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a9b72ed796
Add getgrouplist() to the C library. It scans the group database for a user's supplementary groups and always reports the primary group first. Without CONFIG_LIBC_GROUP_FILE only the primary group is returned, since no membership information is available. The group file is read through lib_get_tempbuffer()/lib_put_tempbuffer() to avoid a heap allocation on every lookup. Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
95 lines
3.3 KiB
C
95 lines
3.3 KiB
C
/****************************************************************************
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* libs/libc/grp/lib_getgrouplist.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <grp.h>
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#include "grp/lib_grp.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: getgrouplist
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*
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* Description:
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* The getgrouplist() function scans the group database to obtain the list
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* of groups that 'user' belongs to. The group 'group' (typically the
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* primary group ID from the password database) is always included in the
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* returned list and is stored as the first element.
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*
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* Input Parameters:
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* user - The user name whose group membership is queried.
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* group - An additional group ID (the primary group) to include.
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* groups - Location to return the list of group IDs.
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* ngroups - On input, the number of slots available in groups. On output,
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* the actual number of group IDs found.
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*
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* Returned Value:
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* On success, the number of group IDs found is returned. If the number of
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* groups exceeds the available space, -1 is returned and ngroups is set to
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* the number of group IDs that would have been returned.
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*
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****************************************************************************/
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int getgrouplist(FAR const char *user, gid_t group, FAR gid_t *groups,
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FAR int *ngroups)
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{
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int maxgroups = *ngroups;
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int count;
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/* The primary group is always reported first. */
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if (maxgroups > 0)
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{
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groups[0] = group;
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}
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count = 1;
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#ifdef CONFIG_LIBC_GROUP_FILE
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/* Scan the group file for any supplementary groups that 'user' belongs to
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* and append their group IDs to the list.
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*/
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grp_findby_user(user, group, groups, maxgroups, &count);
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#else
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/* Without a group file there is no membership information, so only the
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* primary group is reported.
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*/
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UNUSED(user);
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#endif
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/* If the caller's buffer was too small, report the required size and
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* return failure. Otherwise, return the number of group IDs stored.
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*/
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*ngroups = count;
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return count > maxgroups ? -1 : count;
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}
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