From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Tue, 27 Oct 2009 13:42:31 -0400
To: 9fans@9fans.net
Message-ID: <14e87ba61b1fc0026feb67f59a91ed24@ladd.quanstro.net>
In-Reply-To: <<3df301650910231945n522c4592ib25cef16e9830202@mail.gmail.com>>
References: <<3df301650910231945n522c4592ib25cef16e9830202@mail.gmail.com>>
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Subject: Re: [9fans] Plan9 awk vs. GNU awk
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On Fri Oct 23 22:47:46 EDT 2009, michaelmuffin@gmail.com wrote:
> try using [_a-zA-Z][_a-zA-Z0-9] rather than the expanded form. i
> didn't track it down to be sure, but plan 9 awk seem to have a limit
> 34 characters inside square brackets. a rather odd number
>
> cpu% echo hello | awk '/^[abcdefghijklmnopqrstuvwxyzABCDEFGH].+/ {
> line = $0 ; print line }'
> cpu% echo hello | awk '/^[abcdefghijklmnopqrstuvwxyzABCDEFG].+/ { line
> = $0 ; print line }'
> hello

there are two bits to fixing this.  steve simon
submitted an excellent patch, which i applied.
but i think there is still a bug.  34 is as noted a
really wierd number.

a bit of background:  the way cclasses work is
that each entry gets 2 entries.  a start and
an end.  for a-b the start is a and the end is b.
for just a, the start and end are both a.  one
would expect since the original code has 64
spaces, we would get a maximum of 32 chars
per class.  however, /sys/src/ape/lib/regexp/regcomp.h
has
	/* max rune ranges per character class */
	#define NCCRUNE	(sizeof(Reclass)/sizeof(wchar_t))
which is wrong since there is more stuff in Reclass
than an array of wchar_t's.  this is a big problem
since it will scribble 4 bytes past the end of the
Reclass.

these are the diffs i came up with.  they attack
the problem a bit differently, but i think it's a
bit cleaner and worth a few extra lines of diff:

; 9diff regcomp.h
/n/sources/plan9//sys/src/ape/lib/regexp/regcomp.h:1,23 - regcomp.h:1,17
  /*
   *  substitution list
   */
+ enum {
+ 	NSUBEXP	= 32,
+ 	LISTINCREMENT	= 8,
+ };
+
  typedef struct Resublist	Resublist;
  struct	Resublist
  {
- 	Resub	m[32];
+ 	Resub	m[NSUBEXP];
  };

- /* max subexpressions per program */
- Resublist ReSuBlIsT;
- #define NSUBEXP (sizeof(ReSuBlIsT.m)/sizeof(Resub))
-
- /* max character classes per program */
- Reprog	RePrOg;
- #define	NCLASS	(sizeof(RePrOg.class)/sizeof(Reclass))
-
- /* max rune ranges per character class */
- #define NCCRUNE	(sizeof(Reclass)/sizeof(wchar_t))
-
  /*
   * Actions and Tokens (Reinst types)
   *
/n/sources/plan9//sys/src/ape/lib/regexp/regcomp.h:46,52 - regcomp.h:40,45
  /*
   *  regexec execution lists
   */
- #define LISTINCREMENT 8
  typedef struct Relist	Relist;
  struct Relist
  {
; 9diff regexp.h
/n/sources/plan9//sys/include/ape/regexp.h:35,43 - regexp.h:35,50
  /*
   *	character class, each pair of rune's defines a range
   */
+ enum{
+ 	NCCRUNE	= 256,
+ 	NCLASS	= 16,
+ 	NINST		= 5,
+
+ };
+
  struct Reclass{
  	wchar_t	*end;
- 	wchar_t	spans[64];
+ 	wchar_t	spans[NCCRUNE];
  };

  /*
/n/sources/plan9//sys/include/ape/regexp.h:62,69 - regexp.h:69,76
   */
  struct Reprog{
  	Reinst	*startinst;	/* start pc */
- 	Reclass	class[16];	/* .data */
- 	Reinst	firstinst[5];	/* .text */
+ 	Reclass	class[NCLASS];	/* .data */
+ 	Reinst	firstinst[NINST];	/* .text */
  };

  extern Reprog	*regcomp(char*);

- erik