210 lines
6.4 KiB
C
210 lines
6.4 KiB
C
/*
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* Copyright (c) 1991 - 1994, Julianne Frances Haugh
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* Copyright (c) 2008 - 2011, Nicolas François
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the copyright holders or contributors may not be used to
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* endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <config.h>
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#include <assert.h>
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#include <stdio.h>
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#include <errno.h>
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#include "prototypes.h"
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#include "pwio.h"
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#include "getdef.h"
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/*
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* find_new_uid - Find a new unused UID.
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*
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* If successful, find_new_uid provides an unused user ID in the
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* [UID_MIN:UID_MAX] range.
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* This ID should be higher than all the used UID, but if not possible,
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* the lowest unused ID in the range will be returned.
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*
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* Return 0 on success, -1 if no unused UIDs are available.
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*/
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int find_new_uid (bool sys_user,
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uid_t *uid,
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/*@null@*/uid_t const *preferred_uid)
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{
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const struct passwd *pwd;
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uid_t uid_min, uid_max, user_id;
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bool *used_uids;
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assert (uid != NULL);
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if (!sys_user) {
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uid_min = (uid_t) getdef_ulong ("UID_MIN", 1000UL);
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uid_max = (uid_t) getdef_ulong ("UID_MAX", 60000UL);
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if (uid_max < uid_min) {
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(void) fprintf (stderr,
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_("%s: Invalid configuration: UID_MIN (%lu), UID_MAX (%lu)\n"),
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Prog, (unsigned long) uid_min, (unsigned long) uid_max);
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return -1;
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}
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} else {
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uid_min = (uid_t) getdef_ulong ("SYS_UID_MIN", 101UL);
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uid_max = (uid_t) getdef_ulong ("UID_MIN", 1000UL) - 1;
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uid_max = (uid_t) getdef_ulong ("SYS_UID_MAX", (unsigned long) uid_max);
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if (uid_max < uid_min) {
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(void) fprintf (stderr,
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_("%s: Invalid configuration: SYS_UID_MIN (%lu), UID_MIN (%lu), SYS_UID_MAX (%lu)\n"),
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Prog, (unsigned long) uid_min, getdef_ulong ("UID_MIN", 1000UL), (unsigned long) uid_max);
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return -1;
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}
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}
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used_uids = malloc (sizeof (bool) * (uid_max +1));
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if (NULL == used_uids) {
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fprintf (stderr,
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_("%s: failed to allocate memory: %s\n"),
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Prog, strerror (errno));
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return -1;
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}
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memset (used_uids, false, sizeof (bool) * (uid_max + 1));
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if ( (NULL != preferred_uid)
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&& (*preferred_uid >= uid_min)
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&& (*preferred_uid <= uid_max)
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/* Check if the user exists according to NSS */
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&& (getpwuid (*preferred_uid) == NULL)
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/* Check also the local database in case of uncommitted
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* changes */
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&& (pw_locate_uid (*preferred_uid) == NULL)) {
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*uid = *preferred_uid;
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free (used_uids);
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return 0;
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}
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/*
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* Search the entire password file,
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* looking for the largest unused value.
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*
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* We check the list of users according to NSS (setpwent/getpwent),
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* but we also check the local database (pw_rewind/pw_next) in case
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* some users were created but the changes were not committed yet.
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*/
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if (sys_user) {
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uid_t id;
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/* setpwent / getpwent / endpwent can be very slow with
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* LDAP configurations (and many accounts).
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* Since there is a limited amount of IDs to be tested
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* for system accounts, we just check the existence
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* of IDs with getpwuid.
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*/
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user_id = uid_max;
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for (id = uid_max; id >= uid_min; id--) {
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if (getpwuid (id) != NULL) {
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user_id = id - 1;
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used_uids[id] = true;
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}
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}
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(void) pw_rewind ();
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while ((pwd = pw_next ()) != NULL) {
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if ((pwd->pw_uid <= user_id) && (pwd->pw_uid >= uid_min)) {
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user_id = pwd->pw_uid - 1;
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}
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/* create index of used UIDs */
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if (pwd->pw_uid <= uid_max) {
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used_uids[pwd->pw_uid] = true;
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}
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}
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} else {
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user_id = uid_min;
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setpwent ();
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while ((pwd = getpwent ()) != NULL) {
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if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) {
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user_id = pwd->pw_uid + 1;
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}
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/* create index of used UIDs */
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if (pwd->pw_uid <= uid_max) {
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used_uids[pwd->pw_uid] = true;
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}
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}
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endpwent ();
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(void) pw_rewind ();
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while ((pwd = pw_next ()) != NULL) {
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if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) {
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user_id = pwd->pw_uid + 1;
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}
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/* create index of used UIDs */
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if (pwd->pw_uid <= uid_max) {
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used_uids[pwd->pw_uid] = true;
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}
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}
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}
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/*
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* If a user (resp. system user) with UID equal to UID_MAX (resp.
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* UID_MIN) exists, the above algorithm will give us UID_MAX+1
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* (resp. UID_MIN-1) even if not unique. Search for the first free
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* UID starting with UID_MIN (resp. UID_MAX).
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*/
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if (sys_user) {
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if (user_id < uid_min) {
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for (user_id = uid_max; user_id >= uid_min; user_id--) {
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if (false == used_uids[user_id]) {
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break;
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}
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}
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if (user_id < uid_min ) {
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fprintf (stderr,
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_("%s: Can't get unique system UID (no more available UIDs)\n"),
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Prog);
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SYSLOG ((LOG_WARN,
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"no more available UID on the system"));
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free (used_uids);
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return -1;
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}
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}
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} else {
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if (user_id > uid_max) {
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for (user_id = uid_min; user_id <= uid_max; user_id++) {
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if (false == used_uids[user_id]) {
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break;
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}
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}
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if (user_id > uid_max) {
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fprintf (stderr,
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_("%s: Can't get unique UID (no more available UIDs)\n"),
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Prog);
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SYSLOG ((LOG_WARN, "no more available UID on the system"));
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free (used_uids);
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return -1;
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}
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}
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}
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free (used_uids);
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*uid = user_id;
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return 0;
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}
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