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chibi-scheme/lib/chibi/json.c
Alex Shinn 72ec53ca26 More thorough checks for SEXP_MIN_FIXNUM/-1. 
Closes #1006.
2025-01-30 11:44:23 +09:00

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/* json.c -- fast json I/O */
/* Copyright (c) 2020 Alex Shinn. All rights reserved. */
/* Copyright (c) 2020 Ekaitz Zarraga. All rights reserved. */
/* BSD-style license: http://synthcode.com/license.txt */
#include <chibi/eval.h>
static int digit_value (int c) {
return (((c)<='9') ? ((c) - '0') : ((sexp_tolower(c) - 'a') + 10));
}
sexp json_read (sexp ctx, sexp self, sexp in);
sexp sexp_json_read_exception (sexp ctx, sexp self, const char* msg, sexp in, sexp ir) {
sexp res;
sexp_gc_var4(sym, name, str, irr);
sexp_gc_preserve4(ctx, sym, name, str, irr);
name = (sexp_port_name(in) ? sexp_port_name(in) : SEXP_FALSE);
name = sexp_cons(ctx, name, sexp_make_fixnum(sexp_port_line(in)));
str = sexp_c_string(ctx, msg, -1);
irr = ((sexp_pairp(ir) || sexp_nullp(ir)) ? ir : sexp_list1(ctx, ir));
res = sexp_make_exception(ctx, sym = sexp_intern(ctx, "json-read", -1),
str, irr, SEXP_FALSE, name);
sexp_gc_release4(ctx);
return res;
}
sexp sexp_json_write_exception (sexp ctx, sexp self, const char* msg, sexp obj) {
sexp_gc_var2(res, tmp);
sexp_gc_preserve2(ctx, res, tmp);
tmp = sexp_list1(ctx, obj);
res = sexp_user_exception(ctx, self, msg, tmp);
sexp_gc_release2(ctx);
return res;
}
sexp json_read_number (sexp ctx, sexp self, sexp in) {
double res = 0, scale = 1;
int sign = 1, inexactp = 0, scale_sign = 1, ch;
ch = sexp_read_char(ctx, in);
if (ch == '+') {
ch = sexp_read_char(ctx, in);
} else if (ch == '-') {
ch = sexp_read_char(ctx, in);
sign = -1;
}
for ( ; ch != EOF && isdigit(ch); ch = sexp_read_char(ctx, in))
res = res * 10 + ch - '0';
if (ch == '.') {
inexactp = 1;
for (ch = sexp_read_char(ctx, in); isdigit(ch); scale *= 10, ch = sexp_read_char(ctx, in))
res = res * 10 + ch - '0';
res /= scale;
} else if (ch == 'e') {
inexactp = 1;
ch = sexp_read_char(ctx, in);
if (ch == '+') {
ch = sexp_read_char(ctx, in);
} else if (ch == '-') {
ch = sexp_read_char(ctx, in);
scale_sign = -1;
}
for (scale=0; isdigit(ch); ch = sexp_read_char(ctx, in))
scale = scale * 10 + ch - '0';
res *= pow(10.0, scale_sign * scale);
}
if (ch != EOF) sexp_push_char(ctx, ch, in);
return (inexactp || fabs(res) > (double)SEXP_MAX_FIXNUM) ?
sexp_make_flonum(ctx, sign * res) :
sexp_make_fixnum(sign * res); /* always return inexact? */
}
sexp json_read_literal (sexp ctx, sexp self, sexp in, char* name, sexp value) {
int ch;
for (++name; *name; )
if (*(name++) != (ch = sexp_read_char(ctx, in)))
sexp_json_read_exception(ctx, self, "unexpected character in json", in, sexp_make_character(ch));
return value;
}
#define USEQ_LEN 4
long decode_useq(sexp ctx, sexp in) {
long result = 0, i, ch;
for (i=0; i < USEQ_LEN; i++) {
ch = sexp_read_char(ctx, in);
if (!isxdigit(ch)) {
sexp_push_char(ctx, ch, in);
return -1;
}
result = (result << 4) + digit_value(ch);
}
return result;
}
#define INIT_STRING_BUFFER_SIZE 128
sexp json_read_string (sexp ctx, sexp self, sexp in) {
sexp_sint_t size=INIT_STRING_BUFFER_SIZE;
char initbuf[INIT_STRING_BUFFER_SIZE];
char *buf=initbuf, *tmp;
int i=0, ch, len;
long utfchar, utfchar2;
sexp res = SEXP_VOID;
for (ch = sexp_read_char(ctx, in); ch != '"'; ch = sexp_read_char(ctx, in)) {
if (ch == EOF) {
res = sexp_json_read_exception(ctx, self, "unterminated string in json", in, SEXP_NULL);
break;
}
