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.
Change the current process’s real and effective user ID to that specified by integer. 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]
static VALUE
p_uid_change_privilege(obj, id)
VALUE obj, id;
{
int uid;
check_uid_switch();
uid = NUM2INT(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
rb_notimplement();
#endif
} else { /* unprivileged user */
#if defined(HAVE_SETRESUID)
if (setresuid((getuid() == uid)? -1: uid,
(geteuid() == uid)? -1: uid,
(SAVED_USER_ID == uid)? -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)? -1: uid,
(geteuid() == uid)? -1: uid) < 0) rb_sys_fail(0);
} else if (getuid() != uid) {
if (setreuid(uid, (geteuid() == uid)? -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 {
errno = EPERM;
rb_sys_fail(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 {
errno = EPERM;
rb_sys_fail(0);
}
#elif defined HAVE_SETEUID
if (getuid() == uid && SAVED_USER_ID == uid) {
if (seteuid(uid) < 0) rb_sys_fail(0);
} else {
errno = EPERM;
rb_sys_fail(0);
}
#elif defined HAVE_SETUID
if (getuid() == uid && SAVED_USER_ID == uid) {
if (setuid(uid) < 0) rb_sys_fail(0);
} else {
errno = EPERM;
rb_sys_fail(0);
}
#else
rb_notimplement();
#endif
}
return INT2FIX(uid);
}
Returns the effective user ID for this process.
Process.euid #=> 501
static VALUE
proc_geteuid(obj)
VALUE obj;
{
int euid = geteuid();
return INT2FIX(euid);
}
Set the effective user ID, and if possible, the saved user ID of the process to the given integer. 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]
static VALUE
p_uid_grant_privilege(obj, id)
VALUE obj, id;
{
return rb_seteuid_core(NUM2INT(id));
}
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]
static VALUE
p_uid_exchange(obj)
VALUE obj;
{
int uid, euid;
check_uid_switch();
uid = getuid();
euid = geteuid();
#if defined(HAVE_SETRESUID) && !defined(__CHECKER__)
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 INT2FIX(uid);
}
Returns true if the real and effective user IDs of a process may be exchanged on the current platform.
static VALUE
p_uid_exchangeable()
{
#if defined(HAVE_SETRESUID) && !defined(__CHECKER__)
return Qtrue;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
return Qtrue;
#else
return Qfalse;
#endif
}
Returns the (real) user ID of this process.
Process.uid #=> 501
static VALUE
proc_getuid(obj)
VALUE obj;
{
int uid = getuid();
return INT2FIX(uid);
}
Returns true if the current platform has saved user ID functionality.
static VALUE
p_uid_have_saved_id()
{
#if defined(HAVE_SETRESUID) || defined(HAVE_SETEUID) || defined(_POSIX_SAVED_IDS)
return Qtrue;
#else
return Qfalse;
#endif
}
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.
static VALUE
p_uid_switch(obj)
VALUE obj;
{
int uid, euid;
check_uid_switch();
uid = getuid();
euid = geteuid();
if (uid != euid) {
proc_seteuid(obj, INT2FIX(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 INT2FIX(euid);
}
} else if (euid != SAVED_USER_ID) {
proc_seteuid(obj, INT2FIX(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 INT2FIX(uid);
}
} else {
errno = EPERM;
rb_sys_fail(0);
}
#else
static VALUE
p_uid_sw_ensure(obj)
VALUE obj;
{
under_uid_switch = 0;
return p_uid_exchange(obj);
}
Commenting is here to help enhance the documentation. For example, sample code, or clarification of the documentation.
If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.
If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.