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Merged
saghul merged 1 commit into from
Apr 12, 2026
+384 −10
Merged

add btoa()/atob() builtins #1444

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298 changes: 288 additions & 10 deletions quickjs.c
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2500,7 +2500,6 @@ JSContext *JS_NewContextRaw(JSRuntime *rt)
JSContext *JS_NewContext(JSRuntime *rt)
{
JSContext *ctx;

ctx = JS_NewContextRaw(rt);
if (!ctx)
return NULL;
Expand All @@ -2515,7 +2514,7 @@ JSContext *JS_NewContext(JSRuntime *rt)
JS_AddIntrinsicTypedArrays(ctx) ||
JS_AddIntrinsicPromise(ctx) ||
JS_AddIntrinsicWeakRef(ctx) ||
JS_AddIntrinsicDOMException(ctx) ||
JS_AddIntrinsicAToB(ctx) ||
JS_AddPerformance(ctx)) {
JS_FreeContext(ctx);
return NULL;
Expand Down Expand Up @@ -4329,26 +4328,26 @@ JSValue JS_NewStringLen(JSContext *ctx, const char *buf, size_t buf_len)
size_t len;
int kind;

if (buf_len <= 0) {
if (unlikely(buf_len <= 0))
return js_empty_string(ctx->rt);
}

/* Compute string kind and length: 7-bit, 8-bit, 16-bit, 16-bit UTF-16 */
kind = utf8_scan(buf, buf_len, &len);
if (len > JS_STRING_LEN_MAX)
if (unlikely(len > JS_STRING_LEN_MAX))
return JS_ThrowRangeError(ctx, "invalid string length");

switch (kind) {
case UTF8_PLAIN_ASCII:
str = js_alloc_string(ctx, len, 0);
if (!str)
if (unlikely(!str))
return JS_EXCEPTION;
memcpy(str8(str), buf, len);
str8(str)[len] = '\0';
break;
case UTF8_NON_ASCII:
/* buf contains non-ASCII code-points, but limited to 8-bit values */
str = js_alloc_string(ctx, len, 0);
if (!str)
if (unlikely(!str))
return JS_EXCEPTION;
utf8_decode_buf8(str8(str), len + 1, buf, buf_len);
break;
Expand All @@ -4357,7 +4356,7 @@ JSValue JS_NewStringLen(JSContext *ctx, const char *buf, size_t buf_len)
//if (kind & UTF8_HAS_ERRORS)
// return JS_ThrowRangeError(ctx, "invalid UTF-8 sequence");
str = js_alloc_string(ctx, len, 1);
if (!str)
if (unlikely(!str))
return JS_EXCEPTION;
utf8_decode_buf16(str16(str), len, buf, buf_len);
break;
Expand All @@ -4369,10 +4368,11 @@ JSValue JS_NewStringUTF16(JSContext *ctx, const uint16_t *buf, size_t len)
{
JSString *str;

if (!len)
if (unlikely(!len))
return js_empty_string(ctx->rt);

str = js_alloc_string(ctx, len, 1);
if (!str)
if (unlikely(!str))
return JS_EXCEPTION;
memcpy(str16(str), buf, len * sizeof(*buf));
return JS_MKPTR(JS_TAG_STRING, str);
Expand Down Expand Up @@ -60797,6 +60797,284 @@ int JS_AddIntrinsicDOMException(JSContext *ctx)
ctx->class_proto[JS_CLASS_DOM_EXCEPTION] = proto;
return 0;
}
/* base64 */

static const unsigned char b64_enc[64] = {
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
'Q','R','S','T','U','V','W','X','Y','Z',
'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
'q','r','s','t','u','v','w','x','y','z',
'0','1','2','3','4','5','6','7','8','9',
'+','/'
};

enum { K_VAL = 1u, K_WS = 2u };

static const uint8_t b64_val[256] = {
['A']=0, ['B']=1, ['C']=2, ['D']=3, ['E']=4, ['F']=5, ['G']=6, ['H']=7,
['I']=8, ['J']=9, ['K']=10,['L']=11,['M']=12,['N']=13,['O']=14,['P']=15,
['Q']=16,['R']=17,['S']=18,['T']=19,['U']=20,['V']=21,['W']=22,['X']=23,['Y']=24,['Z']=25,
['a']=26,['b']=27,['c']=28,['d']=29,['e']=30,['f']=31,['g']=32,['h']=33,
['i']=34,['j']=35,['k']=36,['l']=37,['m']=38,['n']=39,['o']=40,['p']=41,
['q']=42,['r']=43,['s']=44,['t']=45,['u']=46,['v']=47,['w']=48,['x']=49,['y']=50,['z']=51,
['0']=52,['1']=53,['2']=54,['3']=55,['4']=56,['5']=57,['6']=58,['7']=59,['8']=60,['9']=61,
['+']=62, ['/']=63,
};

