man3p/setreuid.3p

   1 .\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
   2 .TH "SETREUID" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
   3 .\" setreuid
   4 .SH NAME
   5 setreuid \- set real and effective user IDs
   6 .SH SYNOPSIS
   7 .LP
   8 \fB#include <unistd.h>
   9 .br
  10 .sp
  11 int setreuid(uid_t\fP \fIruid\fP\fB, uid_t\fP \fIeuid\fP\fB); \fP
  12 \fB
  13 .br
  14 \fP
  15 .SH DESCRIPTION
  16 .LP
  17 The \fIsetreuid\fP() function shall set the real and effective user
  18 IDs of the current process to the values specified by the
  19 \fIruid\fP and \fIeuid\fP arguments. If \fIruid\fP or \fIeuid\fP is
  20 -1, the corresponding effective or real user ID of the
  21 current process shall be left unchanged.
  22 .LP
  23 A process with appropriate privileges can set either ID to any value.
  24 An unprivileged process can only set the effective user ID
  25 if the \fIeuid\fP argument is equal to either the real, effective,
  26 or saved user ID of the process.
  27 .LP
  28 It is unspecified whether a process without appropriate privileges
  29 is permitted to change the real user ID to match the current
  30 real, effective, or saved set-user-ID of the process.
  31 .SH RETURN VALUE
  32 .LP
  33 Upon successful completion, 0 shall be returned. Otherwise, -1 shall
  34 be returned and \fIerrno\fP set to indicate the error.
  35 .SH ERRORS
  36 .LP
  37 The \fIsetreuid\fP() function shall fail if:
  38 .TP 7
  39 .B EINVAL
  40 The value of the \fIruid\fP or \fIeuid\fP argument is invalid or out-of-range.
  41 .TP 7
  42 .B EPERM
  43 The current process does not have appropriate privileges, and either
  44 an attempt was made to change the effective user ID to a
  45 value other than the real user ID or the saved set-user-ID or an attempt
  46 was made to change the real user ID to a value not
  47 permitted by the implementation.
  48 .sp
  49 .LP
  50 \fIThe following sections are informative.\fP
  51 .SH EXAMPLES
  52 .SS Setting the Effective User ID to the Real User ID
  53 .LP
  54 The following example sets the effective user ID of the calling process
  55 to the real user ID, so that files created later will be
  56 owned by the current user.
  57 .sp
  58 .RS
  59 .nf
  60
  61 \fB#include <unistd.h>
  62 #include <sys/types.h>
  63 \&...
  64 setreuid(getuid(), getuid());
  65 \&...
  66 \fP
  67 .fi
  68 .RE
  69 .SH APPLICATION USAGE
  70 .LP
  71 None.
  72 .SH RATIONALE
  73 .LP
  74 None.
  75 .SH FUTURE DIRECTIONS
  76 .LP
  77 None.
  78 .SH SEE ALSO
  79 .LP
  80 \fIgetegid\fP() , \fIgeteuid\fP() , \fIgetgid\fP() , \fIgetuid\fP()
  81 , \fIsetegid\fP() , \fIseteuid\fP() , \fIsetgid\fP() , \fIsetregid\fP()
  82 , \fIsetuid\fP() , the Base Definitions volume of
  83 IEEE\ Std\ 1003.1-2001, \fI<unistd.h>\fP
  84 .SH COPYRIGHT
  85 Portions of this text are reprinted and reproduced in electronic form
  86 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
  87 -- Portable Operating System Interface (POSIX), The Open Group Base
  88 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
  89 Electrical and Electronics Engineers, Inc and The Open Group. In the
  90 event of any discrepancy between this version and the original IEEE and
  91 The Open Group Standard, the original IEEE and The Open Group Standard
  92 is the referee document. The original Standard can be obtained online at
  93 http://www.opengroup.org/unix/online.html .