Zlib::GzipReader is the class for reading a gzipped file. GzipReader should be used an IO, or -IO-lie, 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 Zlib::GzipReader are just like their counterparts in IO, but they raise Zlib::Error or Zlib::GzipFile::Error exception if an error was found in the gzip file.

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 Zlib::GzipFile::NoFooter, Zlib::GzipFile::CRCError, or Zlib::GzipFile::LengthErrorexception.

  • When an reading request is received beyond the end of file (the end of compressed data). That is, when #read, #gets, or some other methods for reading returns nil.

  • When Zlib::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.

Methods
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Included Modules
Class Public methods
Zlib::GzipReader.new(io)

Creates a GzipReader object associated with io. The GzipReader object reads gzipped data from io, and parses/decompresses them. At least, iomust have a readmethod that behaves same as the readmethod in IO class.

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

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

    Data_Get_Struct(obj, struct gzfile, 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);
    rb_gzfile_ecopts(gz, opt);

    if (rb_respond_to(io, id_path)) {
        gz->path = rb_funcall(gz->io, id_path, 0);
        rb_define_singleton_method(obj, "path", rb_gzfile_path, 0);
    }

    return obj;
}
Zlib::GzipReader.open(filename) {|gz| ... }

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

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

See Zlib::GzipReader documentation for a description.

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(*args)

See Zlib::GzipReader documentation for a description.

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 Zlib::GzipReader documentation for a description.

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 Zlib::GzipReader documentation for a description.

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)

See Zlib::GzipReader documentation for a description.

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;
}
eof()

Returns trueor falsewhether the stream has reached the end.

static VALUE
rb_gzfile_eof_p(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    return GZFILE_IS_FINISHED(gz) ? Qtrue : Qfalse;
}
eof?()

Returns trueor falsewhether the stream has reached the end.

static VALUE
rb_gzfile_eof_p(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    return GZFILE_IS_FINISHED(gz) ? Qtrue : Qfalse;
}
getbyte()

See Zlib::GzipReader documentation for a description.

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

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

See Zlib::GzipReader documentation for a description.

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

    return gzfile_getc(gz);
}
gets(*args)

See Zlib::GzipReader documentation for a description.

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;
}
lineno()

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

static VALUE
rb_gzfile_lineno(VALUE obj)
{
    return INT2NUM(get_gzfile(obj)->lineno);
}
lineno=(p1)

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

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

See Zlib::GzipReader documentation for a description.

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;
}
pos()

Total number of output bytes output so far.

static VALUE
rb_gzfile_total_out(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    return rb_uint2inum(gz->z.stream.total_out - gz->z.buf_filled);
}
read(p1 = v1)

See Zlib::GzipReader documentation for a description.

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

    rb_scan_args(argc, argv, "01", &vlen);
    if (NIL_P(vlen)) {
        return gzfile_read_all(gz);
    }

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

See Zlib::GzipReader documentation for a description.

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 Zlib::GzipReader documentation for a description.

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 Zlib::GzipReader documentation for a description.

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 Zlib::GzipReader documentation for a description.

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;
}
gzipreader.readpartial(maxlen [, outbuf]) => string, outbuf

Reads at most maxlenbytes from the gziped stream but it blocks only if gzipreaderhas no data immediately available. If the optional outbufargument is present, it must reference a String, which will receive the data. It raises EOFErroron end of file.

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.

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

Total number of output bytes output so far.

static VALUE
rb_gzfile_total_out(VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    return rb_uint2inum(gz->z.stream.total_out - gz->z.buf_filled);
}
ungetbyte(p1)

See Zlib::GzipReader documentation for a description.

static VALUE
rb_gzreader_ungetbyte(VALUE obj, VALUE ch)
{
    struct gzfile *gz = get_gzfile(obj);
    gzfile_ungetbyte(gz, NUM2CHR(ch));
    return Qnil;
}
ungetc(p1)

See Zlib::GzipReader documentation for a description.

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));
    return Qnil;
}
unused()

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

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