[Xcb] Questions about XCB using domain sockets.

[Alan Coopersmith]

On 02/26/18 12:13 AM, xc haze wrote:
> Hi:
> When I look at XCB communication，
> static int _xcb_open_abstract(char *protocol, const char *file, size_t filelen)
> {
>     int fd;
>     struct sockaddr_un addr = {0};
>     socklen_t namelen;
> 
>     if (protocol && strcmp("unix",protocol))
>         return -1;
> 
>     strcpy(addr.sun_path + 1, file);
>     addr.sun_family = AF_UNIX;
>     namelen = offsetof(struct sockaddr_un, sun_path) + 1 + filelen;
>    。。。。。。
> ｝
> Why do we add one to addr->sun_path?

Because abstract sockets have the name field start with a byte of 0,
then the actual name, to distinguish them from filesystem pathnames.

See "Address format" in http://man7.org/linux/man-pages/man7/unix.7.html

-- 
	-Alan Coopersmith-               alan.coopersmith at oracle.com
	 Oracle Solaris Engineering - https://blogs.oracle.com/alanc