[英]Why can't I simulate auto-completion with '\t' in busybox
I want to use "yp\\t\\n\\0" to run “ypdomainname” command by exploiting auto-completion in busybox, but it failed. 我想通过利用busybox中的自动补全功能来使用“ yp \\ t \\ n \\ 0”运行“ ypdomainname”命令,但是失败了。 my code and result are below:
我的代码和结果如下:
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/wait.h>
#include <fcntl.h>
#define DEFAULT_BUSYBOX_PATH "/bin/busybox"
#define MAX_BUF 1000
int main()
{
int fd[2];
pid_t pid;
FILE *file;
int status;
if(pipe(fd) < 0){
fprintf(stderr, "pipe error!\n");
return -1;
}
if((pid = fork()) < 0){
fprintf(stderr, "pipe error!\n");
}else if(pid == 0){ //child
close(fd[1]);
int fd_output;
fd_output = open("result", O_CREAT | O_RDWR, 777);
if(fd_output != STDOUT_FILENO){
if(dup2(fd_output, STDOUT_FILENO) != STDOUT_FILENO)
fprintf(stderr, "dup2 error to stdout\n");
}
if(fd[0] != STDIN_FILENO){
if(dup2(fd[0], STDIN_FILENO) != STDIN_FILENO)
fprintf(stderr, "dup2 error to stdin\n");
}
execl(DEFAULT_BUSYBOX_PATH, DEFAULT_BUSYBOX_PATH, "ash", NULL);
close(fd[0]);
close(fd_output);
return 0;
}else{ //parent
close(fd[0]);
char buf[MAX_BUF] = "yp";
buf[2] = '\t';
buf[3] = '\n';
buf[4] = '\0';
write(fd[1], buf, strlen(buf));
close(fd[1]);
return 0;
}
}
What makes me confused is that the character is not changed in function lineedit_read_key()
in file lineedit.c and it will run the function input_tab()
when the character is '\\t'. 让我感到困惑的是,该字符未在文件lineedit.c中的函数
lineedit_read_key()
中更改,并且当字符为'\\ t'时它将运行函数input_tab()
。 input_tab will be executed when character is '\\t' 当字符为'\\ t'时,将执行input_tab
Recently, i took some time to learn about terminal to simulate auto-completion, but i still failed. 最近,我花了一些时间来学习有关终端的模拟自动完成功能,但是我仍然失败了。 My code is below:
我的代码如下:
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <signal.h>
#include <pty.h>
#define DEFAULT_BUSYBOX_PATH "/bin/busybox"
#define MAX_BUF 1000
#define BUFFSIZE 512
typedef void Sigfunc(int);
static void sig_term(int);
static volatile sig_atomic_t sigcaught;
ssize_t writen(int fd, const void *ptr, size_t n){
size_t nleft;
ssize_t nwritten;
nleft = n;
while(nleft > 0){
if((nwritten = write(fd, ptr, nleft)) < 0){
if(nleft == n){
return(-1);
}else{
break;
}
}else if(nwritten == 0) {
break;
}
nleft -= nwritten;
ptr += nwritten;
}
return(n - nleft);
}
Sigfunc *signal_intr(int signo, Sigfunc *func){
struct sigaction act;
struct sigaction oact;
act.sa_handler = func;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
#ifdef SA_INTERRUPT
act.sa_flags |= SA_INTERRUPT;
#endif
if (sigaction(signo, &act, &oact) < 0)
return(SIG_ERR);
return(oact.sa_handler);
}
int ptym_open(char *pts_name, int pts_namesz)
{
char ptr[50];
int fdm;
int err;
if((fdm = posix_openpt(O_RDWR)) < 0){
return(-1);
}
if(grantpt(fdm) < 0){
goto errout;
}
if(unlockpt(fdm) < 0){
goto errout;
}
if(ptsname_r(fdm, ptr, 50) != 0){
goto errout;
}
strncpy(pts_name, ptr, pts_namesz);
pts_name[pts_namesz - 1] = '\0';
return(fdm); /* return fd of master */
errout:
err = errno;
close(fdm);
errno = err;
return(-1);
}
int ptys_open(char *pts_name){
int fds;
if((fds = open(pts_name, O_RDWR)) < 0)
return(-1);
return(fds);
}
pid_t pty_fork(int *ptrfdm, char *slave_name, int slave_namesz, const struct termios *slave_termios, const struct winsize *slave_winsize){
int fdm, fds;
pid_t pid;
char pts_name[20];
if((fdm = ptym_open(pts_name, sizeof(pts_name))) < 0){
fprintf(stderr, "can't open master pty: %s, error %d", pts_name, fdm);
}
if(slave_name != NULL) {
