/
asset.go
283 lines (269 loc) · 8.4 KB
/
asset.go
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package proj2aci
import (
"bytes"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strings"
)
// GetAssetString returns a properly formatted asset string.
func GetAssetString(aciAsset, localAsset string) string {
return getAssetString(aciAsset, localAsset)
}
// PrepareAssets copies given assets to ACI rootfs directory. It also
// tries to copy required shared libraries if an asset is a
// dynamically linked executable or library. placeholderMapping maps
// placeholders (like "<INSTALLDIR>") to actual paths (usually
// something inside temporary directory).
func PrepareAssets(assets []string, rootfs string, placeholderMapping map[string]string) error {
newAssets := assets
processedAssets := make(map[string]struct{})
for len(newAssets) > 0 {
assetsToProcess := newAssets
newAssets = nil
for _, asset := range assetsToProcess {
splitAsset := filepath.SplitList(asset)
if len(splitAsset) != 2 {
return fmt.Errorf("Malformed asset option: '%v' - expected two absolute paths separated with %v", asset, listSeparator())
}
evalSrc, srcErr := evalPath(splitAsset[0])
if srcErr != nil {
return fmt.Errorf("Could not evaluate symlinks in source asset %q: %v", evalSrc, srcErr)
}
evalDest, destErr := evalPath(splitAsset[1])
asset = getAssetString(evalSrc, evalDest)
Debug("Processing asset:", asset)
if _, ok := processedAssets[asset]; ok {
Debug(" skipped")
continue
}
additionalAssets, err := processAsset(asset, rootfs, placeholderMapping)
if destErr != nil {
evalDest, destErr = evalPath(evalDest)
if destErr != nil {
return fmt.Errorf("Could not evaluate symlinks in destination asset %q, even after it was copied to: %v", evalDest, destErr)
}
asset = getAssetString(evalSrc, evalDest)
}
if err != nil {
return err
}
processedAssets[asset] = struct{}{}
newAssets = append(newAssets, additionalAssets...)
}
}
return nil
}
func evalPath(path string) (string, error) {
symlinkDir := filepath.Dir(path)
symlinkBase := filepath.Base(path)
realSymlinkDir, err := filepath.EvalSymlinks(symlinkDir)
if err != nil {
return path, err
}
return filepath.Join(realSymlinkDir, symlinkBase), nil
}
// processAsset validates an asset, replaces placeholders with real
// paths and does the copying. It may return additional assets to be
// processed when asset is an executable or a library.
func processAsset(asset, rootfs string, placeholderMapping map[string]string) ([]string, error) {
splitAsset := filepath.SplitList(asset)
if len(splitAsset) != 2 {
return nil, fmt.Errorf("Malformed asset option: '%v' - expected two absolute paths separated with %v", asset, listSeparator())
}
ACIAsset := replacePlaceholders(splitAsset[0], placeholderMapping)
localAsset := replacePlaceholders(splitAsset[1], placeholderMapping)
if err := validateAsset(ACIAsset, localAsset); err != nil {
return nil, err
}
ACIAssetSubPath := filepath.Join(rootfs, filepath.Dir(ACIAsset))
err := os.MkdirAll(ACIAssetSubPath, 0755)
if err != nil {
return nil, fmt.Errorf("Failed to create directory tree for asset '%v': %v", asset, err)
}
err = copyTree(localAsset, filepath.Join(rootfs, ACIAsset))
if err != nil {
return nil, fmt.Errorf("Failed to copy assets for %q: %v", asset, err)
}
additionalAssets, err := getSoLibs(localAsset)
if err != nil {
return nil, fmt.Errorf("Failed to get dependent assets for %q: %v", localAsset, err)
}
// HACK! if we are copying libc then try to copy libnss_* libs
// (glibc name service switch libs used in networking)
if matched, err := filepath.Match("libc.*", filepath.Base(localAsset)); err == nil && matched {
toGlob := filepath.Join(filepath.Dir(localAsset), "libnss_*")
if matches, err := filepath.Glob(toGlob); err == nil && len(matches) > 0 {
matchesAsAssets := make([]string, 0, len(matches))
for _, f := range matches {
matchesAsAssets = append(matchesAsAssets, getAssetString(f, f))
}
additionalAssets = append(additionalAssets, matchesAsAssets...)
