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eliben / pyelftools

Parsing ELF and DWARF in Python
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Support for .gnu_debuglink DWARF5 Section #525

Open io-no opened 9 months ago

io-no commented 9 months ago

Address #523

I've added support for the .gnu_debuglink section in DWARF5 and made it compliant with the follow_links option. This involved modifying the DWARFInfo constructor to include the new section and creating a new structure in structs.py.

Then, I ran all the tests and updated test/test_refaddr_bitness.py to align with the changes in the constructor structure. All tests were executed successfully.

sevaa commented 9 months ago

The PR looks good. We'd like a test binary, though.

Good point re: the bitness test. It was my doing; I observed the issue on a MachO binary and made a test out of that instead of trying to reproduce on an ELF one. I'll try to supply a less fragile test.

The purpose of gnu_debuglink and gnu_debugaltlink looks, well, identical. Do you know why both exist?

Looks like you ignore the padding and the checksum altogether. It's OK to not parse the section to the very end, you know :)

io-no commented 9 months ago

Hi, I've added a test as requested. I tried to keep the structure and format consistent with the other tests, I hope it's okay.

Regarding the differences between the two sections, I admit that it remains a bit unclear to me as well. From what I understand, the .gnu_debugaltlink section is related to the use of tools such as dwz and is not really part of the standard, unlike .gnu_debuglink which is part of the standard.

I parsed padding and checksum for consistency with what I saw for the implementation of the .gnu_debugaltlink section. No, I don't use them. It might be an idea to use the checksum for future implementations where, in addition to opening the external file, its integrity is also verified. In the meantime, if you prefer, I can also ignore those two fields.

davea42 commented 9 months ago

On 12/13/23 15:05, Gabriele Digregorio wrote:

Regarding the differences between the two sections, I admit that it remains a bit unclear to me as well. From what I understand, the |.gnu_debugaltlink| section is related to the use of tools such as dwz and is not really part of the standard, unlike |.gnu_debuglink| which is part of the standard.

.gnu.debuglink is not part of the DWARF standard. It is not a section that the DWARF standard mentions.

David Anderson