我试图为shell编写一个pty I / O透明过滤器。
以下示例主要有效。大多数程序使用包装器按预期运行。这个例子没有做任何过滤，它的目的只是提供一个框架。
编辑：我在下面的回答中得到了这个例子。我已在此处更新了示例，以反映这一点。
以下是现在正在运行的代码：
/*
This example is public domain. Use as you see fit.
The purpose of this example is show how a process can run a shell transparently and be able to filter it's input and output.
This example does not show off any I/O filtering, it only provides the framework on which that could be added.
Tested only on GNU/Linux with recent kernels and recent g++ and clang++
This example is based on original found here:
https://www.scriptjunkie.us/wp-content/uploads/2011/04/stdioterminallogger.c
There were 2 problems with the code this example was based on.
1) Terminal (re)sizing was not being handled
2) Some applications display incorrectly or keys don't work
a) with 'joe', Enter, Ctrl-M, and Ctrl-J don't work
b) 'joe' has display isues
c) 'snake' (game) has display issues
Also, be aware of this:
#define LOGFILELOCATION "/tmp/.shlog"
in the original code, not this example.
This example does not write produce any files. (intermediate or otherwise)
The following programs do seem to work correctly:
vi, vim, nano, mcedit, htop, top
#1 has been solved with a resize handler (see handler and handleTerminalResize)
Use this in shell's profile/bashrc to indicate pty-filter is present
[ "${inptyfilter}" == "true" ] && PS1="(pty-filter) ${PS1}"
Compile with any of the following:
g++ -std=c++11 pty-filter.cpp -lutil -o pty-filter
g++ -std=c++1y pty-filter.cpp -lutil -o pty-filter
g++ -std=c++1z pty-filter.cpp -lutil -o pty-filter
clang++ -std=c++11 pty-filter.cpp -lutil -o pty-filter
clang++ -std=c++1y pty-filter.cpp -lutil -o pty-filter
clang++ -std=c++1z pty-filter.cpp -lutil -o pty-filter
# for stricter compilation:
clang++ -std=c++1z pty-filter.cpp -lutil -o pty-filter -Wall -Werror -Weverything -Wno-c++98-compat -Wno-missing-prototypes -Wno-disabled-macro-expansion -Wno-vla-extension -Wno-vla
*/
// standard C stuff
#include <cstdio>
#include <cstdlib>
#include <csignal>
#include <cerrno>
#include <cstdarg>
// C++ stuff
#include <string>
// Everything else
#include <pty.h>
#include <unistd.h>
#include <termios.h>
#include <sys/mman.h>
#include <sys/wait.h>
// shared globals
struct sharedBookT {
pid_t childPid;
pid_t parentPid;
pid_t shellPid;
int shellFd;
termios oldTerm, newTerm, shellTerm;
bool readyToQuit;
char fromTerminalBuffer [4096];
char toTerminalBuffer [4096];
char padding [3];
};
// avoid non C++ casts (when used with stricter compilation)
typedef const char* constCharPtrT;
typedef void* voidPtr;
typedef sharedBookT* sharedBookPtrT;
static sharedBookPtrT sharedBookPtr = 0;
// sprintf for std::string
std::string Sprintf (const char* fmt, ...) __attribute__ ((format (printf, 1, 2)));
std::string Sprintf (const char* fmt, ...) {
va_list ap;
va_start (ap, fmt);
const auto n = vsnprintf (0, 0, fmt, ap);
va_end (ap);
char result [n+2];
va_start (ap, fmt);
vsnprintf (result, size_t (n+1), fmt, ap);
va_end (ap);
return std::string (result);
}
// c_str and length shortcut operators for std::string
const char* operator* (const std::string& s) { return s.c_str (); }
size_t operator+ (const std::string& s) { return s.length (); }
// resize shell's pty and notifiy chell of change
void handleTerminalResize () {
sharedBookT& shared = *sharedBookPtr;
winsize ws;
ioctl(0, TIOCGWINSZ, &ws);
ioctl(shared.shellFd, TIOCSWINSZ, &ws);
sigqueue (shared.shellPid, SIGWINCH, {0});
}
// log signal, for convience just to stdout
void logsignal (int signal) {
// can't reliably use regular printf from a signal handler
const auto msg = Sprintf ("Got signal %d\n", signal);
write (1, *msg, +msg);
}
// common signal handler
void handler(int signal, siginfo_t * infoP, void *context __attribute__ ((unused))) {
const auto& si = *infoP;
const auto myPid = getpid ();
sharedBookT& shared = *sharedBookPtr;
// using SIGUSR to notify processes of termination
// (processes must check for it after blocking syscalls)
if (signal == SIGUSR2) { // Notification to quit
shared.readyToQuit = true;
return;
}
auto cc = char (-1);
if (myPid == shared.parentPid) {
// only parent process should handle these
// if child processes handle these as well, there are multiple insertions
switch (si.si_signo) {
case SIGINT: cc = 0x03; break; // "Ctrl-C"
case SIGTSTP: cc = 0x1A; break; // "Ctrl-Z"
case SIGQUIT: cc = 0x1C; break; // "Ctrl-\"
