzfile(obj);
    StringValue(s);
    if (gz->enc2 && gz->enc2 != rb_ascii8bit_encoding()) {
	s = rb_str_conv_enc(s, rb_enc_get(s), gz->enc2);
    }
    gzfile_ungets(gz, (const Bytef*)RSTRING_PTR(s), RSTRING_LEN(s));
    RB_GC_GUARD(s);
    return Qnil;
}

#unused

Returns the rest of the data which had read for parsing gzip format, or nil if the whole gzip file is not parsed yet.

[ GitHub ]

# File 'ext/zlib/zlib.c', line 4011


static VALUE
rb_gzreader_unused(VALUE obj)
{
    struct gzfile *gz;
    TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, gz);
    return gzfile_reader_get_unused(gz);
}

Class: Zlib::GzipReader

Overview

Method Catalogue

Class Method Summary

GzipFile - Inherited

Instance Attribute Summary

GzipFile - Inherited

Instance Method Summary

GzipFile - Inherited

Constructor Details

.new(io, options = {})

Class Method Details

.open(filename) {|gz| ... }

.zcat(io, options = {}, &block) ⇒ nil .zcat(io, options = {}) ⇒ String

Instance Attribute Details

#eof (readonly) Also known as: #eof?

#eof? (readonly)

#lineno (rw)

#lineno=(lineno) (rw)

Instance Method Details

#each(*args) Also known as: #each_line

#each_byte

#each_char

#each_line(*args)

#external_encoding

#getbyte

#getc

#gets(*args)

#pos Also known as: #tell

#read(*args)

#readbyte

#readchar

#readline(*args)

#readlines(*args)

#readpartial(maxlen [, outbuf]) ⇒ String, outbuf

#rewind

#tell

#ungetbyte(ch)

#ungetc(s)

#unused

`GzipFile` - Inherited

`GzipFile` - Inherited

`GzipFile` - Inherited

.zcat(io, options = {}, &block) ⇒ `nil` .zcat(io, options = {}) ⇒ `String`

#readpartial(maxlen [, outbuf]) ⇒ `String`, `outbuf`