Stub out the syscall, not the whole application. The stubbed

out syscall sets errno properly and whines about missing kernel
support.
 -Erik

2 files changed, 36 insertions, 16 deletions

diff --git a/pivot_root.c b/pivot_root.c
index d34dcd7cc..4d7f8a3d1 100644
--- a/pivot_root.c
+++ b/pivot_root.c
@@ -3,24 +3,35 @@
  * pivot_root.c - Change root file system.  Based on util-linux 2.10s
  *
  * busyboxed by Evin Robertson
+ * pivot_root syscall stubbed by Erik Andersen, so it will compile
+ *     regardless of the kernel being used. 
  */
 #include <stdlib.h>
 #include <stdio.h>
+#include <errno.h>
 #include <sys/syscall.h>
 #include <linux/unistd.h>
 #include "busybox.h"
 
 #ifndef __NR_pivot_root
 #warning This kernel does not support the pivot_root syscall
-#warning The pivot_root application is being stubbed out...
-int pivot_root_main(int argc, char **argv)
+#warning The pivot_root system call is being stubbed out...
+int pivot_root(const char * new_root,const char * put_old)
 {
-	printf("Please recompile with a kernel supporting the pivot_root syscall.\n");
-	return 0;
+	/* BusyBox was compiled against a kernel that did not support
+	 *  the pivot_root system call.  To make this application work,
+	 *  you will need to recompile with a kernel supporting the
+	 *  pivot_root system call.
+	 */
+	fprintf(stderr, "\n\nTo make this application work, you will need to recompile\n");
+	fprintf(stderr, "with a kernel supporting the pivot_root system call. -Erik\n\n");
+	errno=ENOSYS;
+	return -1;
 }
 #else
-
 static _syscall2(int,pivot_root,const char *,new_root,const char *,put_old)
+#endif
+
 
 
 int pivot_root_main(int argc, char **argv)
@@ -28,13 +39,12 @@ int pivot_root_main(int argc, char **argv)
     if (argc != 3)
         show_usage();
 
-    if (pivot_root(argv[1],argv[2]) < 0)
-        perror_msg_and_die("pivot_root");
+	if (pivot_root(argv[1],argv[2]) < 0)
+		perror_msg_and_die("pivot_root");
 
     return EXIT_SUCCESS;
 
 }
-#endif
 
 
 /*
diff --git a/util-linux/pivot_root.c b/util-linux/pivot_root.c
index d34dcd7cc..4d7f8a3d1 100644
--- a/util-linux/pivot_root.c
+++ b/util-linux/pivot_root.c
@@ -3,24 +3,35 @@
  * pivot_root.c - Change root file system.  Based on util-linux 2.10s
  *
  * busyboxed by Evin Robertson
+ * pivot_root syscall stubbed by Erik Andersen, so it will compile
+ *     regardless of the kernel being used. 
  */
 #include <stdlib.h>
 #include <stdio.h>
+#include <errno.h>
 #include <sys/syscall.h>
 #include <linux/unistd.h>
 #include "busybox.h"
 
 #ifndef __NR_pivot_root
 #warning This kernel does not support the pivot_root syscall
-#warning The pivot_root application is being stubbed out...
-int pivot_root_main(int argc, char **argv)
+#warning The pivot_root system call is being stubbed out...
+int pivot_root(const char * new_root,const char * put_old)
 {
-	printf("Please recompile with a kernel supporting the pivot_root syscall.\n");
-	return 0;
+	/* BusyBox was compiled against a kernel that did not support
+	 *  the pivot_root system call.  To make this application work,
+	 *  you will need to recompile with a kernel supporting the
+	 *  pivot_root system call.
+	 */
+	fprintf(stderr, "\n\nTo make this application work, you will need to recompile\n");
+	fprintf(stderr, "with a kernel supporting the pivot_root system call. -Erik\n\n");
+	errno=ENOSYS;
+	return -1;
 }
 #else
-
 static _syscall2(int,pivot_root,const char *,new_root,const char *,put_old)
+#endif
+
 
 
 int pivot_root_main(int argc, char **argv)
@@ -28,13 +39,12 @@ int pivot_root_main(int argc, char **argv)
     if (argc != 3)
         show_usage();
 
-    if (pivot_root(argv[1],argv[2]) < 0)
-        perror_msg_and_die("pivot_root");
+	if (pivot_root(argv[1],argv[2]) < 0)
+		perror_msg_and_die("pivot_root");
 
     return EXIT_SUCCESS;
 
 }
-#endif
 
 
 /*