prg13_4shmcreate.c

配套光盘网络编程进程间的通信,网络编程进程间的通信是一本很经典的好书

#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <sys/mman.h>

#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
int main(int argc,char **argv)
{
  int  c,fd,flags;
  char  *ptr;
  off_t  length;
  flags = O_RDWR | O_CREAT;
  if (argc != 3)
  {
  	printf("usage %s: <name> <length>",argv[0]);
  	exit(0);
  }
  
  while((c = getopt(argc,argv,"e")) !=-1)
  {
  	switch(c)
  	{
  		case 'e':
  			flags |= O_EXCL;
  			break;
  	}
  }
  
  length = atoi(argv[2]);
  fd = shm_open(argv[1],flags,FILE_MODE);
  ftruncate(fd,length);
  ptr = mmap(NULL,length,PROT_READ | PROT_WRITE,MAP_SHARED,fd,0);
  shm_unlink(argv[1]);
  exit(0);
}