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// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
package utils
import (
"fmt"
"os"
"os/exec"
"os/user"
"runtime"
"strconv"
"strings"
"sync"
"howett.net/plist"
)
var _ = fmt.Print
type PasswdEntry struct {
Username, Pass, Uid, Gid, Gecos, Home, Shell string
}
func ParsePasswdLine(line string) (PasswdEntry, error) {
parts := strings.Split(line, ":")
if len(parts) == 7 {
return PasswdEntry{parts[0], parts[1], parts[2], parts[3], parts[4], parts[5], parts[6]}, nil
}
return PasswdEntry{}, fmt.Errorf("passwd line has %d colon delimited fields instead of 7", len(parts))
}
func ParsePasswdDatabase(raw string) (ans map[string]PasswdEntry) {
scanner := NewLineScanner(raw)
ans = make(map[string]PasswdEntry)
for scanner.Scan() {
line := scanner.Text()
if entry, e := ParsePasswdLine(line); e == nil {
ans[entry.Uid] = entry
}
}
return ans
}
func ParsePasswdFile(path string) (ans map[string]PasswdEntry, err error) {
raw, err := os.ReadFile(path)
if err != nil {
return nil, err
}
return ParsePasswdDatabase(UnsafeBytesToString(raw)), nil
}
var passwd_err error
var passwd_database = sync.OnceValue(func() (ans map[string]PasswdEntry) {
ans, passwd_err = ParsePasswdFile("/etc/passwd")
return
})
func PwdEntryForUid(uid string) (ans PasswdEntry, err error) {
pwd := passwd_database()
if passwd_err != nil {
return ans, passwd_err
}
ans, found := pwd[uid]
if !found {
return ans, fmt.Errorf("No user matching the UID: %#v found", uid)
}
return ans, nil
}
func parse_dscl_data(raw []byte) (ans map[string]PasswdEntry, err error) {
var pd []any
_, err = plist.Unmarshal(raw, &pd)
if err != nil {
return
}
ans = make(map[string]PasswdEntry, 256)
for _, entry := range pd {
if e, ok := entry.(map[string]any); ok {
item := PasswdEntry{}
for key, a := range e {
array, ok := a.([]any)
if !ok || len(array) == 0 || !strings.HasPrefix(key, "dsAttrTypeNative:") {
continue
}
_, key, _ = strings.Cut(key, ":")
if val, ok := array[0].(string); ok {
switch key {
case "uid":
item.Uid = val
case "gid":
item.Gid = val
case "home":
item.Home = val
case "name":
item.Username = val
case "realname":
item.Gecos = val
case "shell":
item.Shell = val
}
}
}
ans[item.Uid] = item
}
}
return
}
var dscl_error error
var dscl_user_database = sync.OnceValue(func() map[string]PasswdEntry {
c := exec.Command("/usr/bin/dscl", "-plist", ".", "-readall", "/Users", "uid", "gid", "name", "realname", "home", "shell")
raw, err := c.Output()
if err != nil {
dscl_error = err
return nil
}
ans, err := parse_dscl_data(raw)
if err != nil {
dscl_error = err
return nil
}
return ans
})
func LoginShellForUser(u *user.User) (ans string, err error) {
var db map[string]PasswdEntry
switch runtime.GOOS {
case "darwin":
db = dscl_user_database()
err = dscl_error
default:
db = passwd_database()
err = passwd_err
}
if err != nil {
return
}
if rec, found := db[u.Uid]; found {
return rec.Shell, nil
}
return ans, fmt.Errorf("No user record available for user with UID: %#v", u.Uid)
}
func CurrentUser() (ans *user.User, err error) {
ans, err = user.Current()
if err != nil && runtime.GOOS == "darwin" {
uid := strconv.Itoa(os.Geteuid())
db := dscl_user_database()
if dscl_error != nil {
err = dscl_error
return
}
if rec, found := db[uid]; found {
u := user.User{Uid: uid, Gid: rec.Gid, Username: rec.Username, Name: rec.Gecos, HomeDir: rec.Home}
ans = &u
err = nil
} else {
err = fmt.Errorf("Could not find the current uid: %d in the DSCL user database", os.Geteuid())
}
}
return
}
func LoginShellForCurrentUser() (ans string, err error) {
u, err := CurrentUser()
if err != nil {
return ans, err
}
return LoginShellForUser(u)
}
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