Module
The Process::UID module contains a collection of module functions which can be used to portably get, set, and switch the current process’s real, effective, and saved user IDs.
Class Methods
process.c
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static VALUE
p_uid_change_privilege(VALUE obj, VALUE id)
{
rb_uid_t uid;
check_uid_switch();
uid = OBJ2UID(id);
if (geteuid() == 0) { /* root-user */
#if defined(HAVE_SETRESUID)
if (setresuid(uid, uid, uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
#elif defined(HAVE_SETUID)
if (setuid(uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
if (getuid() == uid) {
if (SAVED_USER_ID == uid) {
if (setreuid(-1, uid) < 0) rb_sys_fail(0);
}
else {
if (uid == 0) { /* (r,e,s) == (root, root, x) */
if (setreuid(-1, SAVED_USER_ID) < 0) rb_sys_fail(0);
if (setreuid(SAVED_USER_ID, 0) < 0) rb_sys_fail(0);
SAVED_USER_ID = 0; /* (r,e,s) == (x, root, root) */
if (setreuid(uid, uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
else {
if (setreuid(0, -1) < 0) rb_sys_fail(0);
SAVED_USER_ID = 0;
if (setreuid(uid, uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
}
}
else {
if (setreuid(uid, uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
#elif defined(HAVE_SETRUID) && defined(HAVE_SETEUID)
if (getuid() == uid) {
if (SAVED_USER_ID == uid) {
if (seteuid(uid) < 0) rb_sys_fail(0);
}
else {
if (uid == 0) {
if (setruid(SAVED_USER_ID) < 0) rb_sys_fail(0);
SAVED_USER_ID = 0;
if (setruid(0) < 0) rb_sys_fail(0);
}
else {
if (setruid(0) < 0) rb_sys_fail(0);
SAVED_USER_ID = 0;
if (seteuid(uid) < 0) rb_sys_fail(0);
if (setruid(uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
}
}
else {
if (seteuid(uid) < 0) rb_sys_fail(0);
if (setruid(uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
#else
(void)uid;
rb_notimplement();
#endif
}
else { /* unprivileged user */
#if defined(HAVE_SETRESUID)
if (setresuid((getuid() == uid)? (rb_uid_t)-1: uid,
(geteuid() == uid)? (rb_uid_t)-1: uid,
(SAVED_USER_ID == uid)? (rb_uid_t)-1: uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
if (SAVED_USER_ID == uid) {
if (setreuid((getuid() == uid)? (rb_uid_t)-1: uid,
(geteuid() == uid)? (rb_uid_t)-1: uid) < 0)
rb_sys_fail(0);
}
else if (getuid() != uid) {
if (setreuid(uid, (geteuid() == uid)? (rb_uid_t)-1: uid) < 0)
rb_sys_fail(0);
SAVED_USER_ID = uid;
}
else if (/* getuid() == uid && */ geteuid() != uid) {
if (setreuid(geteuid(), uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
if (setreuid(uid, -1) < 0) rb_sys_fail(0);
}
else { /* getuid() == uid && geteuid() == uid */
if (setreuid(-1, SAVED_USER_ID) < 0) rb_sys_fail(0);
if (setreuid(SAVED_USER_ID, uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
if (setreuid(uid, -1) < 0) rb_sys_fail(0);
}
#elif defined(HAVE_SETRUID) && defined(HAVE_SETEUID)
if (SAVED_USER_ID == uid) {
if (geteuid() != uid && seteuid(uid) < 0) rb_sys_fail(0);
if (getuid() != uid && setruid(uid) < 0) rb_sys_fail(0);
}
else if (/* SAVED_USER_ID != uid && */ geteuid() == uid) {
if (getuid() != uid) {
if (setruid(uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
else {
if (setruid(SAVED_USER_ID) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
if (setruid(uid) < 0) rb_sys_fail(0);
}
}
else if (/* geteuid() != uid && */ getuid() == uid) {
if (seteuid(uid) < 0) rb_sys_fail(0);
if (setruid(SAVED_USER_ID) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
if (setruid(uid) < 0) rb_sys_fail(0);
}
else {
rb_syserr_fail(EPERM, 0);
}
#elif defined HAVE_44BSD_SETUID
if (getuid() == uid) {
/* (r,e,s)==(uid,?,?) ==> (uid,uid,uid) */
if (setuid(uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
}
else {
rb_syserr_fail(EPERM, 0);
}
#elif defined HAVE_SETEUID
if (getuid() == uid && SAVED_USER_ID == uid) {
if (seteuid(uid) < 0) rb_sys_fail(0);
}
else {
rb_syserr_fail(EPERM, 0);
}
#elif defined HAVE_SETUID
if (getuid() == uid && SAVED_USER_ID == uid) {
if (setuid(uid) < 0) rb_sys_fail(0);
}
else {
rb_syserr_fail(EPERM, 0);
}
#else
rb_notimplement();
#endif
}
return id;
}
Change the current process’s real and effective user ID to that specified by user. Returns the new user ID. Not available on all platforms.
