Class: Zlib::GzipWriter

Inherits:
GzipFile show all
Defined in:
zlib.c,
zlib.c

Overview

Zlib::GzipWriter is a class for writing gzipped files. GzipWriter should be used with an instance of IO, or IO-like, object.

Following two example generate the same result.

Zlib::GzipWriter.open('hoge.gz') do |gz|
  gz.write 'jugemu jugemu gokou no surikire...'
end

File.open('hoge.gz', 'w') do |f|
  gz = Zlib::GzipWriter.new(f)
  gz.write 'jugemu jugemu gokou no surikire...'
  gz.close
end

To make like gzip(1) does, run following:

orig = 'hoge.txt'
Zlib::GzipWriter.open('hoge.gz') do |gz|
  gz.mtime = File.mtime(orig)
  gz.orig_name = orig
  gz.write IO.binread(orig)
end

NOTE: Due to the limitation of Ruby's finalizer, you must explicitly close GzipWriter objects by Zlib::GzipWriter#close etc. Otherwise, GzipWriter will be not able to write the gzip footer and will generate a broken gzip file.

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

#Zlib::GzipWriter.new(io, level = nil, strategy = nil, options = {}) ⇒ Object

Creates a GzipWriter object associated with io. level and strategy should be the same as the arguments of Zlib::Deflate.new. The GzipWriter object writes gzipped data to io. io must respond to the write method that behaves the same as IO#write.

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.


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# File 'zlib.c', line 3466

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

    if (argc > 1) {
  opt = rb_check_convert_type(argv[argc-1], T_HASH, "Hash", "to_hash");
  if (!NIL_P(opt)) argc--;
    }

    rb_scan_args(argc, argv, "12", &io, &level, &strategy);
    Data_Get_Struct(obj, struct gzfile, gz);

    /* this is undocumented feature of zlib */
    gz->level = ARG_LEVEL(level);
    err = deflateInit2(&gz->z.stream, gz->level, Z_DEFLATED,
           -MAX_WBITS, DEF_MEM_LEVEL, ARG_STRATEGY(strategy));
    if (err != Z_OK) {
  raise_zlib_error(err, gz->z.stream.msg);
    }
    gz->io = io;
    ZSTREAM_READY(&gz->z);
    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;
}

Class Method Details

.Zlib::GzipWriter.open(filename, level = nil, strategy = nil) {|gz| ... } ⇒ Object

Opens a file specified by filename for writing gzip compressed data, and returns a GzipWriter object associated with that file. Further details of this method are found in Zlib::GzipWriter.new and Zlib::GzipFile.wrap.

Yields:

  • (gz)

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# File 'zlib.c', line 3447

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

Instance Method Details

#<<Object

call-seq: << string

Inputs string into the deflate stream just like Zlib::Deflate#deflate, but returns the Zlib::Deflate object itself. The output from the stream is preserved in output buffer.

#comment=Object

Specify the comment (str) in the gzip header.


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# File 'zlib.c', line 3231

static VALUE
rb_gzfile_set_comment(VALUE obj, VALUE str)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE s;
    char *p;

    if (gz->z.flags & GZFILE_FLAG_HEADER_FINISHED) {
  rb_raise(cGzError, "header is already written");
    }
    s = rb_str_dup(rb_str_to_str(str));
    p = memchr(RSTRING_PTR(s), '\0', RSTRING_LEN(s));
    if (p) {
  rb_str_resize(s, p - RSTRING_PTR(s));
    }
    gz->comment = s;
    return str;
}

#flush(flush = nil) ⇒ Object

Flushes all the internal buffers of the GzipWriter object. The meaning of flush is same as in Zlib::Deflate#deflate. Zlib::SYNC_FLUSH is used if flush is omitted. It is no use giving flush Zlib::NO_FLUSH.


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# File 'zlib.c', line 3507

static VALUE
rb_gzwriter_flush(int argc, VALUE *argv, VALUE obj)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE v_flush;
    int flush;

    rb_scan_args(argc, argv, "01", &v_flush);

    flush = FIXNUMARG(v_flush, Z_SYNC_FLUSH);
    if (flush != Z_NO_FLUSH) {  /* prevent Z_BUF_ERROR */
  zstream_run(&gz->z, (Bytef*)"", 0, flush);
    }

    gzfile_write_raw(gz);
    if (rb_respond_to(gz->io, id_flush)) {
  rb_funcall(gz->io, id_flush, 0);
    }
    return obj;
}

#mtime=Object

Specify the modification time (mtime) in the gzip header. Using a Fixnum or Integer


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# File 'zlib.c', line 3186

static VALUE
rb_gzfile_set_mtime(VALUE obj, VALUE mtime)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE val;

    if (gz->z.flags & GZFILE_FLAG_HEADER_FINISHED) {
  rb_raise(cGzError, "header is already written");
    }

    val = rb_Integer(mtime);
    gz->mtime = NUM2UINT(val);

    return mtime;
}

#orig_name=Object

Specify the original name (str) in the gzip header.


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# File 'zlib.c', line 3207

static VALUE
rb_gzfile_set_orig_name(VALUE obj, VALUE str)
{
    struct gzfile *gz = get_gzfile(obj);
    VALUE s;
    char *p;

    if (gz->z.flags & GZFILE_FLAG_HEADER_FINISHED) {
  rb_raise(cGzError, "header is already written");
    }
    s = rb_str_dup(rb_str_to_str(str));
    p = memchr(RSTRING_PTR(s), '\0', RSTRING_LEN(s));
    if (p) {
  rb_str_resize(s, p - RSTRING_PTR(s));
    }
    gz->orig_name = s;
    return str;
}

#posObject

Total number of input bytes read so far.


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# File 'zlib.c', line 3351

static VALUE
rb_gzfile_total_in(VALUE obj)
{
    return rb_uint2inum(get_gzfile(obj)->z.stream.total_in);
}

Same as IO.

#printfObject

Same as IO.

#putcObject

Same as IO.


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# File 'zlib.c', line 3548

static VALUE
rb_gzwriter_putc(VALUE obj, VALUE ch)
{
    struct gzfile *gz = get_gzfile(obj);
    char c = NUM2CHR(ch);

    gzfile_write(gz, (Bytef*)&c, 1);
    return ch;
}

#putsObject

Same as IO.

#tellObject

Total number of input bytes read so far.


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# File 'zlib.c', line 3351

static VALUE
rb_gzfile_total_in(VALUE obj)
{
    return rb_uint2inum(get_gzfile(obj)->z.stream.total_in);
}

#writeObject

Same as IO.


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# File 'zlib.c', line 3531

static VALUE
rb_gzwriter_write(VALUE obj, VALUE str)
{
    struct gzfile *gz = get_gzfile(obj);

    if (!RB_TYPE_P(str, T_STRING))
  str = rb_obj_as_string(str);
    if (gz->enc2 && gz->enc2 != rb_ascii8bit_encoding()) {
  str = rb_str_conv_enc(str, rb_enc_get(str), gz->enc2);
    }
    gzfile_write(gz, (Bytef*)RSTRING_PTR(str), RSTRING_LEN(str));
    return INT2FIX(RSTRING_LEN(str));
}