зеркало из https://github.com/microsoft/docker.git
459 строки
15 KiB
Go
459 строки
15 KiB
Go
package archive
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import (
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"archive/tar"
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"errors"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"strings"
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"github.com/Sirupsen/logrus"
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"github.com/docker/docker/pkg/system"
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)
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// Errors used or returned by this file.
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var (
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ErrNotDirectory = errors.New("not a directory")
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ErrDirNotExists = errors.New("no such directory")
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ErrCannotCopyDir = errors.New("cannot copy directory")
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ErrInvalidCopySource = errors.New("invalid copy source content")
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)
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// PreserveTrailingDotOrSeparator returns the given cleaned path (after
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// processing using any utility functions from the path or filepath stdlib
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// packages) and appends a trailing `/.` or `/` if its corresponding original
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// path (from before being processed by utility functions from the path or
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// filepath stdlib packages) ends with a trailing `/.` or `/`. If the cleaned
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// path already ends in a `.` path segment, then another is not added. If the
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// clean path already ends in a path separator, then another is not added.
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func PreserveTrailingDotOrSeparator(cleanedPath, originalPath string) string {
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// Ensure paths are in platform semantics
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cleanedPath = normalizePath(cleanedPath)
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originalPath = normalizePath(originalPath)
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if !specifiesCurrentDir(cleanedPath) && specifiesCurrentDir(originalPath) {
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if !hasTrailingPathSeparator(cleanedPath) {
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// Add a separator if it doesn't already end with one (a cleaned
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// path would only end in a separator if it is the root).
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cleanedPath += string(filepath.Separator)
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}
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cleanedPath += "."
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}
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if !hasTrailingPathSeparator(cleanedPath) && hasTrailingPathSeparator(originalPath) {
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cleanedPath += string(filepath.Separator)
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}
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return cleanedPath
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}
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// assertsDirectory returns whether the given path is
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// asserted to be a directory, i.e., the path ends with
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// a trailing '/' or `/.`, assuming a path separator of `/`.
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func assertsDirectory(path string) bool {
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return hasTrailingPathSeparator(path) || specifiesCurrentDir(path)
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}
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// hasTrailingPathSeparator returns whether the given
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// path ends with the system's path separator character.
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func hasTrailingPathSeparator(path string) bool {
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return len(path) > 0 && os.IsPathSeparator(path[len(path)-1])
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}
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// specifiesCurrentDir returns whether the given path specifies
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// a "current directory", i.e., the last path segment is `.`.
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func specifiesCurrentDir(path string) bool {
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return filepath.Base(path) == "."
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}
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// SplitPathDirEntry splits the given path between its directory name and its
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// basename by first cleaning the path but preserves a trailing "." if the
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// original path specified the current directory.
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func SplitPathDirEntry(path string) (dir, base string) {
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cleanedPath := filepath.Clean(normalizePath(path))
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if specifiesCurrentDir(path) {
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cleanedPath += string(filepath.Separator) + "."
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}
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return filepath.Dir(cleanedPath), filepath.Base(cleanedPath)
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}
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// TarResource archives the resource described by the given CopyInfo to a Tar
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// archive. A non-nil error is returned if sourcePath does not exist or is
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// asserted to be a directory but exists as another type of file.
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//
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// This function acts as a convenient wrapper around TarWithOptions, which
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// requires a directory as the source path. TarResource accepts either a
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// directory or a file path and correctly sets the Tar options.
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func TarResource(sourceInfo CopyInfo) (content io.ReadCloser, err error) {
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return TarResourceRebase(sourceInfo.Path, sourceInfo.RebaseName)
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}
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// TarResourceRebase is like TarResource but renames the first path element of
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// items in the resulting tar archive to match the given rebaseName if not "".
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func TarResourceRebase(sourcePath, rebaseName string) (content io.ReadCloser, err error) {
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sourcePath = normalizePath(sourcePath)
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if _, err = os.Lstat(sourcePath); err != nil {
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// Catches the case where the source does not exist or is not a
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// directory if asserted to be a directory, as this also causes an
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// error.
