Need tips debugging a crash porting an app to cygwin caused by sth overwriting a function

[Dalibor Topic]

Hi all,

I'm trying to get kaffe to work again on Cygwin, and I'm quite puzzled 
at a bug I'm seing. Here's what happens:

I fire up a statically linked kaffe-bin.exe in gdb, and disassemble a 
function, findJarFiles in gdb, and result looks reasonable, i.e. it 
looks just like in the disassembly of the object file the function comes 
from.

I try runing kaffe in gdb in order to run the java compiler, and quite 
quickly, it crashes, when it enters the findJarFiles function, with a 
SIGSEGV. The disassembly of the function shows that it's been modified 
to have a few bad opcodes at the start.

Of course, I'd like to know what causes those opcodes to be modified. 
I've tried watch and awatch findJarFiles, awatch *(long *) findJarFiles, 
but despite gdb saying that it's setting a hardware watchpoint, I don't 
get a break in gdb until the function call crashes, which is too late.

So I'm wondering what kind of tips experienced Cygwin developers could 
offer to nail the bug down.

cheers,
dalibor topic


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