[pve-devel] [PATCH qemu-server v2 2/5] add qmeventd
Dominik Csapak
d.csapak at proxmox.com
Wed Oct 17 14:31:20 CEST 2018
this adds a program that can listen to qemu qmp events on a given socket
and if a shutdown event followed by a disconnected socket occurs,
execute the given script with the given and additional arguments
this is useful if we want to cleanup after the qemu process exited,
e.g. tap devices, vgpus, etc.
also we could implement a 'proper' reboot with applying pending changes
and a stop/reboot hoook
for now, this needs a not-yet applied patch[1] to qemu
but this should be trivial to backport
1: https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg01271.html
Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v1:
* use better Makefile variables
* move the variable declarations closer to their use
* declare the argument array statically instead of malloc'ing
Makefile | 12 +++--
qmeventd.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 181 insertions(+), 3 deletions(-)
create mode 100644 qmeventd.c
diff --git a/Makefile b/Makefile
index 1005f20..e97aa16 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,9 @@ VERSION=5.0
PACKAGE=qemu-server
PKGREL=37
-CFLAGS= -O2 -Werror -Wall -Wtype-limits -Wl,-z,relro
+CFLAGS=-O2 -Werror -Wall -Wextra -Wpedantic -Wtype-limits -Wl,-z,relro
+JSON_CFLAGS=$(shell pkg-config --cflags jansson)
+JSON_LIBS=$(shell pkg-config --libs jansson)
DESTDIR=
PREFIX=/usr
@@ -36,6 +38,9 @@ all:
dinstall: deb
dpkg -i ${DEB}
+qmeventd: qmeventd.c
+ $(CC) $(CFLAGS) ${JSON_CFLAGS} -o $@ $< ${JSON_LIBS}
+
qm.bash-completion:
PVE_GENERATING_DOCS=1 perl -I. -T -e "use PVE::CLI::qm; PVE::CLI::qm->generate_bash_completions();" >$@.tmp
mv $@.tmp $@
@@ -44,7 +49,7 @@ qmrestore.bash-completion:
PVE_GENERATING_DOCS=1 perl -I. -T -e "use PVE::CLI::qmrestore; PVE::CLI::qmrestore->generate_bash_completions();" >$@.tmp
mv $@.tmp $@
-PKGSOURCES=qm qm.1 qmrestore qmrestore.1 qmextract qm.conf.5 qm.bash-completion qmrestore.bash-completion
+PKGSOURCES=qm qm.1 qmrestore qmrestore.1 qmextract qm.conf.5 qm.bash-completion qmrestore.bash-completion qmeventd
.PHONY: install
install: ${PKGSOURCES}
@@ -63,6 +68,7 @@ install: ${PKGSOURCES}
make -C PVE install
install -m 0755 qm ${DESTDIR}${SBINDIR}
install -m 0755 qmrestore ${DESTDIR}${SBINDIR}
+ install -m 0755 qmeventd ${DESTDIR}${SBINDIR}
install -m 0755 pve-bridge ${DESTDIR}${VARLIBDIR}/pve-bridge
install -m 0755 pve-bridge-hotplug ${DESTDIR}${VARLIBDIR}/pve-bridge-hotplug
install -m 0755 pve-bridgedown ${DESTDIR}${VARLIBDIR}/pve-bridgedown
@@ -97,7 +103,7 @@ upload: ${DEB}
.PHONY: clean
clean:
make cleanup-docgen
- rm -rf build *.deb *.buildinfo *.changes
+ rm -rf build *.deb *.buildinfo *.changes qmeventd
find . -name '*~' -exec rm {} ';'
diff --git a/qmeventd.c b/qmeventd.c
new file mode 100644
index 0000000..f4eba93
--- /dev/null
+++ b/qmeventd.c
@@ -0,0 +1,172 @@
+/*
+
+ Copyright (C) 2018 Proxmox Server Solutions GmbH
+
+ Copyright: qemumonitor is under GNU GPL, the GNU General Public License.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 dated June, 1991.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ 02111-1307, USA.
