Class: Zlib::GzipReader

Inherits:

GzipFile

• Object
• GzipFile
• Zlib::GzipReader

Includes:

Enumerable

Defined in:

ext/zlib/zlib.c,
ext/zlib/zlib.c

Overview

Zlib::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 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.

• #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 Zlib::GzipFile::NoFooter, Zlib::GzipFile::CRCError, or Zlib::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 Zlib::GzipFile#close method is called after the object reaches the end of file.

• When Zlib::GzipReader#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

• .open(*args) ⇒ Object

  call-seq: Zlib::GzipReader.open(filename) {|gz| … }.

• .zcat(*args) ⇒ Object

  call-seq: Zlib::GzipReader.zcat(io, options = {}, &block) => nil Zlib::GzipReader.zcat(io, options = {}) => string.

Instance Method Summary

• #each(*args) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #each_byte ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #each_char ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #each_line(*args) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #eof ⇒ Object

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

• #eof? ⇒ Boolean

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

• #external_encoding ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #getbyte ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #getc ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #gets(*args) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #initialize(*args) ⇒ Object constructor

  call-seq: Zlib::GzipReader.new(io, options = {}).

• #lineno ⇒ Object

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

• #lineno=(lineno) ⇒ Object

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

• #pos ⇒ Object

  Total number of output bytes output so far.

• #read(*args) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #readbyte ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #readchar ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #readline(*args) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #readlines(*args) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #readpartial(*args) ⇒ Object

  call-seq: gzipreader.readpartial(maxlen [, outbuf]) => string, outbuf.

• #rewind ⇒ Object

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

• #tell ⇒ Object

  Total number of output bytes output so far.

• #ungetbyte(ch) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #ungetc(s) ⇒ Object

  See Zlib::GzipReader documentation for a description.

• #unused ⇒ Object

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

Methods inherited from GzipFile

#close, #closed?, #comment, #crc, #finish, #level, #mtime, #orig_name, #os_code, #sync, #sync=, #to_io, wrap

Constructor Details

#initialize(*args) ⇒ Object

call-seq:

Zlib::GzipReader.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 Zlib::GzipFile::Error exception.

# File 'ext/zlib/zlib.c', line 4020

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(*args) ⇒ Object

call-seq: Zlib::GzipReader.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 Zlib::GzipReader.new and ZLib::GzipFile.wrap.

# File 'ext/zlib/zlib.c', line 3943

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

.zcat(*args) ⇒ Object

call-seq:

Zlib::GzipReader.zcat(io, options = {}, &block) => nil
Zlib::GzipReader.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.

# File 'ext/zlib/zlib.c', line 3965

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 Method Details

#each(*args) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4491

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 ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4216

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 ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4198

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) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4491

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 ⇒ Object

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

# File 'ext/zlib/zlib.c', line 3570

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? ⇒ Boolean

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

Returns:

• (Boolean)

# File 'ext/zlib/zlib.c', line 3570

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;
}

#external_encoding ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4525

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

#getbyte ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4164

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 ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4135

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

    return gzfile_getc(gz);
}

#gets(*args) ⇒ Object

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

# File 'ext/zlib/zlib.c', line 4459

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 ⇒ Object

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

# File 'ext/zlib/zlib.c', line 3409

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

#lineno=(lineno) ⇒ Object

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

# File 'ext/zlib/zlib.c', line 3420

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

#pos ⇒ Object

Total number of output bytes output so far.

# File 'ext/zlib/zlib.c', line 3631

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) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4081

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 ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4182

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 ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4148

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) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4475

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) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4509

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(*args) ⇒ Object

call-seq:

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

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

# File 'ext/zlib/zlib.c', line 4112

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 ⇒ Object

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.

# File 'ext/zlib/zlib.c', line 4054

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

#tell ⇒ Object

Total number of output bytes output so far.

# File 'ext/zlib/zlib.c', line 3631

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));
    }
}

#ungetbyte(ch) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4256

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

#ungetc(s) ⇒ Object

See Zlib::GzipReader documentation for a description.

# File 'ext/zlib/zlib.c', line 4234

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 ⇒ Object

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

# File 'ext/zlib/zlib.c', line 4068

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);
}