diff options
Diffstat (limited to 'vendor/github.com/moby/go-archive/copy.go')
| -rw-r--r-- | vendor/github.com/moby/go-archive/copy.go | 496 |
1 files changed, 496 insertions, 0 deletions
diff --git a/vendor/github.com/moby/go-archive/copy.go b/vendor/github.com/moby/go-archive/copy.go new file mode 100644 index 0000000..77d038c --- /dev/null +++ b/vendor/github.com/moby/go-archive/copy.go @@ -0,0 +1,496 @@ +package archive + +import ( + "archive/tar" + "context" + "errors" + "io" + "os" + "path/filepath" + "strings" + "sync" + + "github.com/containerd/log" +) + +// Errors used or returned by this file. +var ( + ErrNotDirectory = errors.New("not a directory") + ErrDirNotExists = errors.New("no such directory") + ErrCannotCopyDir = errors.New("cannot copy directory") + ErrInvalidCopySource = errors.New("invalid copy source content") +) + +var copyPool = sync.Pool{ + New: func() interface{} { s := make([]byte, 32*1024); return &s }, +} + +func copyWithBuffer(dst io.Writer, src io.Reader) error { + buf := copyPool.Get().(*[]byte) + _, err := io.CopyBuffer(dst, src, *buf) + copyPool.Put(buf) + return err +} + +// PreserveTrailingDotOrSeparator returns the given cleaned path (after +// processing using any utility functions from the path or filepath stdlib +// packages) and appends a trailing `/.` or `/` if its corresponding original +// path (from before being processed by utility functions from the path or +// filepath stdlib packages) ends with a trailing `/.` or `/`. If the cleaned +// path already ends in a `.` path segment, then another is not added. If the +// clean path already ends in a path separator, then another is not added. +func PreserveTrailingDotOrSeparator(cleanedPath string, originalPath string) string { + // Ensure paths are in platform semantics + cleanedPath = normalizePath(cleanedPath) + originalPath = normalizePath(originalPath) + + if !specifiesCurrentDir(cleanedPath) && specifiesCurrentDir(originalPath) { + if !hasTrailingPathSeparator(cleanedPath) { + // Add a separator if it doesn't already end with one (a cleaned + // path would only end in a separator if it is the root). + cleanedPath += string(filepath.Separator) + } + cleanedPath += "." + } + + if !hasTrailingPathSeparator(cleanedPath) && hasTrailingPathSeparator(originalPath) { + cleanedPath += string(filepath.Separator) + } + + return cleanedPath +} + +// assertsDirectory returns whether the given path is +// asserted to be a directory, i.e., the path ends with +// a trailing '/' or `/.`, assuming a path separator of `/`. +func assertsDirectory(path string) bool { + return hasTrailingPathSeparator(path) || specifiesCurrentDir(path) +} + +// hasTrailingPathSeparator returns whether the given +// path ends with the system's path separator character. +func hasTrailingPathSeparator(path string) bool { + return len(path) > 0 && path[len(path)-1] == filepath.Separator +} + +// specifiesCurrentDir returns whether the given path specifies +// a "current directory", i.e., the last path segment is `.`. +func specifiesCurrentDir(path string) bool { + return filepath.Base(path) == "." +} + +// SplitPathDirEntry splits the given path between its directory name and its +// basename by first cleaning the path but preserves a trailing "." if the +// original path specified the current directory. +func SplitPathDirEntry(path string) (dir, base string) { + cleanedPath := filepath.Clean(filepath.FromSlash(path)) + + if specifiesCurrentDir(path) { + cleanedPath += string(os.PathSeparator) + "." + } + + return filepath.Dir(cleanedPath), filepath.Base(cleanedPath) +} + +// TarResource archives the resource described by the given CopyInfo to a Tar +// archive. A non-nil error is returned if sourcePath does not exist or is +// asserted to be a directory but exists as another type of file. +// +// This function acts as a convenient wrapper around TarWithOptions, which +// requires a directory as the source path. TarResource accepts either a +// directory or a file path and correctly sets the Tar options. +func TarResource(sourceInfo CopyInfo) (content io.ReadCloser, err error) { + return TarResourceRebase(sourceInfo.Path, sourceInfo.RebaseName) +} + +// TarResourceRebase is like TarResource but renames the first path element of +// items in the resulting tar archive to match the given rebaseName if not "". +func TarResourceRebase(sourcePath, rebaseName string) (content io.ReadCloser, _ error) { + sourcePath = normalizePath(sourcePath) + if _, err := os.Lstat(sourcePath); err != nil { + // Catches the case where the source does not exist or is not a + // directory if asserted to be a directory, as this also causes an + // error. + return nil, err + } + + // Separate the source path between its directory and + // the entry in that directory which we are archiving. + sourceDir, sourceBase := SplitPathDirEntry(sourcePath) + opts := TarResourceRebaseOpts(sourceBase, rebaseName) + + log.G(context.TODO()).Debugf("copying %q from %q", sourceBase, sourceDir) + return TarWithOptions(sourceDir, opts) +} + +// TarResourceRebaseOpts does not preform the Tar, but instead just creates the rebase +// parameters to be sent to TarWithOptions (the TarOptions struct) +func TarResourceRebaseOpts(sourceBase string, rebaseName string) *TarOptions { + filter := []string{sourceBase} + return &TarOptions{ + IncludeFiles: filter, + IncludeSourceDir: true, + RebaseNames: map[string]string{ + sourceBase: rebaseName, + }, + } +} + +// CopyInfo holds basic info about the source +// or destination path of a copy operation. +type CopyInfo struct { + Path string + Exists bool + IsDir bool + RebaseName string +} + +// CopyInfoSourcePath stats the given path to create a CopyInfo +// struct representing that resource for the source of an archive copy +// operation. The given path should be an absolute local path. A source path +// has all symlinks evaluated that appear before the last path separator ("/" +// on Unix). As it is to be a copy source, the path must exist. +func CopyInfoSourcePath(path string, followLink bool) (CopyInfo, error) { + // normalize the file path and then evaluate the symbol link + // we will use the target file instead of the symbol link if + // followLink is set + path = normalizePath(path) + + resolvedPath, rebaseName, err := ResolveHostSourcePath(path, followLink) + if err != nil { + return CopyInfo{}, err + } + + stat, err := os.Lstat(resolvedPath) + if err != nil { + return CopyInfo{}, err + } + + return CopyInfo{ + Path: resolvedPath, + Exists: true, + IsDir: stat.IsDir(), + RebaseName: rebaseName, + }, nil +} + +// CopyInfoDestinationPath stats the given path to create a CopyInfo +// struct representing that resource for the destination of an archive copy +// operation. The given path should be an absolute local path. +func CopyInfoDestinationPath(path string) (info CopyInfo, err error) { + maxSymlinkIter := 10 // filepath.EvalSymlinks uses 255, but 10 already seems like a lot. + path = normalizePath(path) + originalPath := path + + stat, err := os.Lstat(path) + + if err == nil && stat.Mode()&os.ModeSymlink == 0 { + // The path exists and is not a symlink. + return CopyInfo{ + Path: path, + Exists: true, + IsDir: stat.IsDir(), + }, nil + } + + // While the path is a symlink. + for n := 0; err == nil && stat.Mode()&os.ModeSymlink != 0; n++ { + if n > maxSymlinkIter { + // Don't follow symlinks more than this arbitrary number of times. + return CopyInfo{}, errors.New("too many symlinks in " + originalPath) + } + + // The path is a symbolic link. We need to evaluate it so that the + // destination of the copy operation is the link target and not the + // link itself. This is notably different than CopyInfoSourcePath which + // only evaluates symlinks before the last appearing path separator. + // Also note that it is okay if the last path element is a broken + // symlink as the copy operation should create the target. + var linkTarget string + + linkTarget, err = os.Readlink(path) + if err != nil { + return CopyInfo{}, err + } + + if !filepath.IsAbs(linkTarget) { + // Join with the parent directory. + dstParent, _ := SplitPathDirEntry(path) + linkTarget = filepath.Join(dstParent, linkTarget) + } + + path = linkTarget + stat, err = os.Lstat(path) + } + + if err != nil { + // It's okay if the destination path doesn't exist. We can still + // continue the copy operation if the parent directory exists. + if !os.IsNotExist(err) { + return CopyInfo{}, err + } + + // Ensure destination parent dir exists. + dstParent, _ := SplitPathDirEntry(path) + + parentDirStat, err := os.Stat(dstParent) + if err != nil { + return CopyInfo{}, err + } + if !parentDirStat.IsDir() { + return CopyInfo{}, ErrNotDirectory + } + + return CopyInfo{Path: path}, nil + } + + // The path exists after resolving symlinks. + return CopyInfo{ + Path: path, + Exists: true, + IsDir: stat.IsDir(), + }, nil +} + +// PrepareArchiveCopy prepares the given srcContent archive, which should +// contain the archived resource described by srcInfo, to the destination +// described