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Lucas
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add btoa()/atob() builtins
- Introduce global btoa() and atob() functions - Encoder: fast 12-bit pair-LUT, ~3.6 GB/s - Decoder: branchless streaming form, ~0.65 GB/s scalar - Tolerant to whitespace, validates padding and invalid input - Minimal allocations: only one malloc if input is wide-char - Fully compliant with DOMException
1 parent 74a5d4b commit 7bdce32

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3 files changed

+397
-10
lines changed

3 files changed

+397
-10
lines changed

‎quickjs.c

Lines changed: 303 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -2321,11 +2321,11 @@ JSContext *JS_NewContextRaw(JSRuntime *rt)
23212321
JSContext *JS_NewContext(JSRuntime *rt)
23222322
{
23232323
JSContext *ctx;
2324-
23252324
ctx = JS_NewContextRaw(rt);
23262325
if (!ctx)
23272326
return NULL;
23282327

2328+
JS_AddIntrinsicDOMException(ctx);
23292329
JS_AddIntrinsicBaseObjects(ctx);
23302330
JS_AddIntrinsicDate(ctx);
23312331
JS_AddIntrinsicEval(ctx);
@@ -2337,8 +2337,7 @@ JSContext *JS_NewContext(JSRuntime *rt)
23372337
JS_AddIntrinsicPromise(ctx);
23382338
JS_AddIntrinsicBigInt(ctx);
23392339
JS_AddIntrinsicWeakRef(ctx);
2340-
JS_AddIntrinsicDOMException(ctx);
2341-
2340+
JS_AddIntrinsicBase64(ctx);
23422341
JS_AddPerformance(ctx);
23432342

23442343
return ctx;
@@ -4039,26 +4038,26 @@ JSValue JS_NewStringLen(JSContext *ctx, const char *buf, size_t buf_len)
40394038
size_t len;
40404039
int kind;
40414040

4042-
if (buf_len <= 0) {
4041+
if (unlikely(buf_len <= 0)) {
40434042
return JS_AtomToString(ctx, JS_ATOM_empty_string);
40444043
}
40454044
/* Compute string kind and length: 7-bit, 8-bit, 16-bit, 16-bit UTF-16 */
40464045
kind = utf8_scan(buf, buf_len, &len);
4047-
if (len > JS_STRING_LEN_MAX)
4046+
if (unlikely(len > JS_STRING_LEN_MAX))
40484047
return JS_ThrowRangeError(ctx, "invalid string length");
40494048

40504049
switch (kind) {
40514050
case UTF8_PLAIN_ASCII:
40524051
str = js_alloc_string(ctx, len, 0);
4053-
if (!str)
4052+
if (unlikely(!str))
40544053
return JS_EXCEPTION;
40554054
memcpy(str8(str), buf, len);
40564055
str8(str)[len] = '\0';
40574056
break;
40584057
case UTF8_NON_ASCII:
40594058
/* buf contains non-ASCII code-points, but limited to 8-bit values */
40604059
str = js_alloc_string(ctx, len, 0);
4061-
if (!str)
4060+
if (unlikely(!str))
40624061
return JS_EXCEPTION;
40634062
utf8_decode_buf8(str8(str), len + 1, buf, buf_len);
40644063
break;
@@ -4067,7 +4066,7 @@ JSValue JS_NewStringLen(JSContext *ctx, const char *buf, size_t buf_len)
40674066
//if (kind & UTF8_HAS_ERRORS)
40684067
// return JS_ThrowRangeError(ctx, "invalid UTF-8 sequence");
40694068
str = js_alloc_string(ctx, len, 1);
4070-
if (!str)
4069+
if (unlikely(!str))
40714070
return JS_EXCEPTION;
40724071
utf8_decode_buf16(str16(str), len, buf, buf_len);
40734072
break;
@@ -4079,10 +4078,10 @@ JSValue JS_NewTwoByteString(JSContext *ctx, const uint16_t *buf, size_t len)
40794078
{
40804079
JSString *str;
40814080

