open.c

来自「APUE(第二版)的随书源代码,与第一版的代码相比增加了一些章节的代码(详见第二」· C语言 代码 · 共 36 行

#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) );
}