isastream() | 确定 STREAMS 设备

beyes

原型：

#include <stropts.h>

int isastream (int fildes);

isastream 函数确定文件描述符 fileds 是否表示 STREAMS 设备。如果是，则函数返回 1 ；如果不是，则返回 0 ；如果出错，返回 -1 。

测试代码：

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

int main (int argc, char **argv)
{
        int fd;
        int i;

        if (argc < 2) {
                printf ("Usages: isastreamm file ...");
                exit (EXIT_FAILURE);
        }

        for (i = 0; i < argc; i++) {
                if ((fd = open (argv [i], O_RDONLY)) == -1) {
                        printf ("Can't open %s", argv [i]);
                        continue;
                }

                printf ("%s %s a STREAMS device\n", argv [i], (isastream (fd)) ? "is" : "is not");
        }

        return (0);
}

运行及输出：

[beyes@localhost STREAMS]$ ./isastream.exe /dev/tty /dev/null
./isastream.exe is not a STREAMS device                      
/dev/tty is not a STREAMS device                             
/dev/null is not a STREAMS device