by dstInfo. Returns the possibly modified content archive along +// with the path to the destination directory which it should be extracted to. +func PrepareArchiveCopy(srcContent io.Reader, srcInfo, dstInfo CopyInfo) (dstDir string, content io.ReadCloser, err error) { + // Ensure in platform semantics + srcInfo.Path = normalizePath(srcInfo.Path) + dstInfo.Path = normalizePath(dstInfo.Path) + + // Separate the destination path between its directory and base + // components in case the source archive contents need to be rebased. + dstDir, dstBase := SplitPathDirEntry(dstInfo.Path) + _, srcBase := SplitPathDirEntry(srcInfo.Path) + + switch { + case dstInfo.Exists && dstInfo.IsDir: + // The destination exists as a directory. No alteration + // to srcContent is needed as its contents can be + // simply extracted to the destination directory. + return dstInfo.Path, io.NopCloser(srcContent), nil + case dstInfo.Exists && srcInfo.IsDir: + // The destination exists as some type of file and the source + // content is a directory. This is an error condition since + // you cannot copy a directory to an existing file location. + return "", nil, ErrCannotCopyDir + case dstInfo.Exists: + // The destination exists as some type of file and the source content + // is also a file. The source content entry will have to be renamed to + // have a basename which matches the destination path's basename. + if len(srcInfo.RebaseName) != 0 { + srcBase = srcInfo.RebaseName + } + return dstDir, RebaseArchiveEntries(srcContent, srcBase, dstBase), nil + case srcInfo.IsDir: + // The destination does not exist and the source content is an archive + // of a directory. The archive should be extracted to the parent of + // the destination path instead, and when it is, the directory that is + // created as a result should take the name of the destination path. + // The source content entries will have to be renamed to have a + // basename which matches the destination path's basename. + if len(srcInfo.RebaseName) != 0 { + srcBase = srcInfo.RebaseName + } + return dstDir, RebaseArchiveEntries(srcContent, srcBase, dstBase), nil + case assertsDirectory(dstInfo.Path): + // The destination does not exist and is asserted to be created as a + // directory, but the source content is not a directory. This is an + // error condition since you cannot create a directory from a file + // source. + return "", nil, ErrDirNotExists + default: + // The last remaining case is when the destination does not exist, is + // not asserted to be a directory, and the source content is not an + // archive of a directory. It this case, the destination file will need + // to be created when the archive is extracted and the source content + // entry will have to be renamed to have a basename which matches the + // destination path's basename. + if len(srcInfo.RebaseName) != 0 { + srcBase = srcInfo.RebaseName + } + return dstDir, RebaseArchiveEntries(srcContent, srcBase, dstBase), nil + } +} + +// RebaseArchiveEntries rewrites the given srcContent archive replacing +// an occurrence of oldBase with newBase at the beginning of entry names. +func RebaseArchiveEntries(srcContent io.Reader, oldBase, newBase string) io.ReadCloser { + if oldBase == string(os.PathSeparator) { + // If oldBase specifies the root directory, use an empty string as + // oldBase instead so that newBase doesn't replace the path separator + // that all paths will start with. + oldBase = "" + } + + rebased, w := io.Pipe() + + go func() { + srcTar := tar.NewReader(srcContent) + rebasedTar := tar.NewWriter(w) + + for { + hdr, err := srcTar.Next() + if errors.Is(err, io.EOF) { + // Signals end of archive. + rebasedTar.Close() + w.Close() + return + } + if err != nil { + w.CloseWithError(err) + return + } + + // srcContent tar stream, as served by TarWithOptions(), is + // definitely in PAX format, but tar.Next() mistakenly guesses it + // as USTAR, which creates a problem: if the newBase is >100 + // characters long, WriteHeader() returns an error like + // "archive/tar: cannot encode header: Format specifies USTAR; and USTAR cannot encode Name=...". + // + // To fix, set the format to PAX here. See docker/for-linux issue #484. + hdr.Format = tar.FormatPAX + hdr.Name = strings.Replace(hdr.Name, oldBase, newBase, 1) + if hdr.Typeflag == tar.TypeLink { + hdr.Linkname = strings.Replace(hdr.Linkname, oldBase, newBase, 1) + } + + if err = rebasedTar.WriteHeader(hdr); err != nil { + w.CloseWithError(err) + return + } + + // Ignoring GoSec