[lldb-dev] LLDB does not support the default 8 byte build ID generated by LLD

[Scott Funkenhauser via lldb-dev]

Hey guys,

LLDB uses source/Utility/UUID.cpp to store the build ID. This class only
supports 16 or 20 byte IDs.

When parsing the .note.gnu.build-id ELF section, any build ID between 4 and
20 bytes will be parsed and saved (which will silently fail if the size
isn't 16 or 20 bytes)
https://github.com/llvm-mirror/lldb/blob/4dc18b8ce3f95c2aa33edc4c821909c329e94be9/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp#L1279
.

I discovered this issue because by default LLD will generate a 8 byte build
ID, causing LLDB to ignore the .note.gnu.build-id ELF section and compute a
crc32 at runtime.

Is this a know issue that somebody is already working on? (After a quick
search I couldn't find any open bugs with a similar description).

Does anybody have any objection to modifying UUID::SetBytes to accept any
byte array with a size between 4 - 20 bytes, and pad with zeros to the next
largest supported size (either 16 or 20 bytes).

ex.
Setting a UUID with length of 8, would pad with 8 trailing zeros to have an
overall length of 16.
Setting a UUID with length of 17, would pad with 3 trailing zeros to have
an overall length of 20.

Thanks,
Scott
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