Hi all,
I just had a long debugging session and wanted to comment the result here
on the list.
When using -D_FORTIFY_SOURCE=2 the first ioctl() after open() suddenly
failed. This is due to an inline function "open()" (in bits/fcntl2.h),
that will analyse the call arguments and forward the function call
accordingly. When the second argument is not a compile-time constant,
then the call is forwarded to "__open_2()" instead of "__open_alias()".
So when you write:
open("/dev/rtdm/rtser0", O_RDWR);
then __cobalt_open() will be called. But when you use a function like
this:
int my_function(int mode) {
return open("/dev/rtdm/rtser0", mode);
}
then __open_2() will be called. The consequence is that the following
ioctl(RTSER_RTIOC_SET_CONFIG) fails, as the file descriptor was not
opened by __cobalt_open().
This is a nasty little difference. My solution was to write:
int my_function(int mode) {
return __WRAP(open("/dev/rtdm/rtser0", mode));
}
Maybe this is just ancient history for you, but I had some "fun" to find
this.
Regards,
Jan
Mit freundlichen Grüßen
*Jan Leupold*
Entwicklung
Development
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