create.c

来自「这个是学习嵌入式开发的重要例子」· C语言 代码 · 共 69 行

#include <stdio.h>
#include <stdlib.h>
#include <mqueue.h>
#include <string.h>
#include <errno.h>

#define MQUEUE_NAME	"/mqueue.test.1"

int main(int argc, char **argv)
{
  if (argc < 4)
  {
    fprintf(stdout, "Usage: %s <name> <maxmsg> <msgsize>\n", argv[0]);
    exit(1);
  }

  // Upon successful completion, the function shall return a message queue descriptor; otherwise,  the  func-
  // tion shall return (mqd_t)-1 and set errno to indicate the error.
  mqd_t mqd;

#if 0
  type = struct mq_attr
  {
    long int mq_flags;
    long int mq_maxmsg;
    long int mq_msgsize;
    long int mq_curmsgs;
    long int __pad[4];
  }
#endif

  struct mq_attr attr;

  memset(&attr, 0, sizeof(attr));

  //attr.mq_flags = 
  attr.mq_maxmsg = atol(argv[2]);
  attr.mq_msgsize = atol(argv[3]);
  //attr.mq_curmsgs = 

  //mqd_t mq_open(const char *name, int oflag, ...);
  //mqd_t mq_open(char *name, int flags, int mode, struct mq_attr *attr);
  if ((mqd = mq_open(argv[1], O_CREAT | O_EXCL, 0644, &attr)) == (mqd_t) - 1)
  {
    fprintf(stderr, "mq_open() failed: %s\n", strerror(errno));
    if (errno != EEXIST)
    {
      exit(1);
    }
  }

  fprintf(stdout, "mq_open() successed.\n");
  mq_close(mqd);

#if 0
  //int mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);
  mq_getattr(mqd, &attr);

  fprintf(stdout, "attr.mq_flags = %ld\n", attr.mq_flags);
  fprintf(stdout, "attr.mq_maxmsg = %ld\n", attr.mq_maxmsg);
  fprintf(stdout, "attr.mq_msgsize = %ld\n", attr.mq_msgsize);
  fprintf(stdout, "attr.mq_curmsgs = %ld\n", attr.mq_curmsgs);

  mq_unlink(MQUEUE_NAME);
#endif

  return 0;
}