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morluto
921bb95755
Classify FAT containers using shared architecture, range, and observed slice-header facts rather than the CAFEBABE signature alone. Preserve typed unsupported and malformed reasons, reject malformed sibling slices consistently, and remove repeated range parsing in consumers. Validation: valid small and large JVM classes in public JAR/ZIP inspection, four FAT width/byte-order controls, and focused executable/Mach-O boundary tests. The class fixtures were checked with JDK javap; no new JVM analysis capability is advertised. The Apple selection and Hopper readers retain their existing parsing because they also own oversized-count diagnostics, reserved fields, streaming final-size validation, or source freshness that the shared header result does not represent. Representative public mixed-ZIP inventory probe, four fresh processes with an already warm filesystem cache: first process elapsed 626.8 -> 548.3 ms, CPU 740 -> 740 ms, sampled family peak RSS 375.5 -> 345.4 MiB. Subsequent three-process medians: elapsed 767.2 -> 454.0 ms, CPU 890 -> 640 ms, peak RSS 368.7 -> 346.2 MiB. Estimated output tokens 2310 -> 2292. Concurrent load was uncontrolled, so these observations do not establish a speed improvement. Whole-agent task tokens and schema/call overhead were not measured. Fixes #2317
29 lines
1.0 KiB
TypeScript
29 lines
1.0 KiB
TypeScript
/** Build a valid minimal JVM class file, optionally with an unused UTF-8 constant. */
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export const javaClassFile = (extraUtf8Bytes = 0): Buffer => {
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const utf8 = (value: string): Buffer => {
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const bytes = Buffer.from(value, "utf8");
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const entry = Buffer.alloc(3 + bytes.length);
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entry[0] = 1;
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entry.writeUInt16BE(bytes.length, 1);
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bytes.copy(entry, 3);
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return entry;
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};
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const constants = [
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Buffer.from([7, 0, 2]),
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utf8("Hello"),
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Buffer.from([7, 0, 4]),
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utf8("java/lang/Object"),
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...(extraUtf8Bytes === 0 ? [] : [utf8("x".repeat(extraUtf8Bytes))]),
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];
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const headerAndPool = Buffer.alloc(10);
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headerAndPool.writeUInt32BE(0xcafebabe, 0);
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headerAndPool.writeUInt16BE(0, 4);
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headerAndPool.writeUInt16BE(65, 6);
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headerAndPool.writeUInt16BE(constants.length + 1, 8);
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const classBody = Buffer.alloc(14);
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[0x21, 1, 3, 0, 0, 0, 0].forEach((value, index) =>
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classBody.writeUInt16BE(value, index * 2),
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);
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return Buffer.concat([headerAndPool, ...constants, classBody]);
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};
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