__BUILTIN_OBJECT_SIZE(3) | Library Functions Manual | __BUILTIN_OBJECT_SIZE(3) |
If the size of the object is known, then the __builtin_object_size() function returns the maximum size of all the objects that the compiler knows that they can be pointed to by ptr when type & 2 == 0, and the minimum size when type & 2 != 0.
Note that currently the object size calculation pass is only done at -O1 or above, meaning that this function always returns -1 when the optimizer is off.
There are some discussions about always doing the object size pass, but the issue is that without the optimization pass data sizes are not going to be correct.
For that reason currently code fortification (size-checked replacement functions) is disabled when optimization is off.
July 18, 2012 | NetBSD 7.2 |