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getresgid(2) [debian man page]

SETRESUID(2)						      BSD System Calls Manual						      SETRESUID(2)

getresgid, getresuid, setresgid, setresuid -- get or set real, effective and saved user or group ID LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/types.h> #include <unistd.h> int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid); int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid); int setresgid(gid_t rgid, gid_t egid, gid_t sgid); int setresuid(uid_t ruid, uid_t euid, uid_t suid); DESCRIPTION
The setresuid() system call sets the real, effective and saved user IDs of the current process. The analogous setresgid() sets the real, effective and saved group IDs. Privileged processes may set these IDs to arbitrary values. Unprivileged processes are restricted in that each of the new IDs must match one of the current IDs. Passing -1 as an argument causes the corresponding value to remain unchanged. The getresgid() and getresuid() calls retrieve the real, effective, and saved group and user IDs of the current process, respectively. RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error. ERRORS
[EPERM] The calling process was not privileged and tried to change one or more IDs to a value which was not the current real ID, the current effective ID nor the current saved ID. [EFAULT] An address passed to getresgid() or getresuid() was invalid. SEE ALSO
getegid(2), geteuid(2), getgid(2), getuid(2), issetugid(2), setgid(2), setregid(2), setreuid(2), setuid(2) STANDARDS
These system calls are not available on many platforms. They exist in FreeBSD to support Linux binaries linked against GNU libc2. HISTORY
These functions first appeared in HP-UX. BSD
April 13, 2001 BSD

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SETRESUID(2)						     Linux Programmer's Manual						      SETRESUID(2)

setresuid, setresgid - set real, effective and saved user or group ID SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */ #include <unistd.h> int setresuid(uid_t ruid, uid_t euid, uid_t suid); int setresgid(gid_t rgid, gid_t egid, gid_t sgid); DESCRIPTION
setresuid() sets the real user ID, the effective user ID, and the saved set-user-ID of the calling process. Unprivileged user processes may change the real UID, effective UID, and saved set-user-ID, each to one of: the current real UID, the cur- rent effective UID or the current saved set-user-ID. Privileged processes (on Linux, those having the CAP_SETUID capability) may set the real UID, effective UID, and saved set-user-ID to arbi- trary values. If one of the arguments equals -1, the corresponding value is not changed. Regardless of what changes are made to the real UID, effective UID, and saved set-user-ID, the file system UID is always set to the same value as the (possibly new) effective UID. Completely analogously, setresgid() sets the real GID, effective GID, and saved set-group-ID of the calling process (and always modifies the file system GID to be the same as the effective GID), with the same restrictions for unprivileged processes. RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately. ERRORS
EAGAIN uid does not match the current UID and this call would bring that user ID over its RLIMIT_NPROC resource limit. EPERM The calling process is not privileged (did not have the CAP_SETUID capability) and tried to change the IDs to values that are not permitted. VERSIONS
These calls are available under Linux since Linux 2.1.44. CONFORMING TO
These calls are nonstandard; they also appear on HP-UX and some of the BSDs. NOTES
Under HP-UX and FreeBSD, the prototype is found in <unistd.h>. Under Linux the prototype is provided by glibc since version 2.3.2. The original Linux setresuid() and setresgid() system calls supported only 16-bit user and group IDs. Subsequently, Linux 2.4 added setre- suid32() and setresgid32(), supporting 32-bit IDs. The glibc setresuid() and setresgid() wrapper functions transparently deal with the variations across kernel versions. SEE ALSO
getresuid(2), getuid(2), setfsgid(2), setfsuid(2), setreuid(2), setuid(2), capabilities(7), credentials(7) COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at Linux 2010-11-22 SETRESUID(2)
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