strncpy(slave_name, pts_name, slave_namesz);
slave_name[slave_namesz - 1] = '\0';
}
if((pid = fork()) < 0) {
return(-1);
}else if (pid == 0) { /* child */
if(setsid() < 0){
fprintf(stderr, "setsid error");
}
if((fds = ptys_open(pts_name)) < 0){
fprintf(stderr, "can't open slave pty");
}
close(fdm);
if(slave_termios != NULL) {
if (tcsetattr(fds, TCSANOW, slave_termios) < 0)
fprintf(stderr, "tcsetattr error on slave pty");
}
if(slave_winsize != NULL) {
if (ioctl(fds, TIOCSWINSZ, slave_winsize) < 0)
fprintf(stderr, "TIOCSWINSZ error on slave pty");
}
if(dup2(fds, STDIN_FILENO) != STDIN_FILENO){
fprintf(stderr, "dup2 error to stdin");
}
if(dup2(fds, STDOUT_FILENO) != STDOUT_FILENO){
fprintf(stderr, "dup2 error to stdout");
}
if(dup2(fds, STDERR_FILENO) != STDERR_FILENO){
fprintf(stderr, "dup2 error to stderr");
}
if(fds != STDIN_FILENO && fds != STDOUT_FILENO && fds != STDERR_FILENO){
close(fds);
}
return(0);
} else { /* parent */
*ptrfdm = fdm;
return(pid);
}
}
void loop(int ptym, int ignoreeof)
{
pid_t child;
int nread;
char buf[BUFFSIZE];
if((child = fork()) < 0) {
fprintf(stderr, "fork error");
}else if(child == 0) {
/*for ( ; ; ){
if((nread = read(STDIN_FILENO, buf, BUFFSIZE)) < 0){
fprintf(stderr, "read error from stdin");
}else if(nread == 0){
break;
}
if(writen(ptym, buf, nread) != nread)
fprintf(stderr, "writen error to master pty");
}*/
char *temp_buf = "yp\t\n";
if(writen(ptym, temp_buf, strlen(temp_buf)) != strlen(temp_buf)){
fprintf(stderr, "writen error to master pty");
}
if(ignoreeof == 0){
kill(getppid(), SIGTERM);
}
exit(0);
}
if (signal_intr(SIGTERM, sig_term) == SIG_ERR)
fprintf(stderr, "signal_intr error for SIGTERM");
for( ; ; ){
if ((nread = read(ptym, buf, BUFFSIZE)) <= 0){
}
//printf("nread = %d\n", nread);
if (writen(STDOUT_FILENO, buf, nread) != nread){
fprintf(stderr, "writen error to stdout");
}
}
if (sigcaught == 0){
printf("sigcaught == 0 and kill child\n");
kill(child, SIGTERM);
}
}
static void sig_term(int signo)
{
sigcaught = 1;
}
int main(int argc, char *argv[]){
int fd[2];
pid_t pid;
FILE *file;
int status;
int fdm;
int ignoreeof;
char slave_name[40];
struct termios orig_termios;
struct winsize size;
pid = pty_fork(&fdm, slave_name, sizeof(slave_name), &orig_termios, &size);
if(pid < 0){
fprintf(stderr, "fork error!\n");
}else if(pid == 0){ //child
if(execl(DEFAULT_BUSYBOX_PATH, DEFAULT_BUSYBOX_PATH, "ash", NULL) < 0){
fprintf(stderr, "can't execute: %s", DEFAULT_BUSYBOX_PATH);
}
/*if(execvp(argv[1], &argv[1]) < 0){
fprintf(stderr, "can't execute: %s", argv[1]);
}*/
}
loop(fdm, ignoreeof);
}
like the result of my first try, the result is: ash: yp: not found. 就像我第一次尝试的结果一样,结果是:ash:yp:not found。
Your code fails because a pipe is not a terminal. 您的代码失败,因为管道不是终端。 Many programs will use
isatty(3)
and alike to detect if the standard input is connected to a terminal and adjust their behaviour depending on the result. 许多程序将使用
isatty(3)
等来检测标准输入是否已连接到终端并根据结果调整其行为。
What you can do is to open a pseudo terminal pair using openpty(3)
and run the command with the slave duplicated to its standard input, output and error descriptors, and using the master to communicate with it. 您可以做的是使用
openpty(3)
打开一个伪终端对,并运行从属设备复制到其标准输入,输出和错误描述符的命令,并使用主设备与之进行通信。 Unfortunately I have no time right now writing a full solution as it is rather intricate; 不幸的是,我现在没有时间写一个完整的解决方案,因为它相当复杂。 I've done it ever in Python and it was tricky even there.
我曾经用Python完成过它,即使在那里也很棘手。
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