nspawn: split out pty forwaring logic into ptyfwd.c

1 files changed, 252 insertions, 0 deletions

diff --git a/src/shared/ptyfwd.c b/src/shared/ptyfwd.c
new file mode 100644
index 0000000000..1e2852b1af
--- /dev/null
+++ b/src/shared/ptyfwd.c
@@ -0,0 +1,252 @@
+/*-*- 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"
+
+int process_pty(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 tried_orderly_shutdown = false;
+        _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), -1);
+                if (nfds < 0) {
+
+                        if (errno == EINTR || errno == EAGAIN)
+                                continue;
+
+                        log_error("epoll_wait(): %m");
+                        return -errno;
+                }
+
+                assert(nfds >= 1);
+
+                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) {
+                                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)
+                                                        return 0;
+
+                                                log_info("Trying to halt container. Send SIGTERM again to trigger immediate termination.");
+
+                                                /* This only works for systemd... */
+                                                tried_orderly_shutdown = true;
+
+                                        } else
+                                                return 0;
+                                }
+                        }
+                }
+
+                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 || errno == EPIPE || errno == ECONNRESET || errno == EIO)
+                                                stdin_readable = false;
+                                        else {
+                                                log_error("read(): %m");
+                                                return -errno;
+                                        }
+                                } else
+                                        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 == EPIPE || errno == ECONNRESET || errno == EIO)
+                                                master_writable = false;
+                                        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) {
+
+                                        if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
+                                                master_readable = false;
+                                        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 || errno == EPIPE || errno == ECONNRESET || errno == EIO)
+                                                stdout_writable = false;
+                                        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;
+                                }
+                        }
+                }
+        }
+}