getgrouplist_darwin.go

     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  //go:build cgo && !osusergo
     6  
     7  package user
     8  
     9  /*
    10  #include <unistd.h>
    11  #include <sys/types.h>
    12  #include <stdlib.h>
    13  
    14  static int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
    15  	int* buf = malloc(*ngroups * sizeof(int));
    16  	int rv = getgrouplist(user, (int) group, buf, ngroups);
    17  	int i;
    18  	if (rv == 0) {
    19  		for (i = 0; i < *ngroups; i++) {
    20  			groups[i] = (gid_t) buf[i];
    21  		}
    22  	}
    23  	free(buf);
    24  	return rv;
    25  }
    26  */
    27  import "C"
    28  import (
    29  	"fmt"
    30  	"unsafe"
    31  )
    32  
    33  func getGroupList(name *C.char, userGID C.gid_t, gids *C.gid_t, n *C.int) C.int {
    34  	return C.mygetgrouplist(name, userGID, gids, n)
    35  }
    36  
    37  // groupRetry retries getGroupList with an increasingly large size for n. The
    38  // result is stored in gids.
    39  func groupRetry(username string, name []byte, userGID C.gid_t, gids *[]C.gid_t, n *C.int) error {
    40  	*n = C.int(256 * 2)
    41  	for {
    42  		*gids = make([]C.gid_t, *n)
    43  		rv := getGroupList((*C.char)(unsafe.Pointer(&name[0])), userGID, &(*gids)[0], n)
    44  		if rv >= 0 {
    45  			// n is set correctly
    46  			break
    47  		}
    48  		if *n > maxGroups {
    49  			return fmt.Errorf("user: %q is a member of more than %d groups", username, maxGroups)
    50  		}
    51  		*n = *n * C.int(2)
    52  	}
    53  	return nil
    54  }
    55
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