Apply a patch from Evin Robertson -- new pivot_root applet.

-Erik

Changelog

@@ -1,3 +1,9 @@
+0.50
+	* Evin Robertson -- new pivot_root applet 
+
+
+	 -Erik Andersen, not yet released
+	
 0.49
 
 	* Matt Kraai -- new sort.c

Config.h

@@ -74,6 +74,7 @@
 //#define BB_MT
 //#define BB_NSLOOKUP
 //#define BB_PING
+//#define BB_PIVOT_ROOT
 #define BB_POWEROFF
 //#define BB_PRINTF
 #define BB_PS

applets.h

@@ -245,6 +245,9 @@ const struct BB_applet applets[] = {
 #ifdef BB_PING
 	APPLET("ping", ping_main, _BB_DIR_BIN, ping_usage)
 #endif
+#ifdef BB_PIVOT_ROOT
+	APPLET("pivot_root", pivot_root_main, _BB_DIR_SBIN, pivot_root_usage)
+#endif
 #ifdef BB_POWEROFF
 	APPLET("poweroff", poweroff_main, _BB_DIR_SBIN, poweroff_usage)
 #endif

applets/usage.c

@@ -1012,6 +1012,16 @@ const char ping_usage[] =
 #endif
 #endif
 
+#if defined BB_PIVOT_ROOT
+const char pivot_root_usage[] =
+	"pivot_root new_root put_old"
+#ifndef BB_FEATURE_TRIVIAL_HELP
+	"\n\nMove the current root file system to put_old and make new_root\n"
+	"the new root file system."
+#endif
+	;
+#endif
+
 #if defined BB_POWEROFF
 const char poweroff_usage[] =
 	"poweroff"

include/applets.h

@@ -245,6 +245,9 @@ const struct BB_applet applets[] = {
 #ifdef BB_PING
 	APPLET("ping", ping_main, _BB_DIR_BIN, ping_usage)
 #endif
+#ifdef BB_PIVOT_ROOT
+	APPLET("pivot_root", pivot_root_main, _BB_DIR_SBIN, pivot_root_usage)
+#endif
 #ifdef BB_POWEROFF
 	APPLET("poweroff", poweroff_main, _BB_DIR_SBIN, poweroff_usage)
 #endif

pivot_root.c

@@ -0,0 +1,39 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * pivot_root.c - Change root file system.  Based on util-linux 2.10s
+ *
+ * busyboxed by Evin Robertson
+ */
+#include "busybox.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <linux/unistd.h>
+
+#ifndef __NR_pivot_root
+#error Sorry, but this kernel does not support the pivot_root syscall
+#endif
+
+static _syscall2(int,pivot_root,const char *,new_root,const char *,put_old)
+
+
+int pivot_root_main(int argc, char **argv)
+{
+    if (argc != 3)
+        usage(pivot_root_usage);
+
+    if (pivot_root(argv[1],argv[2]) < 0)
+        perror_msg_and_die("pivot_root");
+
+    return EXIT_SUCCESS;
+
+}
+
+
+/*
+Local Variables:
+c-file-style: "linux"
+c-basic-offset: 4
+tab-width: 4
+End:
+*/

usage.c

@@ -1012,6 +1012,16 @@ const char ping_usage[] =
 #endif
 #endif
 
+#if defined BB_PIVOT_ROOT
+const char pivot_root_usage[] =
+	"pivot_root new_root put_old"
+#ifndef BB_FEATURE_TRIVIAL_HELP
+	"\n\nMove the current root file system to put_old and make new_root\n"
+	"the new root file system."
+#endif
+	;
+#endif
+
 #if defined BB_POWEROFF
 const char poweroff_usage[] =
 	"poweroff"

util-linux/pivot_root.c

@@ -0,0 +1,39 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * pivot_root.c - Change root file system.  Based on util-linux 2.10s
+ *
+ * busyboxed by Evin Robertson
+ */
+#include "busybox.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <linux/unistd.h>
+
+#ifndef __NR_pivot_root
+#error Sorry, but this kernel does not support the pivot_root syscall
+#endif
+
+static _syscall2(int,pivot_root,const char *,new_root,const char *,put_old)
+
+
+int pivot_root_main(int argc, char **argv)
+{
+    if (argc != 3)
+        usage(pivot_root_usage);
+
+    if (pivot_root(argv[1],argv[2]) < 0)
+        perror_msg_and_die("pivot_root");
+
+    return EXIT_SUCCESS;
+
+}
+
+
+/*
+Local Variables:
+c-file-style: "linux"
+c-basic-offset: 4
+tab-width: 4
+End:
+*/