/*-*- 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, true);
fd_nonblock(STDOUT_FILENO, true);
fd_nonblock(master, true);
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(STDOUT_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_stdin_attr, raw_stdin_attr;
struct termios saved_stdout_attr, raw_stdout_attr;
bool saved_stdin = false;
bool saved_stdout = false;
struct winsize ws;
int r;
if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
ioctl(master, TIOCSWINSZ, &ws);
if (tcgetattr(STDIN_FILENO, &saved_stdin_attr) >= 0) {
saved_stdin = true;
raw_stdin_attr = saved_stdin_attr;
cfmakeraw(&raw_stdin_attr);
raw_stdin_attr.c_oflag = saved_stdin_attr.c_oflag;
tcsetattr(STDIN_FILENO, TCSANOW, &raw_stdin_attr);
}
if (tcgetattr(STDOUT_FILENO, &saved_stdout_attr) >= 0) {
saved_stdout = true;
raw_stdout_attr = saved_stdout_attr;
cfmakeraw(&raw_stdout_attr);
raw_stdout_attr.c_iflag = saved_stdout_attr.c_iflag;
raw_stdout_attr.c_lflag = saved_stdout_attr.c_lflag;
tcsetattr(STDOUT_FILENO, TCSANOW, &raw_stdout_attr);
}
r = process_pty_loop(master, mask, kill_pid, signo);
if (saved_stdout)
tcsetattr(STDOUT_FILENO, TCSANOW, &saved_stdout_attr);
if (saved_stdin)
tcsetattr(STDIN_FILENO, TCSANOW, &saved_stdin_attr);
/* STDIN/STDOUT should not be nonblocking normally, so let's
* unconditionally reset it */
fd_nonblock(STDIN_FILENO, false);
fd_nonblock(STDOUT_FILENO, false);
return r;
}