github.com/ltltlt/go-source-code@v0.0.0-20190830023027-95be009773aa/os/user/getgrouplist_darwin.go (about)

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package user
     6  
     7  /*
     8  #include <unistd.h>
     9  #include <sys/types.h>
    10  #include <stdlib.h>
    11  
    12  static int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
    13  	int* buf = malloc(*ngroups * sizeof(int));
    14  	int rv = getgrouplist(user, (int) group, buf, ngroups);
    15  	int i;
    16  	if (rv == 0) {
    17  		for (i = 0; i < *ngroups; i++) {
    18  			groups[i] = (gid_t) buf[i];
    19  		}
    20  	}
    21  	free(buf);
    22  	return rv;
    23  }
    24  */
    25  import "C"
    26  import (
    27  	"fmt"
    28  	"unsafe"
    29  )
    30  
    31  func getGroupList(name *C.char, userGID C.gid_t, gids *C.gid_t, n *C.int) C.int {
    32  	return C.mygetgrouplist(name, userGID, gids, n)
    33  }
    34  
    35  // groupRetry retries getGroupList with an increasingly large size for n. The
    36  // result is stored in gids.
    37  func groupRetry(username string, name []byte, userGID C.gid_t, gids *[]C.gid_t, n *C.int) error {
    38  	*n = C.int(256 * 2)
    39  	for {
    40  		*gids = make([]C.gid_t, *n)
    41  		rv := getGroupList((*C.char)(unsafe.Pointer(&name[0])), userGID, &(*gids)[0], n)
    42  		if rv >= 0 {
    43  			// n is set correctly
    44  			break
    45  		}
    46  		if *n > maxGroups {
    47  			return fmt.Errorf("user: %q is a member of more than %d groups", username, maxGroups)
    48  		}
    49  		*n = *n * C.int(2)
    50  	}
    51  	return nil
    52  }