Use fast text conversion filters to implement php_mb_convert_encoding_ex

Author: alexdowad

ext/mbstring/libmbfl/mbfl/mbfl_convert.c

@@ -348,11 +348,9 @@ int mbfl_filt_conv_common_flush(mbfl_convert_filter *filter)
 	return 0;
 }
 
-zend_string* mb_fast_convert(zend_string *str, const mbfl_encoding *from, const mbfl_encoding *to, uint32_t replacement_char, unsigned int error_mode, unsigned int *num_errors)
+zend_string* mb_fast_convert(unsigned char *in, size_t in_len, const mbfl_encoding *from, const mbfl_encoding *to, uint32_t replacement_char, unsigned int error_mode, unsigned int *num_errors)
 {
 	uint32_t wchar_buf[128];
-	unsigned char *in = (unsigned char*)ZSTR_VAL(str);
-	size_t in_len = ZSTR_LEN(str);
 	unsigned int state = 0;
 
 	mb_convert_buf buf;

ext/mbstring/libmbfl/mbfl/mbfl_convert.h

@@ -81,7 +81,7 @@ MBFLAPI extern int mbfl_filt_conv_common_flush(mbfl_convert_filter *filter);
 MBFLAPI extern void mbfl_convert_filter_devcat(mbfl_convert_filter *filter, mbfl_memory_device *src);
 MBFLAPI extern int mbfl_convert_filter_strcat(mbfl_convert_filter *filter, const unsigned char *p);
 
-MBFLAPI extern zend_string* mb_fast_convert(zend_string *str, const mbfl_encoding *from, const mbfl_encoding *to, uint32_t replacement_char, unsigned int error_mode, unsigned int *num_errors);
+MBFLAPI extern zend_string* mb_fast_convert(unsigned char *in, size_t in_len, const mbfl_encoding *from, const mbfl_encoding *to, uint32_t replacement_char, unsigned int error_mode, unsigned int *num_errors);
 MBFLAPI extern void mb_illegal_output(uint32_t bad_cp, mb_from_wchar_fn fn, mb_convert_buf* buf);
 
 #endif /* MBFL_CONVERT_H */

ext/mbstring/mbstring.c

@@ -2353,39 +2353,15 @@ static inline bool php_mb_is_no_encoding_utf8(enum mbfl_no_encoding no_enc)
 
 MBSTRING_API char *php_mb_convert_encoding_ex(const char *input, size_t length, const mbfl_encoding *to_encoding, const mbfl_encoding *from_encoding, size_t *output_len)
 {
-	mbfl_string string, result, *ret;
-	mbfl_buffer_converter *convd;
-	char *output = NULL;
-
-	if (output_len) {
-		*output_len = 0;
-	}
+	unsigned int num_errors = 0;
+	zend_string *result = mb_fast_convert((unsigned char*)input, length, from_encoding, to_encoding, MBSTRG(current_filter_illegal_substchar), MBSTRG(current_filter_illegal_mode), &num_errors);
 
-	/* initialize string */
-	string.encoding = from_encoding;
-	string.val = (unsigned char *)input;
-	string.len = length;
-
-	/* initialize converter */
-	convd = mbfl_buffer_converter_new(from_encoding, to_encoding, string.len);
-	/* If this assertion fails this means some memory allocation failure which is a bug */
-	ZEND_ASSERT(convd != NULL);
+	MBSTRG(illegalchars) += num_errors;
+	*output_len = ZSTR_LEN(result);
 
-	mbfl_buffer_converter_illegal_mode(convd, MBSTRG(current_filter_illegal_mode));
-	mbfl_buffer_converter_illegal_substchar(convd, MBSTRG(current_filter_illegal_substchar));
-
-	/* do it */
-	mbfl_string_init(&result);
-	ret = mbfl_buffer_converter_feed_result(convd, &string, &result);
-	if (ret) {
-		if (output_len) {
-			*output_len = ret->len;
-		}
-		output = (char *)ret->val;
-	}
-
-	MBSTRG(illegalchars) += mbfl_buffer_illegalchars(convd);
-	mbfl_buffer_converter_delete(convd);
+	char *output = emalloc(ZSTR_LEN(result) + 1);
+	memcpy(output, ZSTR_VAL(result), ZSTR_LEN(result) + 1);
+	efree(result);
 	return output;
 }
 /* }}} */
@@ -2573,7 +2549,7 @@ PHP_FUNCTION(mb_convert_encoding)
 			const mbfl_encoding *from_encoding = from_encodings[0];
 			if (from_encoding->to_wchar && to_encoding->from_wchar) {
 				unsigned int num_errors = 0;
-				RETVAL_STR(mb_fast_convert(input_str, from_encoding, to_encoding, MBSTRG(current_filter_illegal_substchar), MBSTRG(current_filter_illegal_mode), &num_errors));
+				RETVAL_STR(mb_fast_convert((unsigned char*)ZSTR_VAL(input_str), ZSTR_LEN(input_str), from_encoding, to_encoding, MBSTRG(current_filter_illegal_substchar), MBSTRG(current_filter_illegal_mode), &num_errors));
 				MBSTRG(illegalchars) += num_errors;
 				goto out;
 			}

sapi/fuzzer/fuzzer-mbstring.c

@@ -51,7 +51,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
 		return 0;
 	}
 
-	char *Result = php_mb_convert_encoding_ex((char *) Data, Size, ToEncoding, FromEncoding, NULL);
+	size_t output_len;
+	char *Result = php_mb_convert_encoding_ex((char *) Data, Size, ToEncoding, FromEncoding, &output_len);
 	efree(Result);
 	efree(ToEncodingName);
 	efree(FromEncodingName);