Re: Help with gdb needed

[Marcus Müller]

Hi David,

A crash in objc_msgSend() usually means that the object that is being sent a message is an invalid pointer.  Try enabling zombies and see if it reports an object being deallocated.

that's clear - but why can't I print it in gdb? I just want to inspect the pointer, but even that fails.

(gdb) frame 1
#1  0x0000000800d6ade9 in -[GSRunLoopCtxt pollUntil:within:] (
   self=0x806d5e248, _cmd=0x80113b990 <.objc_selector_list+544>, 
   milliseconds=0, contexts=0x806c3bfa8) at GSRunLoopCtxt.m:639
639   [watcher->receiver receivedEvent: watcher->data
(gdb) p watcher
$1 = (struct GSRunLoopWatcher *) 0x8071b8d68
(gdb) p watcher->receiver
Cannot set lwp 100877 registers: Invalid argument
An error occurred while in a function called from GDB.
Evaluation of the _expression_ containing the function
(malloc) will be abandoned.
When the function is done executing, GDB will silently stop.

P.S. On FreeBSD, it's usually best to use gdb from ports, as the one in base doesn't understand DWARF4, which modern clang and gcc both generate.

I'm using [GDB v7.5.1 for FreeBSD], should be good?

Cheers,

  Marcus

-- 

Marcus Müller  .  .  .  http://www.mulle-kybernetik.com/znek/

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