case SIGWINCH: handleTerminalResize (); break;
default: logsignal (signal); break;
}
}
// write control character (if any) to shell's pty
if (-1 < cc) write(shared.shellFd, &cc, 1);
}
// Add common signal handler for each signal
void setupsignal(int signal) {
struct sigaction act;
sigaction(signal, NULL, &act);
act.sa_sigaction = handler;
act.sa_flags |= SA_SIGINFO;
sigaction(signal, &act, NULL);
}
// launch shell with new pty
void launchShell () {
sharedBookT& shared = *sharedBookPtr;
tcgetattr(0, &shared.shellTerm);
const auto pid = forkpty(&shared.shellFd, NULL, &shared.shellTerm, NULL);
if (pid == -1 || pid == 0) {
if (pid == 0) {
shared.shellPid = getpid ();
// inform shell it's pty is being filtered
setenv ("inptyfilter", "true", 1);
exit(execlp("/bin/bash", "bash", NULL));
}
else {
perror ("forkpty failed");
exit (1);
}
}
}
int main () {
// create shared globals structure
sharedBookPtr = sharedBookPtrT (mmap (
NULL, sizeof (sharedBookT),
PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0
));
sharedBookT& shared = *sharedBookPtr;
launchShell ();
shared.parentPid = getpid ();
//Set up handler for signals
setupsignal(SIGINT);
setupsignal(SIGTSTP);
setupsignal(SIGUSR1);
setupsignal(SIGUSR2);
setupsignal(SIGQUIT);
setupsignal(SIGWINCH);
//setupsignal(SIGTTIN);
//setupsignal(SIGTTOU);
// fork to handle output to the terminal
if (0 == fork ()) {
shared.childPid = getpid ();
// loop while reading and echoing the pty's output
for (;;) {
// read from Shell's Pty
const auto charsRead = read (shared.shellFd, shared.toTerminalBuffer, sizeof (shared.toTerminalBuffer));
// if characters were read, echo them and continue
if (0 < charsRead) {
write (1, shared.toTerminalBuffer, size_t (charsRead));
continue;
}
// if error, check if we are done
if ((charsRead == -1) and (errno == EIO)) {
fprintf (stderr, "\nterminating I/O processes\r\n");
// signal parent to exit
sigqueue (shared.parentPid, SIGUSR2, {0});
break;
}
}
fprintf (stderr, "Exiting pty-filter (toTerminal)\r\n");
exit (0);
}
// wait for pids to be updated
while ((0 == shared.shellPid) or (0 == shared.childPid)) usleep (1);
fprintf (stderr, "parent: %d\n", shared.parentPid);
fprintf (stderr, "shell: %d\n", shared.shellPid);
fprintf (stderr, "child: %d\n", shared.childPid);
tcgetattr(0, &shared.oldTerm); // Disable buffered I/O and echo mode for pty
shared.newTerm = shared.oldTerm;
cfmakeraw (&shared.newTerm);
tcsetattr(0, TCSANOW, &shared.newTerm);
// shell needs intial sizing
handleTerminalResize ();
for (;;) {//loop while processing input from pty
const auto charsRead = read (0, shared.fromTerminalBuffer, sizeof (shared.fromTerminalBuffer));
// SIGUSR1 will drop process out of read so flag can be read
if (shared.readyToQuit) {
fprintf (stderr, "Exiting pty-filter (fromTerminal)\r\n");
break;
}
// in we got input from the terminal, pass it on to the shell's pty
if (0 < charsRead) {
write (shared.shellFd, shared.fromTerminalBuffer, size_t (charsRead));
continue;
}
// if error check if we are done
// However, this is never executed, child fork terminates first
if ((charsRead == -1) and (errno == EIO)) break;
}
tcsetattr(0, TCSANOW, &shared.oldTerm); //reset terminal
// wait for child forks to exit
for (;;) {
auto wpid = wait (0);
if (wpid == -1) break;
fprintf (stderr, "%d is done\n", wpid);
}
perror ("status");
return 0;
}
我的问题是，我错过了什么？什么会导致一些程序（如乔和蛇）不规律地显示，而许多其他程序（如vi，vim，nano，mcedit，htop，top）似乎工作正常。
（在我的系统乔和蛇上工作没有＆＃34; pty过滤器＆＃34;。）
编辑：如上所述，它现在有效
答案 0 :(得分：1)
取而代之：
shared.newTerm.c_lflag &= tcflag_t (~ICANON);
shared.newTerm.c_lflag &= tcflag_t (~ECHO);
用这个：
shared.newTerm.c_lflag &= tcflag_t (~(ICANON | ISIG | IEXTEN | ECHO));
shared.newTerm.c_iflag &= tcflag_t (~(BRKINT | ICRNL | IGNBRK | IGNCR | INLCR | INPCK | ISTRIP | IXON | PARMRK));
shared.newTerm.c_oflag &= tcflag_t (~OPOST);
shared.newTerm.c_cc[VMIN] = 1; // 1 char at a time input
shared.newTerm.c_cc[VTIME] = 0;
让它开始正常工作。但是，这似乎不应该有任何影响，因为这是在stdin上完成的：
shared.newTerm.c_oflag &= tcflag_t (~OPOST);
编辑：以下帖子回答了有关tcsetattr的stdin vs stdout的问题。
When setting terminal attributes via tcsetattr(fd.....), can fd be either stdout or stdin?
但无论如何，它现在有效。我会更新我原来的帖子以反映这一点。
编辑：此帖子被标记为相关：Using the linux pseudo terminal API for multiple debug terminals 虽然答案不在该帖子上，但它指出了一个拥有我需要的信息的网站：http://www.man7.org/tlpi/code/online/dist/tty/tty_functions.c.html
编辑：用以下内容替换上述内容也有效。我会相应更新我原来的帖子。：
cfmakeraw (&shared.newTerm);