site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Jeremy, davez On Mar 6, 2008, at 7:53 AM, Jeremy Todd wrote: Regards, Jeremy -----Original Message----- From: Eric Gouriou [mailto:eric.gouriou@pobox.com] 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 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:sarcone@apple.com] Sent: Wednesday, March 05, 2008 6:03 PM To: Jeremy Todd Cc: darwin-dev@lists.apple.com 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 a malloc is detected in the processing thread, we get a very nice call stack in the debugger which makes it trivial to find of these problems. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/zarzycki%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... Depending on how you define run-time, one can conditionally interpose at launch by use of the DYLD_INSERT_LIBRARIES environmental variable. "man dyld" for more information. "man libgmalloc" for precedence. That's good news - the one remaining problem is that it would be nice if I could enable this at runtime. Is it true that interposing must be done by the linker at link-time? I'm also still wondering why the vm_protect() VM_PROT_COPY mechanism described below is failing under Leopard. Surely it must be possible to get write access to the malloc() implementation somehow. For example doesn't gdb need this sort of access? On Mar 5, 2008, at 9:07 PM, Jeremy Todd wrote: [...] problems. We have special debug builds which patch the malloc function, and if the source This email sent to zarzycki@apple.com This email sent to site_archiver@lists.apple.com