p3-5.c

UNIX程序设计教程

#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include "err_exit.h"
int display_file_status_flages(int fd)
{
    int accmode, val;
    if ((val = fcntl(fd, F_GETFL, 0) ) < 0)
       err_exit("fcntl error");
    /* 截取文件访问方式标志 */
    accmode = val & O_ACCMODE;
    /* 打印出所有设置了的标志 */
    if (accmode == O_RDONLY) 
        printf("read only");
    else if (accmode == O_WRONLY) 
        printf( "write only");
    else if (accmode == O_RDWR) 
        printf("read write");
    else {
        printf("unknown access mode\n");
        exit(1);
    }
    if (val & O_APPEND) 
        printf(" , append");
    if (val & O_NONBLOCK) 
        printf(" , nonblocking");
#if !defined(POSIX_SOURCE) && defined(O_SYNC)
     if (val&O_SYNC) 
        printf(", synchronous writes" );
#endif
     putchar('\n' );
     exit(0);
}