Issue #6752 has been updated by matz (Yukihiro Matsumoto).


OK, I agree with enhancement of String#encoding and String#scrub.

Matz.

----------------------------------------
Feature #6752: Replacing ill-formed subsequencce
https://bugs.ruby-lang.org/issues/6752#change-38729

Author: naruse (Yui NARUSE)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: next minor


=begin
== ??
String????????????????????正?????????????????????????????????????????置????????置??????????????????

== ????????
??????確??????????????????????以???????????????
* twitter???title
* IRC?????
* ??????????????? API
* Web????????
?????????????正???????????????????????????????????????????????????????????????????詰???????????尾?????????????
??尾????????????????正?????????????????????????????????
??????????????????????????????????????????????????????中???混?????????????????????????????????????

* https://twitter.com/takahashim/status/18974040397
* https://twitter.com/n0kada/status/215674740705210368
* https://twitter.com/n0kada/status/215686490070585346
* https://twitter.com/hajimehoshi/status/215671146769682432
* http://po-ru.com/diary/fixing-invalid-utf-8-in-ruby-revisited/
* http://stackoverflow.com/questions/2982677/ruby-1-9-invalid-byte-sequence-in-utf-8

== ?????????: 置??????
????????String???
???????????????Unicode系???U+FFFD?????????以??????????????
??????????????空?????????????????????????????????????????????????????????????????????????????????
???????????弱???????????????????????
http://unicode.org/reports/tr36/#UTF-8_Exploit

== API
--- str.encode(str.encoding, invalid: replace, [replace: "???"])
* CSI????????????????????????
* iconv ???????????? glibc iconv ??? GNU libiconv ??? //IGNORE ???????????????????????
* ????????????????述????????????????????????????????(???????)

== ?????????
* ??????????????????????
* fix/repair invalid/illegal bytes/sequence ???????????????????

== ??
=== 鬼?????????
int ret = rb_enc_precise_mbclen(p, e, enc); ???????
MBCLEN_INVALID_P(ret) ??????????????????????????正????????????????????微?????
ONIGENC_CONSTRUCT_MBCLEN_INVALID() ????????????????????????????????????????
鬼??????????????????????影?????????????????????修正?????
?正???????????????????????????仮????????????????????????????????????

=== transcode???????
UCS正???????glibc iconv, GNU libiconv, Perl Encode???????????
CSI???transcode???????????身????????????????????
????????????????????????????????????????????????????????????????????


?????????????鬼??????????????????????????????添???????????????????

 diff --git a/string.c b/string.c
 index d038835..4808f15 100644
 --- a/string.c
 +++ b/string.c
 @@ -7426,6 +7426,199 @@ rb_str_ellipsize(VALUE str, long len)
      return ret;
  }
  
