1 /* `group_member' -- test if process is in a given group. 2 Copyright (C) 1995-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #include <sys/types.h> 20 #include <unistd.h> 21 #include <stdlib.h> 22 #include <limits.h> 23 24 #ifndef NGROUPS_MAX 25 #define NGROUPS_MAX 16 /* First guess. */ 26 #endif 27 28 int __group_member(gid_t gid)29__group_member (gid_t gid) 30 { 31 int n, size; 32 gid_t *groups; 33 34 size = NGROUPS_MAX; 35 do 36 { 37 groups = __alloca (size * sizeof *groups); 38 n = __getgroups (size, groups); 39 size *= 2; 40 } 41 while (n == size / 2); 42 43 while (n-- > 0) 44 if (groups[n] == gid) 45 return 1; 46 47 return 0; 48 } 49 weak_alias (__group_member, group_member) 50