libgo/go/os/user/lookup_unix.go

   1 // Copyright 2011 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 darwin dragonfly freebsd linux netbsd openbsd solaris
   6 // +build cgo
   7
   8 package user
   9
  10 import (
  11         "fmt"
  12         "strconv"
  13         "strings"
  14         "syscall"
  15         "unsafe"
  16 )
  17
  18 /*
  19 #include <unistd.h>
  20 #include <sys/types.h>
  21 #include <pwd.h>
  22 #include <stdlib.h>
  23
  24 static int mygetpwuid_r(int uid, struct passwd *pwd,
  25         char *buf, size_t buflen, struct passwd **result) {
  26  return getpwuid_r(uid, pwd, buf, buflen, result);
  27 }
  28 */
  29
  30 // bytePtrToString takes a NUL-terminated array of bytes and convert
  31 // it to a Go string.
  32 func bytePtrToString(p *byte) string {
  33         a := (*[10000]byte)(unsafe.Pointer(p))
  34         i := 0
  35         for a[i] != 0 {
  36                 i++
  37         }
  38         return string(a[:i])
  39 }
  40
  41 func current() (*User, error) {
  42         return lookupUnix(syscall.Getuid(), "", false)
  43 }
  44
  45 func lookup(username string) (*User, error) {
  46         return lookupUnix(-1, username, true)
  47 }
  48
  49 func lookupId(uid string) (*User, error) {
  50         i, e := strconv.Atoi(uid)
  51         if e != nil {
  52                 return nil, e
  53         }
  54         return lookupUnix(i, "", false)
  55 }
  56
  57 func lookupUnix(uid int, username string, lookupByName bool) (*User, error) {
  58         var pwd syscall.Passwd
  59         var result *syscall.Passwd
  60
  61         // FIXME: Should let buf grow if necessary.
  62         const bufSize = 1024
  63         buf := make([]byte, bufSize)
  64         if lookupByName {
  65                 p := syscall.StringBytePtr(username)
  66                 syscall.Entersyscall()
  67                 rv := libc_getpwnam_r(p,
  68                         &pwd,
  69                         &buf[0],
  70                         bufSize,
  71                         &result)
  72                 syscall.Exitsyscall()
  73                 if rv != 0 {
  74                         return nil, fmt.Errorf("user: lookup username %s: %s", username, syscall.GetErrno())
  75                 }
  76                 if result == nil {
  77                         return nil, UnknownUserError(username)
  78                 }
  79         } else {
  80                 syscall.Entersyscall()
  81                 rv := libc_getpwuid_r(syscall.Uid_t(uid),
  82                         &pwd,
  83                         &buf[0],
  84                         bufSize,
  85                         &result)
  86                 syscall.Exitsyscall()
  87                 if rv != 0 {
  88                         return nil, fmt.Errorf("user: lookup userid %d: %s", uid, syscall.GetErrno())
  89                 }
  90                 if result == nil {
  91                         return nil, UnknownUserIdError(uid)
  92                 }
  93         }
  94         u := &User{
  95                 Uid:      strconv.Itoa(int(pwd.Pw_uid)),
  96                 Gid:      strconv.Itoa(int(pwd.Pw_gid)),
  97                 Username: bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_name))),
  98                 Name:     bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_gecos))),
  99                 HomeDir:  bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_dir))),
 100         }
 101         // The pw_gecos field isn't quite standardized.  Some docs
 102         // say: "It is expected to be a comma separated list of
 103         // personal data where the first item is the full name of the
 104         // user."
 105         if i := strings.Index(u.Name, ","); i >= 0 {
 106                 u.Name = u.Name[:i]
 107         }
 108         return u, nil
 109 }