github/copilot-sdk · error · IOException

Invalid ELF program header metadata: phentsize= + phentsize…

Error message

Invalid ELF program header metadata: phentsize= + phentsize + , phnum= + phnum

What it means

Each program header entry must be at least the minimum size for the ELF class (56 bytes for ELF64, 32 for ELF32) and e_phnum must be positive for any PT_INTERP to exist. Values outside these invariants mean a corrupt header or truncated probe, so an IOException is thrown.

Solutions

1. Increase the probe size so header-derived reads land on real bytes (probe >= e_phoff + e_phentsize * e_phnum).
2. Validate the file with `readelf -l <path>`; if readelf accepts it, your probe is truncated — read more bytes.
3. Reinstall/re-download the binary and verify the checksum.
4. For untrusted inputs, catch IOException and reject with a clear 'corrupt ELF' message.

Example fix

// before
byte[] probe = readHead(path, 128); // too small for many phdrs
String interp = readElfPtInterp(probe);
// after
long fileSize = Files.size(path);
byte[] probe = readHead(path, (int) Math.min(fileSize, 65536));
String interp = readElfPtInterp(probe);

// phentsize >= 56 (ELF64) or 32 (ELF32) and phnum > 0 for a valid table
// ensure probe.length >= phoff + phentsize * phnum before parsing

try {
    String interp = readElfPtInterp(probe);
} catch (IOException e) {
    throw new IOException("Corrupt or truncated ELF (" + e.getMessage() + "); verify the binary", e);
}

When it happens

Trigger: e_phentsize parsed below the class minimum, or e_phnum <= 0 — corrupt ELF header fields, a truncated probe producing garbage offsets/reads, or a mangled download.

Common situations: Binary corruption from transfer or a bad packaging step; probe smaller than the region the header references, so subsequent reads decode garbage; crafted/fuzzed ELF inputs.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Unsupported ELF data encoding: + elfData
• Unsupported ELF class: + elfClass
• Invalid PT_INTERP bounds
• Empty PT_INTERP segment
• ELF probe too small: + size + bytes

AI-assisted analysis of github/copilot-sdk@cd8cf15dc3 (2026-09-09). Data as JSON: /api/errors/85f6c0ef2aa5b133. Report an issue: GitHub.

Appendix: source

Thrown at java/sdk/src/main/java/com/github/copilot/ffi/PlatformDetector.java:202

        if (elfClass == ELF_CLASS_64) {
            phoff = readUInt64(probe, 32, littleEndian);
            phentsize = readUInt16(probe, 54, littleEndian);
            phnum = readUInt16(probe, 56, littleEndian);
            minimumPhentsize = ELF64_PROGRAM_HEADER_SIZE;
        } else if (elfClass == ELF_CLASS_32) {
            phoff = readUInt32(probe, 28, littleEndian);
            phentsize = readUInt16(probe, 42, littleEndian);
            phnum = readUInt16(probe, 44, littleEndian);
            minimumPhentsize = ELF32_PROGRAM_HEADER_SIZE;
        } else {
            throw new IOException("Unsupported ELF class: " + elfClass);
        }

        if (phoff < 0 || phoff >= size) {
            throw new IOException("Program header table offset outside probe window: " + phoff);
        }
        if (phentsize < minimumPhentsize || phnum <= 0) {
            throw new IOException("Invalid ELF program header metadata: phentsize=" + phentsize + ", phnum=" + phnum);
        }

        for (int i = 0; i < phnum; i++) {
            long baseLong = phoff + ((long) i * phentsize);
            if (baseLong < 0 || baseLong > Integer.MAX_VALUE) {
                break;
            }
            int base = (int) baseLong;
            if (base + phentsize > size) {
                break;
            }

            long pType = readUInt32(probe, base, littleEndian);
            if (pType != PT_INTERP) {
                continue;
            }

            long pOffset;

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