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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 db79b5a

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3 files changed

+404
-10
lines changed

3 files changed

+404
-10
lines changed

‎quickjs.c

Lines changed: 311 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 +57994,308 @@ 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 char 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 char B64_PAIR_LUT[4096][2];
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][0] = B64_ENC[a];
58052+
B64_PAIR_LUT[i][1] = B64_ENC[b];
58053+
}
58054+
B64_PAIR_INIT = 1;
58055+
}
58056+
}
58057+
58058+
static inline size_t b64_encode(const uint8_t *src, size_t len, char *dst) {
58059+
b64_pair_init_once();
58060+
size_t i = 0, j = 0;
58061+
size_t main = (len/3)*3;
58062+
58063+
for (; i < main; i += 3, j += 4) {
58064+
uint32_t v = ((uint32_t)src[i] << 16) | ((uint32_t)src[i+1] << 8) | (uint32_t)src[i+2];
58065+
const char *p0 = B64_PAIR_LUT[(v >> 12) & 0xFFF]; // [ sextet0 | sextet1 ]
58066+
const char *p1 = B64_PAIR_LUT[v & 0xFFF]; // [ sextet2 | sextet3 ]
58067+
dst[j+0] = p0[0];
58068+
dst[j+1] = p0[1];
58069+
dst[j+2] = p1[0];
58070+
dst[j+3] = p1[1];
58071+
}
58072+
58073+
size_t rem = len - i;
58074+
if (rem == 1) {
58075+
uint32_t v = ((uint32_t)src[i] << 16);
58076+
dst[j++] = B64_ENC[(v >> 18) & 63];
58077+
dst[j++] = B64_ENC[(v >> 12) & 63];
58078+
dst[j++] = '=';
58079+
dst[j++] = '=';
58080+
} else if (rem == 2) {
58081+
uint32_t v = ((uint32_t)src[i] << 16) | ((uint32_t)src[i+1] << 8);
58082+
dst[j++] = B64_ENC[(v >> 18) & 63];
58083+
dst[j++] = B64_ENC[(v >> 12) & 63];
58084+
dst[j++] = B64_ENC[(v >> 6) & 63];
58085+
dst[j++] = '=';
58086+
}
58087+
return j;
58088+
}
58089+
58090+
static inline size_t
58091+
b64_decode(const char *src, size_t len, uint8_t *dst, int *err)
58092+
{
58093+
uint32_t acc = 0;
58094+
int bits = 0;
58095+
size_t j = 0;
58096+
int seen_pad = 0;
58097+
58098+
if (unlikely(err)) *err = 0;
58099+
58100+
for (size_t i=0; i<len; i++) {
58101+
unsigned ch = (unsigned char)src[i];
58102+
uint8_t flag = B64_FLAGS[ch];
58103+
58104+
if (likely(flag & K_VAL)) {
58105+
// normal sextet
58106+
if (unlikely(seen_pad)) { if (err) *err = 1; return 0; }
58107+
acc = (acc << 6) | B64_VAL[ch];
58108+
bits += 6;
58109+
if (bits >= 8) {
58110+
bits -= 8;
58111+
dst[j++] = (uint8_t)((acc >> bits) & 0xFF);
58112+
}
58113+
} else if (flag & K_WS) {
58114+
// whitespace -> skip
58115+
continue;
58116+
} else if (flag & K_PAD) {
58117+
// '=' padding
58118+
seen_pad = 1;
58119+
// After '=', only ws or '=' is valid
58120+
// Validate remaining input
58121+
for (size_t k=i+1; k<len; k++) {
58122+
unsigned ch2 = (unsigned char)src[k];
58123+
uint8_t f2 = B64_FLAGS[ch2];
58124+
if (f2 & K_WS) continue; // ws
58125+
if (ch2!='=') { if (err) *err = 1; return 0; }
58126+
}
58127+
break;
58128+
} else {
58129+
// invalid
58130+
if (err) *err = 1;
58131+
return 0;
58132+
}
58133+
}
58134+
58135+
// Leftover bits are only valid if 0–2 '=' pads handled it
58136+
if (unlikely(bits >= 6)) {
58137+
if (err) *err = 1;
58138+
return 0;
58139+
}
58140+
58141+
return j;
58142+
}
58143+
58144+
static JSValue js_btoa(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv)
58145+
{
58146+
JSValue val = likely(JS_IsString(argv[0])) ? JS_DupValue(ctx, argv[0])
58147+
: JS_ToString(ctx, argv[0]);
58148+
if (unlikely(JS_IsException(val)))
58149+
return JS_EXCEPTION;
58150+
58151+
JSString *s = JS_VALUE_GET_STRING(val);
58152+
size_t len = (size_t)s->len;
58153+
58154+
const uint8_t *in8 = NULL;
58155+
uint8_t *tmp = NULL;
58156+
58157+
if (likely(!s->is_wide_char)) {
58158+
in8 = (const uint8_t *)str8(s);
58159+
} else {
58160+
const uint16_t *src = str16(s);
58161+
tmp = js_malloc(ctx, likely(len) ? len : 1);
58162+
if (unlikely(!tmp)) {
58163+
JS_FreeValue(ctx, val);
58164+
return JS_ThrowOutOfMemory(ctx);
58165+
}
58166+
for (size_t i = 0; i < len; i++) {
58167+
uint32_t c = src[i];
58168+
if (unlikely(c > 0xFF)) {
58169+
js_free(ctx, tmp);
58170+
JS_FreeValue(ctx, val);
58171+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58172+
"String contains an invalid character");
58173+
}
58174+
tmp[i] = (uint8_t)c;
58175+
}
