machinectl: add new command to spawn a getty inside a container

2 files changed, 175 insertions, 52 deletions

diff --git a/src/shared/ptyfwd.c b/src/shared/ptyfwd.c
index 1e2852b1af..7225b933ff 100644
--- a/src/shared/ptyfwd.c
+++ b/src/shared/ptyfwd.c
@@ -28,12 +28,49 @@
 #include "util.h"
 #include "ptyfwd.h"
 
-int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
+#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 tried_orderly_shutdown = 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);
@@ -103,7 +140,7 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                 ssize_t k;
                 int i, nfds;
 
-                nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1);
+                nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), quit ? 0 : -1);
                 if (nfds < 0) {
 
                         if (errno == EINTR || errno == EAGAIN)
@@ -113,7 +150,8 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                         return -errno;
                 }
 
-                assert(nfds >= 1);
+                if (nfds == 0)
+                        return 0;
 
                 for (i = 0; i < nfds; i++) {
                         if (ev[i].data.fd == STDIN_FILENO) {
@@ -134,45 +172,8 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                                 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;
-                                }
-                        }
+                        } else if (ev[i].data.fd == signal_fd)
+                                process_signalfd = true;
                 }
 
                 while ((stdin_readable && in_buffer_full <= 0) ||
@@ -185,14 +186,26 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                                 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)
+                                        if (errno == EAGAIN)
                                                 stdin_readable = false;
-                                        else {
+                                        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
+                                } 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) {
@@ -200,9 +213,13 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                                 k = write(master, in_buffer, in_buffer_full);
                                 if (k < 0) {
 
-                                        if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
+                                        if (errno == EAGAIN || errno == EIO)
                                                 master_writable = false;
-                                        else {
+                                        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;
                                         }
@@ -219,9 +236,21 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                                 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)
+                                        /* 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 {
+                                        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;
                                         }
@@ -234,9 +263,13 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                                 k = write(STDOUT_FILENO, out_buffer, out_buffer_full);
                                 if (k < 0) {
 
-                                        if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
+                                        if (errno == EAGAIN)
                                                 stdout_writable = false;
-                                        else {
+                                        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;
                                         }
@@ -247,6 +280,91 @@ int process_pty(int master, sigset_t *mask, pid_t kill_pid, int signo) {
                                         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;
+
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index dc35b4d980..d90b808476 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -572,6 +572,10 @@ static inline void umaskp(mode_t *u) {
         umask(*u);
 }
 
+static inline void close_pipep(int (*p)[2]) {
+        close_pipe(*p);
+}
+
 DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, fclose);
 DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, pclose);
 DEFINE_TRIVIAL_CLEANUP_FUNC(DIR*, closedir);
@@ -585,6 +589,7 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, endmntent);
 #define _cleanup_pclose_ _cleanup_(pclosep)
 #define _cleanup_closedir_ _cleanup_(closedirp)
 #define _cleanup_endmntent_ _cleanup_(endmntentp)
+#define _cleanup_close_pipe_ _cleanup_(close_pipep)
 
 _malloc_  _alloc_(1, 2) static inline void *malloc_multiply(size_t a, size_t b) {
         if (_unlikely_(b == 0 || a > ((size_t) -1) / b))