setreuid.2

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)setreuid.2	8.1	9/11/90
.TH setreuid 2
.SH Name
setreuid \- set real and effective user ID's
.SH Syntax
.nf
.B setreuid\fP(\fIruid, euid\fP)
.B int\fP\fIruid, euid\fP;
.fi
.SH Description
.NXR "setreuid system call"
.NXR "real user ID" "setting"
.NXR "effective user ID" "setting"
The real and effective user ID's of the
current process are set according to the arguments.
If
.I ruid
or 
.I euid
is \-1, the current uid is filled in by the system.
.SH Return Values
Upon successful completion, a value of zero (0) is returned.  Otherwise,
a value of \-1 is returned and \fIerrno\fP is set to indicate the error.
.SH Environment
.PP 
.B BSD
.br 
If the process is superuser, or 
.PN ruid
and
.PN euid
matches with the real user ID, the effective user ID, or the saved
set-user-id (as described in 
.MS execve 2
), then the real, effective, and the saved set-user-id are set to
.PN ruid ,
.PN euid ,
and
.PN euid ,
respectively.
.PP 
.B POSIX
.br
.B SYSTEM-FIVE
.br 
When your program is compiled in the POSIX or SYSTEM-FIVE mode,
if both arguments to 
.PN setreuid 
are \-1, the system call returns
a value of \-1 and errno is set to [EINVAL].
.PP
The following semantics apply when using the    
.PN setreuid
function:
.PP
If the process is the superuser, the real, effective, and saved
set-user-id (as described in
.MS execve 2
) are set to
.PN ruid ,
.PN euid ,
and
.PN euid ,
respectively.
.PP
If the process is not the superuser, but the
.PN ruid
and
.PN euid
matches with the real user ID, the effective user ID (only in
the SYSTEM-FIVE and BSD environments), or the saved set-user-id, then the
effective ID is set to 
.PN euid.  
The  real user ID and the saved set-user-id are left unchanged.
.SH Diagnostics
.TP 15
[EPERM]
The current process is not the superuser and the 
.PN euid
and
.PN ruid
specified does not match with the real user ID, the effective user ID
(only in SYSTEM-FIVE and BSD environment), or the saved set-user-id.
.SH See Also
getuid(2), setregid(2), setuid(3)