Validate Mach-O headers before full reads#998
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Pull request overview
This PR updates MachO::MachOFile and MachO::FatFile initialization to validate headers using an incremental read (header first, then the remainder only if the header is acceptable), reducing unnecessary memory use when rejecting malformed binaries while preserving the “single handle” parsing flow and compressed Mach-O behavior.
Changes:
- Read only the header initially in
MachOFile/FatFile, validating it before reading the remainder of the file. - Add regression tests ensuring invalid headers are rejected before a full file read occurs.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
lib/macho/macho_file.rb |
Switches from File.binread to incremental header-first read with early header validation. |
lib/macho/fat_file.rb |
Switches from File.binread to incremental header-first read with early fat header validation. |
test/test_macho.rb |
Adds a test to ensure invalid Mach-O headers fail before full-file reads. |
test/test_fat.rb |
Adds a test to ensure invalid fat headers fail before full-file reads. |
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- Avoid loading large invalid files before `MachOFile` and `FatFile` can reject malformed headers. - Keep successful parsing on one handle so serialisation and mutation continue to use complete file data. - Preserve compressed Mach-O handling when decompression needs the full payload. - Coerce tail reads so a `nil` EOF cannot replace parser errors with `TypeError`.
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MachOFileandFatFilecan reject malformed headers.Fixes #23