Alexandre Julliard writes:
The dll init routine needs to be in the .init section in order to be called first,
Isn't that what attribute((constructor)) does? It places a call to the routine in the .so's initialization section, whatever that section is, so that the routine gets invoked during dlopen(). As far as I know, it's equivalent to the asm() sections it replaces. For example, see the code emitted by BuildDebugFile() in spec32.c ...
attribute((constructor)) is not good enough.
I'm perplexed. What is it that attribute((constructor)) does not do? Perhaps it has a different effect on OBSD than on other systems? How can I test whether it, or whatever asm code I replace it with, is doing the right thing?
Why doesn't it work on OpenBSD? Is the section name different?
AFAICT, OpenBSD uses a section named .ctors containing function pointers, rather than a section containing 'call' opcodes. At least, that's what attribute((constructor)) emits, and looking through the dlfcn and C runtime sources I don't see any other initialization hooks being called. There *is* a section named .init, but any code placed there will be linked after the C function __init() in crtbeginS.c, and will not be executed because that C function returns normally. But the only thing that __init() does is invoke the functions pointed to by .ctors, and add a hook to make sure that the .dtors are called. Wim.
wiml(a)underhill.hhhh.org (Wim Lewis) writes:
There *is* a section named .init, but any code placed there will be linked after the C function __init() in crtbeginS.c, and will not be executed because that C function returns normally. But the only thing that __init() does is invoke the functions pointed to by .ctors, and add a hook to make sure that the .dtors are called.
The way it normally works is that the _init() function is built from the contents of the .init section, so if you add code in .init it's supposed to show up in _init(). Then the C run time adds code in .init that calls the constructors. So there are two separate mechanisms, and the constructors are built on top of the .init stuff. In our case we need to be in .init because the constructors are normally called after the rest of the .init code. -- Alexandre Julliard julliard(a)winehq.com
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Alexandre Julliard -
wiml＠underhill.hhhh.org