 +/*
 + *  call-seq:
 + *    str.fix_invalid -> new_str
 + *
 + *  If the string is well-formed, it returns self.
 + *  If the string has invalid byte sequence, repair it with given replacement
 + *  character.
 + */
 +VALUE
 +rb_str_fix_invalid(VALUE str)
 +{
 +    int cr = ENC_CODERANGE(str);
 +    rb_encoding *enc;
 +    if (cr == ENC_CODERANGE_7BIT || cr == ENC_CODERANGE_VALID)
 +	return rb_str_dup(str);
 +
 +    enc = STR_ENC_GET(str);
 +    if (rb_enc_asciicompat(enc)) {
 +	const char *p = RSTRING_PTR(str);
 +	const char *e = RSTRING_END(str);
 +	const char *p1 = p;
 +	/* 10 should be enough for the usual use case,
 +	 * fixing a wrongly chopped character at the end of the string
 +	 */
 +	long room = 10;
 +	VALUE buf = rb_str_buf_new(RSTRING_LEN(str) + room);
 +	const char *rep;
 +	if (enc == rb_utf8_encoding())
 +	    rep = "\xEF\xBF\xBD";
 +	else
 +	    rep = "?";
 +	cr = ENC_CODERANGE_7BIT;
 +
 +	p = search_nonascii(p, e);
 +	if (!p) {
 +	    p = e;
 +	}
 +	while (p < e) {
 +	    int ret = rb_enc_precise_mbclen(p, e, enc);
 +	    if (MBCLEN_CHARFOUND_P(ret)) {
 +		if ((unsigned char)*p > 127) cr = ENC_CODERANGE_VALID;
 +		p += MBCLEN_CHARFOUND_LEN(ret);
 +	    }
 +	    else if (MBCLEN_INVALID_P(ret)) {
 +		const char *q;
 +		long clen = rb_enc_mbmaxlen(enc);
 +		if (p > p1) rb_str_buf_cat(buf, p1, p - p1);
 +		q = RSTRING_END(buf);
 +
 +		if (e - p < clen) clen = e - p;
 +		if (clen < 3) {
 +		    clen = 1;
 +		}
 +		else {
 +		    long len = RSTRING_LEN(buf);
 +		    clen--;
 +		    rb_str_buf_cat(buf, p, clen);
 +		    for (; clen > 1; clen--) {
 +			ret = rb_enc_precise_mbclen(q, q + clen, enc);
 +			if (MBCLEN_NEEDMORE_P(ret)) {
 +			    break;
 +			}
 +			else if (MBCLEN_INVALID_P(ret)) {
 +			    continue;
 +			}
 +			else {
 +			    rb_bug("shouldn't reach here '%s'", q);
 +			}
 +		    }
 +		    rb_str_set_len(buf, len);
 +		}
 +		p += clen;
 +		p1 = p;
 +		rb_str_buf_cat2(buf, rep);
 +		p = search_nonascii(p, e);
 +		if (!p) {
 +		    p = e;
 +		    break;
 +		}
 +	    }
 +	    else if (MBCLEN_NEEDMORE_P(ret)) {
 +		break;
 +	    }
 +	    else {
 +		rb_bug("shouldn't reach here");
 +	    }
 +	}
 +	if (p1 < p) {
 +	    rb_str_buf_cat(buf, p1, p - p1);
 +	}
 +	if (p < e) {
 +	    rb_str_buf_cat2(buf, rep);
 +	    cr = ENC_CODERANGE_VALID;
 +	}
 +	ENCODING_CODERANGE_SET(buf, rb_enc_to_index(enc), cr);
 +	return buf;
 +    }
 +    else if (rb_enc_dummy_p(enc)) {
 +	return rb_str_dup(str);
 +    }
 +    else {
 +	/* ASCII incompatible */
 +	const char *p = RSTRING_PTR(str);
 +	const char *e = RSTRING_END(str);
 +	const char *p1 = p;
 +	/* 10 should be enough for the usual use case,
 +	 * fixing a wrongly chopped character at the end of the string
 +	 */
 +	long room = 10;
 +	VALUE buf = rb_str_buf_new(RSTRING_LEN(str) + room);
 +	const char *rep;
 +	long mbminlen = rb_enc_mbminlen(enc);
 +	static rb_encoding *utf16be;
 +	static rb_encoding *utf16le;
 +	static rb_encoding *utf32be;
 +	static rb_encoding *utf32le;
 +	if (!utf16be) {
 +	    utf16be = rb_enc_find("UTF-16BE");
 +	    utf16le = rb_enc_find("UTF-16LE");
 +	    utf32be = rb_enc_find("UTF-32BE");
 +	    utf32le = rb_enc_find("UTF-32LE");
 +	}
 +	if (enc == utf16be) {
 +	    rep = "\xFF\xFD";
 +	}
 +	else if (enc == utf16le) {
 +	    rep = "\xFD\xFF";
 +	}
 +	else if (enc == utf32be) {
 +	    rep = "\x00\x00\xFF\xFD";
 +	}
 +	else if (enc == utf32le) {
 +	    rep = "\xFD\xFF\x00\x00";
 +	}
 +	else {
 +	    rep = "?";
 +	}
 +
 +	while (p < e) {
 +	    int ret = rb_enc_precise_mbclen(p, e, enc);
 +	    if (MBCLEN_CHARFOUND_P(ret)) {
 +		p += MBCLEN_CHARFOUND_LEN(ret);
 +	    }
 +	    else if (MBCLEN_INVALID_P(ret)) {
 +		const char *q;
 +		long clen = rb_enc_mbmaxlen(enc);
 +		if (p > p1) rb_str_buf_cat(buf, p1, p - p1);
 +		q = RSTRING_END(buf);
 +
 +		if (e - p < clen) clen = e - p;
 +		if (clen < mbminlen * 3) {
 +		    clen = mbminlen;
 +		}
 +		else {
 +		    long len = RSTRING_LEN(buf);
 +		    clen -= mbminlen;
 +		    rb_str_buf_cat(buf, p, clen);
 +		    for (; clen > mbminlen; clen-=mbminlen) {
 +			ret = rb_enc_precise_mbclen(q, q + clen, enc);
 +			if (MBCLEN_NEEDMORE_P(ret)) {
 +			    break;
 +			}
 +			else if (MBCLEN_INVALID_P(ret)) {
 +			    continue;
 +			}
 +			else {
 +			    rb_bug("shouldn't reach here '%s'", q);
 +			}
 +		    }
 +		    rb_str_set_len(buf, len);
 +		}
 +		p += clen;
 +		p1 = p;
 +		rb_str_buf_cat2(buf, rep);
 +	    }
 +	    else if (MBCLEN_NEEDMORE_P(ret)) {
 +		break;
 +	    }
 +	    else {
 +		rb_bug("shouldn't reach here");
 +	    }
 +	}
 +	if (p1 < p) {
 +	    rb_str_buf_cat(buf, p1, p - p1);
 +	}
 +	if (p < e) {
 +	    rb_str_buf_cat2(buf, rep);
 +	}
 +	ENCODING_CODERANGE_SET(buf, rb_enc_to_index(enc), ENC_CODERANGE_VALID);
 +	return buf;
 +    }
 +}
 +
  /**********************************************************************
   * Document-class: Symbol
   *
 @@ -7882,6 +8075,7 @@ Init_String(void)
      rb_define_method(rb_cString, "getbyte", rb_str_getbyte, 1);
      rb_define_method(rb_cString, "setbyte", rb_str_setbyte, 2);
      rb_define_method(rb_cString, "byteslice", rb_str_byteslice, -1);
 +    rb_define_method(rb_cString, "fix_invalid", rb_str_fix_invalid, 0);
  
