Class: Zlib::GzipReader

Inherits:
GzipFile show all
Includes:
Enumerable
Defined in:
zlib.c

Overview

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

# TODO: test these.  Are they equivalent?  Can GzipReader.new take a
# block?

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 (collapse)

Instance Method Summary (collapse)

Methods inherited from GzipFile

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

Constructor Details

- (Object) 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, io must have a read method that behaves same as the read method in IO class.

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




# File 'zlib.c'

/*
 * call-seq: 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, +io+ must have
 * a +read+ method that behaves same as the +read+ method in IO class.
 *
 * If the gzip file header is incorrect, raises an Zlib::GzipFile::Error
 * exception.
 */
static VALUE
rb_gzreader_initialize(obj, io)
    VALUE obj, io;
{
    struct gzfile *gz;
    int err;

    Data_Get_Struct(obj, struct gzfile, gz);

    /* 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);

    return obj;
}

Class Method Details

+ (Object) 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::GzipReader.wrap.

Yields:

  • (gz) 



# File 'zlib.c'

/*
 * 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::GzipReader.wrap.
 */
static VALUE
rb_gzreader_s_open(argc, argv, klass)
    int argc;
    VALUE *argv;
    VALUE klass;
{
    return gzfile_s_open(argc, argv, klass, "rb");
}

Instance Method Details

- (Object) each

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_each(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    VALUE str;
    while (!NIL_P(str = gzreader_gets(argc, argv, obj))) {
    rb_yield(str);
    }
    return obj;
}

- (Object) each_byte

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_each_byte(obj)
    VALUE obj;
{
    VALUE c;
    while (!NIL_P(c = rb_gzreader_getc(obj))) {
    rb_yield(c);
    }
    return Qnil;
}

- (Object) each_line

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_each(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    VALUE str;
    while (!NIL_P(str = gzreader_gets(argc, argv, obj))) {
    rb_yield(str);
    }
    return obj;
}

- (Object) eof

???




# File 'zlib.c'

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

- (Object) eof?

???




# File 'zlib.c'

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

- (Object) getc

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_getc(obj)
    VALUE obj;
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE dst;

    dst = gzfile_read(gz, 1);
    if (!NIL_P(dst)) {
    dst = INT2FIX((unsigned int)(RSTRING(dst)->ptr[0]) & 0xff);
    }
    return dst;
}

- (Object) gets

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_gets(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    VALUE dst;
    dst = gzreader_gets(argc, argv, obj);
    if (!NIL_P(dst)) {
    rb_lastline_set(dst);
    }
    return dst;
}

- (Object) lineno

???




# File 'zlib.c'

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

- (Object) lineno=

???




# File 'zlib.c'

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

- (Object) pos

???




# File 'zlib.c'

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

- (Object) read

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_read(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE vlen;
    int 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 %d given", len);
    }
    return gzfile_read(gz, len);
}

- (Object) readchar

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_readchar(obj)
    VALUE obj;
{
    VALUE dst;
    dst = rb_gzreader_getc(obj);
    if (NIL_P(dst)) {
    rb_raise(rb_eEOFError, "end of file reached");
    }
    return dst;
}

- (Object) readline

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_readline(argc, argv, obj)
    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;
}

- (Object) readlines

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_readlines(argc, argv, obj)
    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;
}

- (Object) 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.




# File 'zlib.c'

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

- (Object) tell

???




# File 'zlib.c'

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

- (Object) ungetc

See Zlib::GzipReader documentation for a description.




# File 'zlib.c'

/*
 * See Zlib::GzipReader documentation for a description.
 */
static VALUE
rb_gzreader_ungetc(obj, ch)
    VALUE obj, ch;
{
    struct gzfile *gz = get_gzfile(obj);
    gzfile_ungetc(gz, NUM2CHR(ch));
    return Qnil;
}

- (Object) 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.




# File 'zlib.c'

/*
 * Returns the rest of the data which had read for parsing gzip format, or
 * +nil+ if the whole gzip file is not parsed yet.
 */
static VALUE
rb_gzreader_unused(obj)
    VALUE obj;
{
    struct gzfile *gz;
    Data_Get_Struct(obj, struct gzfile, gz);
    return gzfile_reader_get_unused(gz);
}