pypa/pip · error · ELFInvalid

unable to parse machine and section information

Error message

unable to parse machine and section information

What it means

Raised by `ELFFile.__init__` when `struct.unpack` of the program-header format string (`e_fmt`) fails after the e_ident/class/encoding were valid. This means the file had a plausible ELF signature but is too short or malformed to contain the program header table metadata (machine type, phoff, phnum, etc.).

Source

Thrown at src/pip/_vendor/packaging/_elffile.py:88

            raise ELFInvalid(
                f"unrecognized capacity ({self.capacity}) or encoding ({self.encoding})"
            ) from e

        try:
            (
                _,
                self.machine,  # Architecture type.
                _,
                _,
                self._e_phoff,  # Offset of program header.
                _,
                self.flags,  # Processor-specific flags.
                _,
                self._e_phentsize,  # Size of section.
                self._e_phnum,  # Number of sections.
            ) = self._read(e_fmt)
        except struct.error as e:
            raise ELFInvalid("unable to parse machine and section information") from e

    def _read(self, fmt: str) -> tuple[int, ...]:
        return struct.unpack(fmt, self._f.read(struct.calcsize(fmt)))

    @property
    def interpreter(self) -> str | None:
        """
        The path recorded in the ``PT_INTERP`` section header.
        """
        for index in range(self._e_phnum):
            self._f.seek(self._e_phoff + self._e_phentsize * index)
            try:
                data = self._read(self._p_fmt)
            except struct.error:
                continue
            if data[self._p_idx[0]] != 3:  # Not PT_INTERP.
                continue
            self._f.seek(data[self._p_idx[1]])

View on GitHub (pinned to d7d0d0a394)

Solutions

Verify file size meets the minimum ELF header size (52 bytes for 32-bit, 64 for 64-bit) before parsing
Re-download or rebuild the binary; the header is structurally broken
Catch ELFInvalid and report the file as corrupt rather than crashing

Example fix

// before
elf = ELFFile(f)
// after
import os
if os.path.getsize(path) < 64:
    raise ValueError(f'{path} truncated, cannot be a complete ELF')
try:
    elf = ELFFile(f)
except ELFInvalid as e:
    raise ValueError(f'{path} corrupt ELF: {e}') from e

Defensive patterns

Strategy: try-catch

Validate before calling

import os

def is_full_elf_header(path: str) -> bool:
    # 52 bytes for 32-bit, 64 for 64-bit ELF header
    return os.path.getsize(path) >= 64

Type guard

def is_plausible_elf_size(size: int) -> bool:
    return isinstance(size, int) and size >= 64

Try / catch

from packaging._elffile import ELFFile, ELFInvalid
try:
    elf = ELFFile(f)
except ELFInvalid as e:
    if 'machine and section' in str(e):
        log.warning('%s has truncated ELF header', path)
        continue
    raise

Prevention

Verify file size >= 64 bytes before ELF parsing
Re-download binaries that fail header parsing rather than retrying
Catch ELFInvalid distinct from generic exceptions for clear error messages

When it happens

Trigger: A file that is at least 16 bytes with valid magic but truncated before the full ELF header (e.g. exactly 16-52 bytes); a header that was partially overwritten; an `e_ident` that happens to match `\x7fELF` by coincidence in a non-ELF blob.

Common situations: Reading a `.so` that was stripped/cut by a buggy packager; downloading a wheel payload that was truncated mid-transfer; test fixtures created by concatenating a real ELF header prefix with junk.

Related errors

AI-assisted analysis of pypa/pip@d7d0d0a394 (2026-08-04). Data as JSON: /data/errors/009b609d48829d39.json. Report an issue: GitHub.