From: Roy Marples <roy@marples.name>
Date: Tue, 9 Sep 2014 08:22:10 +0000 (+0000)
Subject: Pass SVCNAME from enviromment to hooks so that a service hook
X-Git-Tag: v6.4.4~35
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bac1d910f1f0448292ad8f1b1c4f269a1f2a785e;p=thirdparty%2Fdhcpcd.git

Pass SVCNAME from enviromment to hooks so that a service hook
can know it's name (may not be dhcpcd).
---

diff --git a/README b/README
index fb6eb8ac..3ee66833 100644
--- a/README
+++ b/README
@@ -97,6 +97,20 @@ The configure program attempts to find hooks for systems you have installed.
 To add more simply
 ./configure -with-hook=ntp.conf
 
+Some system services expose the name of the service we are in,
+by default dhcpcd will pick SVCNAME from the environment.
+You can override this in CPPFLAGS+= -DSVCNAME="RC_SVCNAME".
+This is important because dhcpcd will scrub the environment aside from $PATH
+before running hooks.
+This variable could be used to facilitate service re-entry so this chain could
+happen in a custom OS hook:
+  dhcpcd service marked inactive && dhcpcd service starts
+  dependant services are not started because dhcpcd is inactive (not stopped)
+  dhcpcd hook tests $if_oneup && $if_ipwaited
+  if true, mark the dhcpcd service as started and then start dependencies
+  if false and the dhcpcd service was previously started, mark as inactive and
+     stop any dependant services.
+
 
 Compatibility
 -------------
diff --git a/script.c b/script.c
index 7e420f2d..db203f4f 100644
--- a/script.c
+++ b/script.c
@@ -57,6 +57,11 @@
 #include "compat/posix_spawn.h"
 #endif
 
+/* Allow the OS to define another script env var name */
+#ifndef SVCNAME
+#define SVCNAME "SVCNAME"
+#endif
+
 #define DEFAULT_PATH	"PATH=/usr/bin:/usr/sbin:/bin:/sbin"
 
 static const char * const if_params[] = {
@@ -598,7 +603,7 @@ script_runreason(const struct interface *ifp, const char *reason)
 {
 	char *argv[2];
 	char **env = NULL, **ep;
-	char *path, *bigenv;
+	char *svcname, *path, *bigenv;
 	size_t e, elen = 0;
 	pid_t pid;
 	int status = 0;
@@ -620,7 +625,9 @@ script_runreason(const struct interface *ifp, const char *reason)
 		syslog(LOG_ERR, "%s: make_env: %m", ifp->name);
 		return -1;
 	}
-	ep = realloc(env, sizeof(char *) * (elen + 2));
+	/* Resize for PATH and SVCNAME */
+	svcname = getenv(SVCNAME);
+	ep = realloc(env, sizeof(char *) * (elen + 2 + (svcname ? 1 : 0)));
 	if (ep == NULL) {
 		elen = 0;
 		goto out;
@@ -643,6 +650,16 @@ script_runreason(const struct interface *ifp, const char *reason)
 			goto out;
 		}
 	}
+	ep = env;
+	if (svcname) {
+		e = strlen(SVCNAME) + strlen(svcname) + 2;
+		env[++elen] = malloc(e);
+		if (env[elen] == NULL) {
+			elen = 0;
+			goto out;
+		}
+		snprintf(env[elen], e, "%s=%s", SVCNAME, svcname);
+	}
 	env[++elen] = NULL;
 
 	pid = exec_script(ifp->ctx, argv, env);