On 11 Jul 2003 23:50:15 +0100
Alan Cox <alan _at_ lxorguk.ukuu.org.uk> wrote:
> On Gwe, 2003-07-11 at 23:44, Linus Torvalds wrote:
> > On 11 Jul 2003, Alan Cox wrote:
> > >
> > > Lots of kernel drivers rely on the libc definition of strncpy.
> >
> > But that's ok. We _do_ do the padding. I hated it when I wrote it, but as
> > far as I know, the kernel strncpy() has done padding pretty much since day
> > one.
> * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
> * However, the result is not %NUL-terminated if the source exceeds
> * @count bytes.
> */
>
> Only x86 does the padding
I do not undestand Alan's position, if he is for it or against it.
Anyway, in case you want it, here's what I wrote for s390.
I wrote some userland tests, it seems to check out. BUT I warn you,
someone better check my assembly.
-- Pete
diff -ur -X dontdiff linux-2.6.1/arch/s390/lib/strncpy64.S linux-2.6.1-s390/arch/s390/lib/strncpy64.S
--- linux-2.6.1/arch/s390/lib/strncpy64.S 2003-07-13 20:31:50.000000000 -0700
+++ linux-2.6.1-s390/arch/s390/lib/strncpy64.S 2004-01-28 18:48:27.000000000 -0800
@@ -23,8 +23,16 @@
LA 3,1(3)
STC 0,0(1)
LA 1,1(1)
- JZ strncpy_exit # ICM inserted a 0x00
+ JZ strncpy_pad # ICM inserted a 0x00
BRCTG 4,strncpy_loop # R4 -= 1, jump to strncpy_loop if > 0
-strncpy_exit:
BR 14
+strncpy_pad:
+ LTR 4,4
+ JZ strncpy_exit # 0 bytes -> nothing to do
+strncpy_padloop:
+ MVI 0(1),0
+ LA 1,1(1)
+ BRCTG 4,strncpy_padloop
+strncpy_exit:
+ BR 14
diff -ur -X dontdiff linux-2.6.1/arch/s390/lib/strncpy.S linux-2.6.1-s390/arch/s390/lib/strncpy.S
--- linux-2.6.1/arch/s390/lib/strncpy.S 2003-07-13 20:35:16.000000000 -0700
+++ linux-2.6.1-s390/arch/s390/lib/strncpy.S 2004-01-28 18:46:20.000000000 -0800
@@ -23,8 +23,16 @@
LA 3,1(3)
STC 0,0(1)
LA 1,1(1)
- JZ strncpy_exit # ICM inserted a 0x00
+ JZ strncpy_pad # ICM inserted a 0x00
BRCT 4,strncpy_loop # R4 -= 1, jump to strncpy_loop if > 0
-strncpy_exit:
BR 14
+strncpy_pad:
+ LTR 4,4
+ JZ strncpy_exit
+strncpy_padloop:
+ MVI 0(1),0
+ LA 1,1(1)
+ BRCT 4,strncpy_padloop
+strncpy_exit:
+ BR 14
-
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