execve bug

[David Aspinwall <aspinwall@TimesTen.com>]

This is a bug which shows up in the NT port (based no 3.0.5).
It isn't in the NT-specific code, though, and I think would happen on
any system which doesn't support #!, so I'm sending it to zsh-workers
too.

If you have a script called 'dog' whose first line is '#!/bin/sh '
(i.e., has at least one space after the interpreter name), and
the OS doesn't support #!, zsh will wind up calling execve with
an argv of ("/bin/sh", "", "dog").  You get an error like
: : No such file or directory
or if you have multiple spaces,
 :  : Permission denied

Here's a patch to exec.c against 3.0.5 (or at least the version
in the zshsrc file for the NT distribution).


*** ../../zsh-orig/Src/exec.c	Wed May 19 16:16:26 1999
--- exec.c	Fri Jun 11 13:45:06 1999
***************
*** 180,187 ****
  		if (execvebuf[0] == '#') {
  		    if (execvebuf[1] == '!') {
  			for (t0 = 0; t0 != ct; t0++)
! 			    if (execvebuf[t0] == '\n')
  				execvebuf[t0] = '\0';
  			execvebuf[POUNDBANGLIMIT] = '\0';
  			for (ptr = execvebuf + 2; *ptr && *ptr == ' '; ptr++);
  			for (ptr2 = ptr; *ptr && *ptr != ' '; ptr++);
--- 180,196 ----
  		if (execvebuf[0] == '#') {
  		    if (execvebuf[1] == '!') {
  			for (t0 = 0; t0 != ct; t0++)
! 			    if (execvebuf[t0] == '\n') {
  				execvebuf[t0] = '\0';
+ 				/* get rid of trailing spaces */
+ 				for (--t0; t0 > 1; --t0) {
+ 				  if (execvebuf[t0] == ' ') {
+ 				    execvebuf[t0] = '\0';
+ 				  } else {
+ 				    break;
+ 				  }
+ 				}
+ 			    }
  			execvebuf[POUNDBANGLIMIT] = '\0';
  			for (ptr = execvebuf + 2; *ptr && *ptr == ' '; ptr++);
  			for (ptr2 = ptr; *ptr && *ptr != ' '; ptr++);