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return
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}
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// Separate the source path between its directory and
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// the entry in that directory which we are archiving.
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sourceDir, sourceBase := SplitPathDirEntry(sourcePath)
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filter := []string{sourceBase}
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logrus.Debugf("copying %q from %q", sourceBase, sourceDir)
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return TarWithOptions(sourceDir, &TarOptions{
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Compression: Uncompressed,
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IncludeFiles: filter,
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IncludeSourceDir: true,
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RebaseNames: map[string]string{
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sourceBase: rebaseName,
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},
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})
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}
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// CopyInfo holds basic info about the source
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// or destination path of a copy operation.
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type CopyInfo struct {
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Path string
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Exists bool
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IsDir bool
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RebaseName string
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}
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// CopyInfoSourcePath stats the given path to create a CopyInfo
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// struct representing that resource for the source of an archive copy
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// operation. The given path should be an absolute local path. A source path
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// has all symlinks evaluated that appear before the last path separator ("/"
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// on Unix). As it is to be a copy source, the path must exist.
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func CopyInfoSourcePath(path string, followLink bool) (CopyInfo, error) {
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// normalize the file path and then evaluate the symbol link
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// we will use the target file instead of the symbol link if
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// followLink is set
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path = normalizePath(path)
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resolvedPath, rebaseName, err := ResolveHostSourcePath(path, followLink)
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if err != nil {
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return CopyInfo{}, err
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}
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stat, err := os.Lstat(resolvedPath)
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if err != nil {
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return CopyInfo{}, err
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}
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return CopyInfo{
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Path: resolvedPath,
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Exists: true,
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IsDir: stat.IsDir(),
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RebaseName: rebaseName,
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}, nil
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}
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// CopyInfoDestinationPath stats the given path to create a CopyInfo
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// struct representing that resource for the destination of an archive copy
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// operation. The given path should be an absolute local path.
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func CopyInfoDestinationPath(path string) (info CopyInfo, err error) {
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maxSymlinkIter := 10 // filepath.EvalSymlinks uses 255, but 10 already seems like a lot.
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path = normalizePath(path)
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originalPath := path
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stat, err := os.Lstat(path)
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if err == nil && stat.Mode()&os.ModeSymlink == 0 {
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// The path exists and is not a symlink.
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return CopyInfo{
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Path: path,
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Exists: true,
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IsDir: stat.IsDir(),
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}, nil
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}
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// While the path is a symlink.
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for n := 0; err == nil && stat.Mode()&os.ModeSymlink != 0; n++ {
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if n > maxSymlinkIter {
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// Don't follow symlinks more than this arbitrary number of times.
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return CopyInfo{}, errors.New("too many symlinks in " + originalPath)
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}
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// The path is a symbolic link. We need to evaluate it so that the
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// destination of the copy operation is the link target and not the
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// link itself. This is notably different than CopyInfoSourcePath which
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// only evaluates symlinks before the last appearing path separator.
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// Also note that it is okay if the last path element is a broken
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// symlink as the copy operation should create the target.
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var linkTarget string
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linkTarget, err = os.Readlink(path)
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if err != nil {
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return CopyInfo{}, err
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}
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if !system.IsAbs(linkTarget) {
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// Join with the parent directory.
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dstParent, _ := SplitPathDirEntry(path)
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linkTarget = filepath.Join(dstParent, linkTarget)
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}
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path = linkTarget
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stat, err = os.Lstat(path)
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}
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if err != nil {
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// It's okay if the destination path doesn't exist. We can still
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// continue the copy operation if the parent directory exists.
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if !os.IsNotExist(err) {
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return CopyInfo{}, err
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}
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// Ensure destination parent dir exists.
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dstParent, _ := SplitPathDirEntry(path)
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parentDirStat, err := os.Lstat(dstParent)
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if err != nil {
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return CopyInfo{}, err
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}
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if !parentDirStat.IsDir() {
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return CopyInfo{}, ErrNotDirectory
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}
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return CopyInfo{Path: path}, nil
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}
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// The path exists after resolving symlinks.
