morluto
d672cc2399
Decode native binary plists from bounded owned source bytes before conversion can erase scalar values. Share scalar preflight and isolate overlapping decoder records while retaining exact integers, date uncertainty, and original bytes. Refuse numeric payloads that read structural table bytes, and avoid retaining projection metadata when callers only need structural validation. Closes #5701 Closes #5703 Closes #5705 Closes #5782 Closes #5783 Closes #5792
73 lines
2.4 KiB
TypeScript
73 lines
2.4 KiB
TypeScript
export interface BinaryPlistObjectTableLayout {
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readonly offsetWidth: number;
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readonly objectCount: number;
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readonly tableOffset: number;
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}
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/** Read the trailer fields that locate a binary plist's object offset table. */
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export const readBinaryPlistObjectTableLayout = (
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bytes: Buffer,
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): BinaryPlistObjectTableLayout => {
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const trailer = bytes.length - 32;
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return {
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offsetWidth: bytes[trailer + 6] ?? 0,
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objectCount: Number(bytes.readBigUInt64BE(trailer + 8)),
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tableOffset: Number(bytes.readBigUInt64BE(trailer + 24)),
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};
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};
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/** Decode one object's offset-table entry using the table's declared width. */
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export const readBinaryPlistObjectOffset = (
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bytes: Buffer,
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table: BinaryPlistObjectTableLayout,
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objectId: number,
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): number => {
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const entry = table.tableOffset + objectId * table.offsetWidth;
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let offset = 0;
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for (let byte = 0; byte < table.offsetWidth; byte += 1)
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offset = offset * 256 + (bytes[entry + byte] ?? 0);
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return offset;
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};
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/** Repoint one object while preserving the table's declared offset width. */
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export const writeBinaryPlistObjectOffset = (
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bytes: Buffer,
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table: BinaryPlistObjectTableLayout,
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objectId: number,
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offset: number,
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): void => {
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const entry = table.tableOffset + objectId * table.offsetWidth;
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let remaining = offset;
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for (let byte = table.offsetWidth - 1; byte >= 0; byte -= 1) {
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bytes[entry + byte] = remaining & 0xff;
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remaining = Math.floor(remaining / 256);
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}
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if (remaining !== 0) throw new Error("fixture offset width is insufficient");
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};
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/** Finish a small hand-authored binary plist with one-byte object offsets. */
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export const binaryPlistObjectTable = (
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bytes: Buffer,
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objectOffsets: readonly number[],
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tableOffset: number,
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): Buffer => {
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Buffer.from("bplist00", "ascii").copy(bytes);
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bytes.set(objectOffsets, tableOffset);
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const trailer = bytes.length - 32;
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bytes[trailer + 6] = 1;
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bytes[trailer + 7] = 1;
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bytes.writeBigUInt64BE(BigInt(objectOffsets.length), trailer + 8);
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bytes.writeBigUInt64BE(0n, trailer + 16);
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bytes.writeBigUInt64BE(BigInt(tableOffset), trailer + 24);
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return bytes;
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};
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/** Date and empty-data objects deliberately share bytes in a valid offset table. */
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export const binaryPlistWithOverlappingDateAndData = (): Buffer => {
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const bytes = Buffer.alloc(55);
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bytes.set([0xa2, 1, 2, 0x33], 8);
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bytes.writeDoubleBE(0.0005, 12);
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bytes[13] = 0x40;
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return binaryPlistObjectTable(bytes, [8, 11, 13], 20);
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};
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