.github: update upstream actions to latest version

[nsscash/nsscash.git] / passwd.go

diff --git a/passwd.go b/passwd.go
index 2698765212e0975738ebc8d8273140daee528816..6da64762ad2dae302dd9e8c6c097bec08e0a46fb 100644 (file)
--- a/passwd.go
+++ b/passwd.go
@@ -1,6 +1,6 @@
 // Parse /etc/passwd files and serialize them
 
-// Copyright (C) 2019  Simon Ruderich
+// Copyright (C) 2019-2021  Simon Ruderich
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU Affero General Public License as published by
@@ -23,6 +23,7 @@ import (
        "encoding/binary"
        "fmt"
        "io"
+       "math"
        "sort"
        "strconv"
        "strings"
@@ -53,6 +54,11 @@ func ParsePasswds(r io.Reader) ([]Passwd, error) {
                t, err := s.ReadString('\n')
                if err != nil {
                        if err == io.EOF {
+                               if t != "" {
+                                       return nil, fmt.Errorf(
+                                               "no newline in last line: %q",
+                                               t)
+                               }
                                break
                        }
                        return nil, err
@@ -86,7 +92,7 @@ func ParsePasswds(r io.Reader) ([]Passwd, error) {
        return res, nil
 }
 
-func SerializePasswd(p Passwd) []byte {
+func SerializePasswd(p Passwd) ([]byte, error) {
        // Concatenate all (NUL-terminated) strings and store the offsets
        var data bytes.Buffer
        data.Write([]byte(p.Name))
@@ -103,6 +109,11 @@ func SerializePasswd(p Passwd) []byte {
        offShell := uint16(data.Len())
        data.Write([]byte(p.Shell))
        data.WriteByte(0)
+       // Ensure the offsets can fit the length of this entry
+       if data.Len() > math.MaxUint16 {
+               return nil, fmt.Errorf("passwd too large to serialize: %v, %v",
+                       data.Len(), p)
+       }
        size := uint16(data.Len())
 
        var res bytes.Buffer // serialized result
@@ -138,7 +149,7 @@ func SerializePasswd(p Passwd) []byte {
        // struct are 8 byte aligned
        alignBufferTo(&res, 8)
 
-       return res.Bytes()
+       return res.Bytes(), nil
 }
 
 func SerializePasswds(w io.Writer, pws []Passwd) error {
@@ -148,7 +159,11 @@ func SerializePasswds(w io.Writer, pws []Passwd) error {
        for _, p := range pws {
                // TODO: warn about duplicate entries
                offsets[p] = uint64(data.Len())
-               data.Write(SerializePasswd(p))
+               x, err := SerializePasswd(p)
+               if err != nil {
+                       return err
+               }
+               data.Write(x)
        }
 
        // Copy to prevent sorting from modifying the argument