if (i+4 >= size) { /* expand buffer w/ malloc(), later free() it */
tmp = (char*) sexp_malloc(size*2);
if (!tmp) {res = sexp_global(ctx, SEXP_G_OOM_ERROR); break;}
memcpy(tmp, buf, i);
if (size != INIT_STRING_BUFFER_SIZE) free(buf);
buf = tmp;
size *= 2;
}
if (ch == '\\') {
ch = sexp_read_char(ctx, in);
switch (ch) {
case 'n':
buf[i++] = '\n';
break;
case 't':
buf[i++] = '\t';
break;
case 'u':
utfchar = decode_useq(ctx, in);
if (0xd800 <= utfchar && utfchar <= 0xdbff) {
ch = sexp_read_char(ctx, in);
if (ch == '\\') {
ch = sexp_read_char(ctx, in);
if (ch == 'u') {
/* high surrogate followed by another unicode escape */
utfchar2 = decode_useq(ctx, in);
if (0xdc00 <= utfchar2 && utfchar2 <= 0xdfff) {
/* merge low surrogate (otherwise high is left unpaired) */
utfchar = 0x10000 + (((utfchar - 0xd800) << 10) | (utfchar2 - 0xdc00));
} else {
return sexp_json_read_exception(ctx, self, "invalid \\u sequence", in, SEXP_NULL);
}
} else {
sexp_push_char(ctx, ch, in);
sexp_push_char(ctx, '\\', in);
}
} else {
sexp_push_char(ctx, ch, in);
}
}
if (utfchar < 0) {
return sexp_json_read_exception(ctx, self, "invalid \\u sequence", in, SEXP_NULL);
} else {
len = sexp_utf8_char_byte_count(utfchar);
sexp_utf8_encode_char((unsigned char*)buf + i, len, utfchar);
i += len;
}
break;
default:
buf[i++] = ch;
break;
}
} else {
buf[i++] = ch;
}
}
if (!sexp_exceptionp(res)) {
buf[i] = '\0';
res = sexp_c_string(ctx, buf, i);
if (sexp_stringp(res)) sexp_immutablep(res) = 1;
}
if (size != INIT_STRING_BUFFER_SIZE) free(buf);
return res;
}
sexp json_read_array (sexp ctx, sexp self, sexp in) {
sexp_gc_var2(res, tmp);
sexp_gc_preserve2(ctx, res, tmp);
int comma = 1, ch;
res = SEXP_NULL;
while (1) {
ch = sexp_read_char(ctx, in);
if (ch == EOF) {
res = sexp_json_read_exception(ctx, self, "unterminated array in json", in, SEXP_NULL);
break;
} else if (ch == ']') {
if (comma && res != SEXP_NULL) {
res = sexp_json_read_exception(ctx, self, "missing value after comma in json", in, SEXP_NULL);
} else {
res = sexp_nreverse(ctx, res);
res = sexp_list_to_vector(ctx, res);
}
break;
} else if (ch == ',' && comma) {
res = sexp_json_read_exception(ctx, self, "unexpected comma in json array", in, SEXP_NULL);
break;
} else if (ch == ',') {
comma = 1;
} else if (!isspace(ch)) {
if (comma) {
sexp_push_char(ctx, ch, in);
tmp = json_read(ctx, self, in);
if (sexp_exceptionp(tmp)) {
res = tmp;
break;
}
res = sexp_cons(ctx, tmp, res);
comma = 0;
} else {
res = sexp_json_read_exception(ctx, self, "unexpected value in json array", in, SEXP_NULL);
break;
}
}
}
sexp_gc_release2(ctx);
return res;
}
sexp json_read_object (sexp ctx, sexp self, sexp in) {
sexp_gc_var2(res, tmp);
sexp_gc_preserve2(ctx, res, tmp);
int comma = 1, ch;
res = SEXP_NULL;
while (1) {
ch = sexp_read_char(ctx, in);
if (ch == EOF) {
res = sexp_json_read_exception(ctx, self, "unterminated object in json", in, SEXP_NULL);
break;
} else if (ch == '}') {
if (comma && res != SEXP_NULL) {
res = sexp_json_read_exception(ctx, self, "missing value after comma in json object", in, SEXP_NULL);
} else {
res = sexp_nreverse(ctx, res);
}
break;
} else if (ch == ',' && comma) {
res = sexp_json_read_exception(ctx, self, "unexpected comma in json object", in, SEXP_NULL);
break;
} else if (ch == ',') {
comma = 1;
} else if (!isspace(ch)) {
if (comma) {
sexp_push_char(ctx, ch, in);
tmp = json_read(ctx, self, in);
if (sexp_exceptionp(tmp)) {
res = tmp;
break;
} else if (sexp_stringp(tmp)) {
tmp = sexp_string_to_symbol(ctx, tmp);
}