G110. See https://github.com/securego/gosec/pull/433 + // and https://cure53.de/pentest-report_opa.pdf, which recommends to + // replace io.Copy with io.CopyN7. The latter allows to specify the + // maximum number of bytes that should be read. By properly defining + // the limit, it can be assured that a GZip compression bomb cannot + // easily cause a Denial-of-Service. + // After reviewing with @tonistiigi and @cpuguy83, this should not + // affect us, because here we do not read into memory, hence should + // not be vulnerable to this code consuming memory. + //nolint:gosec // G110: Potential DoS vulnerability via decompression bomb (gosec) + if _, err = io.Copy(rebasedTar, srcTar); err != nil { + w.CloseWithError(err) + return + } + } + }() + + return rebased +} + +// CopyResource performs an archive copy from the given source path to the +// given destination path. The source path MUST exist and the destination +// path's parent directory must exist. +func CopyResource(srcPath, dstPath string, followLink bool) error { + var ( + srcInfo CopyInfo + err error + ) + + // Ensure in platform semantics + srcPath = normalizePath(srcPath) + dstPath = normalizePath(dstPath) + + // Clean the source and destination paths. + srcPath = PreserveTrailingDotOrSeparator(filepath.Clean(srcPath), srcPath) + dstPath = PreserveTrailingDotOrSeparator(filepath.Clean(dstPath), dstPath) + + if srcInfo, err = CopyInfoSourcePath(srcPath, followLink); err != nil { + return err + } + + content, err := TarResource(srcInfo) + if err != nil { + return err + } + defer content.Close() + + return CopyTo(content, srcInfo, dstPath) +} + +// CopyTo handles extracting the given content whose +// entries should be sourced from srcInfo to dstPath. +func CopyTo(content io.Reader, srcInfo CopyInfo, dstPath string) error { + // The destination path need not exist, but CopyInfoDestinationPath will + // ensure that at least the parent directory exists. + dstInfo, err := CopyInfoDestinationPath(normalizePath(dstPath)) + if err != nil { + return err + } + + dstDir, copyArchive, err := PrepareArchiveCopy(content, srcInfo, dstInfo) + if err != nil { + return err + } + defer copyArchive.Close() + + options := &TarOptions{ + NoLchown: true, + NoOverwriteDirNonDir: true, + } + + return Untar(copyArchive, dstDir, options) +} + +// ResolveHostSourcePath decides real path need to be copied with parameters such as +// whether to follow symbol link or not, if followLink is true, resolvedPath will return +// link target of any symbol link file, else it will only resolve symlink of directory +// but return symbol link file itself without resolving. +func ResolveHostSourcePath(path string, followLink bool) (resolvedPath, rebaseName string, _ error) { + if followLink { + var err error + resolvedPath, err = filepath.EvalSymlinks(path) + if err != nil { + return "", "", err + } + + resolvedPath, rebaseName = GetRebaseName(path, resolvedPath) + } else { + dirPath, basePath := filepath.Split(path) + + // if not follow symbol link, then resolve symbol link of parent dir + resolvedDirPath, err := filepath.EvalSymlinks(dirPath) + if err != nil { + return "", "", err + } + // resolvedDirPath will have been cleaned (no trailing path separators) so + // we can manually join it with the base path element. + resolvedPath = resolvedDirPath + string(filepath.Separator) + basePath + if hasTrailingPathSeparator(path) && + filepath.Base(path) != filepath.Base(resolvedPath) { + rebaseName = filepath.Base(path) + } + } + return resolvedPath, rebaseName, nil +} + +// GetRebaseName normalizes and compares path and resolvedPath, +// return completed resolved path and rebased file name +func GetRebaseName(path, resolvedPath string) (string, string) { + // linkTarget will have been cleaned (no trailing path separators and dot) so + // we can manually join it with them + var rebaseName string + if specifiesCurrentDir(path) && + !specifiesCurrentDir(resolvedPath) { + resolvedPath += string(filepath.Separator) + "." + } + + if hasTrailingPathSeparator(path) && + !hasTrailingPathSeparator(resolvedPath) { + resolvedPath += string(filepath.Separator) + } + + if filepath.Base(path) != filepath.Base(resolvedPath) { + // In the case where the path had a trailing separator and a symlink + // evaluation has changed the last path component, we will need to + // rebase the name in the archive that is being copied to match the + // originally requested name. + rebaseName = filepath.Base(path) + } + return resolvedPath, rebaseName +} |