58176+
in8 = tmp;
58177+
}
58178+
58179+
if (unlikely(len > (SIZE_MAX - 2) / 3)) {
58180+
if (tmp) js_free(ctx, tmp);
58181+
JS_FreeValue(ctx, val);
58182+
return JS_ThrowRangeError(ctx, "input too large");
58183+
}
58184+
size_t out_len = 4 * ((len + 2) / 3);
58185+
if (unlikely(out_len > JS_STRING_LEN_MAX)) {
58186+
if (tmp) js_free(ctx, tmp);
58187+
JS_FreeValue(ctx, val);
58188+
return JS_ThrowRangeError(ctx, "output too large");
58189+
}
58190+
58191+
JSString *ostr = js_alloc_string(ctx, out_len, /*is_wide=*/0);
58192+
if (unlikely(!ostr)) {
58193+
if (tmp) js_free(ctx, tmp);
58194+
JS_FreeValue(ctx, val);
58195+
return JS_EXCEPTION;
58196+
}
58197+
char *outp = (char *)str8(ostr);
58198+
58199+
size_t written = b64_encode(in8, len, outp);
58200+
outp[written] = '\0';
58201+
ostr->len = out_len; // ensure length matches
58202+
58203+
if (tmp) js_free(ctx, tmp);
58204+
JS_FreeValue(ctx, val);
58205+
return JS_MKPTR(JS_TAG_STRING, ostr);
58206+
}
58207+
58208+
static JSValue js_atob(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv)
58209+
{
58210+
JSValue val = likely(JS_IsString(argv[0])) ? JS_DupValue(ctx, argv[0])
58211+
: JS_ToString(ctx, argv[0]);
58212+
if (unlikely(JS_IsException(val)))
58213+
return JS_EXCEPTION;
58214+
58215+
JSString *s = JS_VALUE_GET_STRING(val);
58216+
size_t slen = (size_t)s->len;
58217+
58218+
const uint8_t *in;
58219+
uint8_t *tmp = NULL;
58220+
58221+
if (likely(!s->is_wide_char)) {
58222+
const uint8_t *p = (const uint8_t *)str8(s);
58223+
// validate ASCII fast path
58224+
for (size_t i = 0; i < slen; i++) {
58225+
if (unlikely(p[i] & 0x80)) {
58226+
JS_FreeValue(ctx, val);
58227+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58228+
"The string to be decoded is not correctly encoded");
58229+
}
58230+
}
58231+
in = p;
58232+
} else {
58233+
const uint16_t *src = str16(s);
58234+
tmp = js_malloc(ctx, likely(slen) ? slen : 1);
58235+
if (unlikely(!tmp)) {
58236+
JS_FreeValue(ctx, val);
58237+
return JS_ThrowOutOfMemory(ctx);
58238+
}
58239+
for (size_t i = 0; i < slen; i++) {
58240+
if (unlikely(src[i] > 0x7F)) {
58241+
js_free(ctx, tmp);
58242+
JS_FreeValue(ctx, val);
58243+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58244+
"The string to be decoded is not correctly encoded");
58245+
}
58246+
tmp[i] = (uint8_t)src[i];
58247+
}
58248+
in = tmp;
58249+
}
58250+
58251+
// Max decoded size: slen*3/4
58252+
if (unlikely(slen > (SIZE_MAX / 3) * 4)) {
58253+
if (tmp) js_free(ctx, tmp);
58254+
JS_FreeValue(ctx, val);
58255+
return JS_ThrowRangeError(ctx, "input too large");
58256+
}
58257+
size_t out_cap = (slen / 4) * 3 + 3; // safe bound
58258+
if (unlikely(out_cap > JS_STRING_LEN_MAX)) {
58259+
if (tmp) js_free(ctx, tmp);
58260+
JS_FreeValue(ctx, val);
58261+
return JS_ThrowRangeError(ctx, "output too large");
58262+
}
58263+
58264+
JSString *ostr = js_alloc_string(ctx, out_cap, /*is_wide=*/0);
58265+
if (unlikely(!ostr)) {
58266+
if (tmp) js_free(ctx, tmp);
58267+
JS_FreeValue(ctx, val);
58268+
return JS_EXCEPTION;
58269+
}
58270+
58271+
uint8_t *dst = (uint8_t *)str8(ostr);
58272+
int err = 0;
58273+
size_t out_len = b64_decode((const char *)in, slen, dst, &err);
58274+
58275+
if (unlikely(tmp)) js_free(ctx, tmp);
58276+
JS_FreeValue(ctx, val);
58277+
58278+
if (unlikely(err)) {
58279+
js_free_string(ctx->rt, ostr);
58280+
return JS_ThrowDOMException(ctx, "InvalidCharacterError",
58281+
"The string to be decoded is not correctly encoded");
58282+
58283+
}
58284+
dst[out_len] = '\0';
58285+
ostr->len = out_len;
58286+
return JS_MKPTR(JS_TAG_STRING, ostr);
58287+
}
58288+
58289+
static const JSCFunctionListEntry js_base64_funcs[] = {
58290+
JS_CFUNC_DEF("btoa", 1, js_btoa),
58291+
JS_CFUNC_DEF("atob", 1, js_atob)};
58292+
58293+
void JS_AddIntrinsicBase64(JSContext *ctx)
58294+
{
58295+
JSValue global = JS_GetGlobalObject(ctx);
58296+
JS_SetPropertyFunctionList(ctx, global, js_base64_funcs, sizeof(js_base64_funcs) / sizeof(js_base64_funcs[0]));
58297+
JS_FreeValue(ctx, global);
58298+
}
5799858299

5799958300
bool JS_DetectModule(const char *input, size_t input_len)
5800058301
{

‎quickjs.h

Lines changed: 1 addition & 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

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