klibc - Jan 2006 - [mips] pipe doesn't work in dash

Pipe doesn't work in dash on mips/mipsel - everything delivered to a
pipe is shown on stdout:

mipsel:
$ echo foo | cat > ~/d
foo
<ctrl-c pressed manually>
$ cat ~/d
$

i386:
$ echo foo | cat > ~/d
$ cat ~/d
foo
$


This may be related to the following warnings during compilation but
I'm not sure:

klibc/arch/mips/syscall.S: Assembler messages:
klibc/arch/mips/syscall.S:12: Warning: Macro instruction expanded into multiple
instructions in a branch delay slot

  KLIBCCC dash/parser.o
dash/parser.c: In function 'readtoken1':
dash/parser.c:1272: warning: 'saveprompt' may be used uninitialized in
this function
dash/parser.c:849: warning: 'prevsyntax' may be used uninitialized in
this function
dash/parser.c:842: warning: variable 'quotef' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:843: warning: variable 'dblquote' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:844: warning: variable 'varnest' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:845: warning: variable 'arinest' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:846: warning: variable 'parenlevel' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:847: warning: variable 'dqvarnest' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:848: warning: variable 'oldstyle' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:849: warning: variable 'prevsyntax' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:1272: warning: variable 'saveprompt' might be clobbered by
'longjmp' or 'vfork'
dash/parser.c:835: warning: argument 'syntax' might be clobbered by
'longjmp' or 'vfork'
  KLIBCCC dash/redir.o

-- 
Martin Michlmayr
http://www.cyrius.com/

Martin Michlmayr wrote:
> Pipe doesn't work in dash on mips/mipsel - everything delivered to a
> pipe is shown on stdout:
> 
> mipsel:
> $ echo foo | cat > ~/d
> foo
> <ctrl-c pressed manually>
> $ cat ~/d
> $
> 
> i386:
> $ echo foo | cat > ~/d
> $ cat ~/d
> foo
> $
> 
> This may be related to the following warnings during compilation but
> I'm not sure:
> 
> klibc/arch/mips/syscall.S: Assembler messages:
> klibc/arch/mips/syscall.S:12: Warning: Macro instruction expanded into
multiple instructions in a branch delay slot
> 
This one is actually OK, although probably a bit ugly (we really should 
expand this out explicitly.)

Unfortunately my MIPS box bit the dust; Ralf said at one point he'd try 
to get me a development board from Broadcom which never materialized; so 
I have absolutely no way to test any of this...

pipe(2) is a weird system call on many architectures, due to attempts at 
staying binary compatible with various weird native-Unix hacks; on MIPS 
it's in special assembly code in arch/mips/pipe.S.

	-hpa

Martin Michlmayr wrote:
> Pipe doesn't work in dash on mips/mipsel - everything delivered to a
> pipe is shown on stdout:
I think I've figured out the problem... in klibc/arch/mips/pipe.S, 
"(a1)" on line 10 should be "4(a0)".  Could you try to make
that change
and see if it works?

	-hpa