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.
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);
TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, 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;
}
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.
static VALUE
rb_gzwriter_s_open(int argc, VALUE *argv, VALUE klass)
{
return gzfile_s_open(argc, argv, klass, "wb");
}
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.
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;
}
Specify the comment (str) in the gzip header.
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;
}
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.
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;
}
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;
}
Specify the original name (str) in the gzip header.
static VALUE
rb_gzfile_total_in(VALUE obj)
{
return rb_uint2inum(get_gzfile(obj)->z.stream.total_in);
}
Total number of input bytes read so far.
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;
}
Same as IO.
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));
RB_GC_GUARD(str);
return INT2FIX(RSTRING_LEN(str));
}
Same as IO.