}
}
return additionalAssets, nil
}
func replacePlaceholders(path string, placeholderMapping map[string]string) string {
Debug("Processing path: ", path)
newPath := path
for placeholder, replacement := range placeholderMapping {
newPath = strings.Replace(newPath, placeholder, replacement, -1)
}
Debug("Processed path: ", newPath)
return newPath
}
func validateAsset(ACIAsset, localAsset string) error {
if !filepath.IsAbs(ACIAsset) {
return fmt.Errorf("Wrong ACI asset: '%v' - ACI asset has to be absolute path", ACIAsset)
}
if !filepath.IsAbs(localAsset) {
return fmt.Errorf("Wrong local asset: '%v' - local asset has to be absolute path", localAsset)
}
fi, err := os.Lstat(localAsset)
if err != nil {
return fmt.Errorf("Error stating %v: %v", localAsset, err)
}
mode := fi.Mode()
if mode.IsDir() || mode.IsRegular() || isSymlink(mode) {
return nil
}
return fmt.Errorf("Can't handle local asset %v - not a file, not a dir, not a symlink", fi.Name())
}
func copyTree(src, dest string) error {
return filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
rootLess := path[len(src):]
target := filepath.Join(dest, rootLess)
mode := info.Mode()
switch {
case mode.IsDir():
err := os.Mkdir(target, mode.Perm())
if err != nil {
return err
}
case mode.IsRegular():
if err := copyRegularFile(path, target); err != nil {
return err
}
case isSymlink(mode):
if err := copySymlink(path, target); err != nil {
return err
}
default:
return fmt.Errorf("Unsupported node %q in assets, only regular files, directories and symlinks are supported.", path, mode.String())
}
return nil
})
}
func copyRegularFile(src, dest string) error {
srcFile, err := os.Open(src)
if err != nil {
return err
}
defer srcFile.Close()
destFile, err := os.Create(dest)
if err != nil {
return err
}
defer destFile.Close()
if _, err := io.Copy(destFile, srcFile); err != nil {
return err
}
fi, err := srcFile.Stat()
if err != nil {
return err
}
if err := destFile.Chmod(fi.Mode().Perm()); err != nil {
return err
}
return nil
}
func copySymlink(src, dest string) error {
symTarget, err := os.Readlink(src)
if err != nil {
return err
}
if err := os.Symlink(symTarget, dest); err != nil {
return err
}
return nil
}
// getSoLibs tries to run ldd on given path and to process its output
// to get a list of shared libraries to copy. This list is returned as
// an array of assets.
//
// man ldd says that running ldd on untrusted executables is dangerous
// (it might run an executable to get the libraries), so possibly this
// should be replaced with objdump. Problem with objdump is that it
// just gives library names, while ldd gives absolute paths to those
// libraries - to use objdump we need to know the $libdir.
func getSoLibs(path string) ([]string, error) {
assets := []string{}
buf := new(bytes.Buffer)
args := []string{
"ldd",
path,
}
if err := RunCmdFull("", args, nil, "", buf, nil); err != nil {
if _, ok := err.(CmdFailedError); !ok {
return nil, err
}
} else {
re := regexp.MustCompile(`(?m)^\t(?:\S+\s+=>\s+)?(\/\S+)\s+\([0-9a-fA-Fx]+\)$`)
for _, matches := range re.FindAllStringSubmatch(string(buf.Bytes()), -1) {
lib := matches[1]
if lib == "" {
continue
}
symlinkedAssets, err := getSymlinkedAssets(lib)
if err != nil {
return nil, err
}
assets = append(assets, symlinkedAssets...)
}
}
return assets, nil
}
// getSymlinkedAssets returns an array of many assets if given path is
// a symlink - useful for getting shared libraries, which are often
// surrounded with a bunch of symlinks.
func getSymlinkedAssets(path string) ([]string, error) {
assets := []string{}
maxLevels := 100
levels := maxLevels
for {
if levels < 1 {
return nil, fmt.Errorf("Too many levels of symlinks (>$d)", maxLevels)
}
fi, err := os.Lstat(path)
if err != nil {
return nil, err
}
asset := getAssetString(path, path)
assets = append(assets, asset)
if !isSymlink(fi.Mode()) {
break
}
symTarget, err := os.Readlink(path)
if err != nil {
return nil, err
}
if filepath.IsAbs(symTarget) {
path = symTarget
} else {
path = filepath.Join(filepath.Dir(path), symTarget)
}
levels--
}
return assets, nil
}
func getAssetString(aciAsset, localAsset string) string {
return fmt.Sprintf("%s%s%s", aciAsset, listSeparator(), localAsset)
}
func isSymlink(mode os.FileMode) bool {
return mode&os.ModeSymlink == os.ModeSymlink
}