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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *  * Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  *  * Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in
     12  *    the documentation and/or other materials provided with the
     13  *    distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
     22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 #include <grp.h>
     29 #include <unistd.h>
     30 #include <stdlib.h>
     31 
     32 #define  INIT_GROUPS  2
     33 
     34 int
     35 initgroups (const char *user, gid_t group)
     36 {
     37     gid_t   groups0[ INIT_GROUPS ];
     38     gid_t*  groups    = groups0;
     39     int     ret       = -1;
     40     int     numgroups = INIT_GROUPS;
     41 
     42     if (getgrouplist(user, group, groups, &numgroups) < 0) {
     43         groups = malloc(numgroups*sizeof(groups[0]));
     44         if (groups == NULL)
     45             return -1;
     46         if (getgrouplist(user,group,groups,&numgroups) < 0) {
     47             goto EXIT;
     48         }
     49     }
     50 
     51     ret = setgroups(numgroups, groups);
     52 
     53 EXIT:
     54     if (groups != groups0)
     55         free(groups);
     56 
     57     return ret;
     58 }
     59