create.c

这个是学习嵌入式开发的重要例子

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <semaphore.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>

int main(int argc, char **argv)
{
  if (argc < 2)
  {
    fprintf(stderr, "Usage: %s <name>\n", argv[0]);
    exit(1);
  }

  sem_t *sem = NULL;
  unsigned int value;

  value = 1;

  //Upon  successful  completion,  the sem_open() function shall return the address of the semaphore. Other-
  //wise, it shall return a value of SEM_FAILED and set errno to indicate the error. The  symbol  SEM_FAILED
  //is  defined  in  the  <semaphore.h>  header. No successful return from sem_open() shall return the value
  //SEM_FAILED.
  //sem_t *sem_open(const char *name, int oflag, ...);
  if ((sem = sem_open(argv[1], O_CREAT | O_EXCL, 0644, value)) == SEM_FAILED)
  {
    fprintf(stderr, "sem_open() failed: %s\n", strerror(errno));
    exit(1);
  }

  fprintf(stdout, "sem_open() successed.\n");

  //int sem_close(sem_t *sem);
  sem_close(sem);

  //int sem_unlink(const char *name);
  //sem_unlink(argv[1]);

  return 0;
}