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diff --git a/lib/list.c b/lib/list.c
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+/*
+ * SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh
+ * SPDX-FileCopyrightText: 1996 - 1997, Marek Michałkiewicz
+ * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <assert.h>
+
+#include "alloc.h"
+#include "prototypes.h"
+#include "defines.h"
+/*
+ * add_list - add a member to a list of group members
+ *
+ * the array of member names is searched for the new member
+ * name, and if not present it is added to a freshly allocated
+ * list of users.
+ */
+/*@only@*/char **
+add_list(/*@returned@*/ /*@only@*/char **list, const char *member)
+{
+ int i;
+ char **tmp;
+
+ assert (NULL != member);
+ assert (NULL != list);
+
+ /*
+ * Scan the list for the new name. Return the original list
+ * pointer if it is present.
+ */
+
+ for (i = 0; list[i] != NULL; i++) {
+ if (strcmp (list[i], member) == 0) {
+ return list;
+ }
+ }
+
+ /*
+ * Allocate a new list pointer large enough to hold all the
+ * old entries, and the new entries as well.
+ */
+
+ tmp = XMALLOC(i + 2, char *);
+
+ /*
+ * Copy the original list to the new list, then append the
+ * new member and NULL terminate the result. This new list
+ * is returned to the invoker.
+ */
+
+ for (i = 0; list[i] != NULL; i++) {
+ tmp[i] = list[i];
+ }
+
+ tmp[i] = xstrdup (member);
+ tmp[i+1] = NULL;
+
+ return tmp;
+}
+
+/*
+ * del_list - delete a member from a list of group members
+ *
+ * the array of member names is searched for the old member
+ * name, and if present it is deleted from a freshly allocated
+ * list of users.
+ */
+
+/*@only@*/char **
+del_list(/*@returned@*/ /*@only@*/char **list, const char *member)
+{
+ int i, j;
+ char **tmp;
+
+ assert (NULL != member);
+ assert (NULL != list);
+
+ /*
+ * Scan the list for the old name. Return the original list
+ * pointer if it is not present.
+ */
+
+ for (i = j = 0; list[i] != NULL; i++) {
+ if (strcmp (list[i], member) != 0) {
+ j++;
+ }
+ }
+
+ if (j == i) {
+ return list;
+ }
+
+ /*
+ * Allocate a new list pointer large enough to hold all the
+ * old entries.
+ */
+
+ tmp = XMALLOC(j + 1, char *);
+
+ /*
+ * Copy the original list except the deleted members to the
+ * new list, then NULL terminate the result. This new list
+ * is returned to the invoker.
+ */
+
+ for (i = j = 0; list[i] != NULL; i++) {
+ if (strcmp (list[i], member) != 0) {
+ tmp[j] = list[i];
+ j++;
+ }
+ }
+
+ tmp[j] = NULL;
+
+ return tmp;
+}
+
+/*
+ * Duplicate a list.
+ * The input list is not modified, but in order to allow the use of this
+ * function with list of members, the list elements are not enforced to be
+ * constant strings here.
+ */
+/*@only@*/char **
+dup_list(char *const *list)
+{
+ int i;
+ char **tmp;
+
+ assert (NULL != list);
+
+ for (i = 0; NULL != list[i]; i++);
+
+ tmp = XMALLOC(i + 1, char *);
+
+ i = 0;
+ while (NULL != *list) {
+ tmp[i] = xstrdup (*list);
+ i++;
+ list++;
+ }
+
+ tmp[i] = NULL;
+ return tmp;
+}
+
+/*
+ * Check if member is part of the input list
+ * The input list is not modified, but in order to allow the use of this
+ * function with list of members, the list elements are not enforced to be
+ * constant strings here.
+ */
+bool is_on_list (char *const *list, const char *member)
+{
+ assert (NULL != member);
+ assert (NULL != list);
+
+ while (NULL != *list) {
+ if (strcmp (*list, member) == 0) {
+ return true;
+ }
+ list++;
+ }
+
+ return false;
+}
+
+/*
+ * comma_to_list - convert comma-separated list to (char *) array
+ */
+
+/*@only@*/char **comma_to_list (const char *comma)
+{
+ char *members;
+ char **array;
+ int i;
+ char *cp;
+ char *cp2;
+
+ assert (NULL != comma);
+
+ /*
+ * Make a copy since we are going to be modifying the list
+ */
+
+ members = xstrdup (comma);
+
+ /*
+ * Count the number of commas in the list
+ */
+
+ for (cp = members, i = 0;; i++) {
+ cp2 = strchr (cp, ',');
+ if (NULL != cp2) {
+ cp = cp2 + 1;
+ } else {
+ break;
+ }
+ }
+
+ /*
+ * Add 2 - one for the ending NULL, the other for the last item
+ */
+
+ i += 2;
+
+ /*
+ * Allocate the array we're going to store the pointers into.
+ */
+
+ array = XMALLOC(i, char *);
+
+ /*
+ * Empty list is special - 0 members, not 1 empty member. --marekm
+ */
+
+ if ('\0' == *members) {
+ *array = NULL;
+ free (members);
+ return array;
+ }
+
+ /*
+ * Now go walk that list all over again, this time building the
+ * array of pointers.
+ */
+
+ for (cp = members, i = 0; cp != NULL; i++)
+ array[i] = strsep(&cp, ",");
+ array[i] = NULL;
+
+ /*
+ * Return the new array of pointers
+ */
+
+ return array;
+}
+