Fix #185: add devmon support, <dev/foo> condition provider

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/Makefile.am

@@ -45,6 +45,7 @@ finit_SOURCES      = api.c	cgroup.c	cgroup.h	\
 		     client.c	client.h			\
 		     cond.c	cond-w.c	cond.h		\
 		     conf.c	conf.h				\
+		     devmon.c   devmon.h			\
 		     exec.c	finit.c		finit.h		\
 		     		stty.c				\
 		     helpers.c	helpers.h			\

src/cond.h

@@ -6,11 +6,13 @@
 #include "svc.h"
 
 #define COND_BASE      "finit/cond"
+#define COND_DEV       "dev/"
 #define COND_PID       "pid/"
 #define COND_SYS       "sys/"
 #define COND_USR       "usr/"
 
 #define _PATH_COND     _PATH_VARRUN COND_BASE "/"
+#define _PATH_CONDDEV  _PATH_COND   COND_DEV
 #define _PATH_CONDPID  _PATH_COND   COND_PID
 #define _PATH_CONDSYS  _PATH_COND   COND_SYS
 #define _PATH_CONDUSR  _PATH_COND   COND_USR

src/conf.c

@@ -40,6 +40,7 @@
 
 #include "finit.h"
 #include "cond.h"
+#include "devmon.h"
 #include "iwatch.h"
 #include "private.h"
 #include "service.h"
@@ -469,6 +470,7 @@ void conf_parse_cond(svc_t *svc, char *cond)
 {
 	size_t i = 0;
 	char *ptr;
+	char *c;
 
 	if (!svc) {
 		errx(1, "Invalid service pointer");
@@ -496,16 +498,17 @@ void conf_parse_cond(svc_t *svc, char *cond)
 	ptr[i] = 0;
 
 	if (i >= sizeof(svc->cond)) {
-		logit(LOG_WARNING, "Too long event list in declaration of %s: %s", svc_ident(svc, NULL, 0), ptr);
+		logit(LOG_WARNING, "%s: too long list of conditions: %s", svc_ident(svc, NULL, 0), ptr);
 		return;
 	}
 
-	if (!strncmp(ptr, "svc/", 4)) {
+	svc->cond[0] = 0;
-		logit(LOG_ERR, "Unsupported cond syntax for %s: <%s", svc_ident(svc, NULL, 0), ptr);
+	for (i = 0, c = strtok(ptr, ","); c; c = strtok(NULL, ","), i++) {
-		return;
+		devmon_add_cond(c);
+		if (i)
+			strlcat(svc->cond, ",", sizeof(svc->cond));
+		strlcat(svc->cond, c, sizeof(svc->cond));
 	}
-
-	strlcpy(svc->cond, ptr, sizeof(svc->cond));
 }
 