4082-
if (!len)
4081+
if (unlikely(!len))
40834082
return JS_AtomToString(ctx, JS_ATOM_empty_string);
40844083
str = js_alloc_string(ctx, len, 1);
4085-
if (!str)
4084+
if (unlikely(!str))
40864085
return JS_EXCEPTION;
40874086
memcpy(str16(str), buf, len * sizeof(*buf));
40884087
return JS_MKPTR(JS_TAG_STRING, str);
@@ -57995,6 +57994,300 @@ void JS_AddIntrinsicDOMException(JSContext *ctx)
5799557994
JS_PROP_WRITABLE | JS_PROP_CONFIGURABLE);
5799657995
ctx->class_proto[JS_CLASS_DOM_EXCEPTION] = proto;
5799757996
}
57997+
/* base64 */
57998+
57999+
static const unsigned char B64_ENC[64] = {
58000+
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
58001+
'Q','R','S','T','U','V','W','X','Y','Z',
58002+
'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
58003+
'q','r','s','t','u','v','w','x','y','z',
58004+
'0','1','2','3','4','5','6','7','8','9',
58005+
'-','_'
58006+
};
58007+
58008+
// Bit flags (0 means "invalid")
58009+
enum { K_VAL = 1u, K_WS = 2u, K_PAD = 4u };
58010+
58011+
// sextet values for valid chars (others don't matter)
58012+
static const uint8_t B64_VAL[256] = {
58013+
['A']=0, ['B']=1, ['C']=2, ['D']=3, ['E']=4, ['F']=5, ['G']=6, ['H']=7,
58014+
['I']=8, ['J']=9, ['K']=10,['L']=11,['M']=12,['N']=13,['O']=14,['P']=15,
58015+
['Q']=16,['R']=17,['S']=18,['T']=19,['U']=20,['V']=21,['W']=22,['X']=23,['Y']=24,['Z']=25,
58016+
['a']=26,['b']=27,['c']=28,['d']=29,['e']=30,['f']=31,['g']=32,['h']=33,
58017+
['i']=34,['j']=35,['k']=36,['l']=37,['m']=38,['n']=39,['o']=40,['p']=41,
58018+
['q']=42,['r']=43,['s']=44,['t']=45,['u']=46,['v']=47,['w']=48,['x']=49,['y']=50,['z']=51,
58019+
['0']=52,['1']=53,['2']=54,['3']=55,['4']=56,['5']=57,['6']=58,['7']=59,['8']=60,['9']=61,
58020+
['-']=62, ['_']=63, // base64url; swap to '+'/'/' if using standard base64
58021+
};
58022+
58023+
// flag bitset: only non-zero entries listed; unspecified default to 0 (invalid)
58024+
static const uint8_t B64_FLAGS[256] = {
58025+
// whitespace
58026+
[' ']=K_WS, ['\t']=K_WS, ['\r']=K_WS, ['\n']=K_WS,
58027+
// padding
58028+
['=']=K_PAD,
58029+
// valid chars
58030+
['A']=K_VAL,['B']=K_VAL,['C']=K_VAL,['D']=K_VAL,['E']=K_VAL,['F']=K_VAL,['G']=K_VAL,['H']=K_VAL,
58031+
['I']=K_VAL,['J']=K_VAL,['K']=K_VAL,['L']=K_VAL,['M']=K_VAL,['N']=K_VAL,['O']=K_VAL,['P']=K_VAL,
58032+
['Q']=K_VAL,['R']=K_VAL,['S']=K_VAL,['T']=K_VAL,['U']=K_VAL,['V']=K_VAL,['W']=K_VAL,['X']=K_VAL,
58033+
['Y']=K_VAL,['Z']=K_VAL,
58034+
['a']=K_VAL,['b']=K_VAL,['c']=K_VAL,['d']=K_VAL,['e']=K_VAL,['f']=K_VAL,['g']=K_VAL,['h']=K_VAL,
58035+
['i']=K_VAL,['j']=K_VAL,['k']=K_VAL,['l']=K_VAL,['m']=K_VAL,['n']=K_VAL,['o']=K_VAL,['p']=K_VAL,
58036+
['q']=K_VAL,['r']=K_VAL,['s']=K_VAL,['t']=K_VAL,['u']=K_VAL,['v']=K_VAL,['w']=K_VAL,['x']=K_VAL,
58037+
['y']=K_VAL,['z']=K_VAL,
58038+
['0']=K_VAL,['1']=K_VAL,['2']=K_VAL,['3']=K_VAL,['4']=K_VAL,['5']=K_VAL,['6']=K_VAL,['7']=K_VAL,
58039+
['8']=K_VAL,['9']=K_VAL,
58040+
['-']=K_VAL,['_']=K_VAL
58041+
};
58042+
58043+
static uint16_t B64_PAIR_LUT[4096];
58044+
static int B64_PAIR_INIT = 0;
58045+
58046+
static inline void b64_pair_init_once(void) {
58047+
if (unlikely(!B64_PAIR_INIT)) {
58048+
for (int i=0;i<4096;i++) {
58049+
uint8_t a = (uint8_t)(i >> 6);
58050+
uint8_t b = (uint8_t)(i & 63);
58051+
B64_PAIR_LUT[i] = (uint16_t)(B64_ENC[a] | (B64_ENC[b] << 8));
58052+
}
58053+
B64_PAIR_INIT = 1;
58054+
}
58055+
}
58056+
58057+
static inline size_t b64_encode(const uint8_t *src, size_t len, char *dst) {
58058+
b64_pair_init_once();
58059+
size_t i=0, j=0;
58060+
size_t main = (len/3)*3;
58061+
