gdb corefile not see function parameters

Question

My application crashed due to uncaught exception (my c++ code throws uncaught exception under certain condition). I am trying to gdb the corefile. The binary library is "not striped". And the stack trace shows the function (my code) from which an uncaught exception is thrown, but when I try to print the function arguments, I always get "no symbol xxx in current context". info args also return "No symbol table info available".

Can anyone shed a light why ? is it due to the uncaught exception which unwind/corrupts the stack ?

Thanks, Frank

A coredump will not necessarily contain all the symbols. This can be due to missing libraries or non-debug built libraries or even compiler optimisation. — Griffin, Sep 11 '17 at 22:27
Also you should try to firs [search stack overflow](https://stackoverflow.com/search?q=gdb+No+symbol+table+info+available) before asking a new question. — Griffin, Sep 11 '17 at 22:31

Employed Russian · Answer 1 · 2017-09-12T03:13:49.943

1

Your binary lacks debug info.

If you built it with gcc, and want to debug the core you already have (if e.g. it's hard to reproduce the crash), you may be able to recover from this by rebuilding the binary with exactly the same source and command lines, adding -g to compile and link commands. (Note: you must use the same compile lines; replacing -O2 with -g wouldn't do.)

If the crash is not hard to reproduce, simply rebuild the binary with -g -O0, run it under GDB, and enjoy "easy" debugging.

The binary library is "not striped".

This doesn't mean what you think it means. Not stripped means that the symbol table is still present in the binary.

GDB will read this symbol table, and use it to map ranges of addresses to function names.

But to recover names and values of local variables and parameters, you must compile with debug info (which is what -g flag does for most compilers).

edited Sep 12 '17 at 03:13

answered Sep 12 '17 at 02:59

Employed Russian

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Should the optimization flag also be lowered? – dlmeetei Sep 12 '17 at 03:05
@dlmeetei Not if you want to analyze already existing `core` file. – Employed Russian Sep 12 '17 at 03:06
But we are asking to recompile – dlmeetei Sep 12 '17 at 03:07
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@dlmeetei Yes. So? Rebuilding the binary with the *exact* same sources and command lines, with addition of `-g`, *often* allows one to analyze a `core` produced by non-debug binary. That's *the* point of my answer. – Employed Russian Sep 12 '17 at 03:09
got it. I usually lower my optimization flags also when compiling with -g – dlmeetei Sep 12 '17 at 03:11

gdb corefile not see function parameters

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