github.com/geraldss/go/src@v0.0.0-20210511222824-ac7d0ebfc235/os/user/getgrouplist_unix.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  // +build dragonfly freebsd !android,linux netbsd openbsd
     6  // +build cgo,!osusergo
     7  
     8  package user
     9  
    10  /*
    11  #include <unistd.h>
    12  #include <sys/types.h>
    13  #include <grp.h>
    14  
    15  static int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
    16  	return getgrouplist(user, group, groups, ngroups);
    17  }
    18  */
    19  import "C"
    20  import (
    21  	"fmt"
    22  	"unsafe"
    23  )
    24  
    25  func getGroupList(name *C.char, userGID C.gid_t, gids *C.gid_t, n *C.int) C.int {
    26  	return C.mygetgrouplist(name, userGID, gids, n)
    27  }
    28  
    29  // groupRetry retries getGroupList with much larger size for n. The result is
    30  // stored in gids.
    31  func groupRetry(username string, name []byte, userGID C.gid_t, gids *[]C.gid_t, n *C.int) error {
    32  	// More than initial buffer, but now n contains the correct size.
    33  	if *n > maxGroups {
    34  		return fmt.Errorf("user: %q is a member of more than %d groups", username, maxGroups)
    35  	}
    36  	*gids = make([]C.gid_t, *n)
    37  	rv := getGroupList((*C.char)(unsafe.Pointer(&name[0])), userGID, &(*gids)[0], n)
    38  	if rv == -1 {
    39  		return fmt.Errorf("user: list groups for %s failed", username)
    40  	}
    41  	return nil
    42  }