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     issetugid — is current process tainted by uid or gid changes


     Standard C Library (libc, -lc)


     #include <unistd.h>



     The issetugid() system call returns 1 if the process environment or memory address space is
     considered “tainted”, and returns 0 otherwise.

     A process is tainted if it was created as a result of an execve(2) system call which had
     either of the setuid or setgid bits set (and extra privileges were given as a result) or if
     it has changed any of its real, effective or saved user or group ID's since it began

     This system call exists so that library routines (eg: libc, libtermcap) can reliably
     determine if it is safe to use information that was obtained from the user, in particular
     the results from getenv(3) should be viewed with suspicion if it is used to control

     A “tainted” status is inherited by child processes as a result of the fork(2) system call
     (or other library code that calls fork, such as popen(3)).

     It is assumed that a program that clears all privileges as it prepares to execute another
     will also reset the environment, hence the “tainted” status will not be passed on.  This is
     important for programs such as su(1) which begin setuid but need to be able to create an
     untainted process.


     The issetugid() system call is always successful, and no return value is reserved to
     indicate an error.


     execve(2), fork(2), setegid(2), seteuid(2), setgid(2), setregid(2), setreuid(2), setuid(2)


     The issetugid() system call first appeared in OpenBSD 2.0 and was also implemented in
     FreeBSD 3.0.