Re: [PATCH/WIP 1/8] wrapper: implement xopen()

On Thu, May 28, 2015 at 5:53 AM, Jeff King [off-list ref] wrote:

On Wed, May 27, 2015 at 09:03:47PM +0200, Torsten Bögershausen wrote:

quoted

The original open can take 2 or 3 parameters, how about this:
int xopen(const char *path, int oflag, ... )
{
        va_list params;
        int mode;
        int fd;

        va_start(params, oflag);
        mode = va_arg(params, int);
        va_end(params);

        fd = open(path, oflag, mode);

Don't you need a conditional on pulling the mode arg off the stack
(i.e., if O_CREAT is in the flags)?

Yeah, we do, as va_arg()'s behavior is undefined if we do not have the
next argument.

The POSIX spec[1] only mentions O_CREAT as requiring the extra
argument, so I guess we'll only need to check for that.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html

Thanks,
Paul