Fix #315: add environment variables to hook scripts

All hook scripts are called with at least one environment variable set,
FINIT_HOOK_NAME, useful when reusing the same hook script for multiple
hook points.  It is set to the string name, also used by the path, e.g.,
hook/net/up.

For all hook points from hook/sys/shutdown and later, FINIT_SHUTDOWN is
also set, to one of:  halt, poweroff, reboot.

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

doc/plugins.md

@@ -112,6 +112,14 @@ at the below hook points.
 See [Run-parts Scripts](config.md#run-parts-scripts) for details on the
 requirements, possibilities, and *limitations* of hook scripts.
 
+All hook scripts are called with at least one environment variable set,
+the hook name, useful when reusing the same hook script for multiple
+hook points:
+
+  - `FINIT_HOOK_NAME`: set to the second label, e.g., `hook/net/up`
+  - `FINIT_SHUTDOWN`: set for `hook/sys/shutdown` and later to one
+    of `halt`, `poweroff`, or `reboot`.
+
 **Example:**
 
     $ mkdir -p /libexec/finit/hook/sys/down
@@ -119,6 +127,10 @@ requirements, possibilities, and *limitations* of hook scripts.
     #!/bin/sh
     echo 'I run just before the reboot() syscall at shutdown/reboot'
     echo 'I have access to /dev since devtmpfs is exempt from umount'
+    echo "FINIT_HOOK_NAME: $FINIT_HOOK_NAME"
+    if [ -n "$FINIT_SHUTDOWN" ]; then
+            echo "FINIT_SHUTDOWN:  $FINIT_SHUTDOWN"
+    fi
     exit 0
     EOF
     $ chmod +x /libexec/finit/hook/sys/foo.sh

plugins/resolvconf.c

@@ -45,7 +45,7 @@ static void setup(void *arg)
 
 	touch("/etc/resolvconf/run/enable-updates");
 	chdir("/etc/resolvconf/run/interface");
-	run_parts("/etc/resolvconf/update.d", "-i", 0);
+	run_parts("/etc/resolvconf/update.d", "-i", NULL, 0);
 	chdir("/");
 }
 

src/exec.c

@@ -441,7 +441,25 @@ pid_t run_sh(char *tty, int noclear, int nowait, struct rlimit rlimit[])
 	return rc;
 }
 
-int run_parts(char *dir, char *cmd, int progress)
+static void run_env(const char *env[])
+{
+	size_t i = 0;
+
+	if (!env)
+		return;
+
+	while (env[i]) {
+		size_t j = i + 1;
+
+		if (!env[j])
+			break;
+
+		setenv(env[i], env[j], 1);
+		i += 2;
+	}
+}
+
+int run_parts(char *dir, char *cmd, const char *env[], int progress)
 {
 	struct dirent **e;
 	int i, num;
@@ -495,6 +513,8 @@ int run_parts(char *dir, char *cmd, int progress)
 		pid = fork();
 		if (!pid) {
 			sig_unblock();
+			run_env(env);
+
 			return execvp(_PATH_BSHELL, argv);
 		}
 

src/finit.c

@@ -602,7 +602,7 @@ static void bootstrap_worker(void *work)
 	 * Run startup scripts in the runparts directory, if any.
 	 */
 	if (runparts && fisdir(runparts) && !rescue)
-		run_parts(runparts, NULL, 1);
+		run_parts(runparts, NULL, NULL, 1);
 
 
 	/*

src/helpers.h

@@ -86,7 +86,7 @@ int     run_interactive (char *cmd, char *fmt, ...) __attribute__ ((format (prin
 int     exec_runtask    (char *cmd, char *args[]);
 pid_t   run_getty       (char *tty, char *cmd, char *args[], int noclear, int nowait, struct rlimit rlimit[]);
 pid_t   run_sh          (char *tty, int noclear, int nowait, struct rlimit rlimit[]);
-int     run_parts       (char *dir, char *cmd, int progress);
+int     run_parts       (char *dir, char *cmd, const char *env[], int progress);
 
 static inline int create(char *path, mode_t mode, uid_t uid, gid_t gid)
 {

src/plugin.c

@@ -42,6 +42,7 @@
 #include "plugin.h"
 #include "private.h"
 #include "service.h"
+#include "sig.h"
 
 #define is_io_plugin(p) ((p)->io.cb && (p)->io.fd > 0)
 #define SEARCH_PLUGIN(str)						\
@@ -203,12 +204,33 @@ static const char *hscript_paths[] = HOOK_TYPES;
 
 void plugin_script_run(hook_point_t no)
 {
+	const char *hook_name = hscript_paths[no];
+	const char *env[] = {
+		"FINIT_HOOK_NAME", hook_name,
+		"FINIT_SHUTDOWN", NULL,
+		NULL,
+	};
 	char path[CMD_SIZE] = "";
 
 	strlcat(path, PLUGIN_HOOK_SCRIPTS_PATH, sizeof(path));
-	strlcat(path, hscript_paths[no] + 4, sizeof(path));
+	strlcat(path, hook_name + 4, sizeof(path));
 
-	run_parts(path, NULL, 0);
+	if (no >= HOOK_SHUTDOWN) {
+		switch (halt) {
+		case SHUT_OFF:
+			env[3] = "poweroff";
+			break;
+		case SHUT_HALT:
+			env[3] = "halt";
+			break;
+		case SHUT_REBOOT:
+			env[3] = "reboot";
+			break;
+		}
+	} else
+		env[2] = NULL;
+
+	run_parts(path, NULL, env, 0);
 }
 #else
 void plugin_script_run(hook_point_t no)

src/sig.c

@@ -302,6 +302,7 @@ void do_shutdown(shutop_t op)
 		sched_setscheduler(1, SCHED_RR, &sched_param);
 	}
 
+	halt = op;
 	if (sdown)
 		run_interactive(sdown, "Calling shutdown hook: %s", sdown);