[Libguestfs] [PATCH v3 5/7] rescue: Modify virt-rescue so it doesn't use direct mode (RHBZ#1152819, RHBZ#1171654).

Instead of using "direct mode" (which was basically a quick hack), virt-rescue now launches the appliance with a running daemon. The daemon doesn't do much -- there is still a bash shell which the user interacts with. The daemon is there simply to provide the initial GUESTFS_LAUNCH_FLAG message and to handle shutdown a bit more gracefully. To interact with the shell, and replacing direct mode, virt-rescue now prints out log messages (the output of the shell), and sends input typed by the user directly to the console socket. This uses the guestfs_internal_get_console_socket API added previously. Most of the complexity behind this is hidden in virt-rescue. This fully fixes the handling of ^C (RHBZ#1152819). Also there were earlier reports that full screen commands like 'vim' didn't work well, (RHBZ#1171654), but in this version vim appears to work fine, albeit only using 80x24 of the screen because of the serial console. --- appliance/init | 101 +++++++++--------- rescue/Makefile.am | 1 + rescue/rescue.c | 306 +++++++++++++++++++++++++++++++++++++++++++++-------- 3 files changed, 316 insertions(+), 92 deletions(-) diff --git a/appliance/init b/appliance/init index bb8b709..fa42c2b 100755 --- a/appliance/init +++ b/appliance/init @@ -159,59 +159,62 @@ if test "$guestfs_verbose" = 1 && test "$guestfs_boot_analysis" != 1; then echo -n "uptime: "; cat /proc/uptime fi -if ! test "$guestfs_rescue" = 1; then - # Run the daemon. - cmd="guestfsd" - eval `grep -Eo 'guestfs_channel=[^[:space:]]+' /proc/cmdline` - if test "x$guestfs_channel" != "x"; then +# Run the daemon. +cmd="guestfsd" +eval `grep -Eo 'guestfs_channel=[^[:space:]]+' /proc/cmdline` +if test "x$guestfs_channel" != "x"; then cmd="$cmd --channel $guestfs_channel" - fi - if test "$guestfs_verbose" = 1; then +fi +if test "$guestfs_verbose" = 1; then cmd="$cmd --verbose" - fi - if test "$guestfs_network" = 1; then +fi +if test "$guestfs_network" = 1; then cmd="$cmd --network" - fi - echo $cmd - $cmd +fi +if ! test "$guestfs_rescue" = 1; then + echo $cmd + $cmd else - # Run virt-rescue shell. - - # Get name of the serial port, from console= passed by libguestfs. - guestfs_serial=$(grep -Eo 'console=[^[:space:]]+' /proc/cmdline | - sed s/console=//) - - # Remove LD_PRELOAD=libSegFault set above. - unset LD_PRELOAD - - :> $HOME/.bashrc - grep -Eo 'TERM=[^[:space:]]+' /proc/cmdline >> $HOME/.bashrc - echo "PS1='><rescue> '" >> $HOME/.bashrc - echo "export TERM PS1" >> $HOME/.bashrc - - # The shell is opened by default on /dev/console, which (on Linux) - # is not a controlling terminal, causing job control to fail. For - # how we work around this, see: - # https://busybox.net/FAQ.html#job_control - run_bash_with_ctty () - { - setsid bash -c \ - "exec bash </dev/$guestfs_serial >/dev/$guestfs_serial 2>&1" - } - - echo - echo "------------------------------------------------------------" - echo - echo "Welcome to virt-rescue, the libguestfs rescue shell." - echo - echo "Note: The contents of / are the rescue appliance." - echo "You have to mount the guest's partitions under /sysroot" - echo "before you can examine them." - echo - run_bash_with_ctty - echo - echo "virt-rescue: Syncing the disk now before exiting ..." - echo + # Run virt-rescue shell. + + # We need a daemon, even in virt-rescue. + $cmd & + + # Get name of the serial port, from console= passed by libguestfs. + guestfs_serial=$(grep -Eo 'console=[^[:space:]]+' /proc/cmdline | + sed