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// Copyright 2011 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 darwin freebsd linux netbsd openbsd
// +build cgo
package user
import (
"fmt"
"strconv"
"strings"
"syscall"
"unsafe"
)
/*
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>
#include <stdlib.h>
static int mygetpwuid_r(int uid, struct passwd *pwd,
char *buf, size_t buflen, struct passwd **result) {
return getpwuid_r(uid, pwd, buf, buflen, result);
}
*/
//extern getpwnam_r
func libc_getpwnam_r(name *byte, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int
//extern getpwuid_r
func libc_getpwuid_r(uid syscall.Uid_t, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int
// bytePtrToString takes a NUL-terminated array of bytes and convert
// it to a Go string.
func bytePtrToString(p *byte) string {
a := (*[10000]byte)(unsafe.Pointer(p))
i := 0
for a[i] != 0 {
i++
}
return string(a[:i])
}
func current() (*User, error) {
return lookupUnix(syscall.Getuid(), "", false)
}
func lookup(username string) (*User, error) {
return lookupUnix(-1, username, true)
}
func lookupId(uid string) (*User, error) {
i, e := strconv.Atoi(uid)
if e != nil {
return nil, e
}
return lookupUnix(i, "", false)
}
func lookupUnix(uid int, username string, lookupByName bool) (*User, error) {
var pwd syscall.Passwd
var result *syscall.Passwd
// FIXME: Should let buf grow if necessary.
const bufSize = 1024
buf := make([]byte, bufSize)
if lookupByName {
p := syscall.StringBytePtr(username)
syscall.Entersyscall()
rv := libc_getpwnam_r(p,
&pwd,
&buf[0],
bufSize,
&result)
syscall.Exitsyscall()
if rv != 0 {
return nil, fmt.Errorf("user: lookup username %s: %s", username, syscall.GetErrno())
}
if result == nil {
return nil, UnknownUserError(username)
}
} else {
syscall.Entersyscall()
rv := libc_getpwuid_r(syscall.Uid_t(uid),
&pwd,
&buf[0],
bufSize,
&result)
syscall.Exitsyscall()
if rv != 0 {
return nil, fmt.Errorf("user: lookup userid %d: %s", uid, syscall.GetErrno())
}
if result == nil {
return nil, UnknownUserIdError(uid)
}
}
u := &User{
Uid: strconv.Itoa(int(pwd.Pw_uid)),
Gid: strconv.Itoa(int(pwd.Pw_gid)),
Username: bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_name))),
Name: bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_gecos))),
HomeDir: bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_dir))),
}
// The pw_gecos field isn't quite standardized. Some docs
// say: "It is expected to be a comma separated list of
// personal data where the first item is the full name of the
// user."
if i := strings.Index(u.Name, ","); i >= 0 {
u.Name = u.Name[:i]
}
return u, nil
}
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