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 (dragonfly || darwin || freebsd || (!android && linux) || netbsd || openbsd || (solaris && !illumos)) && cgo && !osusergo
6
7package user
8
9import (
10	"fmt"
11	"strconv"
12	"unsafe"
13)
14
15/*
16#include <unistd.h>
17#include <sys/types.h>
18*/
19import "C"
20
21const maxGroups = 2048
22
23func listGroups(u *User) ([]string, error) {
24	ug, err := strconv.Atoi(u.Gid)
25	if err != nil {
26		return nil, fmt.Errorf("user: list groups for %s: invalid gid %q", u.Username, u.Gid)
27	}
28	userGID := C.gid_t(ug)
29	nameC := make([]byte, len(u.Username)+1)
30	copy(nameC, u.Username)
31
32	n := C.int(256)
33	gidsC := make([]C.gid_t, n)
34	rv := getGroupList((*C.char)(unsafe.Pointer(&nameC[0])), userGID, &gidsC[0], &n)
35	if rv == -1 {
36		// Mac is the only Unix that does not set n properly when rv == -1, so
37		// we need to use different logic for Mac vs. the other OS's.
38		if err := groupRetry(u.Username, nameC, userGID, &gidsC, &n); err != nil {
39			return nil, err
40		}
41	}
42	gidsC = gidsC[:n]
43	gids := make([]string, 0, n)
44	for _, g := range gidsC[:n] {
45		gids = append(gids, strconv.Itoa(int(g)))
46	}
47	return gids, nil
48}
49