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The following commit(s) were added to refs/heads/master by this push:
new a9b72ed796c libc/grp: add getgrouplist()
a9b72ed796c is described below
commit a9b72ed796c515a1532c36ebccafb6f29978f248
Author: Xiang Xiao <[email protected]>
AuthorDate: Sun Jun 21 01:55:08 2026 +0800
libc/grp: add getgrouplist()
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 <[email protected]>
---
include/grp.h | 2 +
libs/libc/grp/CMakeLists.txt | 2 +-
libs/libc/grp/Make.defs | 2 +-
libs/libc/grp/lib_find_grpfile.c | 122 +++++++++++++++++++++++++++++++++++++++
libs/libc/grp/lib_getgrouplist.c | 95 ++++++++++++++++++++++++++++++
libs/libc/grp/lib_grp.h | 2 +
6 files changed, 223 insertions(+), 2 deletions(-)
diff --git a/include/grp.h b/include/grp.h
index d6297649eaf..1c4f215e54f 100644
--- a/include/grp.h
+++ b/include/grp.h
@@ -72,6 +72,8 @@ int getgrgid_r(gid_t gid, FAR struct group *grp,
FAR char *buf, size_t buflen,
FAR struct group **result);
int initgroups(FAR const char *user, gid_t group);
+int getgrouplist(FAR const char *user, gid_t group, FAR gid_t *groups,
+ FAR int *ngroups);
#undef EXTERN
#if defined(__cplusplus)
diff --git a/libs/libc/grp/CMakeLists.txt b/libs/libc/grp/CMakeLists.txt
index 83312f9b56f..62d98a9056a 100644
--- a/libs/libc/grp/CMakeLists.txt
+++ b/libs/libc/grp/CMakeLists.txt
@@ -20,7 +20,7 @@
#
#
##############################################################################
set(SRCS lib_getgrgid.c lib_getgrgidr.c lib_getgrnam.c lib_getgrnamr.c
- lib_initgroups.c)
+ lib_initgroups.c lib_getgrouplist.c)
if(CONFIG_LIBC_GROUP_FILE)
list(APPEND SRCS lib_find_grpfile.c lib_grp_globals.c)
diff --git a/libs/libc/grp/Make.defs b/libs/libc/grp/Make.defs
index 7680a6f2ba0..2fe4e37fc05 100644
--- a/libs/libc/grp/Make.defs
+++ b/libs/libc/grp/Make.defs
@@ -23,7 +23,7 @@
# Add the grp C files to the build
CSRCS += lib_getgrgid.c lib_getgrgidr.c lib_getgrnam.c lib_getgrnamr.c
-CSRCS += lib_initgroups.c
+CSRCS += lib_initgroups.c lib_getgrouplist.c
ifeq ($(CONFIG_LIBC_GROUP_FILE),y)
CSRCS += lib_find_grpfile.c lib_grp_globals.c
diff --git a/libs/libc/grp/lib_find_grpfile.c b/libs/libc/grp/lib_find_grpfile.c
index d0b90ca83a1..98c4cc48150 100644
--- a/libs/libc/grp/lib_find_grpfile.c
+++ b/libs/libc/grp/lib_find_grpfile.c
@@ -31,6 +31,9 @@
#include <string.h>
#include <grp.h>
#include <assert.h>
+#include <errno.h>
+
+#include <nuttx/lib/lib.h>
#include "grp/lib_grp.h"
@@ -41,6 +44,19 @@
typedef CODE int (grp_foreach_match_t)(FAR const struct group *entry,
uintptr_t arg);
+/* Context used by grp_match_user() to accumulate the group IDs of all the
+ * groups that a given user is a member of.
+ */
+
+struct grp_user_s
+{
+ FAR const char *user; /* User name to search for */
+ gid_t group; /* Primary group to skip (avoid duplicate) */
+ FAR gid_t *grouplist; /* Output array of group IDs */
+ int maxgroups; /* Number of slots in grouplist */
+ int count; /* Number of group IDs found so far */
+};
+
/****************************************************************************
* Private Functions
****************************************************************************/
@@ -93,6 +109,61 @@ static int grp_match_gid(FAR const struct group *entry,
uintptr_t arg)
return match_gid == entry->gr_gid ? 1 : 0;
}
+/****************************************************************************
+ * Name: grp_match_user
+ *
+ * Description:
+ * Called for each record in the group file. If the user (passed via the
+ * context in arg) is a member of the group, its group ID is appended to
+ * the caller's output array. Always returns 0 so that every record in
+ * the file is visited and the total number of matching groups is counted.
+ *
+ * Input Parameters:
+ * entry - The parsed group file record
+ * arg - A pointer to the grp_user_s search context
+ *
+ * Returned Value:
+ * = 0 : Always, so that iteration continues to the end of the file.
+ *
+ ****************************************************************************/
+
+static int grp_match_user(FAR const struct group *entry, uintptr_t arg)
+{
+ FAR struct grp_user_s *ctx = (FAR struct grp_user_s *)arg;
+ FAR char **member;
+
+ /* The primary group has already been accounted for by the caller. Skip
+ * it here to avoid reporting it twice.
+ */
+
+ if (entry->gr_gid == ctx->group)
+ {
+ return 0;
+ }
+
+ /* Check whether the user is listed as a member of this group. */
+
+ for (member = entry->gr_mem; *member != NULL; member++)
+ {
+ if (strcmp(*member, ctx->user) == 0)
+ {
+ /* Append the group ID if there is room in the output array. Keep
+ * counting regardless so the caller learns the required size.
