man2/getresuid.2

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  24 .\" Modified, 2003-05-26, Michael Kerrisk, <mtk.manpages@gmail.com>
  25 .TH GETRESUID 2 2010-11-22 "Linux" "Linux Programmer's Manual"
  26 .SH NAME
  27 getresuid, getresgid \- get real, effective and saved user/group IDs
  28 .SH SYNOPSIS
  29 .BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
  30 .br
  31 .B #include <unistd.h>
  32 .sp
  33 .BI "int getresuid(uid_t *" ruid ", uid_t *" euid ", uid_t *" suid );
  34 .br
  35 .BI "int getresgid(gid_t *" rgid ", gid_t *" egid ", gid_t *" sgid );
  36 .SH DESCRIPTION
  37 .BR getresuid ()
  38 returns the real UID, the effective UID, and the saved set-user-ID
  39 of the calling process, in the arguments
  40 .IR ruid ,
  41 .IR euid ,
  42 and
  43 .IR suid ,
  44 respectively.
  45 .BR getresgid ()
  46 performs the analogous task for the process's group IDs.
  47 .SH RETURN VALUE
  48 On success, zero is returned.
  49 On error, \-1 is returned, and
  50 .I errno
  51 is set appropriately.
  52 .SH ERRORS
  53 .TP
  54 .B EFAULT
  55 One of the arguments specified an address outside the calling program's
  56 address space.
  57 .SH VERSIONS
  58 These system calls appeared on Linux starting with kernel 2.1.44.
  59
  60 The prototypes are given by glibc since version 2.3.2,
  61 provided
  62 .B _GNU_SOURCE
  63 is defined.
  64 .SH CONFORMING TO
  65 These calls are nonstandard;
  66 they also appear on HP-UX and some of the BSDs.
  67 .SH NOTES
  68 The original Linux
  69 .BR getresuid ()
  70 and
  71 .BR getresgid ()
  72 system calls supported only 16-bit user and group IDs.
  73 Subsequently, Linux 2.4 added
  74 .BR getresuid32 ()
  75 and
  76 .BR getresgid32 (),
  77 supporting 32-bit IDs.
  78 The glibc
  79 .BR getresuid ()
  80 and
  81 .BR getresgid ()
  82 wrapper functions transparently deal with the variations across kernel versions.
  83 .SH SEE ALSO
  84 .BR getuid (2),
  85 .BR setresuid (2),
  86 .BR setreuid (2),
  87 .BR setuid (2),
  88 .BR credentials (7)