From 56a89db889078a87f192496c537261cc649d8f87 Mon Sep 17 00:00:00 2001
From: Joachim Wiberg <troglobit@gmail.com>
Date: Sun, 26 Feb 2023 12:24:43 +0100
Subject: [PATCH] Add support run/task/service 'conflict:foo' handling

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
 doc/config.md | 18 ++++++++++++++++++
 src/service.c | 18 +++++++++++++++++-
 src/svc.c     | 45 +++++++++++++++++++++++++++++++++++++++++++++
 src/svc.h     |  2 ++
 4 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/doc/config.md b/doc/config.md
index dbce328e..9ba327c9 100644
--- a/doc/config.md
+++ b/doc/config.md
@@ -721,6 +721,24 @@ optional `name` argument:
 
     name:<service-name>
 
+If multiple instances of a service, with the same `name`, exist.  Set
+the identifier `:ID` to prevent Finit from replacing previous instances:
+
+    service :eth1 ssdpd eth1 -- Windows discovery on eth1
+    service :eth2 ssdpd eth2 -- Windows discovery on eth2
+
+If you have conflicting services and want to prevent them from starting,
+use the `conflict:` argument:
+
+    service [S12345789] udevd -- Device event management daemon
+	run [S] conflict:udevd mdev -s -- Populating device tree
+
+Multiple conflicting services can be separated using `,`:
+
+    service :1 abc
+    service :2 abc
+	service conflict:abc:1,abc:2 cde
+
 As mentioned previously, services are automatically restarted, this is
 configurable with the following options:
 
diff --git a/src/service.c b/src/service.c
index 0ff7afdd..f4e09d0b 100644
--- a/src/service.c
+++ b/src/service.c
@@ -605,6 +605,13 @@ static int service_start(svc_t *svc)
 		}
 	}
 
+	/* Don't start if it conflicts with something else already started */
+	if (svc_conflicts(svc)) {
+		logit(LOG_INFO, "Not starting %s, conflicts with %s",
+		      svc_ident(svc, NULL, 0), svc->conflict);
+		return 1;
+	}
+
 	compose_cmdline(svc, cmdline, sizeof(cmdline));
 	if (svc_is_sysv(svc))
 		logit(LOG_CONSOLE | LOG_NOTICE, "Calling '%s start' ...", cmdline);
@@ -1387,7 +1394,7 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 	char *name = NULL, *halt = NULL, *delay = NULL;
 	char *id = NULL, *env = NULL, *cgroup = NULL;
 	char *pre_script = NULL, *post_script = NULL;
-	char *ready_script = NULL;
+	char *ready_script = NULL, *conflict = NULL;
 	char *notify = NULL;
 	struct tty tty = { 0 };
 	char *dev = NULL;
@@ -1498,6 +1505,8 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 			cgroup = arg; /* only settings */
 		else if (MATCH_CMD(cmd, "cgroup.", arg))
 			cgroup = arg; /* with group */
+		else if (MATCH_CMD(cmd, "conflict:", arg))
+			conflict = arg;
 		else
 			break;
 
@@ -1696,6 +1705,10 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 		strlcpy(svc->file, file, sizeof(svc->file));
 	else
 		memset(svc->file, 0, sizeof(svc->file));
+	if (conflict)
+		strlcpy(svc->conflict, conflict, sizeof(svc->conflict));
+	else
+		memset(svc->conflict, 0, sizeof(svc->conflict));
 	svc->manual  = manual;
 	svc->respawn = respawn;
 	svc->forking = forking;
@@ -2488,6 +2501,9 @@ int service_completed(void)
 		if (!svc_enabled(svc))
 			continue;
 
+		if (svc_conflicts(svc))
+			continue;
+
 		if (strstr(svc->cond, plugin_hook_str(HOOK_SVC_UP)) ||
 		    strstr(svc->cond, plugin_hook_str(HOOK_SYSTEM_UP))) {
 			dbg("Skipping %s(%s), post-strap hook", svc->desc, svc_ident(svc, NULL, 0));
diff --git a/src/svc.c b/src/svc.c
index be1b63fd..9a2b7dc2 100644
--- a/src/svc.c
+++ b/src/svc.c
@@ -619,6 +619,51 @@ int svc_enabled(svc_t *svc)
 	return 1;
 }
 
+/**
+ * svc_conflicts - Check if svc conflicts with any other running svc
+ * @svc:
+ *
+ * Returns:
+ * %TRUE(1) or %FALSE(0)
+ */
+int svc_conflicts(svc_t *svc)
+{
+	char *ptr, *nm;
+	int rc = 0;
+
+	if (!svc->conflict[0])
+		return 0;
+
+	ptr = strdup(svc->conflict);
+	if (!ptr)
+		return 0;
+
+	nm = strtok(ptr, ",");
+	while (nm) {
+		char *name, *id;
+		svc_t *s;
+
+		name = strdupa(nm);
+		id = strchr(name, ':');
+		if (id)
+			id++ = 0;
+		else
+			id = "";
+
+		s = svc_find(name, id);
+		if (s) {
+			if (s->state >= SVC_STOPPING_STATE)
+				rc = 1;
+			break;
+		}
+
+		nm = strtok(NULL, ",");
+	}
+
+	free(ptr);
+	return rc;
+}
+
 /* break up "job:id job:id job:id ..." into several "job:id" tokens */
 static char *tokstr(char *str, size_t len)
 {
diff --git a/src/svc.h b/src/svc.h
index c0d33c90..f31f87dc 100644
--- a/src/svc.h
+++ b/src/svc.h
@@ -181,6 +181,7 @@ typedef struct svc {
 	char	       cmd[MAX_ARG_LEN];
 	char	       args[MAX_NUM_SVC_ARGS][MAX_ARG_LEN];
 	int            args_dirty;
+	char           conflict[MAX_ARG_LEN];
 	char	       desc[MAX_STR_LEN];
 	char	       env[MAX_ARG_LEN];
 	char	       pre_script[MAX_ARG_LEN];
@@ -233,6 +234,7 @@ void	    svc_prune_bootstrap	   (void);
 
 void        svc_enable             (svc_t *svc);
 int         svc_enabled            (svc_t *svc);
+int         svc_conflicts          (svc_t *svc);
 
 int         svc_parse_jobstr       (char *str, size_t len, void *user_data, int (*found)(svc_t *, void *), int (not_found)(char *, char *, void *));