Align SizeOfImage to section boundaries - #5
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Systemcluster merged 2 commits intoAug 11, 2026
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Pull request overview
This PR updates PE image writing logic so SizeOfImage is computed from the highest section’s virtual extent and rounded to SectionAlignment, matching the PE specification and avoiding misaligned image sizes after adding a resource section.
Changes:
- Recompute
SizeOfImagefrom the max(VirtualAddress + VirtualSize)across sections and align it toSectionAlignment. - Add a regression test asserting
SizeOfImageis a multiple ofSectionAlignmentafter resource transfer.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| tests/tests.rs | Adds an assertion that SizeOfImage remains section-aligned after modifying resources. |
| src/image.rs | Replaces incremental SizeOfImage updates with a recomputed, section-aligned value based on section virtual extents. |
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| let size_of_image = section_table | ||
| .iter() | ||
| .map(|section| section.virtual_address + section.virtual_size) | ||
| .max() | ||
| .map(|size| aligned_to(size, windows_header.section_alignment())) | ||
| .unwrap_or_else(|| windows_header.size_of_image()); |
ContributorAuthor
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We can't just use u64, it's a u32 field. I can look at an alternative here though 🤔
Systemcluster
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Aug 10, 2026
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Thank you! |
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The PE specification requires
SizeOfImageto describe the loaded image and be a multiple ofSectionAlignment. Adding a resource section currently increases it by the section’s file-aligned size, which can leave the image misaligned. Instead, we should calculateSizeOfImagefrom the highest section’s virtual extent and round it toSectionAlignment.