s/console=//) + + # Remove LD_PRELOAD=libSegFault set above. + unset LD_PRELOAD + + :> $HOME/.bashrc + grep -Eo 'TERM=[^[:space:]]+' /proc/cmdline >> $HOME/.bashrc + echo "PS1='><rescue> '" >> $HOME/.bashrc + echo "export TERM PS1" >> $HOME/.bashrc + + # The shell is opened by default on /dev/console, which (on Linux) + # is not a controlling terminal, causing job control to fail. For + # how we work around this, see: + # https://busybox.net/FAQ.html#job_control + run_bash_with_ctty () + { + setsid bash -c \ + "exec bash </dev/$guestfs_serial >/dev/$guestfs_serial 2>&1" + } + + echo + echo "------------------------------------------------------------" + echo + echo "Welcome to virt-rescue, the libguestfs rescue shell." + echo + echo "Note: The contents of / (root) are the rescue appliance." + echo "You have to mount the guest's partitions under /sysroot" + echo "before you can examine them." + echo + run_bash_with_ctty + echo + echo "virt-rescue: Syncing the disk now before exiting ..." + echo fi sync diff --git a/rescue/Makefile.am b/rescue/Makefile.am index 7919aaf..99d4b79 100644 --- a/rescue/Makefile.am +++ b/rescue/Makefile.am @@ -30,6 +30,7 @@ virt_rescue_SOURCES = \ virt_rescue_CPPFLAGS = \ -DGUESTFS_WARN_DEPRECATED=1 \ + -DGUESTFS_PRIVATE=1 \ -DLOCALEBASEDIR=\""$(datadir)/locale"\" \ -I$(top_srcdir)/common/utils -I$(top_builddir)/common/utils \ -I$(top_srcdir)/lib -I$(top_builddir)/lib \ diff --git a/rescue/rescue.c b/rescue/rescue.c index 572a844..28a62ce 100644 --- a/rescue/rescue.c +++ b/rescue/rescue.c @@ -23,21 +23,32 @@ #include <string.h> #include <inttypes.h> #include <unistd.h> +#include <fcntl.h> #include <getopt.h> #include <errno.h> #include <error.h> +#include <signal.h> +#include <termios.h> +#include <poll.h> #include <locale.h> #include <assert.h> #include <libintl.h> +#include "full-write.h" +#include "getprogname.h" #include "ignore-value.h" #include "xvasprintf.h" -#include "getprogname.h" #include "guestfs.h" #include "options.h" #include "display-options.h" +static void log_message_callback (guestfs_h *g, void *opaque, uint64_t event, int event_handle, int flags, const char *buf, size_t buf_len, const uint64_t *array, size_t array_len); +static void do_rescue (int sock); +static void raw_tty (void); +static void restore_tty (void); +static void tstp_handler (int sig); +static void cont_handler (int sig); static void add_scratch_disks (int n, struct drv **drvs); static void do_suggestion (struct drv *drvs); @@ -54,6 +65,9 @@ int inspector = 0; int in_guestfish = 0; int in_virt_rescue = 1; +/* Old terminal settings. */ +static struct termios old_termios; + static void __attribute__((noreturn)) usage (int status) { @@ -135,6 +149,16 @@ main (int argc, char *argv[]) int memsize = 0; int smp = 0; int suggest = 0; + char *append_full; + int sock; + + /* Save the initial state of the tty so we always have the original + * state to go back to. + */ + if (tcgetattr (STDIN_FILENO, &old_termios) == -1) { + perror ("tcgetattr: stdin"); + exit (EXIT_FAILURE); + } g = guestfs_create (); if (g == NULL) @@ -295,30 +319,6 @@ main (int argc, char *argv[]) usage (EXIT_FAILURE); } -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wdeprecated-declarations" - /* Setting "direct mode" is required for the rescue appliance. */ - if (guestfs_set_direct (g, 1) == -1) - exit (EXIT_FAILURE); -#pragma GCC diagnostic pop - - { - /* The libvirt backend doesn't support direct mode. As a temporary - * workaround, force the appliance backend, but warn about it. - */ - CLEANUP_FREE char *backend = guestfs_get_backend (g); - if (backend) { - if (STREQ (backend, "libvirt") || - STRPREFIX (backend, "libvirt:")) { - fprintf (stderr, _("%s: warning: virt-rescue doesn't work with the libvirt backend\n" - "at the moment. As a workaround, forcing backend = 'direct'.