afs-supervisor: Add discovery mechanic

Change-Id: Icfcdcc16d0433454c9bb0785d0690f7f173980ae
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

4 files changed, 125 insertions, 13 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 353db3b6..89a181f5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -85,7 +85,7 @@ INSTALL(TARGETS afb-daemon
 ###########################################
 # build and install afb-daemon
 ###########################################
-ADD_EXECUTABLE(afs-supervisor afs-supervisor.c)
+ADD_EXECUTABLE(afs-supervisor afs-supervisor.c afs-discover.c)
 TARGET_LINK_LIBRARIES(afs-supervisor
 	afb-lib
 	${link_libraries}
diff --git a/src/afb-supervision.c b/src/afb-supervision.c
index ecdcbf20..f41ca18b 100644
--- a/src/afb-supervision.c
+++ b/src/afb-supervision.c
@@ -45,6 +45,7 @@
 #include "afb-debug.h"
 #include "verbose.h"
 #include "wrap-json.h"
+#include "jobs.h"
 
 extern struct afb_config *main_config;
 
@@ -111,20 +112,24 @@ static int open_supervisor_socket(const char *path)
 	return fd;
 }
 
-static void cleanup_supervisor(void *nada)
+static void disconnect_supervisor()
 {
-	struct afb_trace *t = __atomic_exchange_n(&trace, NULL, __ATOMIC_RELAXED);
+	struct afb_stub_ws *s;
+	struct afb_trace *t;
+
+	INFO("Disconnecting supervision");
+	s = __atomic_exchange_n(&supervisor, NULL, __ATOMIC_RELAXED);
+	t = __atomic_exchange_n(&trace, NULL, __ATOMIC_RELAXED);
+	if (s)
+		afb_stub_ws_unref(s);
 	if (t)
 		afb_trace_unref(t);
-	supervisor = NULL;
 }
 
-static void disconnect_supervisor()
+static void on_supervisor_hangup(struct afb_stub_ws *s)
 {
-	struct afb_stub_ws *s = __atomic_exchange_n(&supervisor, NULL, __ATOMIC_RELAXED);
-
-	if (s)
-		afb_stub_ws_unref(s);
+	if (s && s == supervisor)
+		disconnect_supervisor();
 }
 
 /* try to connect to supervisor */
@@ -195,6 +200,7 @@ static void try_connect_supervisor()
 		ERROR("Creation of supervisor failed: %m");
 		goto end2;
 	}
+	afb_stub_ws_on_hangup(supervisor, on_supervisor_hangup);
 
 	/* successful termination */
 	goto end;
@@ -205,11 +211,18 @@ end:
 	pthread_mutex_unlock(&mutex);
 }
 
-static void on_sighup(int signum)
+static void try_connect_supervisor_job(int signum, void *args)
 {
+	INFO("Try to connect supervisor after SIGHUP");
 	try_connect_supervisor();
 }
 
+static void on_sighup(int signum)
+{
+	INFO("Supervision received a SIGHUP");
+	jobs_queue(NULL, 0, try_connect_supervisor_job, NULL);
+}
+
 /**
  * initalize the supervision
  */
diff --git a/src/afs-discover.c b/src/afs-discover.c
new file mode 100644
index 00000000..cad95574
--- /dev/null
+++ b/src/afs-discover.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2016, 2017 "IoT.bzh"
+ * Author José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <ctype.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+void afs_discover(const char *pattern, void (*callback)(void *closure, pid_t pid), void *closure)
+{
+	intmax_t n;
+	DIR *dir;
+	struct dirent *ent;
+	char *name;
+	char exe[PATH_MAX], lnk[PATH_MAX];
+
+	dir = opendir("/proc");
+	while ((ent = readdir(dir))) {
+		name = ent->d_name;
+		while (isdigit(*name))
+			name++;
+		if (*name)
+			continue;
+		n = snprintf(exe, sizeof exe, "/proc/%s/exe", ent->d_name);
+		if (n < 0 || (size_t)n >= sizeof exe)
+			continue;
+		n = readlink(exe, lnk, sizeof lnk);
+		if (n < 0 || (size_t)n >= sizeof lnk)
+			continue;
+		lnk[n] = 0;
+		name = lnk;
+		while(*name) {
+			while(*name == '/')
+				name++;
+			if (*name) {
+				if (!strcmp(name, pattern)) {
+					callback(closure, (pid_t)atoi(ent->d_name));
+					break;
+				}
+				while(*++name && *name != '/');
+			}
+		}
+	}
+	closedir(dir);
+}
+
diff --git a/src/afs-supervisor.c b/src/afs-supervisor.c
index 8d76832a..8cf21cb5 100644
--- a/src/afs-supervisor.c
+++ b/src/afs-supervisor.c
@@ -49,6 +49,8 @@
 #include "verbose.h"
 #include "wrap-json.h"
 
+extern void afs_discover(const char *pattern, void (*callback)(void *closure, pid_t pid), void *closure);
+
 /* supervised items */
 struct supervised
 {
@@ -210,6 +212,22 @@ static int make_supervised(int fd, struct afb_cred *cred)
 	return 0;
 }
 
+/**
+ * Search the supervised of 'pid', return it or NULL.
+ */
+static struct supervised *supervised_of_pid(pid_t pid)
+{
+	struct supervised *s;
+
+	pthread_mutex_lock(&mutex);
+	s = superviseds;
+	while (s && pid != s->cred->pid)
+		s = s->next;
+	pthread_mutex_unlock(&mutex);
+
+	return s;
+}
+
 /*
  * handles incoming connection on 'sock'
  */
@@ -252,6 +270,21 @@ static int listening(sd_event_source *src, int fd, uint32_t revents, void *closu
 	return 0;
 }
 
+/*
+ */
+static void discovered_cb(void *closure, pid_t pid)
+{
+	struct supervised *s;
+
+	s = supervised_of_pid(pid);
+	if (!s)
+		kill(pid, SIGHUP);
+}
+
+static void discover_supervised()
+{
+	afs_discover("afb-daemon", discovered_cb, NULL);
+}
 
 /**
  * initalize the supervision
@@ -333,6 +366,8 @@ static void start(int signum, void *arg)
 		exit(1);
 
 	sd_notify(1, "READY=1");
+
+	discover_supervised();
 }
 
 /**
@@ -396,9 +431,7 @@ static void propagate(struct afb_req req, const char *verb)
 		afb_xreq_fail(xreq, "bad-pid", NULL);
 		return;
 	}
-	s = superviseds;
-	while (s && p != (int)s->cred->pid)
-		s = s->next;
+	s = supervised_of_pid((pid_t)p);
 	if (!s) {
 		afb_req_fail(req, "unknown-pid", NULL);
 		return;