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return CopyInfo{
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Path: path,
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Exists: true,
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IsDir: stat.IsDir(),
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}, nil
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}
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// PrepareArchiveCopy prepares the given srcContent archive, which should
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// contain the archived resource described by srcInfo, to the destination
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// described by dstInfo. Returns the possibly modified content archive along
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// with the path to the destination directory which it should be extracted to.
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func PrepareArchiveCopy(srcContent io.Reader, srcInfo, dstInfo CopyInfo) (dstDir string, content io.ReadCloser, err error) {
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// Ensure in platform semantics
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srcInfo.Path = normalizePath(srcInfo.Path)
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dstInfo.Path = normalizePath(dstInfo.Path)
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// Separate the destination path between its directory and base
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// components in case the source archive contents need to be rebased.
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dstDir, dstBase := SplitPathDirEntry(dstInfo.Path)
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_, srcBase := SplitPathDirEntry(srcInfo.Path)
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switch {
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case dstInfo.Exists && dstInfo.IsDir:
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// The destination exists as a directory. No alteration
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// to srcContent is needed as its contents can be
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// simply extracted to the destination directory.
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return dstInfo.Path, ioutil.NopCloser(srcContent), nil
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case dstInfo.Exists && srcInfo.IsDir:
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// The destination exists as some type of file and the source
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// content is a directory. This is an error condition since
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// you cannot copy a directory to an existing file location.
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return "", nil, ErrCannotCopyDir
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case dstInfo.Exists:
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// The destination exists as some type of file and the source content
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// is also a file. The source content entry will have to be renamed to
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// have a basename which matches the destination path's basename.
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if len(srcInfo.RebaseName) != 0 {
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srcBase = srcInfo.RebaseName
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}
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return dstDir, RebaseArchiveEntries(srcContent, srcBase, dstBase), nil
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case srcInfo.IsDir:
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// The destination does not exist and the source content is an archive
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// of a directory. The archive should be extracted to the parent of
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// the destination path instead, and when it is, the directory that is
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// created as a result should take the name of the destination path.
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// The source content entries will have to be renamed to have a
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// basename which matches the destination path's basename.
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if len(srcInfo.RebaseName) != 0 {
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srcBase = srcInfo.RebaseName
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}
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return dstDir, RebaseArchiveEntries(srcContent, srcBase, dstBase), nil
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case assertsDirectory(dstInfo.Path):
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// The destination does not exist and is asserted to be created as a
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// directory, but the source content is not a directory. This is an
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// error condition since you cannot create a directory from a file
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// source.
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return "", nil, ErrDirNotExists
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default:
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// The last remaining case is when the destination does not exist, is
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// not asserted to be a directory, and the source content is not an
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// archive of a directory. It this case, the destination file will need
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// to be created when the archive is extracted and the source content
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// entry will have to be renamed to have a basename which matches the
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// destination path's basename.
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if len(srcInfo.RebaseName) != 0 {
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srcBase = srcInfo.RebaseName
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}
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return dstDir, RebaseArchiveEntries(srcContent, srcBase, dstBase), nil
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}
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}
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// RebaseArchiveEntries rewrites the given srcContent archive replacing
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// an occurrence of oldBase with newBase at the beginning of entry names.
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func RebaseArchiveEntries(srcContent io.Reader, oldBase, newBase string) io.ReadCloser {
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if oldBase == string(os.PathSeparator) {
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// If oldBase specifies the root directory, use an empty string as
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// oldBase instead so that newBase doesn't replace the path separator
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// that all paths will start with.
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oldBase = ""
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}
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rebased, w := io.Pipe()
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go func() {
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srcTar := tar.NewReader(srcContent)
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rebasedTar := tar.NewWriter(w)
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for {
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hdr, err := srcTar.Next()
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if err == io.EOF {
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// Signals end of archive.
