Setuid program and permission denied

Question

We have a wrapper written in C++ that handles our code promotion. It is setuid (u+s) so that any developer can move files to directory owned by our repository owner. This program calls another script that invokes a make. Within this make is a shell macro that invokes which. In Solaris 9 this all works fine. In Solaris 10 it dies with "csh: Permission denied", which is caused by the which. Is Solaris 10 behaving differently? Here is a sample that mimics what we do:
#include <sys/wait.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <setjmp.h>
#include <stdio.h>
#include <sys/param.h>
//#define MAXPATHLEN 200
int main(
char lib_so_src[MAXPATHLEN] ;
char lib_so_lib[MAXPATHLEN] ;
(void)sprintf( lib_so_src, "/mbs/prg/blue10/ref/cvt/a100/test.so.7" ) ;
(void)sprintf( lib_so_lib, "/mbs/prg/blue10/ref/lib/test.so.7" ) ;
setuid(1000);
execlp( "/staff/rstacey/bin/compile", "/staff/rstacey/bin/compile", "", NULL );
where compile is:
cd /mbs/prg/blue10/ref/cvt/a100
echo here
which sbpkg

Answer 1

I suspect you will find that someone has set your "which" script to SUID (if, indeed, this error is originating with that command).
Solaris 10 no longer permits SUID shell scripts. I can't recall off the top of my head how to revert to the old (insecure) behavior and a brief web search didn't yield anything...
But from your description it should be unnecessary because your initial wrapper has already raised your UID to root's.
You might want to look into the process privileges (ppriv) to make this whole setup even more secure.