Date: Wed, 12 Mar 1997 09:37:30 +0100 (MET)
From: Robert Hoehne <robert DOT hoehne AT mathematik DOT tu-chemnitz DOT de>
To: DJGPP workers <djgpp-workers AT delorie DOT com>
Cc: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Subject: Again a patch for _use_lfn.c
Message-Id: <Pine.HPP.3.95q.970312093425.27109A-100000@newton.mathematik.tu-chemnitz.de>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

I made now again a patch for '_use_lfn.c' because even the
last patch from Eli (sorry that I said at first it was OK)
is buggy. To proof this, link the test program (-DTEST) and
run it in a W95 DOS-box with LFN=n and it will report ever
0 but it should report 1 after 'putenv("LFN=y");'.
If you can't run under W95, think about the situation,
that LFN=n and analize the program and you will see also
that result.

The reason for this is in my opinion the invalid modification
of 'filesystem_flags'. I think (as the name it says), this
variable should represent the filesystem status and NOT
the setting of $(LFN).

I have added now a static variable '_lfnenv', which remembers
the last setting of $(LFN) and is updated when the environment
has been changed.

The 'filesystem_flags' are computed now only, if they are
'==_FILESYS_UNKNOWN' or '_use_lfn()' is called for a different
drive.

'_use_lfn()' returns now 1 when the filesystem supports
LFN and $(LFN) is not set to 'n'.

BTW: If $(LFN) is not set, I assume it (in '_lfnenv') as it
was set to 'y'. Is that correct?
And the patch fixes of course also the unneccessary calls to
'getenv()' which was the goal with the first patch from
me and Eli.

OK. Here is now the patch against the '_use_lfn.c' from
djlsr201.zip:

*** src/libc/dos/lfn/_use_lfn.c~	Sat Aug 31 21:09:32 1996
--- src/libc/dos/lfn/_use_lfn.c	Mon Mar 10 19:01:12 1997
***************
*** 17,22 ****
--- 17,23 ----
  
  static int      use_lfn_bss_count = -1;	/* if we are restarted (emacs) */
  static unsigned filesystem_flags  = _FILESYS_UNKNOWN;
+ static char _lfnenv = 'y'; /* remember here $(LFN) */
  static unsigned last_env_changed = 0;
  static int	last_drive; /* drive *letter*, not *number*! */
  
***************
*** 138,150 ****
      }
    }
  
!   if (same_drive_as_last_time
!       && last_env_changed  == __environ_changed
!       && use_lfn_bss_count == __bss_count
!       && filesystem_flags  != _FILESYS_UNKNOWN)	/* paranoia */
!     return (filesystem_flags & _FILESYS_LFN_SUPPORTED) != 0;
!   else
    {
      char *lfnenv;
  
      use_lfn_bss_count = __bss_count;
--- 139,150 ----
      }
    }
  
!   if (!same_drive_as_last_time
!       || last_env_changed  != __environ_changed
!       || use_lfn_bss_count != __bss_count
!       || filesystem_flags  == _FILESYS_UNKNOWN)
    {
+     /* check now the environment for $(LFN) */
      char *lfnenv;
  
      use_lfn_bss_count = __bss_count;
***************
*** 153,168 ****
      lfnenv = getenv ("LFN");
      if(lfnenv && (tolower (lfnenv[0]) == 'n'))
      {
!       filesystem_flags &= ~_FILESYS_LFN_SUPPORTED;
        last_drive = 0;
!       return 0;
      }
    }
  
    if (!same_drive_as_last_time || filesystem_flags == _FILESYS_UNKNOWN)
      filesystem_flags = _get_volume_info (path, 0, 0, 0);
  
!   return (filesystem_flags & _FILESYS_LFN_SUPPORTED) != 0;
  }
  
  #ifdef TEST
--- 153,175 ----
      lfnenv = getenv ("LFN");
      if(lfnenv && (tolower (lfnenv[0]) == 'n'))
      {
!       _lfnenv = 'n';
        last_drive = 0;
!     }
!     else
!     {
!       /* if $(LFN) was not set or != 'n' assume it as 'y' */
!       _lfnenv = 'y';
      }
    }
  
    if (!same_drive_as_last_time || filesystem_flags == _FILESYS_UNKNOWN)
      filesystem_flags = _get_volume_info (path, 0, 0, 0);
  
!           /* Does the filesystem LFN support ? */
!   return ((filesystem_flags & _FILESYS_LFN_SUPPORTED) != 0 &&
!           /* Is it not disabled by the user ? */
!           _lfnenv != 'n');
  }
  
  #ifdef TEST