static const char b64_flags[256] = {
[' ']=K_WS, ['\t']=K_WS, ['\n']=K_WS, ['\f']=K_WS, ['\r']=K_WS,
['A']=K_VAL,['B']=K_VAL,['C']=K_VAL,['D']=K_VAL,['E']=K_VAL,['F']=K_VAL,['G']=K_VAL,['H']=K_VAL,
['I']=K_VAL,['J']=K_VAL,['K']=K_VAL,['L']=K_VAL,['M']=K_VAL,['N']=K_VAL,['O']=K_VAL,['P']=K_VAL,
['Q']=K_VAL,['R']=K_VAL,['S']=K_VAL,['T']=K_VAL,['U']=K_VAL,['V']=K_VAL,['W']=K_VAL,['X']=K_VAL,
['Y']=K_VAL,['Z']=K_VAL,
['a']=K_VAL,['b']=K_VAL,['c']=K_VAL,['d']=K_VAL,['e']=K_VAL,['f']=K_VAL,['g']=K_VAL,['h']=K_VAL,
['i']=K_VAL,['j']=K_VAL,['k']=K_VAL,['l']=K_VAL,['m']=K_VAL,['n']=K_VAL,['o']=K_VAL,['p']=K_VAL,
['q']=K_VAL,['r']=K_VAL,['s']=K_VAL,['t']=K_VAL,['u']=K_VAL,['v']=K_VAL,['w']=K_VAL,['x']=K_VAL,
['y']=K_VAL,['z']=K_VAL,
['0']=K_VAL,['1']=K_VAL,['2']=K_VAL,['3']=K_VAL,['4']=K_VAL,['5']=K_VAL,['6']=K_VAL,['7']=K_VAL,
['8']=K_VAL,['9']=K_VAL,
['+']=K_VAL,['/']=K_VAL,
};

static size_t b64_encode(const uint8_t *src, size_t len, char *dst)
{
size_t i = 0, j = 0;
size_t main_len = (len / 3) * 3;

for (; i < main_len; i += 3, j += 4) {
uint32_t v = 65536*src[i] + 256*src[i + 1] + src[i + 2];
dst[j + 0] = b64_enc[(v >> 18) & 63];
dst[j + 1] = b64_enc[(v >> 12) & 63];
dst[j + 2] = b64_enc[(v >> 6) & 63];
dst[j + 3] = b64_enc[v & 63];
}

size_t rem = len - i;
if (rem == 1) {
uint32_t v = 65536*src[i];
dst[j++] = b64_enc[(v >> 18) & 63];
dst[j++] = b64_enc[(v >> 12) & 63];
dst[j++] = '=';
dst[j++] = '=';
} else if (rem == 2) {
uint32_t v = 65536*src[i] + 256*src[i + 1];
dst[j++] = b64_enc[(v >> 18) & 63];
dst[j++] = b64_enc[(v >> 12) & 63];
dst[j++] = b64_enc[(v >> 6) & 63];
dst[j++] = '=';
}
return j;
}

/* Implements https://infra.spec.whatwg.org/#forgiving-base64-decode */
static size_t
b64_decode(const char *src, size_t len, uint8_t *dst, int *err)
{
size_t i, j;
uint32_t acc;
int seen, pad;
unsigned ch;

acc = 0;
seen = 0;
for (i = 0, j = 0; i < len; i++) {
ch = (unsigned char)src[i];
if ((b64_flags[ch] & K_WS))
continue;
if (!(b64_flags[ch] & K_VAL))
break;
acc = (acc << 6) | b64_val[ch];
seen++;
if (seen == 4) {
dst[j++] = (acc >> 16) & 0xFF;
dst[j++] = (acc >> 8) & 0xFF;
dst[j++] = acc & 0xFF;
seen = 0;
acc = 0;
}
}

if (seen != 0) {
if (seen == 3) {
dst[j++] = (acc >> 10) & 0xFF;
dst[j++] = (acc >> 2) & 0xFF;
} else if (seen == 2) {
dst[j++] = (acc >> 4) & 0xFF;
} else {
*err = 1;
return 0;
}
for (pad = 0; i < len; i++) {
ch = (unsigned char)src[i];
if (pad < 2 && ch == '=')
pad++;
else if (!(b64_flags[ch] & K_WS))
break;
}
if (pad != 0 && seen + pad != 4) {
*err = 1;
return 0;
}
}

*err = i < len;
return j;
}

static JSValue js_btoa(JSContext *ctx, JSValueConst this_val,
int argc, JSValueConst *argv)
{
const uint8_t *in8;
uint8_t *tmp = NULL;
uint8_t *outp;
JSValue val, ret = JS_EXCEPTION;
JSString *s, *ostr;
size_t len, out_len, written;

val = JS_ToString(ctx, argv[0]);
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@bnoordhuis bnoordhuis Apr 11, 2026

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Maybe set ret = JS_EXCEPTION here, then you don't have to ret = ThingThatThrows(ctx) everywhere.

