[PATCH] D42872: Fix handling of zero-size segments in llvm-objcopy

[vit9696 via Phabricator via llvm-commits]

vit9696 added a comment.

I think I could have missed the point of the description a little, but I know of at least a total of 3 cases regarding ELF header:

- ELF header is present in PT_LOAD segment
- ELF header is mentioned in PT_PHDR segment
- ELF header is not mentioned or present anywhere, but the segment data starts at a random offset the linker decided to use.

The file I have is the third case, and I think there is no way to find the real size of ELF header (and properly skip it) without iterating over the segments and finding the lowest Offset segment which FileSize is not zero. Correct me if I am wrong, but I do not see how the suggested approach gets around it.

I am not too opposed to writing a slightly larger patch, but I'd rather not do it in a wrong way, and due to the lack of proper ELF format format definitions it is very easy to.

If you are fine with the iteration & a FileSize check I should be able to update the patch with these changes in the reasonable future.


Repository:
  rL LLVM

https://reviews.llvm.org/D42872