On 12/12/13 03:02, Allan McRae wrote:
On 12/12/13 02:44, Dave Reisner wrote:
On Thu, Dec 12, 2013 at 02:14:19AM +1000, Allan McRae wrote:
On 12/12/13 00:24, Jeremy Heiner wrote:
On Tue, Dec 10, 2013 at 11:58 PM, Allan McRae <allan@archlinux.org> wrote:
I am still looking for something cleaner than the proposed #define/#undef approach which feels a bit hacky
Here is a third (well, 4th, since "do nothing" is always on the table) option which lies between "just document" and "macro shenanigans"... Following the lead of 'alpm_capabilities', add:
How about #5...
diff --git a/lib/libalpm/alpm.c b/lib/libalpm/alpm.c index 878c38b..a41c07d 100644 --- a/lib/libalpm/alpm.c +++ b/lib/libalpm/alpm.c @@ -52,6 +52,12 @@ alpm_handle_t SYMEXPORT *alpm_initialize(const char *root, const char *dbpath, const char *lf = "db.lck"; size_t lockfilelen; alpm_handle_t *myhandle = _alpm_handle_new(); + + /* calculate off_t size at runtime */ + size_t off_t_size = ((char *)((off_t *)0 + 1) - (char *)(off_t *)0); + + if(off_t_size != sizeof(off_t)) { + myerr = ALPM_ERR_OFF_T_SIZE; + goto cleanup; + }
I do not believe this actually works as intended. There's nothing "at runtime" about this, especially when optimizations are involved (even with -O1). Your off_t_size will be calculated at compile time and therefore the comparison that follows will never fail. The instructions generated for the off_t_size is effectively:
mov $0x8,%eax
Or, when LFS isn't enabled:
mov $0x4,%eax
This version looks like it should survive optimization:
off_t x; size_t off_t_size = ((char *)(&(x) + 1) - (char *)&(x));
And nope... smart compiler.