From 1551310aa5484a483cad4e6ae4a358cb509cbef8 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 29 Jun 2025 20:49:14 -0400
Subject: usr.sbin: init: Allow start path to be overridden

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/kern/init_main.c |  7 ++++---
 usr.sbin/init/main.c | 21 +++++++++++++++------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 797319f..dfb058a 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -44,10 +44,11 @@
 #include <vm/vm.h>
 #include <string.h>
 
+#define _START_PATH "/usr/sbin/init"
 #if defined(_INSTALL_MEDIA)
-#define _START_PATH "/usr/sbin/install"
+#define _START_ARG "/usr/sbin/install"
 #else
-#define _START_PATH "/usr/sbin/init"
+#define _START_ARG NULL
 #endif  /* _INSTALL_MEDIA  */
 
 struct proc g_proc0;
@@ -64,7 +65,7 @@ start_init(void)
 {
     struct proc *td = this_td();
     struct execve_args execve_args;
-    char *argv[] = { _START_PATH, NULL, NULL };
+    char *argv[] = { _START_PATH, _START_ARG, NULL };
     char *envp[] = { NULL };
 
     kprintf("starting init...\n");
diff --git a/usr.sbin/init/main.c b/usr.sbin/init/main.c
index 7ad7946..bad8201 100644
--- a/usr.sbin/init/main.c
+++ b/usr.sbin/init/main.c
@@ -34,13 +34,22 @@
 #define INIT_RC_PATH "/usr/rc/init.rc"
 
 int
-main(void)
+main(int argc, char **argv)
 {
-    char *argv[] = { SHELL_PATH, INIT_RC_PATH, NULL };
-    char *envp[] = { NULL };
+    char *start_argv[] = { SHELL_PATH, INIT_RC_PATH, NULL };
+    char *start_envp[] = { NULL };
 
-    spawn(SHELL_PATH, argv, envp, 0);
-    argv[1] = NULL;
-    spawn(SHELL_PATH, argv, envp, SPAWN_WAIT);
+    spawn(SHELL_PATH, start_argv, start_envp, 0);
+    start_argv[1] = NULL;
+
+    /*
+     * We can override the start program header
+     * if there is something specified.
+     */
+    if (argc > 1) {
+        start_argv[0] = argv[1];
+    }
+
+    spawn(start_argv[0], start_argv, start_envp, SPAWN_WAIT);
     return 0;
 }
-- 
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