What you're doing now isn't wrong but ⤴️ is what we do in most places.

if (unlikely(JS_IsException(val)))
return JS_EXCEPTION;

s = JS_VALUE_GET_STRING(val);
len = (size_t)s->len;

if (likely(!s->is_wide_char)) {
in8 = (const uint8_t *)str8(s);
} else {
const uint16_t *src = str16(s);
tmp = js_malloc(ctx, likely(len) ? len : 1);
if (unlikely(!tmp))
goto fail;
for (size_t i = 0; i < len; i++) {
uint32_t c = src[i];
if (unlikely(c > 0xFF)) {
JS_ThrowDOMException(ctx, "InvalidCharacterError",
"String contains an invalid character");
goto fail;
}
tmp[i] = (uint8_t)c;
}
in8 = tmp;
}

if (unlikely(len > (SIZE_MAX - 2) / 3)) {
JS_ThrowRangeError(ctx, "input too large");
goto fail;
}
out_len = 4 * ((len + 2) / 3);
if (unlikely(out_len > JS_STRING_LEN_MAX)) {
JS_ThrowRangeError(ctx, "output too large");
goto fail;
}

ostr = js_alloc_string(ctx, out_len, 0);
if (unlikely(!ostr))
goto fail;

outp = str8(ostr);
written = b64_encode(in8, len, (char *)outp);
outp[written] = '\0';
ostr->len = out_len;
ret = JS_MKPTR(JS_TAG_STRING, ostr);
fail:
if (tmp)
js_free(ctx, tmp);
JS_FreeValue(ctx, val);
return ret;
}

static JSValue js_atob(JSContext *ctx, JSValueConst this_val,
int argc, JSValueConst *argv)
{
const uint8_t *in;
uint8_t *tmp = NULL, *outp;
JSValue val, ret = JS_EXCEPTION;
JSString *s, *ostr;
size_t slen, out_cap, out_len;
int err;

val = JS_ToString(ctx, argv[0]);
if (unlikely(JS_IsException(val)))
return JS_EXCEPTION;

s = JS_VALUE_GET_STRING(val);
slen = (size_t)s->len;

if (likely(!s->is_wide_char)) {
const uint8_t *p = (const uint8_t *)str8(s);
for (size_t i = 0; i < slen; i++) {
if (unlikely(p[i] & 0x80)) {
JS_ThrowDOMException(ctx, "InvalidCharacterError",
"The string to be decoded is not correctly encoded");
goto fail;
}
}
in = p;
} else {
const uint16_t *src = str16(s);
tmp = js_malloc(ctx, likely(slen) ? slen : 1);
if (unlikely(!tmp))
goto fail;
for (size_t i = 0; i < slen; i++) {
if (unlikely(src[i] > 0x7F)) {
JS_ThrowDOMException(ctx, "InvalidCharacterError",
"The string to be decoded is not correctly encoded");
goto fail;
}
tmp[i] = (uint8_t)src[i];
}
in = tmp;
}

if (unlikely(slen > (SIZE_MAX / 3) * 4)) {
JS_ThrowRangeError(ctx, "input too large");
goto fail;
}
out_cap = (slen / 4) * 3 + 3;
if (unlikely(out_cap > JS_STRING_LEN_MAX)) {
JS_ThrowRangeError(ctx, "output too large");
goto fail;
}

ostr = js_alloc_string(ctx, out_cap, 0);
if (unlikely(!ostr))
goto fail;

outp = str8(ostr);
err = 0;
out_len = b64_decode((const char *)in, slen, outp, &err);

if (unlikely(err)) {
js_free_string(ctx->rt, ostr);
JS_ThrowDOMException(ctx, "InvalidCharacterError",
"The string to be decoded is not correctly encoded");
goto fail;
}
outp[out_len] = '\0';
ostr->len = out_len;
ret = JS_MKPTR(JS_TAG_STRING, ostr);
fail:
if (tmp)
js_free(ctx, tmp);
JS_FreeValue(ctx, val);
return ret;
}

static const JSCFunctionListEntry js_base64_funcs[] = {
JS_CFUNC_DEF("btoa", 1, js_btoa),
JS_CFUNC_DEF("atob", 1, js_atob),
};

int JS_AddIntrinsicAToB(JSContext *ctx)
{
if (!JS_IsRegisteredClass(ctx->rt, JS_CLASS_DOM_EXCEPTION)) {
if (JS_AddIntrinsicDOMException(ctx))
return -1;
}
JS_SetPropertyFunctionList(ctx, ctx->global_obj,
js_base64_funcs, countof(js_base64_funcs));
return 0;
}

bool JS_DetectModule(const char *input, size_t input_len)
{
Expand Down
1 change: 1 addition & 0 deletions quickjs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,7 @@ JS_EXTERN int JS_AddIntrinsicBigInt(JSContext *ctx);
JS_EXTERN int JS_AddIntrinsicWeakRef(JSContext *ctx);
JS_EXTERN int JS_AddPerformance(JSContext *ctx);
JS_EXTERN int JS_AddIntrinsicDOMException(JSContext *ctx);
JS_EXTERN int JS_AddIntrinsicAToB(JSContext *ctx);

/* for equality comparisons and sameness */
JS_EXTERN int JS_IsEqual(JSContext *ctx, JSValueConst op1, JSValueConst op2);
Expand Down
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