1 /*
2  * mq_open.c - open a message queue.
3  */
4 
5 #include <errno.h>
6 #include <stdarg.h>
7 #include <stddef.h>
8 #include <sys/syscall.h>
9 
10 #include <mqueue.h>
11 
12 #ifdef __NR_mq_open
13 
14 #define __NR___syscall_mq_open __NR_mq_open
15 static __inline__ _syscall4(int, __syscall_mq_open, const char *, name,
16 			int, oflag, __kernel_mode_t, mode, void *, attr);
17 /*
18  * Establish connection between a process and a message queue and
19  * return message queue descriptor or (mqd_t) -1 on error.
20  * oflag determines the type of access used. If O_CREAT is on oflag, the
21  * third argument is taken as a `mode_t', the mode of the created
22  * message queue, and the fourth argument is taken as `struct mq_attr *',
23  * pointer to message queue attributes.
24  * If the fourth argument is NULL, default attributes are used.
25  */
mq_open(const char * name,int oflag,...)26 mqd_t mq_open(const char *name, int oflag, ...)
27 {
28 	mode_t mode;
29 	struct mq_attr *attr;
30 
31 	if (name[0] != '/') {
32 		__set_errno(EINVAL);
33 		return -1;
34 	}
35 
36 	mode = 0;
37 	attr = NULL;
38 
39 	if (oflag & O_CREAT) {
40 		va_list ap;
41 
42 		va_start(ap, oflag);
43 		mode = va_arg(ap, mode_t);
44 		attr = va_arg(ap, struct mq_attr *);
45 
46 		va_end(ap);
47 	}
48 
49 	return __syscall_mq_open(name + 1, oflag, mode, attr);
50 }
51 
52 #endif
53