github.com/code-reading/golang@v0.0.0-20220303082512-ba5bc0e589a3/go/src/os/user/lookup_stubs.go (about)

     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  //go:build (!cgo && !windows && !plan9) || android || (osusergo && !windows && !plan9)
     6  // +build !cgo,!windows,!plan9 android osusergo,!windows,!plan9
     7  
     8  package user
     9  
    10  import (
    11  	"errors"
    12  	"fmt"
    13  	"os"
    14  	"runtime"
    15  	"strconv"
    16  )
    17  
    18  func init() {
    19  	groupImplemented = false
    20  }
    21  
    22  func current() (*User, error) {
    23  	uid := currentUID()
    24  	// $USER and /etc/passwd may disagree; prefer the latter if we can get it.
    25  	// See issue 27524 for more information.
    26  	u, err := lookupUserId(uid)
    27  	if err == nil {
    28  		return u, nil
    29  	}
    30  
    31  	homeDir, _ := os.UserHomeDir()
    32  	u = &User{
    33  		Uid:      uid,
    34  		Gid:      currentGID(),
    35  		Username: os.Getenv("USER"),
    36  		Name:     "", // ignored
    37  		HomeDir:  homeDir,
    38  	}
    39  	// On Android, return a dummy user instead of failing.
    40  	switch runtime.GOOS {
    41  	case "android":
    42  		if u.Uid == "" {
    43  			u.Uid = "1"
    44  		}
    45  		if u.Username == "" {
    46  			u.Username = "android"
    47  		}
    48  	}
    49  	// cgo isn't available, but if we found the minimum information
    50  	// without it, use it:
    51  	if u.Uid != "" && u.Username != "" && u.HomeDir != "" {
    52  		return u, nil
    53  	}
    54  	var missing string
    55  	if u.Username == "" {
    56  		missing = "$USER"
    57  	}
    58  	if u.HomeDir == "" {
    59  		if missing != "" {
    60  			missing += ", "
    61  		}
    62  		missing += "$HOME"
    63  	}
    64  	return u, fmt.Errorf("user: Current requires cgo or %s set in environment", missing)
    65  }
    66  
    67  func listGroups(*User) ([]string, error) {
    68  	if runtime.GOOS == "android" || runtime.GOOS == "aix" {
    69  		return nil, fmt.Errorf("user: GroupIds not implemented on %s", runtime.GOOS)
    70  	}
    71  	return nil, errors.New("user: GroupIds requires cgo")
    72  }
    73  
    74  func currentUID() string {
    75  	if id := os.Getuid(); id >= 0 {
    76  		return strconv.Itoa(id)
    77  	}
    78  	// Note: Windows returns -1, but this file isn't used on
    79  	// Windows anyway, so this empty return path shouldn't be
    80  	// used.
    81  	return ""
    82  }
    83  
    84  func currentGID() string {
    85  	if id := os.Getgid(); id >= 0 {
    86  		return strconv.Itoa(id)
    87  	}
    88  	return ""
    89  }