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// Copyright 2022 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bytes"
"debug/elf"
"encoding/binary"
"reflect"
"testing"
)
func Test_elfIdentifierFromReaderAt_BadElfFile(t *testing.T) {
tests := []struct {
name string
contents string
}{
{
name: "empty",
contents: "",
},
{
name: "text",
contents: "#!/bin/bash\necho foobar",
},
{
name: "empty elf",
contents: emptyElfFile(),
},
{
name: "short section header",
contents: shortSectionHeaderElfFile(),
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
buf := bytes.NewReader([]byte(tt.contents))
_, err := elfIdentifierFromReaderAt(buf, "<>", false)
if err == nil {
t.Errorf("expected error reading bad elf file without allowMissing")
}
_, err = elfIdentifierFromReaderAt(buf, "<>", true)
if err != nil {
t.Errorf("expected no error reading bad elf file with allowMissing, got %q", err.Error())
}
})
}
}
func Test_readNote(t *testing.T) {
note := []byte{
0x04, 0x00, 0x00, 0x00,
0x10, 0x00, 0x00, 0x00,
0x03, 0x00, 0x00, 0x00,
0x47, 0x4e, 0x55, 0x00,
0xca, 0xaf, 0x44, 0xd2, 0x82, 0x78, 0x68, 0xfe, 0xc0, 0x90, 0xa3, 0x43, 0x85, 0x36, 0x6c, 0xc7,
}
descs, err := readNote(bytes.NewBuffer(note), binary.LittleEndian)
if err != nil {
t.Fatalf("unexpected error in readNote: %s", err)
}
expectedDescs := map[string][]byte{
"GNU\x00": []byte{0xca, 0xaf, 0x44, 0xd2, 0x82, 0x78, 0x68, 0xfe, 0xc0, 0x90, 0xa3, 0x43, 0x85, 0x36, 0x6c, 0xc7},
}
if !reflect.DeepEqual(descs, expectedDescs) {
t.Errorf("incorrect return, want %#v got %#v", expectedDescs, descs)
}
}
// emptyElfFile returns an elf file header with no program headers or sections.
func emptyElfFile() string {
ident := [elf.EI_NIDENT]byte{}
identBuf := bytes.NewBuffer(ident[0:0:elf.EI_NIDENT])
binary.Write(identBuf, binary.LittleEndian, []byte("\x7fELF"))
binary.Write(identBuf, binary.LittleEndian, elf.ELFCLASS64)
binary.Write(identBuf, binary.LittleEndian, elf.ELFDATA2LSB)
binary.Write(identBuf, binary.LittleEndian, elf.EV_CURRENT)
binary.Write(identBuf, binary.LittleEndian, elf.ELFOSABI_LINUX)
binary.Write(identBuf, binary.LittleEndian, make([]byte, 8))
header := elf.Header64{
Ident: ident,
Type: uint16(elf.ET_EXEC),
Machine: uint16(elf.EM_X86_64),
Version: uint32(elf.EV_CURRENT),
Entry: 0,
Phoff: uint64(binary.Size(elf.Header64{})),
Shoff: uint64(binary.Size(elf.Header64{})),
Flags: 0,
Ehsize: uint16(binary.Size(elf.Header64{})),
Phentsize: 0x38,
Phnum: 0,
Shentsize: 0x40,
Shnum: 0,
Shstrndx: 0,
}
buf := &bytes.Buffer{}
binary.Write(buf, binary.LittleEndian, header)
return buf.String()
}
// shortSectionHeader returns an elf file header with a section header that extends past the end of
// the file.
func shortSectionHeaderElfFile() string {
ident := [elf.EI_NIDENT]byte{}
identBuf := bytes.NewBuffer(ident[0:0:elf.EI_NIDENT])
binary.Write(identBuf, binary.LittleEndian, []byte("\x7fELF"))
binary.Write(identBuf, binary.LittleEndian, elf.ELFCLASS64)
binary.Write(identBuf, binary.LittleEndian, elf.ELFDATA2LSB)
binary.Write(identBuf, binary.LittleEndian, elf.EV_CURRENT)
binary.Write(identBuf, binary.LittleEndian, elf.ELFOSABI_LINUX)
binary.Write(identBuf, binary.LittleEndian, make([]byte, 8))
header := elf.Header64{
Ident: ident,
Type: uint16(elf.ET_EXEC),
Machine: uint16(elf.EM_X86_64),
Version: uint32(elf.EV_CURRENT),
Entry: 0,
Phoff: uint64(binary.Size(elf.Header64{})),
Shoff: uint64(binary.Size(elf.Header64{})),
Flags: 0,
Ehsize: uint16(binary.Size(elf.Header64{})),
Phentsize: 0x38,
Phnum: 0,
Shentsize: 0x40,
Shnum: 1,
Shstrndx: 0,
}
buf := &bytes.Buffer{}
binary.Write(buf, binary.LittleEndian, header)
binary.Write(buf, binary.LittleEndian, []byte{0})
return buf.String()
}