d60473c7ba
Apparently bash doesn't turn off non-blocking mode on stdin/stdout when reading from it, so be nice to bash. Ideally bash would do this on its own for robustness reasons, though. https://bugs.freedesktop.org/show_bug.cgi?id=70622
387 lines
16 KiB
C
387 lines
16 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010-2013 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <sys/epoll.h>
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#include <sys/signalfd.h>
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#include <sys/ioctl.h>
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#include <limits.h>
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#include <termios.h>
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#include "util.h"
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#include "ptyfwd.h"
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#define ESCAPE_USEC USEC_PER_SEC
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static bool look_for_escape(usec_t *timestamp, unsigned *counter, const char *buffer, size_t n) {
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const char *p;
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assert(timestamp);
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assert(counter);
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assert(buffer);
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assert(n > 0);
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for (p = buffer; p < buffer + n; p++) {
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/* Check for ^] */
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if (*p == 0x1D) {
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usec_t nw = now(CLOCK_MONOTONIC);
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if (*counter == 0 || nw > *timestamp + USEC_PER_SEC) {
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*timestamp = nw;
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*counter = 1;
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} else {
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(*counter)++;
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if (*counter >= 3)
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return true;
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}
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} else {
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*timestamp = 0;
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*counter = 0;
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}
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}
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return false;
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}
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static int process_pty_loop(int master, sigset_t *mask, pid_t kill_pid, int signo) {
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char in_buffer[LINE_MAX], out_buffer[LINE_MAX];
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size_t in_buffer_full = 0, out_buffer_full = 0;
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struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
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bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
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bool stdin_hangup = false, stdout_hangup = false, master_hangup = false;
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bool tried_orderly_shutdown = false, process_signalfd = false, quit = false;
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usec_t escape_timestamp = 0;
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unsigned escape_counter = 0;
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_cleanup_close_ int ep = -1, signal_fd = -1;
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assert(master >= 0);
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assert(mask);
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assert(kill_pid == 0 || kill_pid > 1);
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assert(signo >= 0 && signo < _NSIG);
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fd_nonblock(STDIN_FILENO, true);
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fd_nonblock(STDOUT_FILENO, true);
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fd_nonblock(master, true);
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signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC);
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if (signal_fd < 0) {
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log_error("signalfd(): %m");
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return -errno;
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}
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ep = epoll_create1(EPOLL_CLOEXEC);
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if (ep < 0) {
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log_error("Failed to create epoll: %m");
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return -errno;
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}
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/* We read from STDIN only if this is actually a TTY,
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* otherwise we assume non-interactivity. */
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if (isatty(STDIN_FILENO)) {
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zero(stdin_ev);
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stdin_ev.events = EPOLLIN|EPOLLET;
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stdin_ev.data.fd = STDIN_FILENO;
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if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0) {
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log_error("Failed to register STDIN in epoll: %m");
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return -errno;
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}
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}
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zero(stdout_ev);
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stdout_ev.events = EPOLLOUT|EPOLLET;
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stdout_ev.data.fd = STDOUT_FILENO;
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zero(master_ev);
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master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
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master_ev.data.fd = master;
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zero(signal_ev);
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signal_ev.events = EPOLLIN;
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signal_ev.data.fd = signal_fd;
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if (epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0) {
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if (errno != EPERM) {
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log_error("Failed to register stdout in epoll: %m");
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return -errno;
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}
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/* stdout without epoll support. Likely redirected to regular file. */
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stdout_writable = true;
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}
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if (epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
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epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
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log_error("Failed to register fds in epoll: %m");
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return -errno;
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}
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for (;;) {
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struct epoll_event ev[16];
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ssize_t k;
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int i, nfds;
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nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), quit ? 0 : -1);
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if (nfds < 0) {
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if (errno == EINTR || errno == EAGAIN)
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continue;
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log_error("epoll_wait(): %m");
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return -errno;
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}
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if (nfds == 0)
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return 0;
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for (i = 0; i < nfds; i++) {
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if (ev[i].data.fd == STDIN_FILENO) {
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if (ev[i].events & (EPOLLIN|EPOLLHUP))
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stdin_readable = true;
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} else if (ev[i].data.fd == STDOUT_FILENO) {
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if (ev[i].events & (EPOLLOUT|EPOLLHUP))
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stdout_writable = true;
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} else if (ev[i].data.fd == master) {
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if (ev[i].events & (EPOLLIN|EPOLLHUP))
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master_readable = true;
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if (ev[i].events & (EPOLLOUT|EPOLLHUP))
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master_writable = true;
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} else if (ev[i].data.fd == signal_fd)
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process_signalfd = true;
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}
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while ((stdin_readable && in_buffer_full <= 0) ||
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(master_writable && in_buffer_full > 0) ||
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(master_readable && out_buffer_full <= 0) ||
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(stdout_writable && out_buffer_full > 0)) {
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if (stdin_readable && in_buffer_full < LINE_MAX) {
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k = read(STDIN_FILENO, in_buffer + in_buffer_full, LINE_MAX - in_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN)
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stdin_readable = false;
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else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) {
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stdin_readable = false;
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stdin_hangup = true;
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epoll_ctl(ep, EPOLL_CTL_DEL, STDIN_FILENO, NULL);
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} else {
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log_error("read(): %m");
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return -errno;
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}
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} else {
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/* Check if ^] has been
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* pressed three times within
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* one second. If we get this
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* we quite immediately. */