\n"), - getprogname ()); - if (guestfs_set_backend (g, "direct") == -1) - exit (EXIT_FAILURE); - } - } - } - /* Set other features. */ if (memsize > 0) if (guestfs_set_memsize (g, memsize) == -1) @@ -330,16 +330,15 @@ main (int argc, char *argv[]) if (guestfs_set_smp (g, smp) == -1) exit (EXIT_FAILURE); - { - /* Kernel command line must include guestfs_rescue=1 (see - * appliance/init) as well as other options. - */ - CLEANUP_FREE char *append_full = xasprintf ("guestfs_rescue=1%s%s", - append ? " " : "", - append ? append : ""); - if (guestfs_set_append (g, append_full) == -1) - exit (EXIT_FAILURE); - } + /* Kernel command line must include guestfs_rescue=1 (see + * appliance/init) as well as other options. + */ + append_full = xasprintf ("guestfs_rescue=1%s%s", + append ? " " : "", + append ? append : ""); + if (guestfs_set_append (g, append_full) == -1) + exit (EXIT_FAILURE); + free (append_full); /* Add drives. */ add_drives (drvs, 'a'); @@ -347,20 +346,241 @@ main (int argc, char *argv[]) /* Free up data structures, no longer needed after this point. */ free_drives (drvs); - /* Run the appliance. This won't return until the user quits the - * appliance. + /* Add an event handler to print "log messages". These will be the + * output of the appliance console during launch and shutdown. + * After launch, we will read the console messages directly from the + * socket and they won't be passed through the event callback. */ - if (!verbose) - guestfs_set_error_handler (g, NULL, NULL); + if (guestfs_set_event_callback (g, log_message_callback, + GUESTFS_EVENT_APPLIANCE, 0, NULL) == -1) + exit (EXIT_FAILURE); - /* We expect launch to fail, so ignore the return value, and don't - * bother with explicit guestfs_shutdown either. + /* Run the appliance. */ + if (guestfs_launch (g) == -1) + exit (EXIT_FAILURE); + + sock = guestfs_internal_get_console_socket (g); + if (sock == -1) + exit (EXIT_FAILURE); + + /* Try to set all sockets to non-blocking. */ + if (fcntl (STDIN_FILENO, F_SETFL, O_NONBLOCK) == -1) + perror ("could not set stdin to non-blocking"); + if (fcntl (STDOUT_FILENO, F_SETFL, O_NONBLOCK) == -1) + perror ("could not set stdout to non-blocking"); + if (fcntl (sock, F_SETFL, O_NONBLOCK) == -1) + perror ("could not set console socket to non-blocking"); + + /* Put stdin in raw mode so that we can receive ^C and other + * special keys. */ - ignore_value (guestfs_launch (g)); + raw_tty (); + + /* Restore the tty settings when the process exits. */ + atexit (restore_tty); + + /* Catch tty stop and cont signals so we can cleanup. + * See https://www.gnu.org/software/libc/manual/html_node/Signaling-Yourself.html + */ + signal (SIGTSTP, tstp_handler); + signal (SIGCONT, cont_handler); + + do_rescue (sock); + + /* Shut down the appliance. */ + guestfs_push_error_handler (g, NULL, NULL); + if (guestfs_shutdown (g) == -1) { + const char *err; + + /* Ignore "appliance closed the connection unexpectedly" since + * this can happen if the user reboots the appliance. + */ + if (guestfs_last_errno (g) == EPIPE) + goto next; + /* Otherwise it's a real error. */ + err = guestfs_last_error (g); + fprintf (stderr, "libguestfs: error: %s\n", err); + exit (EXIT_FAILURE); + } + next: + guestfs_pop_error_handler (g); guestfs_close (g); - exit (EXIT_SUCCESS); + exit (EXIT_SUCCESS); /* implicitly calls restore_tty */ +} + +static void +log_message_callback (guestfs_h *g, void *opaque, uint64_t event, + int event_handle, int flags, + const char *buf, size_t buf_len, + const uint64_t *array, size_t array_len) +{ + if (buf_len > 0) { + ignore_value (full_write (STDOUT_FILENO, buf, buf_len)); + } +} + +/* This is the main loop for virt-rescue. We read and write + * directly to the console socket. + */ +#define BUFSIZE 4096 +static char rbuf[BUFSIZE]; /* appliance -> local tty */ +static char wbuf[BUFSIZE]; /* local tty -> appliance */ + +static void +do_rescue (int sock) +{ + size_t rlen = 0; + size_t wlen = 0; + + while (sock >= 0 || rlen > 0) { + struct pollfd fds[3]; + nfds_t nfds = 2; + int r; + ssize_t n; + + fds[0].fd = STDIN_FILENO; + fds[0].events = 0; + if (BUFSIZE-wlen > 0) + fds[0].events = POLLIN; + fds[0].revents = 0; + + fds[1].fd = STDOUT_FILENO; + fds[1].events = 0; + if (rlen > 0) + fds[1].events |= POLLOUT; + fds[1].revents = 0; + + if (sock >= 0) { + fds[2].fd = sock; + fds[2].events = 0; + if (BUFSIZE-rlen > 0) + fds[2].events |= POLLIN; + if (wlen > 0) + fds[2].events |= POLLOUT; + fds[2].revents = 0; + nfds++; + } + + r = poll (fds, nfds, -1); + if (r == -1) { + if (errno == EINTR || errno == EAGAIN) + continue; + perror ("poll"); + return; + } + + /* Input from local tty. */ + if ((fds[0].revents & POLLIN) != 0) { + assert (BUFSIZE-wlen > 0); + n = read (STDIN_FILENO, wbuf+wlen, BUFSIZE-wlen); + if (n == -1) { + if (errno == EINTR || errno == EAGAIN) + continue; + perror ("read"); + return; + } + if (n == 0) { + /* We don't expect this to happen. Maybe the whole tty went away? + * Anyway, we should exit as soon as possible. + */ + return; + } + if (n > 0) + wlen += n; + } + + /* Log message from appliance. */ + if (nfds > 2 && (fds[2].revents & POLLIN) != 0) { + assert (BUFSIZE-rlen > 0); + n = read (sock, rbuf+rlen, BUFSIZE-rlen); + if (n == -1) { + if (errno == EINTR || errno == EAGAIN) + continue; + if (errno == ECONNRESET) + goto appliance_closed; + perror ("read"); + return; + } + if (n == 0) { + appliance_closed: + sock = -1; + /* Don't actually close the socket, because it's owned by + * the guestfs handle. + */ + continue; + } + if (n > 0) + rlen += n; + } + + /* Write log messages to local tty. */ + if ((fds[1].revents & POLLOUT) != 0) { + assert (rlen > 0); + n = write (STDOUT_FILENO, rbuf, rlen); + if (n == -1) { + perror ("write"); + continue; + } + rlen -= n; + memmove (rbuf, rbuf+n, rlen); + } + + /* Write commands to the appliance. */ + if (nfds > 2 && (fds[2].revents & POLLOUT) != 0) { + assert (wlen > 0); + n = write (sock, wbuf, wlen); + if (n == -1) { + perror ("write"); + continue; + } + wlen -= n; + memmove (wbuf, wbuf+n, wlen); + } + } +} + +/* Put the tty in raw mode. */ +static void +raw_tty (void) +{ + struct termios termios; + + if (tcgetattr (STDIN_FILENO, &termios) == -1) { + perror ("tcgetattr: stdin"); + exit (EXIT_FAILURE); + } + cfmakeraw (&termios); + if (tcsetattr (STDIN_FILENO, TCSANOW, &termios) == -1) { + perror ("tcsetattr: stdin"); + exit (EXIT_FAILURE); + } +} + +/* Restore the tty to (presumably) cooked mode as it was when + * the program was started. + */ +static void +restore_tty (void) +{ + tcsetattr (STDIN_FILENO, TCSANOW, &old_termios); +} + +/* When we get SIGTSTP, switch back to cooked mode. */ +static void +tstp_handler (int sig) +{ + restore_tty (); + signal (SIGTSTP, SIG_DFL); + raise (SIGTSTP); +} + +/* When we get SIGCONF, switch to raw mode. */ +static void +cont_handler (int sig) +{ + raw_tty (); } static void suggest_filesystems (void); -- 2.9.3