int main(void)
{
int fd;
pid_t pid;
if ((fd = creat("templock", FILE_MODE)) < 0)
err_sys("creat error");
if (write(fd, "ab", 2) != 2)
err_sys("write error");
TELL_WAIT();
if ((pid = fork()) < 0){
err_sys("fork error");
}else if(pid == 0){/*child*/
lockabyte("child", fd, 0);
TELL_PARENT(getppid());
WAIT_PARENT();
lockabyte("child", fd, 1);
}else{
lockabyte("parent", fd, 1);
TELL_CHILD(pid);
WAIT_CHILD();
lockabyte("parent", fd, 0);
}
exit(0);
}
int main(int argc, char *argv[])
{
int fd;
pid_t pid;
/*Create a file and write two bytes to it*/
fd = Open("templock", O_RDWR | O_CREAT | O_TRUNC, FILE_MODE) ;
if(write(fd, "ab", 2) != 2)
err_sys("write error");
TELL_WAIT();
pid = Fork();
if(pid == 0)
{
lockabyte("child", fd, 0);
TELL_PARENT(getppid());
WAIT_PARENT();
lockabyte("child", fd, 1);
}else
{
lockabyte("parent", fd, 1);
TELL_CHILD(pid);
WAIT_CHILD();
lockabyte("parent", fd, 0);
}
return 0;
}
/* gcc apue.h apue_err.c figure-14.5.c figure-10.24.c figure-14.7.c */
int
main(void)
{
int fd;
pid_t pid;
/*
* Create a file and write two bytes to it.
*/
if ((fd = creat("templock", FILE_MODE)) < 0)
err_sys("creat error");
if (write(fd, "ab", 2) != 2)
err_sys("write error");
TELL_WAIT(); /* figure-10.24.c */
if ((pid = fork()) < 0) {
err_sys("fork error");
} else if (pid == 0) { /* child */
lockabyte("child", fd, 0);
TELL_PARENT(getppid());
WAIT_PARENT();
lockabyte("child", fd, 1);
} else { /* parent */
lockabyte("parent", fd, 1);
TELL_CHILD(pid);
WAIT_CHILD();
lockabyte("parent", fd, 0);
}
exit(0);
}
int main(int argc, char* argv[])
{
int fd;
pid_t pid;
if((fd = creat("templock", FILEMODE)) < 0)
printf("creat error");
if(write(fd, "ab", 2) != 2)
printf("write error");
TELL_WAIT();
if((pid = fork()) < 0)
printf("fork error");
else if(pid == 0)
{
lockabyte("child:", fd, 0);
TELL_PARENT(getpid());
WAIT_PARENT();
lockabyte("child:", fd, 1);
}
else
{
lockabyte("parent:", fd, 1);
TELL_CHILD(pid);
WAIT_CHILD();
lockabyte("parent:", fd, 0);
}
exit(0);
}
int main(void)
{
int fd;
pid_t pid;
/* 建立檔案並寫兩個位元組*/
if ((fd = creat("templock", 0666)) < 0)
err_exit("creat error");
write(fd, "ab", 2) ;
if((pid = fork())==0) { /* 子執行緒 */
lockabyte("child", fd, 1);
sleep(2); /* 留出時間以便父執行緒鎖住位元組2 */
lockabyte("child", fd, 2);
} else { /* 父執行緒 */
lockabyte("parent", fd, 2);
sleep(2); /* 留出時間以便子執行緒鎖住位元組1 */
lockabyte("parent", fd, 1);
}
exit(EXIT_SUCCESS);
}