      rb_define_method(rb_cString, "to_i", rb_str_to_i, -1);
      rb_define_method(rb_cString, "to_f", rb_str_to_f, 0);
 diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
 index 47f349c..2b0cfeb 100644
 --- a/test/ruby/test_string.rb
 +++ b/test/ruby/test_string.rb
 @@ -2031,6 +2031,29 @@ class TestString < Test::Unit::TestCase
  
      assert_equal(u("\x82")+("\u3042"*9), ("\u3042"*10).byteslice(2, 28))
    end
 +
 +  def test_fix_invalid
 +    assert_equal("\uFFFD\uFFFD\uFFFD", "\x80\x80\x80".fix_invalid)
 +    assert_equal("\uFFFDA", "\xF4\x80\x80A".fix_invalid)
 +
 +    # exapmles in Unicode 6.1.0 D93b
 +    assert_equal("\x41\uFFFD\uFFFD\x41\uFFFD\x41",
 +                 "\x41\xC0\xAF\x41\xF4\x80\x80\x41".fix_invalid)
 +    assert_equal("\x41\uFFFD\uFFFD\uFFFD\x41",
 +                 "\x41\xE0\x9F\x80\x41".fix_invalid)
 +    assert_equal("\u0061\uFFFD\uFFFD\uFFFD\u0062\uFFFD\u0063\uFFFD\uFFFD\u0064",
 +                 "\x61\xF1\x80\x80\xE1\x80\xC2\x62\x80\x63\x80\xBF\x64".fix_invalid)
 +
 +    assert_equal("abcdefghijklmnopqrstuvwxyz\u0061\uFFFD\uFFFD\uFFFD\u0062\uFFFD\u0063\uFFFD\uFFFD\u0064",
 +                 "abcdefghijklmnopqrstuvwxyz\x61\xF1\x80\x80\xE1\x80\xC2\x62\x80\x63\x80\xBF\x64".fix_invalid)
 +
 +    assert_equal("\uFFFD\u3042".encode("UTF-16BE"),
 +                 "\xD8\x00\x30\x42".force_encoding(Encoding::UTF_16BE).
 +                 fix_invalid)
 +    assert_equal("\uFFFD\u3042".encode("UTF-16LE"),
 +                 "\x00\xD8\x42\x30".force_encoding(Encoding::UTF_16LE).
 +                 fix_invalid)
 +  end
  end
  
  class TestString2 < TestString
=end



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