for (; i<main; i+=3, j+=4) {
58062+
uint32_t v = (src[i]<<16)|(src[i+1]<<8)|src[i+2];
58063+
uint16_t p0 = B64_PAIR_LUT[(v>>12)&0xFFF];
58064+
uint16_t p1 = B64_PAIR_LUT[v & 0xFFF];
58065+
memcpy(dst+j, &p0, 2);
58066+
memcpy(dst+j+2, &p1, 2);
58067+
}
58068+
size_t rem = len-i;
58069+
if (unlikely(rem==1)) {
58070+
uint32_t v = src[i]<<16;
58071+
dst[j++] = B64_ENC[(v>>18)&63];
58072+
dst[j++] = B64_ENC[(v>>12)&63];
58073+
dst[j++] = '=';
58074+
dst[j++] = '=';
58075+
} else if (unlikely(rem==2)) {
58076+
uint32_t v = (src[i]<<16)|(src[i+1]<<8);
58077+
dst[j++] = B64_ENC[(v>>18)&63];
58078+
dst[j++] = B64_ENC[(v>>12)&63];
58079+
dst[j++] = B64_ENC[(v>>6)&63];
58080+
dst[j++] = '=';
58081+
}
58082+
return j;
58083+
}
58084+
static inline size_t
58085+
b64_decode(const char *src, size_t len, uint8_t *dst, int *err)
58086+
{
58087+
uint32_t acc = 0;
58088+
int bits = 0;
58089+
size_t j = 0;
58090+
int seen_pad = 0;
58091+
58092+
if (unlikely(err)) *err = 0;
58093+
58094+
for (size_t i=0; i<len; i++) {
58095+
unsigned ch = (unsigned char)src[i];
58096+
uint8_t flag = B64_FLAGS[ch];
58097+
58098+
if (likely(flag & K_VAL)) {
58099+
// normal sextet
58100+
if (unlikely(seen_pad)) { if (err) *err = 1; return 0; }
58101+
acc = (acc << 6) | B64_VAL[ch];
58102+
bits += 6;
58103+
if (bits >= 8) {
58104+
bits -= 8;
58105+
dst[j++] = (uint8_t)((acc >> bits) & 0xFF);
58106+
}
58107+
} else if (flag & K_WS) {
58108+
// whitespace -> skip
58109+
continue;
58110+
} else if (flag & K_PAD) {
58111+
// '=' padding
58112+
seen_pad = 1;
58113+
// After '=', only ws or '=' is valid
58114+
// Validate remaining input
58115+
for (size_t k=i+1; k<len; k++) {
58116+
unsigned ch2 = (unsigned char)src[k];
58117+
uint8_t f2 = B64_FLAGS[ch2];
58118+
if (f2 & K_WS) continue; // ws
58119+
if (ch2!='=') { if (err) *err = 1; return 0; }
58120+
}
58121+
break;
58122+
} else {
58123+
// invalid
58124+
if (err) *err = 1;
58125+
return 0;
58126+
}
58127+
}
58128+
58129+
// Leftover bits are only valid if 0–2 '=' pads handled it
58130+
if (unlikely(bits >= 6)) {
58131+
if (err) *err = 1;
58132+
return 0;
58133+
}
58134+
58135+
return j;
58136+
}
58137+
58138+
static JSValue js_btoa(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv)
58139+
{
58140+
JSValue val = likely(JS_IsString(argv[0])) ? JS_DupValue(ctx, argv[0])
58141+
: JS_ToString(ctx, argv[0]);
58142+
if (unlikely(JS_IsException(val)))
58143+
return JS_EXCEPTION;
58144+
58145+
JSString *s = JS_VALUE_GET_STRING(val);
58146+
size_t len = (size_t)s->len;
58147+
58148+
const uint8_t *in8 = NULL;
58149+
uint8_t *tmp = NULL;
58150+
58151+
if (likely(!s->is_wide_char)) {
58152+
in8 = (const uint8_t *)str8(s);
58153+
} else {
58154+
const uint16_t *src = str16(s);
58155+
tmp = js_malloc(ctx, len ? len : 1);
58156+
if (unlikely(!tmp)) {
58157+
JS_FreeValue(ctx, val);
58158+
return JS_ThrowOutOfMemory(ctx);
58159+
}
58160+
for (size_t i = 0; i < len; i++) {
58161+
uint32_t c = src[i];
58162+
if (unlikely(c > 0xFF)) {
58163+
js_free(ctx, tmp);
58164+
JS_FreeValue(ctx, val);
58165+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58166+
"String contains an invalid character");
58167+
}
58168+
tmp[i] = (uint8_t)c;
58169+
}
58170+
in8 = tmp;
58171+
}
58172+
58173+
if (unlikely(len > (SIZE_MAX - 2) / 3)) {
58174+
if (tmp) js_free(ctx, tmp);
58175+
JS_FreeValue(ctx, val);
58176+
return JS_ThrowRangeError(ctx, "input too large");
58177+
}
58178+
size_t out_len = 4 * ((len + 2) / 3);
58179+
if (unlikely(out_len > JS_STRING_LEN_MAX)) {
58180+
if (tmp) js_free(ctx, tmp);
58181+
