librt/mq_open.c

   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  */
  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