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if (look_for_escape(&escape_timestamp, &escape_counter, in_buffer + in_buffer_full, k))
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return !quit;
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in_buffer_full += (size_t) k;
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}
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}
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if (master_writable && in_buffer_full > 0) {
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k = write(master, in_buffer, in_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN || errno == EIO)
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master_writable = false;
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else if (errno == EPIPE || errno == ECONNRESET) {
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master_writable = master_readable = false;
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master_hangup = true;
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epoll_ctl(ep, EPOLL_CTL_DEL, master, NULL);
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} else {
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log_error("write(): %m");
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return -errno;
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}
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} else {
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assert(in_buffer_full >= (size_t) k);
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memmove(in_buffer, in_buffer + k, in_buffer_full - k);
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in_buffer_full -= k;
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}
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}
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if (master_readable && out_buffer_full < LINE_MAX) {
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k = read(master, out_buffer + out_buffer_full, LINE_MAX - out_buffer_full);
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if (k < 0) {
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/* Note that EIO on the master
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* device might be cause by
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* vhangup() or temporary
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* closing of everything on
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* the other side, we treat it
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* like EAGAIN here and try
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* again. */
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if (errno == EAGAIN || errno == EIO)
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master_readable = false;
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else if (errno == EPIPE || errno == ECONNRESET) {
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master_readable = master_writable = false;
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master_hangup = true;
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epoll_ctl(ep, EPOLL_CTL_DEL, master, NULL);
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} else {
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log_error("read(): %m");
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return -errno;
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}
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} else
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out_buffer_full += (size_t) k;
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}
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if (stdout_writable && out_buffer_full > 0) {
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k = write(STDOUT_FILENO, out_buffer, out_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN)
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stdout_writable = false;
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else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) {
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stdout_writable = false;
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stdout_hangup = true;
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epoll_ctl(ep, EPOLL_CTL_DEL, STDOUT_FILENO, NULL);
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} else {
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log_error("write(): %m");
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return -errno;
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}
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} else {
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assert(out_buffer_full >= (size_t) k);
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memmove(out_buffer, out_buffer + k, out_buffer_full - k);
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out_buffer_full -= k;
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}
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}
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}
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if (process_signalfd) {
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struct signalfd_siginfo sfsi;
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ssize_t n;
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n = read(signal_fd, &sfsi, sizeof(sfsi));
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if (n != sizeof(sfsi)) {
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if (n >= 0) {
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log_error("Failed to read from signalfd: invalid block size");
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return -EIO;
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}
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if (errno != EINTR && errno != EAGAIN) {
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log_error("Failed to read from signalfd: %m");
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return -errno;
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}
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} else {
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if (sfsi.ssi_signo == SIGWINCH) {
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struct winsize ws;
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/* The window size changed, let's forward that. */
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if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
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ioctl(master, TIOCSWINSZ, &ws);
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} else if (sfsi.ssi_signo == SIGTERM && kill_pid > 0 && signo > 0 && !tried_orderly_shutdown) {
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if (kill(kill_pid, signo) < 0)
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quit = true;
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else {
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log_info("Trying to halt container. Send SIGTERM again to trigger immediate termination.");
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/* This only works for systemd... */
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tried_orderly_shutdown = true;
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}
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} else
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/* Signals that where
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* delivered via signalfd that
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* we didn't know are a reason
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* for us to quit */
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quit = true;
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}
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}
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if (stdin_hangup || stdout_hangup || master_hangup) {
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/* Exit the loop if any side hung up and if
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* there's nothing more to write or nothing we
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* could write. */
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if ((out_buffer_full <= 0 || stdout_hangup) &&
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(in_buffer_full <= 0 || master_hangup))
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return !quit;
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}
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}
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}
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int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
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struct termios saved_stdin_attr, raw_stdin_attr;
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struct termios saved_stdout_attr, raw_stdout_attr;
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bool saved_stdin = false;
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bool saved_stdout = false;
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struct winsize ws;
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int r;
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if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
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ioctl(master, TIOCSWINSZ, &ws);
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if (tcgetattr(STDIN_FILENO, &saved_stdin_attr) >= 0) {
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saved_stdin = true;
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raw_stdin_attr = saved_stdin_attr;
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cfmakeraw(&raw_stdin_attr);
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raw_stdin_attr.c_oflag = saved_stdin_attr.c_oflag;
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tcsetattr(STDIN_FILENO, TCSANOW, &raw_stdin_attr);
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}
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if (tcgetattr(STDOUT_FILENO, &saved_stdout_attr) >= 0) {
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saved_stdout = true;
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raw_stdout_attr = saved_stdout_attr;
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cfmakeraw(&raw_stdout_attr);
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raw_stdout_attr.c_iflag = saved_stdout_attr.c_iflag;
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raw_stdout_attr.c_lflag = saved_stdout_attr.c_lflag;
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tcsetattr(STDOUT_FILENO, TCSANOW, &raw_stdout_attr);
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}
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r = process_pty_loop(master, mask, kill_pid, signo);
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if (saved_stdout)
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tcsetattr(STDOUT_FILENO, TCSANOW, &saved_stdout_attr);
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if (saved_stdin)
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tcsetattr(STDIN_FILENO, TCSANOW, &saved_stdin_attr);
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/* STDIN/STDOUT should not be nonblocking normally, so let's
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* unconditionally reset it */
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fd_nonblock(STDIN_FILENO, false);
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fd_nonblock(STDOUT_FILENO, false);
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return r;
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}
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