Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!snorkelwacker!bloom-beacon!eru!hagbard!sunic!bmc.uu.se!kuling!jand
From: jand@kuling.UUCP (Jan Dj{rv)
Newsgroups: comp.lang.perl
Subject: Re: Tom Christiansen's man program no longer works with pl28
Keywords: perl pl28 man xenix
Message-ID: <1652@kuling.UUCP>
Date: 6 Sep 90 06:33:59 GMT
References: <578@seer.UUCP>
Reply-To: jand@kuling.UUCP (Jan Dj{rv)
Organization: Dept. of Computer Systems, Uppsala University, Sweden
Lines: 102

In article <578@seer.UUCP> bll@seer.UUCP (Brad Lanam) writes:
>
>    I just brought perl up to patchlevel 28, and everything except
>Tom Christiansen's man program seems to work.  It can't seem to find
>anything in the dbm database.  I rebuilt the database, but that didn't
>help.  He uses those eval things...  I can't figure out how to print
>out what is in the dbm array.
>
>    Has anyone else had this problem?

The man program uses ndbm and PL 28 has problems with it. It's not anything
wrong with Tom's program, it's perl.

The first problem is that perl doesn't allow open of a dbm file readonly.
Here's my patch for that:
*** hash.c.Distributed	Fri Aug 17 12:26:43 1990
--- hash.c	Mon Aug 20 09:19:37 1990
***************
*** 538,543 ****
--- 538,545 ----
  	tb->tbl_dbm = dbm_open(fname, O_RDWR|O_CREAT, mode);
      if (!tb->tbl_dbm)
  	tb->tbl_dbm = dbm_open(fname, O_RDWR, mode);
+     if (!tb->tbl_dbm)
+ 	tb->tbl_dbm = dbm_open(fname, O_RDONLY, mode);
  #else
      if (dbmrefcnt++)
  	fatal("Old dbm can only open one database");
***************
*** 551,556 ****
--- 553,560 ----
      }
      tb->tbl_dbm = dbminit(fname) >= 0;
  #endif
+     if (!tb->tbl_array && tb->tbl_dbm != 0)
+ 	Newz(507,tb->tbl_array, tb->tbl_max + 1, HENT*);
      return tb->tbl_dbm != 0;
  }
  

The other problem (the one you encountered) was discovered by
Andrew Vignaux <Andrew.Vignaux@comp.vuw.ac.nz>. I include his posting here.
With these two patches Tom's man works OK for me.

	Jan D.

Andrew Vignaux writes:

I think the problem is in the lazy array creation that went in in
pl.28.  hfetch() only creates the array if the access is an lval and
it hasn't been stored into already.  Unfortunately, dbm files can
already have stuff in them.  The local fix:

      if (!tb->tbl_array) {
! 	if (lval)
  	    Newz(503,tb->tbl_array, tb->tbl_max + 1, HENT*);

to

      if (!tb->tbl_array) {
! 	if (lval || tb->tbl_dbm)
  	    Newz(503,tb->tbl_array, tb->tbl_max + 1, HENT*);

works, but it means that

	dbmopen(FOO,"foo",0666); print defined(%FOO), "\n";

still prints 0.

Here's a completely unofficial patch that (I think) fixes this
problem.  I'm posting this because I can't believe I'm the only one
who depends on dbm files in perl.  I don't want to go back to 18
because of the lack of dbmopen(FOO, "foo", undef) ;-)

*** ./hash.c~	Tue Aug 14 21:17:53 1990
--- ./hash.c	Sat Aug 18 14:22:50 1990
***************
*** 551,556 ****
--- 551,558 ----
      }
      tb->tbl_dbm = dbminit(fname) >= 0;
  #endif
+     if (!tb->tbl_array && tb->tbl_dbm != 0)
+ 	Newz(507,tb->tbl_array, tb->tbl_max + 1, HENT*);
      return tb->tbl_dbm != 0;
  }


This fix also means that

	dbmopen(FOO,"foo",undef); print defined(%FOO), "\n";
and
	dbmopen(BAR,"bar",0666); print defined(%BAR), "\n";

prints 0 if "foo.dir" doesn't exist, or "bar.{dir,pag}" can't be
created.

Both "fixes" pass make test on a MORE/bsd hp300.

Andrew
-- 
Domain address: Andrew.Vignaux@comp.vuw.ac.nz