class Zlib::GzipReader
Zlib::GzipReader is the class for reading a gzipped file.GzipReader should be used as anIO, or -IO-like, object.
Zlib::GzipReader.open('hoge.gz') {|gz|printgz.read}File.open('hoge.gz')do|f|gz =Zlib::GzipReader.new(f)printgz.readgz.closeend
Method Catalogue¶↑
The following methods inZlib::GzipReader are just like their counterparts inIO, but they raiseZlib::Error orZlib::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, raisesZlib::GzipFile::NoFooter,Zlib::GzipFile::CRCError, orZlib::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#closemethod is called after the object reaches the end of file.When
Zlib::GzipReader#unusedmethod is called after the object reaches the end of file.
The rest of the methods are adequately described in their own documentation.
Public Class Methods
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static VALUErb_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;}Creates aGzipReader object associated withio. TheGzipReader object reads gzipped data fromio, and parses/decompresses it. Theio must have aread method that behaves same as theIO#read.
Theoptions hash may be used to set the encoding of the data.:external_encoding,:internal_encoding and:encoding may be set as inIO::new.
If the gzip file header is incorrect, raises anZlib::GzipFile::Error exception.
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static VALUErb_gzreader_s_open(int argc, VALUE *argv, VALUE klass){ return gzfile_s_open(argc, argv, klass, "rb");}Opens a file specified byfilename as a gzipped file, and returns aGzipReader object associated with that file. Further details of this method are inZlib::GzipReader.new and ZLib::GzipFile.wrap.
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static VALUErb_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;}Decompresses all gzip data in theio, handling multiple gzip streams until the end of theio. 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 returnsnil. If a block is not given, the method returns the concatenation of all uncompressed data in all gzip streams.
Public Instance Methods
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}Returnstrue orfalse whether the stream has reached the end.
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static VALUErb_gzreader_external_encoding(VALUE self){ return rb_enc_from_encoding(get_gzfile(self)->enc);}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_gzreader_getc(VALUE obj){ struct gzfile *gz = get_gzfile(obj); return gzfile_getc(gz);}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description. However, note that this method can returnnil even ifeof? returns false, unlike the behavior ofFile#gets.
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static VALUErb_gzfile_lineno(VALUE obj){ return INT2NUM(get_gzfile(obj)->lineno);}The line number of the last row read from this file.
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static VALUErb_gzfile_set_lineno(VALUE obj, VALUE lineno){ struct gzfile *gz = get_gzfile(obj); gz->lineno = NUM2INT(lineno); return lineno;}Specify line number of the last row read from this file.
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static VALUErb_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)); }}Total number of output bytes output so far.
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static VALUErb_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);}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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);}Reads at mostmaxlen bytes from the gzipped stream but it blocks only ifgzipreader has no data immediately available. If the optionaloutbuf argument is present, it must reference aString, which will receive the data. It raisesEOFError on end of file.
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static VALUErb_gzreader_rewind(VALUE obj){ struct gzfile *gz = get_gzfile(obj); gzfile_reader_rewind(gz); return INT2FIX(0);}Resets the position of the file pointer to the point created theGzipReader object. The associatedIO object needs to respond to theseek method.
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static VALUErb_gzreader_ungetbyte(VALUE obj, VALUE ch){ struct gzfile *gz = get_gzfile(obj); gzfile_ungetbyte(gz, NUM2CHR(ch)); return Qnil;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_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;}SeeZlib::GzipReader documentation for a description.
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static VALUErb_gzreader_unused(VALUE obj){ struct gzfile *gz; TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, gz); return gzfile_reader_get_unused(gz);}Returns the rest of the data which had read for parsing gzip format, ornil if the whole gzip file is not parsed yet.