ksh autoloading

[Zefram <zefram@dcs.warwick.ac.uk>]

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This patch changes the way ksh autoloading is handled.  Currently it is
a kludge in execshfunc(), that if a function that was just autoloaded
redefines itself on first execution, it is executed again.  This breaks
on functions that really want to redefine themselves, which some do,
and in any case isn't applied to functions autoloaded for other purposes,
such as chpwd or widget functions.

The new scheme is that when a list has been read from the file and parsed,
it is examined to see if it is *in its entirety* a definition of the
function being loaded.  If it is, then the contents of that definition
is used, rather than the complete list.  This has much better defined
semantics than the old method.

 -zefram

      *** Src/exec.c	1997/03/22 07:00:53	1.53
      --- Src/exec.c	1997/03/26 02:57:18
      ***************
      *** 2482,2505 ****
        	if (!(funcdef = getfpfunc(nam))) {
        	    zerr("function not found: %s", nam, 0);
        	    lastval = 1;
      ! 	} else {
      ! 	    PERMALLOC {
      ! 		shf->flags &= ~PM_UNDEFINED;
      ! 		funcdef = shf->funcdef = (List) dupstruct(funcdef);
      ! 	    } LASTALLOC;
      ! 
      ! 	    /* Execute the function definition, we just retrived */
      ! 	    doshfunc(shf->funcdef, cmd->args, shf->flags, 0);
      ! 
      ! 	    /* See if this file defined the autoloaded function *
      ! 	     * by name.  If so, we execute it again.            */
      ! 	    if ((shf = (Shfunc) shfunctab->getnode(shfunctab, nam))
      ! 		&& shf->funcdef && shf->funcdef != funcdef)
      ! 		doshfunc(shf->funcdef, cmd->args, shf->flags, 0);
      ! 	}
      !     } else
      ! 	/* Normal shell function execution */
      ! 	doshfunc(shf->funcdef, cmd->args, shf->flags, 0);
            if (!list_pipe)
        	deletefilelist(last_file_list);
        }
      --- 2482,2497 ----
        	if (!(funcdef = getfpfunc(nam))) {
        	    zerr("function not found: %s", nam, 0);
        	    lastval = 1;
      ! 	    goto end;
      ! 	}
      ! 	shf->flags &= ~PM_UNDEFINED;
      ! 	PERMALLOC {
      ! 	    shf->funcdef = (List) dupstruct(funcdef);
      ! 	} LASTALLOC;
      !     }
      !     doshfunc(shf->funcdef, cmd->args, shf->flags, 0);
      ! 
      !     end:
            if (!list_pipe)
        	deletefilelist(last_file_list);
        }
      ***************
      *** 2658,2664 ****
        			r = parse_string(d);
        		    } LASTALLOC;
        		    zfree(d, len + 1);
      ! 		    return r;
        		} else {
        		    zfree(d, len + 1);
        		    close(fd);
      --- 2650,2656 ----
        			r = parse_string(d);
        		    } LASTALLOC;
        		    zfree(d, len + 1);
      ! 		    return stripkshdef(r, s);
        		} else {
        		    zfree(d, len + 1);
        		    close(fd);
      ***************
      *** 2669,2674 ****
      --- 2661,2697 ----
        	}
            }
            return NULL;
      + }
      + 
      + /* Handle ksh-style autoloading.  Given the list read from an autoload file, *
      +  * and the name of the function being defined, check to see if the file      *
      +  * consists entirely of a single definition for that function.  If so,       *
      +  * use the contents of that definition.  Otherwise, use the entire file.     */
      + 
      + /**/
      + List
      + stripkshdef(List l, char *name)
      + {
      +     Sublist s;
      +     Pline p;
      +     Cmd c;
      +     if(!l)
      + 	return NULL;
      +     if(l->type != Z_SYNC || l->right)
      + 	return l;
      +     s = l->left;
      +     if(s->flags || s->right)
      + 	return l;
      +     p = s->left;
      +     if(p->right)
      + 	return l;
      +     c = p->left;
      +     if(c->type != FUNCDEF || c->flags ||
      + 	nonempty(c->redir) || nonempty(c->vars) ||
      + 	empty(c->args) || lastnode(c->args) != firstnode(c->args) ||
      + 	strcmp(name, peekfirst(c->args)))
      + 	return l;
      +     return c->u.list;
        }
        
        /* check to see if AUTOCD applies here */

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