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I'm trying to generate a log of all identified symbols in a binary file. The application i'm trying to inspect is busybox. I've created a Pin Tool that successfully captures symbols (no demangling) and place them underneath the module they belong to, and worked just fine for many binaries except busybox. For example this command:

pin -t <pin-tool-shared-object> busybox -ls

Was able to generate only the following output:

MODULE busybox:
.init
.plt
.text

# eof

Not finding any of the desired symbols. Unsure of where the problem was, I tried many variations of the nm command. The output was always the same:

$ nm -an /bin/busybox | c++filt
nm: /bin/busybox: no symbol
$ nm -an -D /bin/busybox | c++filt
nm: /bin/busybox: no symbol
$ nm -D /bin/busybox | c++filt
nm: /bin/busybox: no symbol

What is happening here and how can I get a trace of the called symbols in this case (or at least a static nm-like output of these symbols).

The full Pin tool code is found here, as it might be the problem too.

EDIT

Running the tool in verbose mode -v, that generates the sequential call graph, gives me traces like these when in busybox basic blocks:

0x404970 | CALL .plt
0x42d41f | RET
0x404970 | CALL .plt
0x42d41f | RET
0x43bcd1 | CALL .text
0x4053fb | CALL .text
0x4040d0 | CALL .plt
0x405416 | RET
0x43bcf6 | RET
0x404740 | CALL .plt

Which is nowhere near helpful. Apparently there are no exported symbols in this module.

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Sounds like the binary has ben stripped (had its symbol table removed). Since busybox is usually compiled statically to not have any external dependencies and be entirely self-contained, it does not need even dynamic symbols to function. You'll just have to figure out how to achieve your goal without symbols.

  • The symbols are just what I'm looking for. I'm seeing if I can compile it without stripping it. It's open source, which might help. – Gabriel Vasconcelos Oct 3 '16 at 18:07
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    Correct. I was able to make an unstripped version. There's a make option specifically and clearly for that purpose make busybox_unstripped. – Gabriel Vasconcelos Oct 4 '16 at 1:19

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