tools: xenbackendd for NetBSD

Attached patch introduces xenbackendd. It is used on NetBSD
to launch the hotplug scripts. Later xenbackendd can be improved to
also launch qemu-dm as child process and will notice when qemu-dm
crashes.

The changes the patch makes:
- rename hotplug scripts as xenbackendd expects them
  (current names were taken from pkgsrc)
- install hotplug scripts as executable scripts
- introduce xenbackendd
- build/install/launch on NetBSD only

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>

2 files changed, 360 insertions, 0 deletions

diff --git a/tools/xenbackendd/Makefile b/tools/xenbackendd/Makefile
new file mode 100644
index 0000000000..4421f7d27e
--- /dev/null
+++ b/tools/xenbackendd/Makefile
@@ -0,0 +1,41 @@
+# Copyright (c) 2009 Advanced Micro Devices, Inc.
+#
+# 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; under version 2 of the License.
+#
+# 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.
+
+XEN_ROOT=../..
+include $(XEN_ROOT)/tools/Rules.mk
+
+CFLAGS  += -Werror
+CFLAGS  += $(CFLAGS_libxenstore)
+CPPFLAGS += -DXEN_SCRIPT_DIR="\"$(XEN_SCRIPT_DIR)\""
+LDFLAGS += $(LDFLAGS_libxenstore)
+
+SBIN = xenbackendd
+
+.PHONY: all
+all: build
+
+.PHONY: build
+build: $(SBIN)
+
+.PHONY: install
+install: build
+	$(INSTALL_DIR) $(DESTDIR)$(SBINDIR)
+	$(INSTALL_PROG) xenbackendd $(DESTDIR)$(SBINDIR)
+
+.PHONY: clean
+clean:
+	rm -f $(SBIN) $(DEPS)
+
+
+%: %.c Makefile
+	$(CC) $(CFLAGS) $(CPPFLAGS) $< $(LDFLAGS) -o $@
+
+-include $(DEPS)
diff --git a/tools/xenbackendd/xenbackendd.c b/tools/xenbackendd/xenbackendd.c
new file mode 100644
index 0000000000..852a11536f
--- /dev/null
+++ b/tools/xenbackendd/xenbackendd.c
@@ -0,0 +1,319 @@
+/* $NetBSD: xenbackendd.c,v 1.1.1.1 2008/08/07 20:26:57 cegger Exp $ */
+/*
+ * Copyright (C) 2006 Manuel Bouyer <bouyer@netbsd.org>
+ * Copyright (C) 2009 Christoph Egger <Christoph.Egger@amd.com>
+ *
+ *  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; under version 2 of the License.
+ * 
+ *  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
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <syslog.h>
+
+#include <xs.h>
+
+#define DEVTYPE_UNKNOWN 0
+#define DEVTYPE_VIF 1
+#define DEVTYPE_VBD 2
+
+#define DOMAIN_PATH "/local/domain/0"
+
+#ifndef XEN_SCRIPT_DIR
+#error XEN_SCRIPT_DIR not defined
+#endif
+
+#ifndef VBD_SCRIPT
+#define VBD_SCRIPT XEN_SCRIPT_DIR"/block"
+#endif
+#ifndef LOG_FILE
+#define LOG_FILE "/var/log/xen/xenbackendd.log"
+#endif
+#ifndef PID_FILE
+#define PID_FILE "/var/run/xenbackendd.pid"
+#endif
+
+
+struct xs_handle *xs;
+
+int fflag = 0;
+int dflag = 0;
+
+const char *vbd_script = NULL;
+const char *log_file = NULL;
+const char *pidfile = NULL;
+
+static void
+dolog(int pri, const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+	fflush(stderr);
+	va_start(ap, fmt);
+	vsyslog(pri, fmt, ap);
+	va_end(ap);
+}
+
+static void
+dodebug(const char *fmt, ...)
+{
+	va_list ap;
+
+	if (dflag == 0)
+		return;
+	va_start(ap, fmt);
+	vfprintf(stdout, fmt, ap);
+	va_end(ap);
+	printf("\n");
+	fflush(stdout);
+}
+
+static void
+doexec(const char *cmd, const char *arg1, const char *arg2)
+{
+	dodebug("exec %s %s %s", cmd, arg1, arg2);
+	switch(vfork()) {
+	case -1:
+		dolog(LOG_ERR, "can't vfork: %s", strerror(errno));
+		break;
+	case 0:
+		execl(cmd, cmd, arg1, arg2, NULL);
+		dolog(LOG_ERR, "can't exec %s: %s", cmd, strerror(errno));
+		exit(EXIT_FAILURE);
+		/* NOTREACHED */
+		break;
+	default:
+		wait(NULL);
+		break;
+	}
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr,
+	    "usage: %s [-d] [-f] [-l log_file] [-p pif_file] [-s vbd_script]\n",
+	    getprogname());
+	exit(EXIT_FAILURE);
+}
+
+static int
+xen_setup(void)
+{
+	xs = xs_daemon_open();
+	if (xs == NULL) {
+		dolog(LOG_ERR,
+		    "Failed to contact xenstore (%s).  Is it running?",
+		    strerror(errno));
+		goto out;
+	}
+
+	if (!xs_watch(xs, DOMAIN_PATH, "backend")) {