 struct rlimit_name {

src/devmon.c

@@ -0,0 +1,275 @@
+/* Device node monitor for the Finit condition engine
+ *
+ * Copyright (c) 2022  Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <fnmatch.h>
+#include <glob.h>
+#include <limits.h>
+#include <paths.h>
+
+#include "finit.h"
+#include "cond.h"
+#include "helpers.h"
+#include "pid.h"
+#include "plugin.h"
+#include "service.h"
+#include "iwatch.h"
+
+static struct iwatch iw_devmon;
+static uev_t devw;
+static int fd;
+
+struct dev_node {
+	TAILQ_ENTRY(dev_node) link;
+	char   *name;
+	size_t  refcnt;
+};
+
+static TAILQ_HEAD(, dev_node) dev_node_list = TAILQ_HEAD_INITIALIZER(dev_node_list);
+
+static struct dev_node *find_node(const char *cond)
+{
+	struct dev_node *node, *tmp;
+
+	TAILQ_FOREACH_SAFE(node, &dev_node_list, link, tmp) {
+		if (string_compare(node->name, cond))
+			return node;
+	}
+
+	return NULL;
+}
+
+static void drop_node(struct dev_node *node)
+{
+	if (!node)
+		return;
+
+	node->refcnt--;
+	if (node->refcnt)
+		return;
+
+	TAILQ_REMOVE(&dev_node_list, node, link);
+	free(node->name);
+	free(node);
+}
+
+void devmon_add_cond(const char *cond)
+{
+	struct dev_node *node;
+
+	if (!cond || strncmp(cond, "dev/", 4)) {
+		dbg("no match");
+		return;
+	}
+
+	dbg("%s", cond);
+	node = find_node(cond);
+	if (node) {
+		node->refcnt++;
+		return;
+	}
+
+	node = malloc(sizeof(*node));
+	if (!node) {
+	fail:
+		warn("failed allocating node %s", cond);
+		return;
+	}
+
+	node->name = strdup(cond);
+	if (!node->name) {
+		free(node);
+		goto fail;
+	}
+	node->refcnt = 1;
+
+	TAILQ_INSERT_TAIL(&dev_node_list, node, link);
+}
+
+void devmon_del_cond(const char *cond)
+{
+	if (!cond || strcmp(cond, "dev/"))
+		return;
+
+	drop_node(find_node(cond));
+}
+
+static int devmon_add_path(struct iwatch *iw, char *path)
+{
+	char *ptr;
+
+	ptr = strstr(path, "dev/");
+	if (ptr) {
+		char *slash;
+
+		ptr += 4;
+		slash = strchr(ptr, '/');
+		if (slash) {
+			ptr = slash++;
+			slash = strchr(ptr, '/');
+			if (slash) {
+				dbg("Path too deep, skipping.");
+				return -1;
+			}
+		}
+	}
+
+	return iwatch_add1(iw, path, IN_CREATE | IN_DELETE);
+}
+
+static void devmon_update_conds(char *dir, char *name, uint32_t mask)
+{
+	char fn[PATH_MAX];
+	char *cond;
+
+	paste(fn, sizeof(fn), dir, name);
+	cond = &fn[1];
+
+	dbg("path: %s, mask: %08x, cond: %s", fn, mask, cond);
+	if (!find_node(cond)) {
+		dbg("unregistered, skipping %s", cond);
+		return;
+	}
+
+	if (mask & IN_CREATE)
+		cond_set(cond);
+	else if (mask & IN_DELETE)
+		cond_clear(cond);
+}
+
+/* synthesize events in case of new run dirs */
+static void devmon_scandir(struct iwatch *iw, char *dir, int len)
+{
+	char path[len + 6];
+	glob_t gl;
+	size_t i;
+	int rc;
+
+	snprintf(path, sizeof(path), "%s/*", dir);
+	rc = glob(path, GLOB_NOSORT, NULL, &gl);
+	if (rc && rc != GLOB_NOMATCH)
+		return;
+
+	for (i = 0; i < gl.gl_pathc; i++) {
+		dbg("scan found %s", gl.gl_pathv[i]);
+		devmon_update_conds(dir, gl.gl_pathv[i], IN_CREATE);
+	}
+	globfree(&gl);
+}
+
+/*
+ * create/remove sub-directory in monitored directory
+ */
+static void devmon_handle_dir(struct iwatch *iw, char *dir, char *name, int mask)
+{
+	char path[strlen(dir) + strlen(name) + 2];
+	struct iwatch_path *iwp;
+
+	paste(path, sizeof(path), dir, name);
+	dbg("path: %s", path);
+
+	iwp = iwatch_find_by_path(iw, path);
+
+	if (mask & IN_CREATE) {
+		if (!iwp) {
+			if (!devmon_add_path(iw, path))
+				devmon_scandir(iw, path, sizeof(path));
+		}
+	} else if (mask & IN_DELETE) {
+		if (iwp)
+			iwatch_del(&iw_devmon, iwp);
+	}
+}
+
+static void devmon_cb(uev_t *w, void *arg, int events)
+{
+	static char ev_buf[8 *(sizeof(struct inotify_event) + NAME_MAX + 1) + 1];
+	struct inotify_event *ev;
+	ssize_t sz;
+	size_t off;
+
+	sz = read(w->fd, ev_buf, sizeof(ev_buf) - 1);
+	if (sz <= 0) {
+		err(1, "invalid inotify event");
+		return;
+	}
+	ev_buf[sz] = 0;
+
+	for (off = 0; off < (size_t)sz; off += sizeof(*ev) + ev->len) {
+		struct iwatch_path *iwp;
+
+		if (off + sizeof(*ev) > (size_t)sz)
+			break;
+
+		ev = (struct inotify_event *)&ev_buf[off];
+		if (off + sizeof(*ev) + ev->len > (size_t)sz)
+			break;
+
+		if (!ev->mask)
+			continue;
+
+		/* Find base path for this event */
+		iwp = iwatch_find_by_wd(&iw_devmon, ev->wd);
+		if (!iwp)
+			continue;
+
+		if (ev->mask & IN_ISDIR) {
+			devmon_handle_dir(&iw_devmon, iwp->path, ev->name, ev->mask);
+			continue;
+		}
+
+		dbg("Got %s", ev->name);
+		if (ev->mask & (IN_CREATE | IN_DELETE))
+			devmon_update_conds(iwp->path, ev->name, ev->mask);
+	}
+}
+
+void devmon_init(void)
+{
+	char dir[MAX_ARG_LEN];
+
+	fd = iwatch_init(&iw_devmon);
+	if (fd < 0)
+		return;
+
+	if (mkpath(pid_runpath(_PATH_CONDDEV, dir, sizeof(dir)), 0755) && errno != EEXIST) {
+		err(1, "Failed creating %s condition directory, %s", COND_DEV, _PATH_CONDDEV);
+		return;
+	}
+
+	if (uev_io_init(ctx, &devw, devmon_cb, NULL, fd, UEV_READ)) {
+		err(1, "Failed setting up I/O callback for /dev watcher");
+		close(fd);
+		return;
+	}
+
+	strlcpy(dir, _PATH_DEV, sizeof(dir));
+	if (devmon_add_path(&iw_devmon, dir))
+		iwatch_exit(&iw_devmon);
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

