Handling Elf.ksy parsing exceptions

[taviso]

Hello, I'm trying to integrate kaitai into my application, if I try to parse /bin/ls from Ubuntu 18.04 with Elf.ksy, I get an exception. I verified the same thing happens on the Web IDE.

I guess it's not clear to me if I should be handling this error, or if it's a bug?

To reproduce, load the attached binary (It's an original unmodified binary, you could also get it from here.

Then use the Web IDE to expand Elf.header.sectionHeaders[25].body.

The error is:

Parse error: undefined
Call stack: undefined KaitaiEOFError: requested 4832 bytes, but only 2104 bytes available

[taviso]

Oops, github rejected my attachment, lets try this instead.

sample.elf.gz

[GreyCat]

elf.ksy actually currently fails to compile at all now with this error:

elf.ksy:!:!: found duplicate key 1879048193

So I assume that you're using old ksc v0.8, which allows these duplicate keys.

In general, if it's a valid source ELF file (and it looks like it's a valid file), then any exception is an indicator of a problem in format specification. You should never get exceptions during parsing if the source file is valid.

So, I would start with:

• Fixing duplicate key problem with elf.ksy
• Retrying with latest ksc
• Potentially, pinpointing and fixing a bug in elf.ksy related to the section that you've demonstrated, using file you've given

[generalmimon]

See kaitai-io/kaitai_struct_formats#279

[generalmimon]

To put it in perspective, the issue kaitai-io/kaitai_struct_formats#279 resolved the problem with duplicate keys, but I tested the sample.elf file using the latest revision of the executable/elf.ksy spec in https://ide.kaitai.io/devel/ and the problem after expanding Elf.header.sectionHeaders[25].body still persists.

[solemnwarning]

Just a heads up - the bunzip2 executable which is initially open in the web IDE has the same problem. You can see the error in the console, and when trying to export the header to JSON (which doesn't work).

[armijnhemel]

Looking at the screenshot: the section has type NOBITS meaning that there is no data associated with it and size doesn't describe actual file data.

[armijnhemel]

Also see kaitai-io/kaitai_struct_formats#517

[armijnhemel]

Should have been fixed now: kaitai-io/kaitai_struct_formats@4d74a6c

[generalmimon]

Should have been fixed now: kaitai-io/kaitai_struct_formats@4d74a6c

I confirm that the sample.elf test file from #754 (comment) now works => closing.