Andrew Pinski wrote:
On Sat, 2006-11-11 at 22:18 -0800, Ian Lance Taylor wrote:
Your code will be safe on all counts if you change buf from int[] to
char[]. The language standard grants a special exemption to char*
pointers. Without that exemption, it would be impossible to write
malloc in C.
As I recall, we chose int[] for alignment reasons, figuring we'd have no
guarantees on the alignment of a char[].
Actually it is not that what the C standard allows. What the C standard
says is accesses via the character type is always valid and the normal
type (and signed/unsigned version of both the normal and character
type). This means accessing an element of the character array via any
other type except via an unsigned/signed character type is undefined.
Right, I've just read that text as well, which is why I'm still
wondering. But as Ian said, we never do any loads or stores into the
actual buf, so it seems we don't need to care care whether its value is
defined or not. If that's a safe assumption, then I propose that this is
a rule worth stating:
aliasing means two pointers point to the same memory
if only one pointer is ever used to access that memory, aliasing
doesn't matter
--
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc
OpenLDAP Core Team http://www.openldap.org/project/
