issetugid.2   [plain text]


.\"	$OpenBSD: issetugid.2,v 1.7 1997/02/18 00:16:09 deraadt Exp $
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.Dd August, 25 1996
.Dt ISSETUGID 2
.Os OpenBSD 2.0
.Sh NAME
.Nm issetugid
.Nd is current executable running setuid or setgid
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn issetugid void
.Sh DESCRIPTION
The
.Fn issetugid
function returns 1 if the process was made setuid or setgid as
the result of the last
.Fn execve
system call.
Otherwise it returns 0.
.Pp
This system call exists so that library routines (inside libc, libtermlib,
or other libraries) can gaurantee safe behavior when used inside
setuid or setgid programs.
Some library routines may not be passed sufficient information to know
if the current program was started setuid or setgid because higher level
calling code may have made changes to the uid or the euid.
In particular, it is wise to use this call to determine if a
pathname returned from a
.Fn getenv
call may safely be used to
.Fn open
the specified file.
.Pp
.Fn issetugid
is unaffected by calls to
.Fn setuid ,
.Fn fork ,
and other such calls.  It is only controlled by
.Fn execve .
.Sh ERRORS
The
.Fn issetugid
function is always successful, and no return value is reserved to
indicate an error.
.Sh SEE ALSO
.Xr execve 2 ,
.Xr setuid 2 ,
.Xr seteuid 2,
.Xr setgid 2 ,
.Xr setegid 2
.Sh HISTORY
A
.Fn lstat
function call appeared in
OpenBSD 2.0