PATCH: Re: PATCH: 3.1.4: autocd to directory in $PATH (2)

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxx>]

On Oct 12,  2:18pm, Peter Stephenson wrote:
} Subject: PATCH: 3.1.4: autocd to directory in $PATH (2)
}
} The directory does get stat'ed twice, but it's hard to avoid without
} more fiddling around with special cases.  The next fix does at least
} mean it's restricted to twice altogether.

It bothers me that this happens on every command execution.

Here's a patch, which must be applied on top of Peter's patch, that
restricts the two calls to stat to cases where an autocd might occur.
Specifically, this means:
    * autocd is set
    * the shell is reading commands from stdin
    * there are no I/O redirections to perform
    * there are no command arguments to pass
[I simply moved computation of these four conditions to the top of the
function, then tested the result both in the original context and also
before calling isreallycom().]

Thus there should be no performance penalty (compared to previous zsh
versions) for the great majority of commands, nor for any command if
you don't set autocd.

I did have two remarks about isreallycom():

} + isreallycom(Cmdnam cn)
} + {
} +     char fullnam[MAXCMDLEN];

Other places in the code use PATH_MAX size buffer for the same purpose.
Which is better?

There also seems to be inconsistency as to:

} +     strcpy(fullnam, cn->u.name ? *(cn->u.name) : "");
} +     strcat(fullnam, "/");
} +     strcat(fullnam, cn->nam);

as opposed to:
                    z = buf;
                    strucpy(&z, *pp);
                    *z++ = '/';
                    strcpy(z, arg0);

My patch doesn't change any of that stuff, I'm just pointing it out.

Index: Src/exec.c
===================================================================
*** exec.c	1998/10/14 18:19:05	1.4
--- exec.c	1998/10/14 18:22:09
***************
*** 1495,1500 ****
--- 1495,1504 ----
  
      if (type == SIMPLE && !nullexec) {
  	char *s;
+ 	char trycd = (isset(AUTOCD) && isset(SHINSTDIN)
+ 		      && empty(cmd->redir) && !empty(args)
+ 		      && !nextnode(firstnode(args))
+ 		      && *(char *)peekfirst(args));
  
  	DPUTS(empty(args), "BUG: empty(args) in exec.c");
  	if (!hn) {
***************
*** 1502,1508 ****
  	    char *cmdarg = (char *) peekfirst(args);
  
  	    hn = cmdnamtab->getnode(cmdnamtab, cmdarg);
! 	    if (hn && !isreallycom((Cmdnam)hn)) {
  		cmdnamtab->removenode(cmdnamtab, cmdarg);
  		cmdnamtab->freenode(hn);
  		hn = NULL;
--- 1506,1512 ----
  	    char *cmdarg = (char *) peekfirst(args);
  
  	    hn = cmdnamtab->getnode(cmdnamtab, cmdarg);
! 	    if (hn && trycd && !isreallycom((Cmdnam)hn)) {
  		cmdnamtab->removenode(cmdnamtab, cmdarg);
  		cmdnamtab->freenode(hn);
  		hn = NULL;
***************
*** 1516,1524 ****
  
  	/* If no command found yet, see if it  *
  	 * is a directory we should AUTOCD to. */
! 	if (!hn && isset(AUTOCD) && isset(SHINSTDIN) && empty(cmd->redir)
! 	    && !nextnode(firstnode(args)) && *(char *)peekfirst(args)
! 	    && (s = cancd(peekfirst(args)))) {
  	    peekfirst(args) = (void *) s;
  	    pushnode(args, dupstring("cd"));
  	    if ((hn = builtintab->getnode(builtintab, "cd")))
--- 1520,1526 ----
  
  	/* If no command found yet, see if it  *
  	 * is a directory we should AUTOCD to. */
! 	if (!hn && trycd && (s = cancd(peekfirst(args)))) {
  	    peekfirst(args) = (void *) s;
  	    pushnode(args, dupstring("cd"));
  	    if ((hn = builtintab->getnode(builtintab, "cd")))


-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com