[Libguestfs] [PATCH v2 5/6] rescue: Modify virt-rescue so it doesn't use direct mode (RHBZ#1152819, RHBZ#1171654).
Richard W.M. Jones
rjones at redhat.com
Fri Mar 3 21:59:28 UTC 2017
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 | 262 ++++++++++++++++++++++++++++++++++++++++++++---------
3 files changed, 272 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..556c344 100644
--- a/rescue/rescue.c
+++ b/rescue/rescue.c
@@ -23,21 +23,28 @@
#include <string.h>
#include <inttypes.h>
#include <unistd.h>
+#include <fcntl.h>
#include <getopt.h>
#include <errno.h>
#include <error.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 restore_tty (void);
static void add_scratch_disks (int n, struct drv **drvs);
static void do_suggestion (struct drv *drvs);
@@ -54,6 +61,9 @@ 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 +145,9 @@ main (int argc, char *argv[])
int memsize = 0;
int smp = 0;
int suggest = 0;
+ char *append_full;
+ int sock;
+ struct termios termios;
g = guestfs_create ();
if (g == NULL)
@@ -295,30 +308,6 @@ 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 +319,15 @@ 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 +335,208 @@ 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);
+
+ /* Put stdin in raw mode so that we can receive ^C and other
+ * special keys.
*/
- ignore_value (guestfs_launch (g));
+ if (tcgetattr (STDIN_FILENO, &termios) == -1) {
+ perror ("tcgetattr: stdin");
+ exit (EXIT_FAILURE);
+ }
+ old_termios = termios;
+ cfmakeraw (&termios);
+ if (tcsetattr (STDIN_FILENO, TCSANOW, &termios) == -1) {
+ perror ("tcsetattr: stdin");
+ 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");
+
+ /* Restore the tty settings when the process exits. */
+ atexit (restore_tty);
+
+ 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);
+ }
+ }
+}
+
+static void
+restore_tty (void)
+{
+ tcsetattr (STDIN_FILENO, TCSANOW, &old_termios);
}
static void suggest_filesystems (void);
--
2.9.3
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