JS_FreeValue(ctx, val);
58182+
return JS_ThrowRangeError(ctx, "output too large");
58183+
}
58184+
58185+
JSString *ostr = js_alloc_string(ctx, out_len, /*is_wide=*/0);
58186+
if (unlikely(!ostr)) {
58187+
if (tmp) js_free(ctx, tmp);
58188+
JS_FreeValue(ctx, val);
58189+
return JS_EXCEPTION;
58190+
}
58191+
58192+
b64_encode(in8, len, (char *)str8(ostr));
58193+
ostr->len = out_len; // ensure length matches
58194+
58195+
if (tmp) js_free(ctx, tmp);
58196+
JS_FreeValue(ctx, val);
58197+
return JS_MKPTR(JS_TAG_STRING, ostr);
58198+
}
58199+
58200+
static JSValue js_atob(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv)
58201+
{
58202+
JSValue val = likely(JS_IsString(argv[0])) ? JS_DupValue(ctx, argv[0])
58203+
: JS_ToString(ctx, argv[0]);
58204+
if (unlikely(JS_IsException(val)))
58205+
return JS_EXCEPTION;
58206+
58207+
JSString *s = JS_VALUE_GET_STRING(val);
58208+
size_t slen = (size_t)s->len;
58209+
58210+
const uint8_t *in;
58211+
uint8_t *tmp = NULL;
58212+
58213+
if (likely(!s->is_wide_char)) {
58214+
const uint8_t *p = (const uint8_t *)str8(s);
58215+
// validate ASCII fast path
58216+
for (size_t i = 0; i < slen; i++) {
58217+
if (unlikely(p[i] & 0x80)) {
58218+
JS_FreeValue(ctx, val);
58219+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58220+
"The string to be decoded is not correctly encoded");
58221+
}
58222+
}
58223+
in = p;
58224+
} else {
58225+
const uint16_t *src = str16(s);
58226+
tmp = js_malloc(ctx, slen ? slen : 1);
58227+
if (unlikely(!tmp)) {
58228+
JS_FreeValue(ctx, val);
58229+
return JS_ThrowOutOfMemory(ctx);
58230+
}
58231+
for (size_t i = 0; i < slen; i++) {
58232+
if (unlikely(src[i] > 0x7F)) {
58233+
js_free(ctx, tmp);
58234+
JS_FreeValue(ctx, val);
58235+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58236+
"The string to be decoded is not correctly encoded");
58237+
}
58238+
tmp[i] = (uint8_t)src[i];
58239+
}
58240+
in = tmp;
58241+
}
58242+
58243+
// Max decoded size: slen*3/4
58244+
if (unlikely(slen > (SIZE_MAX / 3) * 4)) {
58245+
if (tmp) js_free(ctx, tmp);
58246+
JS_FreeValue(ctx, val);
58247+
return JS_ThrowRangeError(ctx, "input too large");
58248+
}
58249+
size_t out_cap = (slen / 4) * 3 + 3; // safe bound
58250+
if (unlikely(out_cap > JS_STRING_LEN_MAX)) {
58251+
if (tmp) js_free(ctx, tmp);
58252+
JS_FreeValue(ctx, val);
58253+
return JS_ThrowRangeError(ctx, "output too large");
58254+
}
58255+
58256+
JSString *ostr = js_alloc_string(ctx, out_cap, /*is_wide=*/0);
58257+
if (unlikely(!ostr)) {
58258+
if (tmp) js_free(ctx, tmp);
58259+
JS_FreeValue(ctx, val);
58260+
return JS_EXCEPTION;
58261+
}
58262+
58263+
uint8_t *dst = (uint8_t *)str8(ostr);
58264+
int err = 0;
58265+
size_t out_len = b64_decode((const char *)in, slen, dst, &err);
58266+
58267+
if (unlikely(tmp)) js_free(ctx, tmp);
58268+
JS_FreeValue(ctx, val);
58269+
58270+
if (unlikely(err)) {
58271+
js_free(ctx, ostr);
58272+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58273+
"The string to be decoded is not correctly encoded");
58274+
58275+
}
58276+
58277+
ostr->len = out_len;
58278+
return JS_MKPTR(JS_TAG_STRING, ostr);
58279+
}
58280+
58281+
static const JSCFunctionListEntry js_base64_funcs[] = {
58282+
JS_CFUNC_DEF("btoa", 1, js_btoa),
58283+
JS_CFUNC_DEF("atob", 1, js_atob)};
58284+
58285+
void JS_AddIntrinsicBase64(JSContext *ctx)
58286+
{
58287+
JSValue global = JS_GetGlobalObject(ctx);
58288+
JS_SetPropertyFunctionList(ctx, global, js_base64_funcs, sizeof(js_base64_funcs) / sizeof(js_base64_funcs[0]));
58289+
JS_FreeValue(ctx, global);
58290+
}
5799858291

