/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010-2013 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <sys/epoll.h> #include <sys/signalfd.h> #include <sys/ioctl.h> #include <limits.h> #include <termios.h> #include "util.h" #include "ptyfwd.h" #define ESCAPE_USEC USEC_PER_SEC static bool look_for_escape(usec_t *timestamp, unsigned *counter, const char *buffer, size_t n) { const char *p; assert(timestamp); assert(counter); assert(buffer); assert(n > 0); for (p = buffer; p < buffer + n; p++) { /* Check for ^] */ if (*p == 0x1D) { usec_t nw = now(CLOCK_MONOTONIC); if (*counter == 0 || nw > *timestamp + USEC_PER_SEC) { *timestamp = nw; *counter = 1; } else { (*counter)++; if (*counter >= 3) return true; } } else { *timestamp = 0; *counter = 0; } } return false; } static int process_pty_loop(int master, sigset_t *mask, pid_t kill_pid, int signo) { char in_buffer[LINE_MAX], out_buffer[LINE_MAX]; size_t in_buffer_full = 0, out_buffer_full = 0; struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev; bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false; bool stdin_hangup = false, stdout_hangup = false, master_hangup = false; bool tried_orderly_shutdown = false, process_signalfd = false, quit = false; usec_t escape_timestamp = 0; unsigned escape_counter = 0; _cleanup_close_ int ep = -1, signal_fd = -1; assert(master >= 0); assert(mask); assert(kill_pid == 0 || kill_pid > 1); assert(signo >= 0 && signo < _NSIG); fd_nonblock(STDIN_FILENO, 1); fd_nonblock(STDOUT_FILENO, 1); fd_nonblock(master, 1); signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC); if (signal_fd < 0) { log_error("signalfd(): %m"); return -errno; } ep = epoll_create1(EPOLL_CLOEXEC); if (ep < 0) { log_error("Failed to create epoll: %m"); return -errno; } /* We read from STDIN only if this is actually a TTY, * otherwise we assume non-interactivity. */ if (isatty(STDIN_FILENO)) { zero(stdin_ev); stdin_ev.events = EPOLLIN|EPOLLET; stdin_ev.data.fd = STDIN_FILENO; if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0) { log_error("Failed to register STDIN in epoll: %m"); return -errno; } } zero(stdout_ev); stdout_ev.events = EPOLLOUT|EPOLLET; stdout_ev.data.fd = STDOUT_FILENO; zero(master_ev); master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET; master_ev.data.fd = master; zero(signal_ev); signal_ev.events = EPOLLIN; signal_ev.data.fd = signal_fd; if (epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0) { if (errno != EPERM) { log_error("Failed to register stdout in epoll: %m"); return -errno; } /* stdout without epoll support. Likely redirected to regular file. */ stdout_writable = true; } if (epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 || epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) { log_error("Failed to register fds in epoll: %m"); return -errno; } for (;;) { struct epoll_event ev[16]; ssize_t k; int i, nfds; nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), quit ? 0 : -1); if (nfds < 0) { if (errno == EINTR || errno == EAGAIN) continue; log_error("epoll_wait(): %m"); return -errno; } if (nfds == 0) return 0; for (i = 0; i < nfds; i++) { if (ev[i].data.fd == STDIN_FILENO) { if (ev[i].events & (EPOLLIN|EPOLLHUP)) stdin_readable = true; } else if (ev[i].data.fd == STDOUT_FILENO) { if (ev[i].events & (EPOLLOUT|EPOLLHUP)) stdout_writable = true; } else if (ev[i].data.fd == master) { if (ev[i].events & (EPOLLIN|EPOLLHUP)) master_readable = true; if (ev[i].events & (EPOLLOUT|EPOLLHUP)) master_writable = true; } else if (ev[i].data.fd == signal_fd) process_signalfd = true; } while ((stdin_readable && in_buffer_full <= 0) || (master_writable && in_buffer_full > 0) || (master_readable && out_buffer_full <= 0) || (stdout_writable && out_buffer_full > 0)) { if (stdin_readable && in_buffer_full < LINE_MAX) { k = read(STDIN_FILENO, in_buffer + in_buffer_full, LINE_MAX - in_buffer_full); if (k < 0) { if (errno == EAGAIN) stdin_readable = false; else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) { stdin_readable = false; stdin_hangup = true; epoll_ctl(ep, EPOLL_CTL_DEL, STDIN_FILENO, NULL); } else { log_error("read(): %m"); return -errno; } } else { /* Check if ^] has been * pressed three times within * one second. If we get this * we quite immediately. */ if (look_for_escape(&escape_timestamp, &escape_counter, in_buffer + in_buffer_full, k)) return !quit; in_buffer_full += (size_t) k; } } if (master_writable && in_buffer_full > 0) { k = write(master, in_buffer, in_buffer_full); if (k < 0) { if (errno == EAGAIN || errno == EIO) master_writable = false; else if (errno == EPIPE || errno == ECONNRESET) { master_writable = master_readable = false; master_hangup = true; epoll_ctl(ep, EPOLL_CTL_DEL, master, NULL); } else { log_error("write(): %m"); return -errno; } } else { assert(in_buffer_full >= (size_t) k); memmove(in_buffer, in_buffer + k, in_buffer_full - k); in_buffer_full -= k; } } if (master_readable && out_buffer_full < LINE_MAX) { k = read(master, out_buffer + out_buffer_full, LINE_MAX - out_buffer_full); if (k < 0) { /* Note that EIO on the master * device might be cause by * vhangup() or temporary * closing of everything on * the other side, we treat it * like EAGAIN here and try * again. */ if (errno == EAGAIN || errno == EIO) master_readable = false; else if (errno == EPIPE || errno == ECONNRESET) { master_readable = master_writable = false; master_hangup = true; epoll_ctl(ep, EPOLL_CTL_DEL, master, NULL); } else { log_error("read(): %m"); return -errno; } } else out_buffer_full += (size_t) k; } if (stdout_writable && out_buffer_full > 0) { k = write(STDOUT_FILENO, out_buffer, out_buffer_full); if (k < 0) { if (errno == EAGAIN) stdout_writable = false; else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) { stdout_writable = false; stdout_hangup = true; epoll_ctl(ep, EPOLL_CTL_DEL, STDOUT_FILENO, NULL); } else { log_error("write(): %m"); return -errno; } } else { assert(out_buffer_full >= (size_t) k); memmove(out_buffer, out_buffer + k, out_buffer_full - k); out_buffer_full -= k; } } } if (process_signalfd) { struct signalfd_siginfo sfsi; ssize_t n; n = read(signal_fd, &sfsi, sizeof(sfsi)); if (n != sizeof(sfsi)) { if (n >= 0) { log_error("Failed to read from signalfd: invalid block size"); return -EIO; } if (errno != EINTR && errno != EAGAIN) { log_error("Failed to read from signalfd: %m"); return -errno; } } else { if (sfsi.ssi_signo == SIGWINCH) { struct winsize ws; /* The window size changed, let's forward that. */ if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0) ioctl(master, TIOCSWINSZ, &ws); } else if (sfsi.ssi_signo == SIGTERM && kill_pid > 0 && signo > 0 && !tried_orderly_shutdown) { if (kill(kill_pid, signo) < 0) quit = true; else { log_info("Trying to halt container. Send SIGTERM again to trigger immediate termination."); /* This only works for systemd... */ tried_orderly_shutdown = true; } } else /* Signals that where * delivered via signalfd that * we didn't know are a reason * for us to quit */ quit = true; } } if (stdin_hangup || stdout_hangup || master_hangup) { /* Exit the loop if any side hung up and if * there's nothing more to write or nothing we * could write. */ if ((out_buffer_full <= 0 || stdout_hangup) && (in_buffer_full <= 0 || master_hangup)) return !quit; } } } int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) { struct termios saved_attr; bool saved = false; struct winsize ws; int r; if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0) ioctl(master, TIOCSWINSZ, &ws); if (tcgetattr(STDIN_FILENO, &saved_attr) >= 0) { struct termios raw_attr; saved = true; raw_attr = saved_attr; cfmakeraw(&raw_attr); raw_attr.c_lflag &= ~ECHO; tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr); } r = process_pty_loop(master, mask, kill_pid, signo); if (saved) tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr); return r; }