Re: bin/38004: /bin/sh truncates a message for unobvious reasons

[David Laight <david%l8s.co.uk@localhost>]

The following reply was made to PR bin/38004; it has been noted by GNATS.

From: David Laight <david%l8s.co.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: bin/38004: /bin/sh truncates a message for unobvious reasons
Date: Sun, 13 Apr 2008 21:30:53 +0100

 On Sun, Apr 13, 2008 at 03:05:02AM +0000, David Holland wrote:
 > The following reply was made to PR bin/38004; it has been noted by GNATS.
 > 
 > From: David Holland <dholland-bugs%netbsd.org@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc: gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
 > yamt%mwd.biglobe.ne.jp@localhost
 > Subject: Re: bin/38004: /bin/sh truncates a message for unobvious reasons
 > Date: Sun, 13 Apr 2008 03:03:59 +0000
 > 
 >  On Tue, Feb 12, 2008 at 06:35:01PM +0000, David Laight wrote:
 >   >  > >Fix:
 >   >  > +#if 1
 >   >  > +     len = sizeof(ps->cmd);
 >   >  > +#else
 >   >  >       if (iflag || mflag || sizeof ps->cmd < 100)
 >   >  >               len = sizeof(ps->cmd);
 >   >  >       else
 >   >  >               len = sizeof(ps->cmd) / 10;
 >   >  > +#endif
 >   >  
 >   >  When is this a problem?
 >   >  IIRC the purpose of the test is to speed up shell scripts - where it
 >   >  is really pointless regenerating the command line in this form at all.
 >  
 >  Shouldn't the proper fix for that to be to either save a copy of the
 >  original command line string, or to only produce the string when it's
 >  needed? Or am I missing something obvious?
 
 It needs the command string after substitutions, this only exits as a
 tree, and the tree nodes are allocated from a 'stack allocator' and
 are all thrown away (by resetting the base) once the comand is started.
 Thus you have to walk the tree nodes to generate a printable string.
 
 (I'm sure Mr Bourne's shell didn't use this sort of parser!)
 
        David
 
 -- 
 David Laight: david%l8s.co.uk@localhost