On Wed, Apr 11, 2012 at 06:33:26PM -0700, Chase Douglas wrote: > On 04/11/2012 04:53 PM, Peter Hutterer wrote: > > On Mon, Apr 09, 2012 at 11:17:26AM -0700, Chase Douglas wrote: [...] > > - the API is rather shocking, replacing one vararg function with a number of > > mixed calls makes it really hard to grep for the message. > > a poor man's printf parsing that searches for %d, %s and %x would help > > here. > > Variadic argument implementation is some of the blackest magic of C > code, and varies a great deal even between architectures of glibc. I > don't know if we can be sure that variadic arguments will always be > signal safe. They aren't mentioned in the POSIX signal(7) man page as > safe functions. > > I doubt we would actually support Interix SUA, for example, but it is > POSIX compliant and its man page says va_* functions are not signal > safe: http://www.suacommunity.com/man/3/varargs.3.html. > > > - given that input drivers almost always use signal-sensitive processing, > > making xf86IDrvMsg signal safe would go a long way > > It's variadic, so I don't think that will be possible. I know there's > bound to be some pain here that reaches device drivers, but I don't see > a way around it.
sorry to pick this up so late. I've been banging my head against the wacom driver, finding a good way to log debug messages while parsing events and the crux of the matter is the vararg stuff. I went searching again and found that signal(7) lists execle() and that function takes a variable number of parameters. execle is a POSIX requirement, va_list and friends must be vararg-compatible, which means we can have a normal implementation of the log messaging functions. Cheers, Peter _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
