-----Original Message-----
From: Eric Gouriou [mailto:email@hidden]
Sent: Thursday, March 06, 2008 1:06 AM
To: Jeremy Todd
Cc: Darwin Dev
Subject: Re: vm_protect with VM_PROT_COPY not working on Leopard
On Mar 5, 2008, at 9:07 PM, Jeremy Todd wrote:
This looks interesting, but I'm curious whether it will allow me to
replace all invocations of malloc. For example if my code calls a
function defined in some system library, and that function in turn
calls malloc(), will it call my interposed malloc?
Yes, even calls to malloc() from within libc / libsystem
(e.g., strdup()).
malloc (and friends) is one of those entry points for which
interposing is part of the ABI contract. Direct calls to its
default implementation are not allowed, everything must go
through the dynamic symbol resolution.
Such guarantees do not exist in general for other library
entry points.
Intra-library calls are frequently done directly, bypassing
the dyld logic.
Eric
Jeremy
-----Original Message-----
From: Chris Sarcone [mailto:email@hidden]
Sent: Wednesday, March 05, 2008 6:03 PM
To: Jeremy Todd
Cc: email@hidden
Subject: Re: vm_protect with VM_PROT_COPY not working on Leopard
Jeremy --
You might find this helpful:
http://developer.apple.com/documentation/DeveloperTools/Concep
tual/DynamicLibraries/DynamicLibraries.pdf
Search for "interposing".
-- Chris
On Mar 5, 2008, at 2:44 PM, Jeremy Todd wrote:
Hi,
I'm trying to patch the malloc function
[...]
In case anyone is wondering, I need to do this as part of our
development process for audio plug-ins. These plug-ins should not
call certain functions (including malloc) from the high-priority
processing thread to avoid priority inversion and related
problems.
We have special debug builds which patch the malloc
function, and if
a malloc is detected in the processing thread, we get a very nice
call stack in the debugger which makes it trivial to find
the source
of these problems.