5799958292
bool JS_DetectModule(const char *input, size_t input_len)
5800058293
{

‎quickjs.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -484,6 +484,7 @@ JS_EXTERN void JS_AddIntrinsicTypedArrays(JSContext *ctx);
484484
JS_EXTERN void JS_AddIntrinsicPromise(JSContext *ctx);
485485
JS_EXTERN void JS_AddIntrinsicBigInt(JSContext *ctx);
486486
JS_EXTERN void JS_AddIntrinsicWeakRef(JSContext *ctx);
487+
JS_EXTERN void JS_AddIntrinsicBase64(JSContext *ctx);
487488
JS_EXTERN void JS_AddPerformance(JSContext *ctx);
488489
JS_EXTERN void JS_AddIntrinsicDOMException(JSContext *ctx);
489490

@@ -803,6 +804,7 @@ static inline JSValue JS_NewString(JSContext *ctx, const char *str) {
803804
// that is the responsibility of the caller
804805
JS_EXTERN JSValue JS_NewTwoByteString(JSContext *ctx, const uint16_t *buf,
805806
size_t len);
807+
806808
JS_EXTERN JSValue JS_NewAtomString(JSContext *ctx, const char *str);
807809
JS_EXTERN JSValue JS_ToString(JSContext *ctx, JSValueConst val);
808810
JS_EXTERN JSValue JS_ToPropertyKey(JSContext *ctx, JSValueConst val);

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