Setting a watchpoint on errno in gdb
debugging, errno, gdb, libc, watchpoint
Solution
`errno` is not just a static variable anymore. Here's how it appears to userland apps on Linux (from my local `/usr/include/x86_64-linux-gnu/bits/errno.h`):
# define errno (*__errno_location ())
This is to get error state per thread.
Problem
I'm trying to find out when errno changes. At first, I tried "watch errno" in gdb, which led to the error ``` Cannot find thread-local variables on this target ``` I was able to fix this by compiling with "-pthread". However, it still doesn't work and I now get the error ``` Cannot find shared library `/usr/lib/debug/lib/x86_64-linux-gnu/libc-2.13.so' in dynamic linker's load module list ``` when I type "watch errno". What do I need to do such that setting a watchpoint on errno works?