issetugid(2)                                                       System Calls                                                       issetugid(2)

NAME

       issetugid - determine if current executable is running setuid or setgid

SYNOPSIS

       #include <unistd.h>

       int issetugid(void);

DESCRIPTION

       The issetugid() function enables library functions (in libtermlib, libc, or other libraries) to guarantee safe behavior when used in setuid
       or setgid programs or programs that run with more privileges after a succesful exec(2). Some library functions might be passed insufficient
       information  and  not  know  whether  the  current program was started setuid or setgid because a higher level calling code might have made
       changes to the uid, euid, gid, or egid. These low-level library functions are therefore unable to determine if they are being run with ele-
       vated or normal privileges.

       The  issetugid()  function should be used to determine if a path name returned from a getenv(3C) call can be used safely to open the speci-
       fied file. It is often not safe to open such a file because the status of the effective uid is not known.

       The result of a call to issetugid() is unaffected by calls to setuid(), setgid(), or other such calls.  In case of a call to  fork(2),  the
       child process inherits the same status.

       The  status of issetugid() is affected only by execve() (see exec(2)). If a child process executes a new executable file, a new issetugid()
       status will be based on the existing process's uid, euid, gid, and egid permissions and on the modes of the executable  file.  If  the  new
       executable  file  modes  are setuid or setgid, or if the existing process is executing the new image with uid != euid or gid != egid, or if
       the permitted set before the call to the exec function is not a superset of the inheritable set at that time, issetugid() returns 1 in  the
       new process.

RETURN VALUES

       The  issetugid() function returns 1 if the process was made setuid or setgid as the result of the last or a previous call to execve(). Oth-
       erwise it returns 0.

ERRORS

       The issetugid() function is always successful. No return value is reserved to indicate an error.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Interface Stability          |Evolving                     |
       +-----------------------------+-----------------------------+
       |MT-Level                     |Async-Signal-Safe            |
       +-----------------------------+-----------------------------+

SEE ALSO

       exec(2), fork(2), setuid(2), getenv(3C), attributes(5), privileges(5)

SunOS 5.10                                                          19 Feb 2003                                                       issetugid(2)