rw.kex

'set novalue on'  /* force KEXX and its way of SIGNAL ON NOVALUE  */

/* usage:         [MACRO] RW                                      */
/* example:       RW                                              */
/* requires:      Kedit 5.0               (Frank Ellermann, 1999) */
/* purpose:       allow write access on a modified read-only file */
/*                by renaming the r/o and locking the edited file */
/* caveat:        if another program has write access on the r/o  */
/*                file you should not enforce r/w access with RW  */
/* algorithm:                                                     */
/* 1 - rename r/o file UVW.XYZ to UVW.OLD (resp. UVW.TMP) on disk */
/* 2 - rename edited UVX.XYZ to UVW.OLD (resp. UVW.TMP) in memory */
/* 3 - edit new r/w file UVW.XYZ with enabled file locking        */
/* 4 - copy old r/o file to new (locked) r/w file UVW.XYZ on disk */
/* 5 - save modified file (UVW.OLD in memory) by PUTD ALL on disk */
/* 6 - load modified file (UVW.XYZ in memory) by GET (5+6 = copy) */

/* probably this is overkill, but I found no straight forward way */
/* to get rid of Kedit's filestatus.2() = READONLY (DOS ATTRIB -R */
/* won't help).                                                   */

   if ft.1() = 'OLD' then EXT = 'tmp'  ; else EXT = 'old'   /* 1  */
   RO = fm.1() || fp.1()
   if fp.1() <> '\'  then RO  = RO || '\'
   RW = RO || fn.2() || '.' || ft.2()
   RO = RO || fn.2() || '.' || EXT
   'rename "' || RW || '" "' || RO || '"' ; if rc <> 0 then exit rc

   'fileid "' || RO || '"'                                  /* 2  */
   if rc <> 0 then do                  /* ...undo rename and exit */
      EXT = rc ; 'rename "' || RO || '" "' RW || '"'     ;  exit EXT
   end

   'kedit "' || RW || '" (lock new nodefext)'               /* 3  */
   if rc <> 0 then do                  /* ...undo rename and exit */
      EXT = rc ;  'rename "' || RO || '" "' RW || '"'
                  'fileid "' || RW || '"'                ;  exit EXT
   end

   'nomsg get "' || RO || '"'          /* save OLD RO as RW file  */
   if rc == 0 then 'SSave' ; if rc = 0 then 'refresh'       /* 4  */
   if rc <> 0 then do
      EXT = rc ;  'rename "' || RO || '" "' RW || '"'
      'qquit'  ;  'kedit  "' || RO || '" (new)'
      'emsg panic - cannot save file "' || RW || '"'     ;  exit EXT
   end

   'kedit "' || RO || '" (new)'           ; if rc <> 0 then exit rc
   'range -* +*'  ;  'all' ;  'putd all'  ; if rc <> 0 then exit rc
   'qquit'                                                  /* 5  */

   'kedit "' || RW || '" (new nodefext)'  ; if rc <> 0 then exit rc
   'delete all'   ;  'nomsg get'          ; EXT = rc        /* 6  */
   'msg delete renamed r/o file "' || RO || '" later'
   'cmsg SAVE'                                           ;  exit EXT