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[ruby/json] json_string_unescape: use memchr to search for backslashes

Browse Source 
https://github.com/ruby/json/commit/5e6cfcf724
This commit is contained in:
Jean Boussier 2025-01-16 18:31:18 +01:00 committed by Hiroshi SHIBATA
parent ba8f22c040
commit df8f93848e
Notes: git 2025-01-20 07:09:20 +00:00 
Merged: https://github.com/ruby/ruby/pull/12598
1 changed files with 73 additions and 82 deletions
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155
ext/json/parser/parser.c
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@ -592,96 +592,87 @@ static VALUE json_string_unescape(JSON_ParserState *state, const char *string, c
}
}
pe = memchr(p, '\\', bufferSize);
if (RB_UNLIKELY(pe == NULL)) {
return build_string(string, stringEnd, intern, symbolize);
}
VALUE result = rb_str_buf_new(bufferSize);
rb_enc_associate_index(result, utf8_encindex);
buffer = RSTRING_PTR(result);
bufferStart = buffer;
while (pe < stringEnd) {
if (*pe == '\\') {
unescape = (char *) "?";
unescape_len = 1;
if (pe > p) {
MEMCPY(buffer, p, char, pe - p);
buffer += pe - p;
}
switch (*++pe) {
case 'n':
unescape = (char *) "\n";
break;
case 'r':
unescape = (char *) "\r";
break;
case 't':
unescape = (char *) "\t";
break;
case '"':
unescape = (char *) "\"";
break;
case '\\':
unescape = (char *) "\\";
break;
case 'b':
unescape = (char *) "\b";
break;
case 'f':
unescape = (char *) "\f";
break;
case 'u':
if (pe > stringEnd - 4) {
raise_parse_error("incomplete unicode character escape sequence at '%s'", p);
} else {
uint32_t ch = unescape_unicode((unsigned char *) ++pe);
pe += 3;
/* To handle values above U+FFFF, we take a sequence of
* \uXXXX escapes in the U+D800..U+DBFF then
* U+DC00..U+DFFF ranges, take the low 10 bits from each
* to make a 20-bit number, then add 0x10000 to get the
* final codepoint.
*
* See Unicode 15: 3.8 "Surrogates", 5.3 "Handling
* Surrogate Pairs in UTF-16", and 23.6 "Surrogates
* Area".
*/
if ((ch & 0xFC00) == 0xD800) {
pe++;
if (pe > stringEnd - 6) {
raise_parse_error("incomplete surrogate pair at '%s'", p);
}
if (pe[0] == '\\' && pe[1] == 'u') {
uint32_t sur = unescape_unicode((unsigned char *) pe + 2);
ch = (((ch & 0x3F) << 10) | ((((ch >> 6) & 0xF) + 1) << 16)
| (sur & 0x3FF));
pe += 5;
} else {
unescape = (char *) "?";
break;
}
}
unescape_len = convert_UTF32_to_UTF8(buf, ch);
unescape = buf;
}
break;
default:
p = pe;
continue;
}
MEMCPY(buffer, unescape, char, unescape_len);
buffer += unescape_len;
p = ++pe;
} else {
pe++;
while ((pe = memchr(pe, '\\', stringEnd - pe))) {
unescape = (char *) "?";
unescape_len = 1;
if (pe > p) {
MEMCPY(buffer, p, char, pe - p);
buffer += pe - p;
}
switch (*++pe) {
case 'n':
unescape = (char *) "\n";
break;
case 'r':
unescape = (char *) "\r";
break;
case 't':
unescape = (char *) "\t";
break;
case '"':
unescape = (char *) "\"";
break;
case '\\':
unescape = (char *) "\\";
break;
case 'b':
unescape = (char *) "\b";
break;
case 'f':
unescape = (char *) "\f";
break;
case 'u':
if (pe > stringEnd - 4) {
raise_parse_error("incomplete unicode character escape sequence at '%s'", p);
} else {
uint32_t ch = unescape_unicode((unsigned char *) ++pe);
pe += 3;
/* To handle values above U+FFFF, we take a sequence of
* \uXXXX escapes in the U+D800..U+DBFF then
* U+DC00..U+DFFF ranges, take the low 10 bits from each
* to make a 20-bit number, then add 0x10000 to get the
* final codepoint.
*
* See Unicode 15: 3.8 "Surrogates", 5.3 "Handling
* Surrogate Pairs in UTF-16", and 23.6 "Surrogates
* Area".
*/
if ((ch & 0xFC00) == 0xD800) {
pe++;
if (pe > stringEnd - 6) {
raise_parse_error("incomplete surrogate pair at '%s'", p);
}
if (pe[0] == '\\' && pe[1] == 'u') {
uint32_t sur = unescape_unicode((unsigned char *) pe + 2);
ch = (((ch & 0x3F) << 10) | ((((ch >> 6) & 0xF) + 1) << 16)
| (sur & 0x3FF));
pe += 5;
} else {
unescape = (char *) "?";
break;
}
}
unescape_len = convert_UTF32_to_UTF8(buf, ch);
unescape = buf;
}
break;
default:
p = pe;
continue;
}
MEMCPY(buffer, unescape, char, unescape_len);
buffer += unescape_len;
p = ++pe;
}
if (pe > p) {
MEMCPY(buffer, p, char, pe - p);
buffer += pe - p;
if (stringEnd > p) {
MEMCPY(buffer, p, char, stringEnd - p);
buffer += stringEnd - p;
}
rb_str_set_len(result, buffer - bufferStart);