[fpc-devel] FPC shared lib called from C shared lib called from C main program crashes

[Lukas Zeller]

Hello,

I already dug through the archives but found nothing really related to  
a weird problem I have with a FPC shared lib which is used by a C  
shared lib which in turn is a plugin to a C main program.

The net effect is that the FPC library crashes (apparently when trying  
to allocate a FPC object) when just used as-is, but works wonderfully  
if I put a Write(' ') into the FPC library's begin end.

I'm not familiar with FPC runtime internals, so I can only guess that  
this Write (a WriteLn works as well, as long as it goes to stdout)  
triggers some initialisation code of the FPC runtime that is otherwise  
not called. I tried calling System.SysInitStdIO instead, hoping it  
would maybe initialize the same thing a Write() does, but it did not  
work, as other blind flight attempts to find a better fix than this  
Write() didn't either.

I guess I really need to understand how the FPC runtime expects to be  
initialized when located in a shared lib, but I couln't find any hint  
so far in the FPC docs nor in the list archives.

The FPC shared library is implicitly loaded as a dependency of the C  
shared lib plugin, which in turn is loaded by dlopen() from the C main  
program. I run the program on Mac OS X and Linux (but not on Windows).

I can modify the C shared lib plugin and the FPC shared lib, but not  
the main program (so it's out of question to have the FPC runtime  
linked into the main program).

I'd really be glad if someone has any pointers or ideas how to  
correctly fix this problem. I do understand shared lib technical  
details and problems in general, but am a FPC newbie and have no idea  
what the specifics regarding the FPC runtime might be.

Thanks for any help in advance!

Lukas

(luz_info at synthesis.ch)