Fix problems with ISO-2022-KR conversion

• The legacy conversion code did not emit an error marker if an
  escape sequence was truncated.

• BOTH old and new conversion code would shift from KSC5601
  (KS X 1001) mode to ASCII mode on an invalid escape sequence.
  This doesn't make any sense.

Author: alexdowad

ext/mbstring/libmbfl/filters/mbfilter_iso2022_kr.c

@@ -145,7 +145,7 @@ int mbfl_filt_conv_2022kr_wchar(int c, mbfl_convert_filter *filter)
 		if (c == '$') {
 			filter->status++;
 		} else {
-			filter->status = 0;
+			filter->status &= ~0xF;
 			CK((*filter->output_function)(MBFL_BAD_INPUT, filter->data));
 		}
 		break;
@@ -154,7 +154,7 @@ int mbfl_filt_conv_2022kr_wchar(int c, mbfl_convert_filter *filter)
 		if (c == ')') {
 			filter->status++;
 		} else {
-			filter->status = 0;
+			filter->status &= ~0xF;
 			CK((*filter->output_function)(MBFL_BAD_INPUT, filter->data));
 		}
 		break;
@@ -258,6 +258,10 @@ int mbfl_filt_conv_wchar_2022kr(int c, mbfl_convert_filter *filter)
 
 static int mbfl_filt_conv_any_2022kr_flush(mbfl_convert_filter *filter)
 {
+	if (filter->status & 0xF) {
+		/* Escape sequence or 2-byte character was truncated */
+		(*filter->output_function)(MBFL_BAD_INPUT, filter->data);
+	}
 	/* back to ascii */
 	if (filter->status & 0x10) {
 		CK((*filter->output_function)(0x0f, filter->data)); /* shift in */
@@ -305,7 +309,6 @@ static size_t mb_iso2022kr_to_wchar(unsigned char **in, size_t *in_len, uint32_t
 						p--;
 				}
 				*out++ = MBFL_BAD_INPUT;
-				*state = ASCII;
 			}
 		} else if (c == 0xF) {
 			*state = ASCII;

ext/mbstring/tests/iso2022kr_encoding.phpt

@@ -114,6 +114,9 @@ convertInvalidString("\xFF\x86", "\x1B\$)C%", "UTF-16BE", "ISO-2022-KR");
 // character at the end of a string, although the string was already ending in ASCII mode
 convertValidString("\x68\x46\x00a", "\x1B\$)C\x0E\x68\x46\x0Fa", "UTF-16BE", "ISO-2022-KR", false);
 
+// Regression test: Don't shift from KS X 1001 to ASCII mode on invalid escape sequence
+convertInvalidString("\x0E\x1BX\x74\x30", "\x00%\x76\x20", "ISO-2022-KR", "UTF-16BE", false);
+
 // Test "long" illegal character markers
 mb_substitute_character("long");
 convertInvalidString("\x1B", "%", "ISO-2022-KR", "UTF-8");