+
+ Author: Dominik Csapak <d.csapak at proxmox.com>
+
+ qemumonitor connects to a given qmp socket, and waits for a
+ shutdown event followed by the closing of the socket,
+ it then calls the given script with following arguments
+
+ SCRIPT [ARGUMENTS] <graceful> <guest> <was_reset>
+
+ parameter explanation:
+
+ graceful:
+ 1|0 depending if it saw a shutdown event before the socket closed
+
+ guest:
+ 1|0 depending if the shutdown was requested from the guest
+
+ was_reset:
+ 1|0 depending if the shutdown was actually a request
+
+*/
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include <jansson.h>
+
+typedef int json_bool_t;
+typedef enum { STATE_PRECONNECTING, STATE_CONNECTING, STATE_CONNECTED } state_t;
+
+#define QMP_ANSWER "{ \"execute\":\"qmp_capabilities\" }\n"
+
+static void usage(char *name)
+{
+ fprintf(stderr, "Usage: %s SOCKET SCRIPT [ARGUMENTS...]\n", name);
+}
+
+int main(int argc, char *argv[])
+{
+ if (argc < 3) {
+ usage(argv[0]);
+ exit(EXIT_FAILURE);
+ }
+
+ size_t pathlen = strlen(argv[1]);
+ struct sockaddr_un serv_addr;
+
+ if (pathlen > sizeof(serv_addr.sun_path)) {
+ fprintf(stderr, "path is too long\n");
+ exit(EXIT_FAILURE);
+ }
+
+ memset(&serv_addr, 0, sizeof(serv_addr));
+ serv_addr.sun_family = AF_UNIX;
+ memcpy(&(serv_addr.sun_path), argv[1], pathlen);
+
+ int sock = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (sock == -1) {
+ fprintf(stderr, "cannot create unix socket: %s\n", strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+
+ if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
+ close(sock);
+ fprintf(stderr, "error connecting to %s: %s\n", argv[1], strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+
+ FILE *socketfile = fdopen(sock, "r");
+ if (socketfile == NULL) {
+ close(sock);
+ fprintf(stderr, "error opening %s: %s\n", argv[1], strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+
+ json_t *json;
+ json_bool_t guest = 0;
+ json_bool_t reset = 0;
+ json_bool_t graceful_shutdown = 0;
+ state_t qmp_state = STATE_PRECONNECTING;
+
+ while (!feof(socketfile)) {
+ json_error_t err; // result not used
+ json = json_loadf(socketfile, JSON_DISABLE_EOF_CHECK, &err);
+
+ // ignore parser errors
+ if (json == NULL)
+ continue;
+
+ switch (qmp_state) {
+ case STATE_PRECONNECTING:
+ if (json_unpack(json, "{s: {s:{}, s:[]}}", "QMP", "version",
+ "capabilities") == 0) {
+ ssize_t len;
+ do {
+ len = write(sock, QMP_ANSWER, sizeof(QMP_ANSWER) - 1);
+ } while (len < 0 && errno == EINTR);
+ if (len != sizeof(QMP_ANSWER) - 1) {
+ fprintf(stderr, "cannot write to qmp socket: %s\n",
+ strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ qmp_state = STATE_CONNECTING;
+ }
+ break;
+ case STATE_CONNECTING:
+ if (json_unpack(json, "{s:{}}", "return") == 0) {
+ qmp_state = STATE_CONNECTED;
+ if (daemon(0, 0) == -1) {
+ fprintf(stderr, "cannot daemonize: %s\n",
+ strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ }
+ break;
+ case STATE_CONNECTED: {
+ const char *event;
+ if (json_unpack(json, "{s:s, s:{s:b, s:b}}", "event", &event,
+ "data", "guest", &guest, "was_reset", &reset) == 0) {
+ if (strcmp(event, "SHUTDOWN") == 0)
+ graceful_shutdown = 1;
+ }
+ break;
+ }
+ }
+ json_decref(json);
+ }
+ fclose(socketfile);
+
+ char *script = argv[2];
+ char **args = malloc((size_t)(argc+2) * sizeof(*args));
+
+ for (int i = 0; i < argc - 2; i++)
+ args[i] = argv[i+2];
+
+ char shutdown_args[6] = {
+ graceful_shutdown ? '1' : '0', 0,
+ guest ? '1' : '0', 0,
+ reset ? '1' : '0', 0,
+ };
+
+ args[argc-2] = &shutdown_args[0];
+ args[argc-1] = &shutdown_args[2];
+ args[argc] = &shutdown_args[4];
+ args[argc+1] = NULL;
+
+ execvp(script, args);
+ exit(1);
+}
--
2.11.0
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