冬天OS（三十七）：shabby

冬天OS（三十七）：shabby_shell

本文主要是介绍冬天OS（三十七）：shabby_shell，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

--------------------------------------------------------

shabby_shell

--------------------------------------------------------

起名为 shabby_shell 是因为他太简单了 ...

·Init 函数
void Init()
{int fd_stdin = open("/dev_tty0", O_RDWR);assert(fd_stdin == 0);int fd_stdout = open("/dev_tty0", O_RDWR);assert(fd_stdout == 1);printf("Init() is running ...\n");/* extract `cmd.tar' */untar("/cmd.tar");char *tty_list[] = {"/dev_tty1", "/dev_tty2"};int i;for (i = 0; i < sizeof(tty_list) / sizeof(tty_list[0]); i++){int pid = fork();if (pid != 0){ /* parent process */printf("[parent is running, child pid:%d]\n", pid);}else{ /* child process */printf("[child is running, pid:%d]\n", getpid());close(fd_stdin);close(fd_stdout);shabby_shell(tty_list[i]);assert(0);}}while (1){int s;int child = wait(&s);printf("child (%d) exited with status: %d.\n", child, s);}assert(0);
}

——在 fork 之后，如果是父进程，接着 fork 下一个 shell 或者退出循环循环为每个子进程提供 wait 服务，如果是子进程，阻塞在 shabby_shell 执行 shell！

·shabby_shell 函数
void shabby_shell(const char *tty_name)
{int fd_stdin = open(tty_name, O_RDWR);assert(fd_stdin == 0);int fd_stdout = open(tty_name, O_RDWR);assert(fd_stdout == 1);char rdbuf[128];while (1){write(1, "$ ", 2);int r = read(0, rdbuf, 70);rdbuf[r] = 0;int argc = 0;char *argv[PROC_ORIGIN_STACK];char *p = rdbuf;char *s;int word = 0;char ch;do /* 解析输入的字符串，拆分字符串，构造字符串指针数组 */{ch = *p;if (*p != ' ' && *p != 0 && !word){s = p;word = 1;}if ((*p == ' ' || *p == 0) && word){word = 0;argv[argc++] = s;*p = 0;}p++;} while (ch);argv[argc] = 0; /* 最后的 0 参数 */int fd = open(argv[0], O_RDWR); /* 打开子程序文件 */if (fd == -1){if (rdbuf[0]){write(1, "{", 1);write(1, rdbuf, r);write(1, "}\n", 2);}}else{close(fd);int pid = fork();if (pid != 0){ /* parent */int s;wait(&s);}else{   /* child */execv(argv[0], argv);}}}close(1);close(0);
}

——遇见正确的命令，fork + exec + exit 一遍，这一趟回来之后继续执行 shell ！

运行