.github: update upstream actions to latest version

[nsscash/nsscash.git] / group.go

diff --git a/group.go b/group.go
index 214f91438d78740a331c487cbfe5ecab1355718c..018a0c32716c665c690c78903b6eccdb5435ac54 100644 (file)
--- a/group.go
+++ b/group.go
@@ -1,6 +1,6 @@
 // Parse /etc/group 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"
@@ -67,6 +68,11 @@ func ParseGroups(r io.Reader) ([]Group, 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
@@ -102,7 +108,7 @@ func ParseGroups(r io.Reader) ([]Group, error) {
        return res, nil
 }
 
-func SerializeGroup(g Group) []byte {
+func SerializeGroup(g Group) ([]byte, error) {
        le := binary.LittleEndian
 
        // Concatenate all (NUL-terminated) strings and store the offsets
@@ -130,6 +136,11 @@ func SerializeGroup(g Group) []byte {
        }
        // And the group members concatenated as above
        data.Write(mems.Bytes())
+       // Ensure the offsets can fit the length of this entry
+       if data.Len() > math.MaxUint16 {
+               return nil, fmt.Errorf("group too large to serialize: %v, %v",
+                       data.Len(), g)
+       }
        size := uint16(data.Len())
 
        var res bytes.Buffer // serialized result
@@ -158,7 +169,7 @@ func SerializeGroup(g Group) []byte {
        // struct are 8 byte aligned
        alignBufferTo(&res, 8)
 
-       return res.Bytes()
+       return res.Bytes(), nil
 }
 
 func SerializeGroups(w io.Writer, grs []Group) error {
@@ -168,7 +179,11 @@ func SerializeGroups(w io.Writer, grs []Group) error {
        for _, g := range grs {
                // TODO: warn about duplicate entries
                offsets[toKey(g)] = uint64(data.Len())
-               data.Write(SerializeGroup(g))
+               x, err := SerializeGroup(g)
+               if err != nil {
+                       return err
+               }
+               data.Write(x)
        }
 
        // Copy to prevent sorting from modifying the argument
@@ -179,7 +194,7 @@ func SerializeGroups(w io.Writer, grs []Group) error {
        tmp := make([]byte, 8)
 
        // Create index "sorted" in input order, used when iterating over all
-       // passwd entries (getgrent_r); keeping the original order makes
+       // group entries (getgrent_r); keeping the original order makes
        // debugging easier
        var indexOrig bytes.Buffer
        for _, g := range grs {