+ */
+
+ if (ctx->count < ctx->maxgroups)
+ {
+ ctx->grouplist[ctx->count] = entry->gr_gid;
+ }
+
+ ctx->count++;
+ break;
+ }
+ }
+
+ return 0;
+}
+
/****************************************************************************
* Name: grp_foreach
*
@@ -337,3 +408,54 @@ int grp_findby_gid(gid_t gid, FAR struct group *entry, FAR
char *buffer,
return grp_foreach(grp_match_gid, (uintptr_t)gid, entry, buffer, buflen);
}
+
+/****************************************************************************
+ * Name: grp_findby_user
+ *
+ * Description:
+ * Scan the group file and collect the group IDs of all groups that have
+ * 'user' as a member, excluding the primary group 'group'.
+ *
+ * Input Parameters:
+ * user - The user name to search for
+ * group - The primary group ID to exclude from the search
+ * grouplist - Location to return the matching group IDs
+ * maxgroups - The number of slots available in grouplist
+ * count - On input, the number of group IDs already stored in
+ * grouplist. On output, the total number of group IDs found
+ * (which may exceed maxgroups).
+ *
+ * Returned Value:
+ * Zero (OK) is returned on success. A negated errno value is returned on
+ * any failure.
+ *
+ ****************************************************************************/
+
+int grp_findby_user(FAR const char *user, gid_t group,
+ FAR gid_t *grouplist, int maxgroups, FAR int *count)
+{
+ struct grp_user_s ctx;
+ struct group entry;
+ FAR char *buffer;
+ int ret;
+
+ buffer = lib_get_tempbuffer(GRPBUF_RESERVE_SIZE);
+ if (buffer == NULL)
+ {
+ return -ENOMEM;
+ }
+
+ ctx.user = user;
+ ctx.group = group;
+ ctx.grouplist = grouplist;
+ ctx.maxgroups = maxgroups;
+ ctx.count = *count;
+
+ ret = grp_foreach(grp_match_user, (uintptr_t)&ctx, &entry, buffer,
+ GRPBUF_RESERVE_SIZE);
+
+ *count = ctx.count;
+ lib_put_tempbuffer(buffer);
+
+ return ret < 0 ? ret : 0;
+}
diff --git a/libs/libc/grp/lib_getgrouplist.c b/libs/libc/grp/lib_getgrouplist.c
new file mode 100644
index 00000000000..a497434cdb1
--- /dev/null
+++ b/libs/libc/grp/lib_getgrouplist.c
@@ -0,0 +1,95 @@
+/****************************************************************************
+ * libs/libc/grp/lib_getgrouplist.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership. The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <grp.h>
+
+#include "grp/lib_grp.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: getgrouplist
+ *
+ * Description:
+ * The getgrouplist() function scans the group database to obtain the list
+ * of groups that 'user' belongs to. The group 'group' (typically the
+ * primary group ID from the password database) is always included in the
+ * returned list and is stored as the first element.
+ *
+ * Input Parameters:
+ * user - The user name whose group membership is queried.
+ * group - An additional group ID (the primary group) to include.
+ * groups - Location to return the list of group IDs.
+ * ngroups - On input, the number of slots available in groups. On output,
+ * the actual number of group IDs found.
+ *
+ * Returned Value:
+ * On success, the number of group IDs found is returned. If the number of
+ * groups exceeds the available space, -1 is returned and ngroups is set to
+ * the number of group IDs that would have been returned.
+ *
+ ****************************************************************************/
+
+int getgrouplist(FAR const char *user, gid_t group, FAR gid_t *groups,
+ FAR int *ngroups)
+{
+ int maxgroups = *ngroups;
+ int count;
+
+ /* The primary group is always reported first. */
+
+ if (maxgroups > 0)
+ {
+ groups[0] = group;
+ }
+
+ count = 1;
+
+#ifdef CONFIG_LIBC_GROUP_FILE
+ /* Scan the group file for any supplementary groups that 'user' belongs to
+ * and append their group IDs to the list.
+ */
+
+ grp_findby_user(user, group, groups, maxgroups, &count);
+#else
+ /* Without a group file there is no membership information, so only the
+ * primary group is reported.
+ */
+
+ UNUSED(user);
+#endif
+
+ /* If the caller's buffer was too small, report the required size and
+ * return failure. Otherwise, return the number of group IDs stored.
+ */
+
+ *ngroups = count;
+ return count > maxgroups ? -1 : count;
+}
diff --git a/libs/libc/grp/lib_grp.h b/libs/libc/grp/lib_grp.h
index a7dbf0efb05..0d84dd39652 100644
--- a/libs/libc/grp/lib_grp.h
+++ b/libs/libc/grp/lib_grp.h
@@ -83,6 +83,8 @@ int grp_findby_name(FAR const char *gname, FAR struct group
*entry,
FAR char *buffer, size_t buflen);
int grp_findby_gid(gid_t gid, FAR struct group *entry, FAR char *buffer,
size_t buflen);
+int grp_findby_user(FAR const char *user, gid_t group,
+ FAR gid_t *grouplist, int maxgroups, FAR int *count);
#endif
#undef EXTERN
