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| 1 | +// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net> |
| 2 | + |
| 3 | +package utils |
| 4 | + |
| 5 | +import ( |
| 6 | + "fmt" |
| 7 | + "os" |
| 8 | + "os/exec" |
| 9 | + "os/user" |
| 10 | + "runtime" |
| 11 | + "strconv" |
| 12 | + "strings" |
| 13 | + |
| 14 | + "howett.net/plist" |
| 15 | +) |
| 16 | + |
| 17 | +var _ = fmt.Print |
| 18 | + |
| 19 | +type PasswdEntry struct { |
| 20 | + Username, Pass, Uid, Gid, Gecos, Home, Shell string |
| 21 | +} |
| 22 | + |
| 23 | +func ParsePasswdLine(line string) (PasswdEntry, error) { |
| 24 | + parts := strings.Split(line, ":") |
| 25 | + if len(parts) == 7 { |
| 26 | + return PasswdEntry{parts[0], parts[1], parts[2], parts[3], parts[4], parts[5], parts[6]}, nil |
| 27 | + } |
| 28 | + return PasswdEntry{}, fmt.Errorf("passwd line has %d colon delimited fields instead of 7", len(parts)) |
| 29 | +} |
| 30 | + |
| 31 | +func ParsePasswdDatabase(raw string) (ans map[string]PasswdEntry) { |
| 32 | + scanner := NewLineScanner(raw) |
| 33 | + ans = make(map[string]PasswdEntry) |
| 34 | + for scanner.Scan() { |
| 35 | + line := scanner.Text() |
| 36 | + if entry, e := ParsePasswdLine(line); e == nil { |
| 37 | + ans[entry.Uid] = entry |
| 38 | + } |
| 39 | + } |
| 40 | + return ans |
| 41 | +} |
| 42 | + |
| 43 | +func ParsePasswdFile(path string) (ans map[string]PasswdEntry, err error) { |
| 44 | + raw, err := os.ReadFile(path) |
| 45 | + if err != nil { |
| 46 | + return nil, err |
| 47 | + } |
| 48 | + return ParsePasswdDatabase(UnsafeBytesToString(raw)), nil |
| 49 | +} |
| 50 | + |
| 51 | +var passwd_err error |
| 52 | +var passwd_database = Once(func() (ans map[string]PasswdEntry) { |
| 53 | + ans, passwd_err = ParsePasswdFile("/etc/passwd") |
| 54 | + return |
| 55 | +}) |
| 56 | + |
| 57 | +func PwdEntryForUid(uid string) (ans PasswdEntry, err error) { |
| 58 | + pwd := passwd_database() |
| 59 | + if passwd_err != nil { |
| 60 | + return ans, passwd_err |
| 61 | + } |
| 62 | + ans, found := pwd[uid] |
| 63 | + if !found { |
| 64 | + return ans, fmt.Errorf("No user matching the UID: %#v found", uid) |
| 65 | + } |
| 66 | + return ans, nil |
| 67 | +} |
| 68 | + |
| 69 | +func parse_dscl_data(raw []byte) (ans map[string]PasswdEntry, err error) { |
| 70 | + var pd []any |
| 71 | + _, err = plist.Unmarshal(raw, &pd) |
| 72 | + if err != nil { |
| 73 | + return |
| 74 | + } |
| 75 | + ans = make(map[string]PasswdEntry, 256) |
| 76 | + for _, entry := range pd { |
| 77 | + if e, ok := entry.(map[string]any); ok { |
| 78 | + item := PasswdEntry{} |
| 79 | + for key, a := range e { |
| 80 | + array, ok := a.([]any) |
| 81 | + if !ok || len(array) == 0 || !strings.HasPrefix(key, "dsAttrTypeNative:") { |
| 82 | + continue |
| 83 | + } |
| 84 | + _, key, _ = strings.Cut(key, ":") |
| 85 | + if val, ok := array[0].(string); ok { |
| 86 | + switch key { |
| 87 | + case "uid": |
| 88 | + item.Uid = val |
| 89 | + case "gid": |
| 90 | + item.Gid = val |
| 91 | + case "home": |
| 92 | + item.Home = val |
| 93 | + case "name": |
| 94 | + item.Username = val |
| 95 | + case "realname": |
| 96 | + item.Gecos = val |
| 97 | + case "shell": |
| 98 | + item.Shell = val |
| 99 | + } |
| 100 | + } |
| 101 | + } |
| 102 | + ans[item.Uid] = item |
| 103 | + } |
| 104 | + } |
| 105 | + return |
| 106 | +} |
| 107 | + |
| 108 | +var dscl_error error |
| 109 | + |
| 110 | +var dscl_user_database = Once(func() map[string]PasswdEntry { |
| 111 | + c := exec.Command("/usr/bin/dscl", "-plist", ".", "-readall", "/Users", "uid", "gid", "name", "realname", "home", "shell") |
| 112 | + raw, err := c.Output() |
| 113 | + if err != nil { |
| 114 | + dscl_error = err |
| 115 | + return nil |
| 116 | + } |
| 117 | + ans, err := parse_dscl_data(raw) |
| 118 | + if err != nil { |
| 119 | + dscl_error = err |
| 120 | + return nil |
| 121 | + } |
| 122 | + return ans |
| 123 | + |
| 124 | +}) |
| 125 | + |
| 126 | +func LoginShellForUser(u *user.User) (ans string, err error) { |
| 127 | + var db map[string]PasswdEntry |
| 128 | + switch runtime.GOOS { |
| 129 | + case "darwin": |
| 130 | + db = dscl_user_database() |
| 131 | + err = dscl_error |
| 132 | + default: |
| 133 | + db = passwd_database() |
| 134 | + err = passwd_err |
| 135 | + } |
| 136 | + if err != nil { |
| 137 | + return |
| 138 | + } |
| 139 | + if rec, found := db[u.Uid]; found { |
| 140 | + return rec.Shell, nil |
| 141 | + } |
| 142 | + return ans, fmt.Errorf("No user record available for user with UID: %#v", u.Uid) |
| 143 | +} |
| 144 | + |
| 145 | +func CurrentUser() (ans *user.User, err error) { |
| 146 | + ans, err = user.Current() |
| 147 | + if err != nil && runtime.GOOS == "darwin" { |
| 148 | + uid := strconv.Itoa(os.Geteuid()) |
| 149 | + db := dscl_user_database() |
| 150 | + if dscl_error != nil { |
| 151 | + err = dscl_error |
| 152 | + return |
| 153 | + } |
| 154 | + if rec, found := db[uid]; found { |
| 155 | + u := user.User{Uid: uid, Gid: rec.Gid, Username: rec.Username, Name: rec.Gecos, HomeDir: rec.Home} |
| 156 | + ans = &u |
| 157 | + err = nil |
| 158 | + } else { |
| 159 | + err = fmt.Errorf("Could not find the current uid: %d in the DSCL user database", os.Geteuid()) |
| 160 | + } |
| 161 | + } |
| 162 | + return |
| 163 | +} |
| 164 | + |
| 165 | +func LoginShellForCurrentUser() (ans string, err error) { |
| 166 | + u, err := CurrentUser() |
| 167 | + if err != nil { |
| 168 | + return ans, err |
| 169 | + } |
| 170 | + return LoginShellForUser(u) |
| 171 | +} |
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