X-Git-Url: https://ruderich.org/simon/gitweb/?p=nsscash%2Fnsscash.git;a=blobdiff_plain;f=passwd.go;h=6da64762ad2dae302dd9e8c6c097bec08e0a46fb;hp=90351900b334b4e9154683eeb437aedff54d0b06;hb=HEAD;hpb=e7085e4751da534f2b0290df32ba06d09802a037

diff --git a/passwd.go b/passwd.go
index 9035190..6da6476 100644
--- 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"
@@ -44,13 +45,24 @@ type Passwd struct {
 }
 
 // ParsePasswds parses a file in the format of /etc/passwd and returns all
-// entries as Passwd structs.
+// entries as slice of Passwd structs.
 func ParsePasswds(r io.Reader) ([]Passwd, error) {
 	var res []Passwd
 
-	s := bufio.NewScanner(r)
-	for s.Scan() {
-		t := s.Text()
+	s := bufio.NewReader(r)
+	for {
+		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
+		}
 
 		x := strings.Split(t, ":")
 		if len(x) != 7 {
@@ -73,18 +85,14 @@ func ParsePasswds(r io.Reader) ([]Passwd, error) {
 			Gid:    gid,
 			Gecos:  x[4],
 			Dir:    x[5],
-			Shell:  x[6],
+			// ReadString() contains the delimiter
+			Shell: strings.TrimSuffix(x[6], "\n"),
 		})
 	}
-	err := s.Err()
-	if err != nil {
-		return nil, err
-	}
-
 	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))
@@ -101,6 +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
@@ -134,14 +147,9 @@ func SerializePasswd(p Passwd) []byte {
 	res.Write(data.Bytes())
 	// We must pad each entry so that all uint64 at the beginning of the
 	// struct are 8 byte aligned
-	l := res.Len()
-	if l%8 != 0 {
-		for i := 0; i < 8-l%8; i++ {
-			res.WriteByte(0)
-		}
-	}
+	alignBufferTo(&res, 8)
 
-	return res.Bytes()
+	return res.Bytes(), nil
 }
 
 func SerializePasswds(w io.Writer, pws []Passwd) error {
@@ -151,7 +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