[Process.uid, Process.euid] #=> [0, 0] Process::UID.change_privilege(31) #=> 31 [Process.uid, Process.euid] #=> [31, 31]
process.c
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static VALUE
proc_geteuid(VALUE obj)
{
rb_uid_t euid = geteuid();
return UIDT2NUM(euid);
}
Returns the effective user ID for the current process.
Process.euid # => 501
process.c
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static VALUE
p_uid_from_name(VALUE self, VALUE id)
{
return UIDT2NUM(OBJ2UID(id));
}
Get the user ID by the name. If the user is not found, ArgumentError will be raised.
Process::UID.from_name("root") #=> 0 Process::UID.from_name("nosuchuser") #=> can't find user for nosuchuser (ArgumentError)
process.c
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static VALUE
p_uid_grant_privilege(VALUE obj, VALUE id)
{
rb_seteuid_core(OBJ2UID(id));
return id;
}
Set the effective user ID, and if possible, the saved user ID of the process to the given user. Returns the new effective user ID. Not available on all platforms.
[Process.uid, Process.euid] #=> [0, 0] Process::UID.grant_privilege(31) #=> 31 [Process.uid, Process.euid] #=> [0, 31]
process.c
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static VALUE
p_uid_exchange(VALUE obj)
{
rb_uid_t uid;
#if defined(HAVE_SETRESUID) || (defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID))
rb_uid_t euid;
#endif
check_uid_switch();
uid = getuid();
#if defined(HAVE_SETRESUID) || (defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID))
euid = geteuid();
#endif
#if defined(HAVE_SETRESUID)
if (setresuid(euid, uid, uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
if (setreuid(euid,uid) < 0) rb_sys_fail(0);
SAVED_USER_ID = uid;
#else
rb_notimplement();
#endif
return UIDT2NUM(uid);
}
Exchange real and effective user IDs and return the new effective user ID. Not available on all platforms.
[Process.uid, Process.euid] #=> [0, 31] Process::UID.re_exchange #=> 0 [Process.uid, Process.euid] #=> [31, 0]
process.c
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static VALUE
p_uid_exchangeable(VALUE _)
{
#if defined(HAVE_SETRESUID)
return Qtrue;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
return Qtrue;
#else
return Qfalse;
#endif
}
Returns true if the real and effective user IDs of a process may be exchanged on the current platform.
process.c
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static VALUE
proc_getuid(VALUE obj)
{
rb_uid_t uid = getuid();
return UIDT2NUM(uid);
}
Returns the (real) user ID of the current process.
Process.uid # => 1000
process.c
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static VALUE
p_uid_have_saved_id(VALUE _)
{
#if defined(HAVE_SETRESUID) || defined(HAVE_SETEUID) || defined(_POSIX_SAVED_IDS)
return Qtrue;
#else
return Qfalse;
#endif
}
Returns true if the current platform has saved user ID functionality.
process.c
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static VALUE
p_uid_switch(VALUE obj)
{
rb_uid_t uid, euid;
check_uid_switch();
uid = getuid();
euid = geteuid();
if (uid != euid) {
proc_seteuid(uid);
if (rb_block_given_p()) {
under_uid_switch = 1;
return rb_ensure(rb_yield, Qnil, p_uid_sw_ensure, SAVED_USER_ID);
}
else {
return UIDT2NUM(euid);
}
}
else if (euid != SAVED_USER_ID) {
proc_seteuid(SAVED_USER_ID);
if (rb_block_given_p()) {
under_uid_switch = 1;
return rb_ensure(rb_yield, Qnil, p_uid_sw_ensure, euid);
}
else {
return UIDT2NUM(uid);
}
}
else {
rb_syserr_fail(EPERM, 0);
}
UNREACHABLE_RETURN(Qnil);
}
Switch the effective and real user IDs of the current process. If a block is given, the user IDs will be switched back after the block is executed. Returns the new effective user ID if called without a block, and the return value of the block if one is given.