execve bug

execve bug

[David Aspinwall]

This is a bug which shows up in the NT port (based on 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.

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++);




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Re: execve bug

[Bart Schaefer]

On Jun 14,  1:13pm, David Aspinwall wrote:
} Subject: execve bug
}
} 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").

Thanks for pointing this out.  The same problem happens with a trailing
tab, so I think the following patch is better.  There was also no reason
for the old code wandereding all the way to t0 == ct clobbering newlines
once the first one was found.

Index: Src/exec.c
==========================================================================
@@ -251,7 +251,9 @@
 		    if (execvebuf[1] == '!') {
 			for (t0 = 0; t0 != ct; t0++)
 			    if (execvebuf[t0] == '\n')
-				execvebuf[t0] = '\0';
+				break;
+			while (inblank(execvebuf[t0]))
+			    execvebuf[t0--] = '\0';
 			execvebuf[POUNDBANGLIMIT] = '\0';
 			for (ptr = execvebuf + 2; *ptr && *ptr == ' '; ptr++);
 			for (ptr2 = ptr; *ptr && *ptr != ' '; ptr++);

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

execve bug

[David Aspinwall]

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++);