@eslint/json
Version:
JSON linting plugin for ESLint
142 lines (141 loc) • 6.49 kB
JavaScript
/**
* @fileoverview Rule to detect unsafe values in JSON.
* @author Bradley Meck Farias
*/
//-----------------------------------------------------------------------------
// Type Definitions
//-----------------------------------------------------------------------------
/**
* @import { JSONRuleDefinition } from "../types.js";
* @typedef {"unsafeNumber"|"unsafeInteger"|"unsafeZero"|"subnormal"|"loneSurrogate"} NoUnsafeValuesMessageIds
* @typedef {JSONRuleDefinition<{ MessageIds: NoUnsafeValuesMessageIds }>} NoUnsafeValuesRuleDefinition
*/
//-----------------------------------------------------------------------------
// Helpers
//-----------------------------------------------------------------------------
/*
* This rule is based on the JSON grammar from RFC 8259, section 6.
* https://tools.ietf.org/html/rfc8259#section-6
*
* Also, this rule is based on the JSON5 grammar from json5.org, section 6.
* https://spec.json5.org/#numbers
*
* We separately capture the integer and fractional parts of a number, so that
* we can check for unsafe numbers that will evaluate to Infinity.
*/
const NUMBER = /^[+-]?(?<int>0|([1-9]\d*))?(?:\.(?<frac>\d*))?(?:e[+-]?\d+)?$/iu;
const NON_ZERO = /[1-9]/u;
//-----------------------------------------------------------------------------
// Rule Definition
//-----------------------------------------------------------------------------
/** @type {NoUnsafeValuesRuleDefinition} */
const rule = {
meta: {
type: "problem",
languages: ["json/json", "json/jsonc", "json/json5"],
docs: {
recommended: true,
description: "Disallow JSON values that are unsafe for interchange",
dialects: ["JSON", "JSONC", "JSON5"],
url: "https://github.com/eslint/json/tree/main/docs/rules/no-unsafe-values.md",
},
messages: {
unsafeNumber: "The number '{{ value }}' will evaluate to Infinity.",
unsafeInteger: "The integer '{{ value }}' is outside the safe integer range.",
unsafeZero: "The number '{{ value }}' will evaluate to zero.",
subnormal: "Unexpected subnormal number '{{ value }}' found, which may cause interoperability issues.",
loneSurrogate: "Lone surrogate '{{ surrogate }}' found.",
},
},
create(context) {
return {
Number(node) {
const value = context.sourceCode.getText(node);
if (Number.isFinite(node.value) !== true) {
context.report({
loc: node.loc,
messageId: "unsafeNumber",
data: { value },
});
}
else {
// Also matches -0, intentionally
if (node.value === 0) {
// If the value has been rounded down to 0, but there was some
// fraction or non-zero part before the e-, this is a very small
// number that doesn't fit inside an f64.
const match = value.match(NUMBER);
if (match === null) {
return;
}
// If any part of the number other than the exponent has a
// non-zero digit in it, this number was not intended to be
// evaluated down to a zero.
if (NON_ZERO.test(match.groups.int) ||
NON_ZERO.test(match.groups.frac)) {
context.report({
loc: node.loc,
messageId: "unsafeZero",
data: { value },
});
}
}
else if (!/[.e]/iu.test(value)) {
// Intended to be an integer
if (node.value > Number.MAX_SAFE_INTEGER ||
node.value < Number.MIN_SAFE_INTEGER) {
context.report({
loc: node.loc,
messageId: "unsafeInteger",
data: { value },
});
}
}
else {
// Floating point. Check for subnormal.
const buffer = new ArrayBuffer(8);
const view = new DataView(buffer);
view.setFloat64(0, node.value, false);
const asBigInt = view.getBigUint64(0, false);
// Subnormals have an 11-bit exponent of 0 and a non-zero mantissa.
if ((asBigInt & 0x7ff0000000000000n) === 0n) {
context.report({
loc: node.loc,
messageId: "subnormal",
// Value included so that it's seen in scientific notation
data: {
value,
},
});
}
}
}
},
String(node) {
if (node.value.isWellFormed) {
if (node.value.isWellFormed()) {
return;
}
}
// match any high surrogate and, if it exists, a paired low surrogate
// match any low surrogate not already matched
const surrogatePattern = /[\uD800-\uDBFF][\uDC00-\uDFFF]?|[\uDC00-\uDFFF]/gu;
/** @type {RegExpExecArray | null} */
let match;
while ((match = surrogatePattern.exec(node.value)) !== null) {
// only need to report non-paired surrogates
if (match[0].length < 2) {
context.report({
loc: node.loc,
messageId: "loneSurrogate",
data: {
surrogate: JSON.stringify(match[0]).slice(1, -1),
},
});
}
}
},
};
},
};
export default rule;