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如何操作伪终端：
伪终端的使用是成对出现的，分为master 和 slaver
主设备：/dev/ptmx （i850上的主设备名）
从设备：动态生成：/dev/pts/0.......x
功能：写入主设备的信息，可以从从设备上读出；写入从设备的信息，可以从主设备读出。用以实现对串口的多路复用。
以下是测试代码
Ubuntu 下的编译方法：
gcc -Wall ptyhost.c -o ptyhost -util /lib/libutil-2.9.so
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# include <unistd.h>
# include <sys/types.h>
# include <linux/limits.h>
# include <pty.h> /* for openpty and forkpty */
#include <utmp.h> /* for login_tty */
#include <time.h>
# include <pty.h> /* for openpty and forkpty */
#include <utmp.h> /* for login_tty */
int main(int argc, char *argv[])
{
int rtnVal=0;
int mpty, spty, c=0, dev=0;
char *pName=NULL;
char ptyBuff[100] = {'\0'};
char sptyname[20] = {'\0'};
rtnVal = openpty(&mpty, &spty, sptyname, NULL, NULL);/＊该函数遍历系统中的伪终端匹配对，如果能找到一组未使用的，则返回1，否则返回－1，成功返回时mpty会带出匹配对中主设备的文件描述符，spty会带出从设备的文件描述符，第三个实参如果不空的话，它会带出从设备的路径名！后边两个参数是在设置终端属性，一般是不要的，据说伪终端对属性设置是忽略的＊/
// Check if Pseudo-Term pair was created
if(rtnVal != -1)
{
pName = ptsname(mpty);//get slave device name, the arg is the master device
printf("Name of slave side is <%s> fd = %d\n", pName, spty);
strcpy(sptyname, pName);
printf("my sptyname is %s\n",sptyname);
//test write to mpty and read from spty*************
char temp[50] = {"hell\nworld ! i have write to mpty!"};
char temp2[100] = {'\0'};
c = write(mpty,temp,5);
if(c <=0)
printf("ERROR : can not write to mpty\n");
sleep(3);
printf("write %d charactors to mpty success\n",c);
sleep(3);
printf("try to read from spty\n");
sleep(3);
c = read(spty,temp2,5);
if(c <=0)
printf("ERROR : can not read from mpty\n");
printf("read from spty %d charactors success\n",c);
printf("\n>>>>> %s <<<<<\n\n___________________\n",temp2);
//**************************************************
// Go into loop and read what is sent to Slave side of pair
while(1)
{
c = read(mpty, ptyBuff, 100);
if(c > 0)
{
printf("###-<%d>\n", c);
printf("buff:__|%s",ptyBuff);
}
}
}
else
{
printf("PseudoTerm, creation failed...\n");
}
return rtnVal;
} http://blog.163.com/coder_jack@126
伪终端的操作：
以下是源码，来自/fsl_myandroid_r6/external/qemu/vl.c line 2545
r7里面都已经没有了！真快呀！哈哈
/* Once Solaris has openpty(), this is going to be removed. */
int openpty(int *amaster, int *aslave, char *name,
struct termios *termp, struct winsize *winp)
{
const char *slave;
int mfd = -1, sfd = -1;
*amaster = *aslave = -1;
mfd = open("/dev/ptmx", O_RDWR | O_NOCTTY);
if (mfd < 0)
goto err;
if (grantpt(mfd) == -1 || unlockpt(mfd) == -1)
goto err;
if ((slave = ptsname(mfd)) == NULL)
goto err;
if ((sfd = open(slave, O_RDONLY | O_NOCTTY)) == -1)
goto err;
if (ioctl(sfd, I_PUSH, "ptem") == -1 ||
(termp != NULL && tcgetattr(sfd, termp) < 0))
goto err;
if (amaster)
*amaster = mfd;
if (aslave)
*aslave = sfd;
if (winp)
ioctl(sfd, TIOCSWINSZ, winp);
return 0;
err:
if (sfd != -1)
close(sfd);
close(mfd);
return -1;
} http:
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