From de552874d2074ac48ea4b834d61c54e1b6971be3 Mon Sep 17 00:00:00 2001
From: Erik Andersen
Date: Sun, 23 Jan 2000 01:34:05 +0000
Subject: Some busybox updates.  You no longer _have_ to put a "-" in front of
 tar options, logger is better behaved and has a "-t" option now.  init now
 supports the kernel chroot patch, so you can chroot to a new device and
 umount the old root.  -Erik

---
 init/init.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 86 insertions(+), 5 deletions(-)

(limited to 'init')

diff --git a/init/init.c b/init/init.c
index 9134363..b0a8582 100644
--- a/init/init.c
+++ b/init/init.c
@@ -147,7 +147,9 @@ void message(int device, char *fmt, ...)
 	va_start(arguments, fmt);
 	vsnprintf(msg, sizeof(msg), fmt, arguments);
 	va_end(arguments);
+	openlog( "init", 0, LOG_DAEMON);
 	syslog(LOG_DAEMON|LOG_NOTICE, msg);
+	closelog();
     }
 
 #else
@@ -268,7 +270,7 @@ static void console_init()
 #if #cpu(sparc)
     /* sparc kernel supports console=tty[ab] parameter which is also 
      * passed to init, so catch it here */
-    else if ((s = getenv("console")) != NULL) {*/
+    else if ((s = getenv("console")) != NULL) {
 	/* remap tty[ab] to /dev/ttyS[01] */
 	if (strcmp( s, "ttya" )==0)
 	    snprintf(console, sizeof(console)-1, "%s", SERIAL_CON0);
@@ -507,7 +509,83 @@ static void reboot_signal(int sig)
     exit(0);
 }
 
-#endif
+#if defined BB_FEATURE_INIT_CHROOT
+static void check_chroot(int sig)
+{
+    char *argv_init[2] = { "init", NULL, };
+    char *envp_init[3] = { "HOME=/", "TERM=linux", NULL, };
+    char rootpath[256], *tc;
+    int fd;
+
+    if ((fd = open("/proc/sys/kernel/init-chroot", O_RDONLY)) == -1) {
+	message(CONSOLE, "SIGHUP recived, but could not open proc file\r\n");
+	sleep(2);
+	return;
+    }
+    if (read(fd, rootpath, sizeof(rootpath)) == -1) {
+	message(CONSOLE, "SIGHUP recived, but could not read proc file\r\n");
+	sleep(2);
+	return;
+    }
+    close(fd);
+
+    if (rootpath[0] == '\0') {
+	message(CONSOLE, "SIGHUP recived, but new root is not valid: %s\r\n",
+		rootpath);
+	sleep(2);
+	return;
+    }
+
+    tc = strrchr(rootpath, '\n');
+    *tc = '\0';
+    
+    /* Ok, making it this far means we commit */
+    message(CONSOLE, "Please stand by, changing root to `%s'.\r\n", rootpath);
+
+    /* kill all other programs first */
+    message(CONSOLE, "Sending SIGTERM to all processes.\r\n");
+    kill(-1, SIGTERM);
+    sleep(2);
+    sync();
+
+    message(CONSOLE, "Sending SIGKILL to all processes.\r\n");
+    kill(-1, SIGKILL);
+    sleep(2);
+    sync();
+
+    /* ok, we don't need /proc anymore. we also assume that the signaling
+     * process left the rest of the filesystems alone for us */
+    umount("/proc");
+
+    /* Ok, now we chroot. Hopefully we only have two things mounted, the
+     * new chroot'd mount point, and the old "/" mount. s,
+     * we go ahead and unmount the old "/". This should trigger the kernel
+     * to set things up the Right Way(tm). */
+
+    if (!chroot(rootpath))
+	umount("/dev/root");
+
+    /* If the chroot fails, we are already too far to turn back, so we
+     * continue and hope that executing init below will revive the system */
+
+    /* close all of our descriptors and open new ones */
+    close(0);
+    close(1);
+    close(2);
+    open("/dev/console", O_RDWR, 0);
+    dup(0);
+    dup(0);
+
+    message(CONSOLE, "Executing real init...\r\n");
+    /* execute init in the (hopefully) new root */
+    execve("/sbin/init",argv_init,envp_init);
+
+    message(CONSOLE, "ERROR: Could not exec new init. Hit ctrl+alt+delete to reboot.\r\n");
+    return;
+} 
+#endif /* BB_FEATURE_INIT_CHROOT */
+
+#endif /* ! DEBUG_INIT */
 
 void new_initAction (initActionEnum action,
 	char* process, char* cons)
@@ -516,10 +594,10 @@ void new_initAction (initActionEnum action,
 
     /* If BusyBox detects that a serial console is in use, 
      * then entries containing non-empty id fields will _not_ be run.
+     * The exception to this rule is the null device.
      */
-    if (secondConsole == NULL && *cons != '\0') {
+    if (secondConsole == NULL && (*cons != '\0' || strncmp(cons, "null", 4)))
 	return;
-    }
 
     newAction = calloc ((size_t)(1), sizeof(initAction));
     if (!newAction) {
@@ -662,7 +740,7 @@ extern int init_main(int argc, char **argv)
     int status;
 
 #ifndef DEBUG_INIT
-    /* Expect to be PID 1 iff we are run as init (not linuxrc) */
+    /* Expect to be PID 1 if we are run as init (not linuxrc) */
     if (getpid() != 1 && strstr(argv[0], "init")!=NULL ) {
 	usage( "init\n\nInit is the parent of all processes.\n\n"
 		"This version of init is designed to be run only by the kernel\n");
@@ -676,6 +754,9 @@ extern int init_main(int argc, char **argv)
     signal(SIGUSR2, reboot_signal);
     signal(SIGINT, reboot_signal);
     signal(SIGTERM, reboot_signal);
+#if defined BB_FEATURE_INIT_CHROOT
+    signal(SIGHUP, check_chroot);
+#endif
 
     /* Turn off rebooting via CTL-ALT-DEL -- we get a 
      * SIGINT on CAD so we can shut things down gracefully... */
-- 
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