open.c

unix环境高级编程的源代码

#include    "open.h"
#include    <sys/uio.h>        /* struct iovec */

/* Open the file by sending the "name" and "oflag" to the
 * connection server and reading a file descriptor back. */

int
csopen(char *name, int oflag)
{
    int                len;
    char            buf[10];
    struct iovec    iov[3];
    static int        csfd = -1;

    if (csfd < 0) {        /* open connection to conn server */
        if ( (csfd = cli_conn(CS_OPEN)) < 0)
            err_sys("cli_conn error");
    }

    sprintf(buf, " %d", oflag);        /* oflag to ascii */
    iov[0].iov_base = CL_OPEN " ";
    iov[0].iov_len  = strlen(CL_OPEN) + 1;
    iov[1].iov_base = name;
    iov[1].iov_len  = strlen(name);
    iov[2].iov_base = buf;
    iov[2].iov_len  = strlen(buf) + 1;
                            /* null at end of buf always sent */
    len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
    if (writev(csfd, &iov[0], 3) != len)
        err_sys("writev error");

                    /* read back descriptor */
                    /* returned errors handled by write() */
    return( recv_fd(csfd, write) );
}