8c060833c8
Thanks to Peter Vrabec. * NEWS, libmisc/find_new_gid.c, libmisc/find_new_uid.c: Build an index of used IDs to avoid a database request for each id in the allowed range (when the highest allowed ID is already used). This speedups the addition of users or groups when the highest allowed ID is already used. The additional memory usage of the tools should be acceptable when UID_MAX/SYS_UID_MAX are set to a reasonable number.
127 lines
4.1 KiB
C
127 lines
4.1 KiB
C
/*
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* Copyright (c) 1991 - 1994, Julianne Frances Haugh
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* Copyright (c) 2008 , 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 "prototypes.h"
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#include "groupio.h"
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#include "getdef.h"
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/*
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* find_new_gid - Find a new unused GID.
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*
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* If successful, find_new_gid provides an unused group ID in the
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* [GID_MIN:GID_MAX] range.
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* This ID should be higher than all the used GID, 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 GIDs are available.
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*/
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int find_new_gid (bool sys_group, gid_t *gid, gid_t const *preferred_gid)
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{
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const struct group *grp;
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gid_t gid_min, gid_max, group_id;
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char *used_gids;
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assert (gid != NULL);
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if (!sys_group) {
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gid_min = getdef_ulong ("GID_MIN", 1000L);
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gid_max = getdef_ulong ("GID_MAX", 60000L);
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} else {
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gid_min = getdef_ulong ("SYS_GID_MIN", 1L);
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gid_max = getdef_ulong ("GID_MIN", 1000L) - 1;
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gid_max = getdef_ulong ("SYS_GID_MAX", (unsigned long) gid_max);
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}
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used_gids = alloca (sizeof (char) * gid_max +1);
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memset (used_gids, 0, sizeof (char) * gid_max + 1);
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if ( (NULL != preferred_gid)
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&& (*preferred_gid >= gid_min)
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&& (*preferred_gid <= gid_max)
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/* Check if the user exists according to NSS */
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&& (getgrgid (*preferred_gid) == NULL)
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/* Check also the local database in case of uncommitted
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* changes */
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&& (gr_locate_gid (*preferred_gid) == NULL)) {
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*gid = *preferred_gid;
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return 0;
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}
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group_id = gid_min;
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/*
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* Search the entire group file,
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* looking for the largest unused value.
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*
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* We check the list of groups according to NSS (setgrent/getgrent),
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* but we also check the local database (gr_rewind/gr_next) in case
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* some groups were created but the changes were not committed yet.
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*/
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setgrent ();
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gr_rewind ();
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while ( ((grp = getgrent ()) != NULL)
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|| ((grp = gr_next ()) != NULL)) {
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if ((grp->gr_gid >= group_id) && (grp->gr_gid <= gid_max)) {
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group_id = grp->gr_gid + 1;
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}
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/* create index of used GIDs */
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if (grp->gr_gid <= gid_max) {
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used_gids[grp->gr_gid] = 1;
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}
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}
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endgrent ();
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/*
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* If a group with GID equal to GID_MAX exists, the above algorithm
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* will give us GID_MAX+1 even if not unique. Search for the first
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* free GID starting with GID_MIN.
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*/
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if (group_id == gid_max + 1) {
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for (group_id = gid_min; group_id < gid_max; group_id++) {
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if (0 == used_gids[grp->gr_gid]) {
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break;
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}
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}
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if (group_id == gid_max) {
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fprintf (stderr, _("%s: Can't get unique GID (no more available GIDs)\n"), Prog);
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SYSLOG ((LOG_WARN, "no more available GID on the system"));
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return -1;
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}
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}
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*gid = group_id;
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return 0;
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}
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