[src/trunk]: src/sys/kern Provide binary compatibility for architectures that...

[martin <martin%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/8ac7489f8d7c
branches:  trunk
changeset: 785880:8ac7489f8d7c
user:      martin <martin%NetBSD.org@localhost>
date:      Thu Apr 04 12:51:39 2013 +0000

description:
Provide binary compatibility for architectures that (erroneously) had
a larger MAXPARTITIONS value (and thus larger struct disklabel).

diffstat:

 sys/kern/sys_generic.c |  45 +++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 41 insertions(+), 4 deletions(-)

diffs (95 lines):

diff -r 7816160bdef8 -r 8ac7489f8d7c sys/kern/sys_generic.c
--- a/sys/kern/sys_generic.c    Thu Apr 04 12:50:03 2013 +0000
+++ b/sys/kern/sys_generic.c    Thu Apr 04 12:51:39 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_generic.c,v 1.128 2012/01/25 00:28:36 christos Exp $       */
+/*     $NetBSD: sys_generic.c,v 1.129 2013/04/04 12:51:39 martin Exp $ */
 
 /*-
  * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_generic.c,v 1.128 2012/01/25 00:28:36 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_generic.c,v 1.129 2013/04/04 12:51:39 martin Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -526,6 +526,12 @@
        void            *data, *memp;
 #define        STK_PARAMS      128
        u_long          stkbuf[STK_PARAMS/sizeof(u_long)];
+#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
+       size_t          zero_last = 0;
+#define        zero_size(SZ)   ((SZ)+zero_last)
+#else
+#define        zero_size(SZ)   (SZ)
+#endif
 
        memp = NULL;
        alloc_size = 0;
@@ -563,7 +569,34 @@
         * but only copyin/out the smaller amount.
         */
        if (IOCGROUP(com) == 'd') {
+#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
+               u_long ocom = com;
+#endif
                u_long ncom = com ^ (DIOCGDINFO ^ DIOCGDINFO32);
+
+#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
+       /*
+        * Userland might use struct disklabel that is bigger than the
+        * the kernel version (historic accident) - alloc userland
+        * size and zero unused part on copyout.
+        */
+#define        DISKLABELLENDIFF        (sizeof(struct partition)       \
+                                      *(__TMPBIGMAXPARTITIONS-MAXPARTITIONS))
+#define        IOCFIXUP(NIOC)  ((NIOC&~(IOCPARM_MASK<<IOCPARM_SHIFT))  | \
+                          (IOCPARM_LEN(NIOC)-DISKLABELLENDIFF)<<IOCPARM_SHIFT)
+
+               switch (IOCFIXUP(ocom)) {
+               case DIOCGDINFO:
+               case DIOCWDINFO:
+               case DIOCSDINFO:
+               case DIOCGDEFLABEL:
+                       com = ncom = IOCFIXUP(ocom);
+                       zero_last = DISKLABELLENDIFF;
+                       size -= DISKLABELLENDIFF;
+                       goto done;
+               }
+#endif
+
                switch (ncom) {
                case DIOCGDINFO:
                case DIOCWDINFO:
@@ -574,6 +607,9 @@
                                alloc_size = IOCPARM_LEN(DIOCGDINFO);
                        break;
                }
+#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
+               done: ;
+#endif
        }
        if (size > IOCPARM_MAX) {
                error = ENOTTY;
@@ -615,7 +651,7 @@
                         * Zero the buffer so the user always
                         * gets back something deterministic.
                         */
-                       memset(data, 0, size);
+                       memset(data, 0, zero_size(size));
                } else if (com&IOC_VOID) {
                        *(void **)data = SCARG(uap, data);
                }
@@ -648,7 +684,8 @@
                 * already set and checked above.
                 */
                if (error == 0 && (com&IOC_OUT) && size) {
-                       error = copyout(data, SCARG(uap, data), size);
+                       error = copyout(data, SCARG(uap, data),
+                           zero_size(size));
                        ktrgenio(SCARG(uap, fd), UIO_READ, SCARG(uap, data),
                            size, error);
                }