tmp = sexp_cons(ctx, tmp, SEXP_VOID);
for (ch = sexp_read_char(ctx, in); isspace(ch); ch = sexp_read_char(ctx, in))
;
if (ch != ':') {
res = sexp_json_read_exception(ctx, self, "missing colon in json object", in, sexp_make_character(ch));
break;
}
sexp_cdr(tmp) = json_read(ctx, self, in);
if (sexp_exceptionp(sexp_cdr(tmp))) {
res = sexp_cdr(tmp);
break;
}
res = sexp_cons(ctx, tmp, res);
comma = 0;
} else {
res = sexp_json_read_exception(ctx, self, "unexpected value in json object", in, SEXP_NULL);
break;
}
}
}
sexp_gc_release2(ctx);
return res;
}
sexp json_read (sexp ctx, sexp self, sexp in) {
sexp res;
int ch = ' ';
while (isspace(ch))
ch = sexp_read_char(ctx, in);
switch (ch) {
case '{':
res = json_read_object(ctx, self, in);
break;
case '[':
res = json_read_array(ctx, self, in);
break;
case '"':
res = json_read_string(ctx, self, in);
break;
case '-': case '+':
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
sexp_push_char(ctx, ch, in);
res = json_read_number(ctx, self, in);
break;
case 'n': case 'N':
res = json_read_literal(ctx, self, in, "null", sexp_intern(ctx, "null", -1));
break;
case 't': case 'T':
res = json_read_literal(ctx, self, in, "true", SEXP_TRUE);
break;
case 'f': case 'F':
res = json_read_literal(ctx, self, in, "false", SEXP_FALSE);
break;
case '}':
res = sexp_json_read_exception(ctx, self, "unexpected closing brace in json", in, SEXP_NULL);
break;
case ']':
res = sexp_json_read_exception(ctx, self, "unexpected closing bracket in json", in, SEXP_NULL);
break;
default:
res = sexp_json_read_exception(ctx, self, "unexpected character in json", in, sexp_make_character(ch));
break;
}
return res;
}
sexp sexp_json_read (sexp ctx, sexp self, sexp_sint_t n, sexp in) {
sexp_assert_type(ctx, sexp_iportp, SEXP_IPORT, in);
return json_read(ctx, self, in);
}
sexp json_write (sexp ctx, sexp self, sexp obj, sexp out);
#define FLONUM_SIGNIFICANT_DIGITS 10
#define FLONUM_EXP_MAX_DIGITS 3
sexp json_write_flonum(sexp ctx, sexp self, const sexp obj, sexp out) {
if (sexp_infp(obj) || sexp_nanp(obj)) {
return sexp_json_write_exception(ctx, self, "unable to encode number", obj);
}
/* Extra space for signs (x2), dot, E and \0 */
char cout[FLONUM_SIGNIFICANT_DIGITS + FLONUM_EXP_MAX_DIGITS + 5];
snprintf(cout, sizeof(cout), "%.*G", FLONUM_SIGNIFICANT_DIGITS, sexp_flonum_value(obj));
sexp_write_string(ctx, cout, out);
return SEXP_VOID;
}
sexp json_write_string(sexp ctx, sexp self, const sexp obj, sexp out) {
char cout[32]; /* oversized to avoid snprintf warnings */
unsigned long ch, chh, chl;
sexp i, end = sexp_make_string_cursor(sexp_string_size(obj));
sexp_write_char(ctx, '"', out);
for (i = sexp_make_string_cursor(0); i < end;
i = sexp_string_cursor_next(obj, i)) {
ch = sexp_unbox_character(sexp_string_cursor_ref(ctx, obj, i));
if (ch < 0x7F) {
switch (ch) {
case '\\':
sexp_write_string(ctx, "\\\\", out);
break;
case '\b':
sexp_write_string(ctx, "\\b", out);
break;
case '\f':
sexp_write_string(ctx, "\\f", out);
break;
case '\n':
sexp_write_string(ctx, "\\n", out);
break;
case '\r':
sexp_write_string(ctx, "\\r", out);
break;
case '\t':
sexp_write_string(ctx, "\\t", out);
break;
default:
sexp_write_char(ctx, ch, out);
break;
}
} else if (ch <= 0xFFFF) {
snprintf(cout, sizeof(cout), "\\u%04lX", ch);
sexp_write_string(ctx, cout, out);
} else {
// Surrogate pair
chh = (0xD800 - (0x10000 >> 10) + ((ch) >> 10));
chl = (0xDC00 + ((ch) & 0x3FF));
if (chh > 0xFFFF || chl > 0xFFFF) {
return sexp_json_write_exception(ctx, self, "unable to encode string", obj);
