code review 3946041: syscall: fix mksysnum_linux.sh

syscall: fix mksysnum_linux.sh

A few system call numbers on x86 Linux are
defined in terms of a previous definition,

e.g.,
	#define __NR_timer_create	259
	#define __NR_timer_settime	(__NR_timer_create+1)
	...
	#define __NR_mq_open		277
	#define __NR_mq_unlink		(__NR_mq_open+1)

This change assumes the numbers are sorted
sequentially in the input file.

[ality, 2011-01-10 13:21:33]

Hello rsc (cc: golang-dev@googlegroups.com),

I'd like you to review this change.

[bradfitzgoog, 2011-01-10 16:44:46]

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
File src/pkg/syscall/mksysnum_linux.sh (right):

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
src/pkg/syscall/mksysnum_linux.sh:27: $prev = $2;
It's bad practice to use $2 here after a call to a function.  You can't
generally guarantee that $2 hasn't been clobbered at this point.  This could
bite us in the future.

You should preserve these into lexical variables before calling fmt()

[rsc, 2011-01-11 16:02:02]

LGTM

Please fix and I will submit.

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
File src/pkg/syscall/mksysnum_linux.sh (right):

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
src/pkg/syscall/mksysnum_linux.sh:26: fmt($1, $2);
$prev = $2;
fmt($1, $2);

(what brad said)

[ality, 2011-01-11 19:25:26]

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
File src/pkg/syscall/mksysnum_linux.sh (right):

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
src/pkg/syscall/mksysnum_linux.sh:26: fmt($1, $2);
On 2011/01/11 16:02:02, rsc wrote:
> $prev = $2;
> fmt($1, $2);
> 
> (what brad said)

Done.

http://codereview.appspot.com/3946041/diff/2001/src/pkg/syscall/mksysnum_linu...
src/pkg/syscall/mksysnum_linux.sh:27: $prev = $2;
On 2011/01/10 16:44:46, bradfitzwork wrote:
> It's bad practice to use $2 here after a call to a
> function.  You can't generally guarantee that $2
> hasn't been clobbered at this point.  This could bite
> us in the future.
>
> You should preserve these into lexical variables
> before calling fmt()

Thanks. I know just enough Perl to be dangerous.

[rsc, 2011-01-11 19:37:02]

LGTM

[rsc, 2011-01-11 19:38:17]

*** Submitted as http://code.google.com/p/go/source/detail?r=7220a25dbacf ***

syscall: fix mksysnum_linux.sh

A few system call numbers on x86 Linux are
defined in terms of a previous definition,

e.g.,
	#define __NR_timer_create	259
	#define __NR_timer_settime	(__NR_timer_create+1)
	...
	#define __NR_mq_open		277
	#define __NR_mq_unlink		(__NR_mq_open+1)

This change assumes the numbers are sorted
sequentially in the input file.

R=rsc, bradfitzwork
CC=golang-dev
http://codereview.appspot.com/3946041

Committer: Russ Cox <rsc@golang.org>