__builtin_object_size(3) [netbsd man page]

__BUILTIN_OBJECT_SIZE(3)				   BSD Library Functions Manual 				  __BUILTIN_OBJECT_SIZE(3)

NAME

     __builtin_object_size -- return the size of the given object

SYNOPSIS

     size_t
     __builtin_object_size(void *ptr, int type);

DESCRIPTION

     The __builtin_object_size() function is a gcc(1) built-in function that returns the size of the ptr object if known at compile time and the
     object does not have any side effects.

RETURN VALUES

     If the size of the object is not known or it has side effects the __builtin_object_size() function returns:

	   (size_t)-1  for type 0 and 1.

	   (size_t)0   for type 2 and 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.

SEE ALSO

     gcc(1), __builtin_return_address(3), attribute(3), ssp(3)

HISTORY

     The __builtin_object_size() appeared in GCC 4.1.

CAVEATS

     This is a non-standard, compiler-specific extension.

BSD
								 December 19, 2010							       BSD

__BUILTIN_RETURN_ADDRESS(3)				   BSD Library Functions Manual 			       __BUILTIN_RETURN_ADDRESS(3)

NAME

     __builtin_return_address -- the return address of a function

SYNOPSIS

     void *
     __builtin_return_address(unsigned int level);

     void *
     __builtin_frame_address(unsigned int level);

DESCRIPTION

     The __builtin_return_address() is a GNU extension for obtaining the return address of the current function or one of the callers of the cur-
     rent function.

     The parameter level specifies the number of frames that should be scanned up in the call stack.  A value 0 returns the address of the current
     function, a value 1 requests the address of the caller of the current function, a value 2 asks for the address of the caller's caller, and so
     forth.  If the top of the call stack has been reached, the function will return 0.  Note also that on some architectures it is only possible
     to determine the address of the current function.	In such cases a value 0 is returned.  Thus, it is usually safe to only use the value 0 for
     level.

     The __builtin_frame_address() behaves similarly, but returns the address of the function frame rather than the return address of the func-
     tion.

SEE ALSO

     gcc(1), __builtin_object_size(3)

CAVEATS

     These are non-standard, compiler-specific extensions.

BSD
								 December 19, 2010							       BSD