gdb unable to break on lstat call

Question

Hello all,

I'm debugging PHP 5.2.9 and everything works fine, but today during debugging I see that gdb don't stop when I set:

(gdb) break lstat

the breakpoint is in the list

(gdb) info breakpoints
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x00002aaaaf810ea0 

but, as written before, during execution gdb don't stop when lstat function is called. Note that I'm sure that lstat is called by PHP engine because I can see the call using strace.

Please help me, what's wrong with gdb?

Answer 1

strace is showing you that PHP is calling the system call lstat, however your breakpoint is actually on the library function lstat(). It's possible that it's a different library call that is directly calling the lstat system call.

What does ltrace show?

Answer 2

Try to set catchpoint on lstat syscall

(gdb) catch syscall lstat
Catchpoint 1 (syscall 'lstat' [107])
(gdb)

You will need gdb 7.0 or above