+		dolog(LOG_ERR, "xenstore watch on backend fails.");
+		goto out;
+	}
+	return 0;
+
+ out:
+	if (xs) {
+		xs_daemon_close(xs);
+		xs = NULL;
+	}
+	return -1;
+}
+
+int
+main(int argc, char * const argv[])
+{
+	char **vec;
+	unsigned int num;
+	char *s;
+	int state;
+	char *sstate;
+	char *p;
+	char buf[80];
+	int type = DEVTYPE_UNKNOWN;
+	int ch;
+	int debug_fd;
+	FILE *pidfile_f;
+
+	while ((ch = getopt(argc, argv, "dfl:p:s:")) != -1) {
+		switch (ch) {
+		case 'd':
+			dflag = 1;
+			break;
+		case 'f':
+			fflag = 1;
+			break;
+		case 'l':
+			log_file = optarg;
+			break;
+		case 'p':
+			pidfile = pidfile;
+		case 's':
+			vbd_script = optarg;
+			break;
+		default:
+			usage();
+		}
+	}
+
+	if (vbd_script == NULL)
+		vbd_script = VBD_SCRIPT;
+	if (pidfile == NULL)
+		pidfile = PID_FILE;
+	if (log_file == NULL)
+		log_file = LOG_FILE;
+
+	openlog("xenbackendd", LOG_PID | LOG_NDELAY, LOG_DAEMON);
+
+	if (fflag == 0) {
+		/* open log file */
+		debug_fd = open(log_file, O_RDWR | O_CREAT | O_TRUNC, 0644);
+		if (debug_fd == -1) {
+			dolog(LOG_ERR, "can't open %s: %s",
+			    log_file, strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	if (fflag == 0) {
+		/* daemonize */
+		pidfile_f = fopen(pidfile, "w");
+		if (pidfile_f == NULL) {
+			dolog(LOG_ERR, "can't open %s: %s",
+			    pidfile, strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+		if (daemon(0, 0) < 0) {
+			dolog(LOG_ERR, "can't daemonize: %s",
+			    strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+		fprintf(pidfile_f, "%d\n", (int)getpid());
+		fclose(pidfile_f);
+
+		/* redirect stderr to log file */
+		if (dup2(debug_fd, STDERR_FILENO) < 0) {
+			dolog(LOG_ERR, "can't redirect stderr to %s: %s\n",
+			    log_file, strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+
+		/* also redirect stdout if we're in debug mode */
+		if (dflag) {
+			if (dup2(debug_fd, STDOUT_FILENO) < 0) {
+				dolog(LOG_ERR,
+				    "can't redirect stdout to %s: %s\n",
+				    log_file, strerror(errno));
+				exit(EXIT_FAILURE);
+			}
+		}
+
+		close(debug_fd);
+		debug_fd = -1;
+	}
+
+	if (xen_setup() < 0)
+		exit(EXIT_FAILURE);
+
+	for (;;) {
+		vec = xs_read_watch(xs, &num);
+		if (!vec) {
+			dolog(LOG_ERR, "xs_read_watch: NULL\n");
+			continue;
+		}
+
+		if (strlen(vec[XS_WATCH_PATH]) < sizeof("state"))
+			goto next1;
+
+		/* find last component of path, check if it's "state" */
+		p = &vec[XS_WATCH_PATH][
+		    strlen(vec[XS_WATCH_PATH]) - sizeof("state")];
+		if (p[0] != '/')
+			goto next1;
+		p[0] = '\0';
+		p++;
+		if (strcmp(p, "state") != 0)
+			goto next1;
+
+		snprintf(buf, sizeof(buf), "%s/state", vec[XS_WATCH_PATH]);
+		sstate = xs_read(xs, XBT_NULL, buf, 0);
+		if (sstate == NULL) {
+			dolog(LOG_ERR,
+			    "Failed to read %s (%s)", buf, strerror(errno));
+			goto next1;
+		}
+
+		state = atoi(sstate);
+		snprintf(buf, sizeof(buf), "%s/hotplug-status",
+		    vec[XS_WATCH_PATH]);
+		s = xs_read(xs, XBT_NULL, buf, 0);
+		if (s != NULL && state != 6 /* XenbusStateClosed */)
+			goto next2;
+
+		if (strncmp(vec[XS_WATCH_PATH],
+		    DOMAIN_PATH "/backend/vif",
+		    strlen(DOMAIN_PATH "/backend/vif")) == 0)
+			type = DEVTYPE_VIF;
+
+		if (strncmp(vec[XS_WATCH_PATH],
+		    DOMAIN_PATH "/backend/vbd",
+		    strlen(DOMAIN_PATH "/backend/vbd")) == 0)
+			type = DEVTYPE_VBD;
+
+		switch(type) {
+		case DEVTYPE_VIF:
+			if (s)
+				free(s);
+			snprintf(buf, sizeof(buf), "%s/script",
+			    vec[XS_WATCH_PATH]);
+			s = xs_read(xs, XBT_NULL, buf, 0);
+			if (s == NULL) {
+				dolog(LOG_ERR,
+				    "Failed to read %s (%s)", buf,
+				    strerror(errno));
+				goto next2;
+			}
+			doexec(s, vec[XS_WATCH_PATH], sstate);
+			break;
+
+		case DEVTYPE_VBD:
+			doexec(vbd_script, vec[XS_WATCH_PATH], sstate);
+			break;
+
+		default:
+			break;
+		}
+
+next2:
+		if (s)
+			free(s);
+		free(sstate);
+
+next1:
+		free(vec);
+	}
+
+	return 0;
+}