}
snprintf(cout, sizeof(cout), "\\u%04lX\\u%04lX", chh, chl);
sexp_write_string(ctx, cout, out);
}
}
sexp_write_char(ctx, '"', out);
return SEXP_VOID;
}
sexp json_write_array(sexp ctx, sexp self, const sexp obj, sexp out) {
sexp tmp;
int len = sexp_vector_length(obj), i;
sexp_write_string(ctx, "[", out);
for (i = 0; i < len; ++i) {
tmp = json_write(ctx, self, sexp_vector_ref(obj, sexp_make_fixnum(i)), out);
if (sexp_exceptionp(tmp)) {
return tmp;
}
if (i < len - 1) {
sexp_write_char(ctx, ',', out);
}
}
sexp_write_string(ctx, "]", out);
return SEXP_VOID;
}
sexp json_write_object(sexp ctx, sexp self, const sexp obj, sexp out) {
sexp ls, cur, key, val;
sexp_gc_var2(tmp, res);
if (sexp_length(ctx, obj) == SEXP_FALSE)
sexp_json_write_exception(ctx, self, "unable to encode circular list", obj);
sexp_gc_preserve2(ctx, tmp, res);
res = SEXP_VOID;
sexp_write_char(ctx, '{', out);
for (ls = obj; sexp_pairp(ls); ls = sexp_cdr(ls)) {
if (ls != obj)
sexp_write_char(ctx, ',', out);
cur = sexp_car(ls);
if (!sexp_pairp(cur)) {
res = sexp_json_write_exception(ctx, self, "unable to encode key-value pair: not a pair", obj);
break;
}
key = sexp_car(cur);
if (!sexp_symbolp(key)) {
res = sexp_json_write_exception(ctx, self, "unable to encode key: not a symbol", key);
break;
}
tmp = sexp_symbol_to_string(ctx, key);
tmp = json_write(ctx, self, tmp, out);
if (sexp_exceptionp(tmp)) {
res = tmp;
break;
}
sexp_write_char(ctx, ':', out);
val = sexp_cdr(cur);
tmp = json_write(ctx, self, val, out);
if (sexp_exceptionp(tmp)) {
res = tmp;
break;
}
}
sexp_write_char(ctx, '}', out);
sexp_gc_release2(ctx);
return res;
}
sexp json_write (sexp ctx, sexp self, const sexp obj, sexp out) {
sexp_gc_var1(res);
sexp_gc_preserve1(ctx, res);
res = SEXP_VOID;
if (sexp_symbolp(obj)) {
res = sexp_write(ctx, obj, out);
} else if (sexp_stringp(obj)) {
res = json_write_string(ctx, self, obj, out);
} else if (sexp_listp(ctx, obj) == SEXP_TRUE) {
res = json_write_object(ctx, self, obj, out);
} else if (sexp_vectorp(obj)) {
res = json_write_array(ctx, self, obj, out);
} else if (sexp_fixnump(obj)) {
res = sexp_write(ctx, obj, out);
} else if (sexp_flonump(obj)) {
res = json_write_flonum(ctx, self, obj, out);
#if SEXP_USE_BIGNUMS
} else if (sexp_bignump(obj)) {
res = sexp_make_flonum(ctx, sexp_bignum_to_double(obj));
res = json_write_flonum(ctx, self, res, out);
#endif
} else if (obj == SEXP_FALSE) {
sexp_write_string(ctx, "false", out);
} else if (obj == SEXP_TRUE) {
sexp_write_string(ctx, "true", out);
} else if (obj == SEXP_NULL) {
sexp_write_string(ctx, "null", out);
} else if (sexp_pairp(obj)) {
res = sexp_json_write_exception(ctx, self, "unable to encode elemente: key-value pair out of object", obj);
} else {
res = sexp_json_write_exception(ctx, self, "unable to encode element", obj);
}
sexp_gc_release1(ctx);
return res;
}
sexp sexp_json_write (sexp ctx, sexp self, sexp_sint_t n, sexp obj, sexp out) {
sexp_assert_type(ctx, sexp_oportp, SEXP_OPORT, out);
return json_write(ctx, self, obj, out);
}
sexp sexp_init_library (sexp ctx, sexp self, sexp_sint_t n, sexp env, const char* version, const sexp_abi_identifier_t abi) {
if (!(sexp_version_compatible(ctx, version, sexp_version)
&& sexp_abi_compatible(ctx, abi, SEXP_ABI_IDENTIFIER)))
return SEXP_ABI_ERROR;
sexp_define_foreign(ctx, env, "json-read", 1, sexp_json_read);
sexp_define_foreign(ctx, env, "json-write", 2, sexp_json_write);
return SEXP_VOID;
}
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