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// Copyright 2023 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package build
import (
"archive/tar"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strings"
"time"
"github.com/google/syzkaller/pkg/config"
"github.com/google/syzkaller/pkg/osutil"
)
type android struct{}
type BuildParams struct {
BuildScript string `json:"build_script"`
EnvVars []string `json:"env_vars"`
Flags []string `json:"flags"`
AdditionalImages []string `json:"additional_images"`
AutoconfPath string `json:"autoconf_path"`
ConfigPath string `json:"config_path"`
}
var ccCompilerRegexp = regexp.MustCompile(`#define\s+CONFIG_CC_VERSION_TEXT\s+"(.*)"`)
func parseConfig(conf []byte) (*BuildParams, error) {
buildCfg := new(BuildParams)
if err := config.LoadData(conf, buildCfg); err != nil {
return nil, fmt.Errorf("failed to parse build config: %w", err)
}
if buildCfg.BuildScript == "" {
return nil, fmt.Errorf("build script not specified for Android build")
}
if buildCfg.ConfigPath == "" {
return nil, fmt.Errorf("kernel config path not specified for Android build")
}
return buildCfg, nil
}
func (a android) readCompiler(path string) (string, error) {
bytes, err := os.ReadFile(path)
if err != nil {
return "", err
}
result := ccCompilerRegexp.FindSubmatch(bytes)
if result == nil {
return "", fmt.Errorf("%s does not contain build information", path)
}
return string(result[1]), nil
}
func (a android) build(params Params) (ImageDetails, error) {
var details ImageDetails
if params.CmdlineFile != "" {
return details, fmt.Errorf("cmdline file is not supported for android images")
}
if params.SysctlFile != "" {
return details, fmt.Errorf("sysctl file is not supported for android images")
}
buildCfg, err := parseConfig(params.Build)
if err != nil {
return details, fmt.Errorf("error parsing android configs: %w", err)
}
// Build kernel.
cmd := osutil.Command(fmt.Sprintf("./%v", buildCfg.BuildScript), buildCfg.Flags...)
cmd.Dir = params.KernelDir
cmd.Env = append(cmd.Env, buildCfg.EnvVars...)
if _, err := osutil.Run(time.Hour, cmd); err != nil {
return details, fmt.Errorf("failed to build kernel: %w", err)
}
buildDistDir := filepath.Join(params.KernelDir, "dist")
vmlinux := filepath.Join(buildDistDir, "vmlinux")
if buildCfg.AutoconfPath != "" {
details.CompilerID, err = a.readCompiler(filepath.Join(params.KernelDir, buildCfg.AutoconfPath))
if err != nil {
return details, fmt.Errorf("failed to read compiler: %w", err)
}
}
if err := osutil.CopyFile(vmlinux, filepath.Join(params.OutputDir, "obj", "vmlinux")); err != nil {
return details, fmt.Errorf("failed to copy vmlinux: %w", err)
}
if err := osutil.CopyFile(filepath.Join(params.KernelDir, buildCfg.ConfigPath),
filepath.Join(params.OutputDir, "obj", "kernel.config")); err != nil {
return details, fmt.Errorf("failed to copy kernel config: %w", err)
}
imageFile, err := os.Create(filepath.Join(params.OutputDir, "image"))
if err != nil {
return details, fmt.Errorf("failed to create output file: %w", err)
}
defer imageFile.Close()
if err := a.copyModuleFiles(filepath.Join(params.KernelDir, "out"), params.OutputDir); err != nil {
return details, fmt.Errorf("failed copying module files: %w", err)
}
images := append(buildCfg.AdditionalImages, "boot.img")
if err := a.embedImages(imageFile, buildDistDir, images...); err != nil {
return details, fmt.Errorf("failed to embed images: %w", err)
}
details.Signature, err = elfBinarySignature(vmlinux, params.Tracer)
if err != nil {
return details, fmt.Errorf("failed to generate signature: %w", err)
}
return details, nil
}
func (a android) copyModuleFiles(srcDir, dstDir string) error {
err := filepath.Walk(srcDir,
func(path string, info os.FileInfo, err error) error {
if err != nil {
return fmt.Errorf("error walking out dir: %w", err)
}
// Staging directories contain stripped module object files.
if strings.Contains(path, "staging") {
return nil
}
if filepath.Ext(path) == ".ko" {
if err := osutil.CopyFile(path, filepath.Join(dstDir, info.Name())); err != nil {
return fmt.Errorf("error copying file: %w", err)
}
}
return nil
})
if err != nil {
return fmt.Errorf("failed to copy module objects: %w", err)
}
return nil
}
func (a android) embedImages(w io.Writer, srcDir string, imageNames ...string) error {
tw := tar.NewWriter(w)
defer tw.Close()
for _, name := range imageNames {
path := filepath.Join(srcDir, name)
data, err := os.ReadFile(path)
if err != nil {
return fmt.Errorf("failed to read %q: %w", name, err)
}
if err := tw.WriteHeader(&tar.Header{
Name: name,
Mode: 0600,
Size: int64(len(data)),
}); err != nil {
return fmt.Errorf("failed to write header for %q: %w", name, err)
}
if _, err := tw.Write(data); err != nil {
return fmt.Errorf("failed to write data for %q: %w", name, err)
}
}
if err := tw.Close(); err != nil {
return fmt.Errorf("close archive: %w", err)
}
return nil
}
func (a android) clean(kernelDir, targetArch string) error {
if err := osutil.RemoveAll(filepath.Join(kernelDir, "out")); err != nil {
return fmt.Errorf("failed to clean 'out' directory: %w", err)
}
if err := osutil.RemoveAll(filepath.Join(kernelDir, "dist")); err != nil {
return fmt.Errorf("failed to clean 'dist' directory: %w", err)
}
return nil
}
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