[9fans] Drawterm on Linux/PowerPC

[9fans] Drawterm on Linux/PowerPC

[Sven Moritz Hallberg]

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Hello 9fans,

I've tried to get drawterm to work on my Linux/PowerPC machine. I
_think_ I have "dt2k". I got it from this CVS repo:

	:pserver:anoncvs@cvs.pdos.csail.mit.edu/cvs drawterm

(BTW, it was kind of hard to confirm that this -- appearently -- is in
fact dt2k...)

Unfortunately it doesn't work. The fmtprint functions seem to do stuff
with va_lists that my system doesn't like. Specifically, fmtprint and
many other functions try to assign va_list's to fields in a Fmt
structure. This is simply rejected by my GCC (I tried versions 3.3, 3.4,
and 4.0.2):

gcc -Wall -Wno-missing-braces -ggdb -I.. -I../include -I../kern -c
-I/usr/X11R6/include -D_THREAD_SAFE -pthread -O2 fmtprint.c
fmtprint.c: In function 'fmtprint':
fmtprint.c:20: error: incompatible types in assignment

I tried to replace all the offending assignments with calls to memcpy:

/*      va = f->args; */
        memcpy(&va, &(f->args), sizeof(va_list));

This results in successfull compilation, but immediately crashes drawterm:

$ gdb ./drawterm
[..snip..]
(gdb) runStarting program: /home/pesco/Halde/drawterm/drawterm
[Thread debugging using libthread_db enabled]
[New Thread 805479776 (LWP 12368)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 805479776 (LWP 12368)]
0x10048500 in _runefmt (f=0x7fb7f3f8) at dofmt.c:234
234             x[0] = va_arg(f->args, int);

I've read in

http://www.cs.bell-labs.com/wiki/plan9/THM_2005-06-23_Summary/

that "[Ericvh] has [dt2k] working in ppc-linux". So:


	Eric, can I have your code?

	When will this find its way into the drawterm CVS?

	How can I help?


Greetings,
Sven Moritz

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Re: [9fans] Drawterm on Linux/PowerPC

[Eric Van Hensbergen]

On 1/13/06, Sven Moritz Hallberg <sm@khjk.org> wrote:
> Hello 9fans,
>
> I've tried to get drawterm to work on my Linux/PowerPC machine. I
> _think_ I have "dt2k". I got it from this CVS repo:
>
>         :pserver:anoncvs@cvs.pdos.csail.mit.edu/cvs drawterm
>
> (BTW, it was kind of hard to confirm that this -- appearently -- is in
> fact dt2k...)
>
> Unfortunately it doesn't work. The fmtprint functions seem to do stuff
> with va_lists that my system doesn't like. Specifically, fmtprint and
> many other functions try to assign va_list's to fields in a Fmt
> structure. This is simply rejected by my GCC (I tried versions 3.3, 3.4,
> and 4.0.2):
>
> gcc -Wall -Wno-missing-braces -ggdb -I.. -I../include -I../kern -c
> -I/usr/X11R6/include -D_THREAD_SAFE -pthread -O2 fmtprint.c
> fmtprint.c: In function 'fmtprint':
> fmtprint.c:20: error: incompatible types in assignment
>
> I tried to replace all the offending assignments with calls to memcpy:
>
> /*      va = f->args; */
>         memcpy(&va, &(f->args), sizeof(va_list));
>
> This results in successfull compilation, but immediately crashes drawterm:
>
> $ gdb ./drawterm
> [..snip..]
> (gdb) runStarting program: /home/pesco/Halde/drawterm/drawterm
> [Thread debugging using libthread_db enabled]
> [New Thread 805479776 (LWP 12368)]
>
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 805479776 (LWP 12368)]
> 0x10048500 in _runefmt (f=0x7fb7f3f8) at dofmt.c:234
> 234             x[0] = va_arg(f->args, int);
>
> I've read in
>
> http://www.cs.bell-labs.com/wiki/plan9/THM_2005-06-23_Summary/
>
> that "[Ericvh] has [dt2k] working in ppc-linux". So:
>
>
>         Eric, can I have your code?
>
>         When will this find its way into the drawterm CVS?
>
>         How can I help?
>

I'll dig up what I have and see about reving into to the most recent
versions of drawterm and then sending a patch here.

Essentially you were on the right path, but the wrong solution.
man va_copy and look at the plan9ports fmtprint code for how to do
this right on ppc/linux.
I'll try to send something out today.

