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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build dragonfly darwin freebsd !android,linux netbsd openbsd
package user
import (
"fmt"
"strconv"
"syscall"
)
/*
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
*/
func listGroups(u *User) ([]string, error) {
ug, err := strconv.Atoi(u.Gid)
if err != nil {
return nil, fmt.Errorf("user: list groups for %s: invalid gid %q", u.Username, u.Gid)
}
userGID := syscall.Gid_t(ug)
nameC, err := syscall.BytePtrFromString(u.Username)
if err != nil {
return nil, fmt.Errorf("user: invalid user name %q: %v", strconv.Quote(u.Username), err)
}
n := int32(256)
gidsC := make([]syscall.Gid_t, n)
syscall.Entersyscall()
rv := libc_getgrouplist(nameC, userGID, &gidsC[0], &n)
syscall.Exitsyscall()
if rv == -1 {
// More than initial buffer, but now n contains the correct size.
const maxGroups = 2048
if n > maxGroups {
return nil, fmt.Errorf("user: list groups for %s: member of more than %d groups", u.Username, maxGroups)
}
gidsC = make([]syscall.Gid_t, n)
syscall.Entersyscall()
rv := libc_getgrouplist(nameC, userGID, &gidsC[0], &n)
syscall.Exitsyscall()
if rv == -1 {
return nil, fmt.Errorf("user: list groups for %s failed (changed groups?)", u.Username)
}
}
gidsC = gidsC[:n]
gids := make([]string, 0, n)
for _, g := range gidsC[:n] {
gids = append(gids, strconv.Itoa(int(g)))
}
return gids, nil
}
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