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ISSETUGID(2)                BSD System Calls Manual               ISSETUGID(2)

NAME
     issetugid -- is current process tainted by uid or gid changes

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     issetugid(void);

DESCRIPTION
     The issetugid() system call returns 1 if the process environment or mem-ory memory
     ory 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 privi-leges privileges
     leges 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 execution.

     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 operation.

     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.

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

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

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

BSD                             August 25, 1996                            BSD