         -eric

Re: [9fans] Drawterm on Linux/PowerPC

[Sven Moritz Hallberg]

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Eric Van Hensbergen schrieb:
> Essentially you were on the right path, but the wrong solution.
> man va_copy and look at the plan9ports fmtprint code for how to do
> this right on ppc/linux.

Hah, I'm such an idiot, overlooked va_copy although it's right in the
manpage. Anyway, I've replace the assignments with va_copy/va_end pairs,
as in plan9ports and drawterm seems to work! At least it compiles,
starts, and complains that I didn't tell it any server... :)

Attached is the output of cvs diff.


Thanks alot for the pointer,

Sven Moritz

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Index: libc/fmtprint.c
===================================================================
RCS file: /cvs/drawterm/libc/fmtprint.c,v
retrieving revision 1.1
diff -r1.1 fmtprint.c
20c20,21
< 	va = f->args;
---
> 	va_copy(va, f->args);
> 	va_end(f->args);
27c28,29
< 	f->args = va;
---
> 	va_copy(f->args, va);
> 	va_end(va);
Index: libc/fmtvprint.c
===================================================================
RCS file: /cvs/drawterm/libc/fmtvprint.c,v
retrieving revision 1.1
diff -r1.1 fmtvprint.c
20,21c20,23
< 	va = f->args;
< 	f->args = args;
---
> 	va_copy(va, f->args);
> 	va_end(f->args);
> 	va_copy(f->args, args);
> 	va_end(args);
26c28,29
< 	f->args = va;
---
> 	va_copy(f->args, va);
> 	va_end(va);
Index: libc/runevseprint.c
===================================================================
RCS file: /cvs/drawterm/libc/runevseprint.c,v
retrieving revision 1.1
diff -r1.1 runevseprint.c
18c18,19
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);
Index: libc/runevsmprint.c
===================================================================
RCS file: /cvs/drawterm/libc/runevsmprint.c,v
retrieving revision 1.1
diff -r1.1 runevsmprint.c
60c60,61
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);
Index: libc/runevsnprint.c
===================================================================
RCS file: /cvs/drawterm/libc/runevsnprint.c,v
retrieving revision 1.1
diff -r1.1 runevsnprint.c
18c18,19
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);
Index: libc/vfprint.c
===================================================================
RCS file: /cvs/drawterm/libc/vfprint.c,v
retrieving revision 1.1
diff -r1.1 vfprint.c
29c29,30
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);
Index: libc/vseprint.c
===================================================================
RCS file: /cvs/drawterm/libc/vseprint.c,v
retrieving revision 1.1
diff -r1.1 vseprint.c
18c18,19
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);
Index: libc/vsmprint.c
===================================================================
RCS file: /cvs/drawterm/libc/vsmprint.c,v
retrieving revision 1.1
diff -r1.1 vsmprint.c
60c60,61
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);
Index: libc/vsnprint.c
===================================================================
RCS file: /cvs/drawterm/libc/vsnprint.c,v
retrieving revision 1.1
diff -r1.1 vsnprint.c
18c18,19
< 	f.args = args;
---
> 	va_copy(f.args, args);
> 	va_end(args);

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Re: [9fans] Drawterm on Linux/PowerPC

[C H Forsyth]

>Hah, I'm such an idiot, overlooked va_copy although it's right in the

you're not an idiot.  it's a late addition, very late (and i'm not so sure about the people
that forced it to be added).

[9fans] Drawterm on Linux/PowerPC

[erik quanstrom]

Sven Moritz Hallberg <sm@khjk.org> writes

[...]
| gcc -Wall -Wno-missing-braces -ggdb -I.. -I../include -I../kern -c
| -I/usr/X11R6/include -D_THREAD_SAFE -pthread -O2 fmtprint.c
| fmtprint.c: In function 'fmtprint':
| fmtprint.c:20: error: incompatible types in assignment
| 
| I tried to replace all the offending assignments with calls to memcpy:
| 
| /*      va = f->args; */
|         memcpy(&va, &(f->args), sizeof(va_list));

try: (from plan9port)

int
fmtprint(Fmt *f, char *fmt, ...)
{
	va_list va;
	int n;

	f->flags = 0;
	f->width = 0;
	f->prec = 0;
	va_copy(va, f->args);
	va_end(f->args);
	va_start(f->args, fmt);
	n = dofmt(f, fmt);
	va_end(f->args);
	f->flags = 0;
	f->width = 0;
	f->prec = 0;
	va_copy(f->args,va);
	va_end(va);
	if(n >= 0)
		return 0;
	return n;
}

- erik