src/devmon.h

@@ -0,0 +1,32 @@
+/* Device node monitor for the Finit condition engine
+ *
+ * Copyright (c) 2022  Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef FINIT_DEVMON_H_
+#define FINIT_DEVMON_H_
+
+void devmon_add_cond(const char *cond);
+void devmon_del_cond(const char *cond);
+
+void devmon_init(void);
+
+#endif /* FINIT_DEVMON_H_ */

src/finit.c

@@ -48,6 +48,7 @@
 #include "cgroup.h"
 #include "cond.h"
 #include "conf.h"
+#include "devmon.h"
 #include "helpers.h"
 #include "private.h"
 #include "plugin.h"
@@ -801,6 +802,7 @@ int main(int argc, char *argv[])
 	 * Initialize .conf system and load static /etc/finit.conf then
 	 * tell the world what we used.
 	 */
+	devmon_init();
 	conf_init(&loop);
 	conf_saverc();
 

src/service.c

@@ -43,6 +43,7 @@
 #include "client.h"
 #include "conf.h"
 #include "cond.h"
+#include "devmon.h"
 #include "finit.h"
 #include "helpers.h"
 #include "pid.h"
@@ -1696,10 +1697,16 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
  */
 void service_unregister(svc_t *svc)
 {
+	char *c;
+
 	if (!svc)
 		return;
 
 	service_stop(svc);
+
+	for (c = strtok(svc->cond, ","); c; c = strtok(NULL, ","))
+		devmon_del_cond(c);
+
 	svc_del(svc);
 }