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rebasedTar.Close()
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w.Close()
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return
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}
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if err != nil {
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w.CloseWithError(err)
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return
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}
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hdr.Name = strings.Replace(hdr.Name, oldBase, newBase, 1)
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if err = rebasedTar.WriteHeader(hdr); err != nil {
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w.CloseWithError(err)
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return
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}
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if _, err = io.Copy(rebasedTar, srcTar); err != nil {
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w.CloseWithError(err)
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return
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}
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}
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}()
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return rebased
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}
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// CopyResource performs an archive copy from the given source path to the
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// given destination path. The source path MUST exist and the destination
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// path's parent directory must exist.
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func CopyResource(srcPath, dstPath string, followLink bool) error {
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var (
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srcInfo CopyInfo
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err error
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)
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// Ensure in platform semantics
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srcPath = normalizePath(srcPath)
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dstPath = normalizePath(dstPath)
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// Clean the source and destination paths.
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srcPath = PreserveTrailingDotOrSeparator(filepath.Clean(srcPath), srcPath)
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dstPath = PreserveTrailingDotOrSeparator(filepath.Clean(dstPath), dstPath)
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if srcInfo, err = CopyInfoSourcePath(srcPath, followLink); err != nil {
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return err
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}
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content, err := TarResource(srcInfo)
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if err != nil {
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return err
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}
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defer content.Close()
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return CopyTo(content, srcInfo, dstPath)
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}
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// CopyTo handles extracting the given content whose
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// entries should be sourced from srcInfo to dstPath.
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func CopyTo(content io.Reader, srcInfo CopyInfo, dstPath string) error {
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// The destination path need not exist, but CopyInfoDestinationPath will
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// ensure that at least the parent directory exists.
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dstInfo, err := CopyInfoDestinationPath(normalizePath(dstPath))
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if err != nil {
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return err
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}
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dstDir, copyArchive, err := PrepareArchiveCopy(content, srcInfo, dstInfo)
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if err != nil {
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return err
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}
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defer copyArchive.Close()
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options := &TarOptions{
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NoLchown: true,
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NoOverwriteDirNonDir: true,
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}
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return Untar(copyArchive, dstDir, options)
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}
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// ResolveHostSourcePath decides real path need to be copied with parameters such as
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// whether to follow symbol link or not, if followLink is true, resolvedPath will return
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// link target of any symbol link file, else it will only resolve symlink of directory
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// but return symbol link file itself without resolving.
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func ResolveHostSourcePath(path string, followLink bool) (resolvedPath, rebaseName string, err error) {
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if followLink {
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resolvedPath, err = filepath.EvalSymlinks(path)
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if err != nil {
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return
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}
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resolvedPath, rebaseName = GetRebaseName(path, resolvedPath)
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} else {
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dirPath, basePath := filepath.Split(path)
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// if not follow symbol link, then resolve symbol link of parent dir
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var resolvedDirPath string
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resolvedDirPath, err = filepath.EvalSymlinks(dirPath)
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if err != nil {
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return
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}
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// resolvedDirPath will have been cleaned (no trailing path separators) so
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// we can manually join it with the base path element.
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resolvedPath = resolvedDirPath + string(filepath.Separator) + basePath
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if hasTrailingPathSeparator(path) && filepath.Base(path) != filepath.Base(resolvedPath) {
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rebaseName = filepath.Base(path)
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}
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}
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return resolvedPath, rebaseName, nil
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}
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// GetRebaseName normalizes and compares path and resolvedPath,
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// return completed resolved path and rebased file name
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func GetRebaseName(path, resolvedPath string) (string, string) {
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// linkTarget will have been cleaned (no trailing path separators and dot) so
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// we can manually join it with them
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var rebaseName string
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if specifiesCurrentDir(path) && !specifiesCurrentDir(resolvedPath) {
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resolvedPath += string(filepath.Separator) + "."
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}
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if hasTrailingPathSeparator(path) && !hasTrailingPathSeparator(resolvedPath) {
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resolvedPath += string(filepath.Separator)
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}
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if filepath.Base(path) != filepath.Base(resolvedPath) {
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// In the case where the path had a trailing separator and a symlink
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// evaluation has changed the last path component, we will need to
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// rebase the name in the archive that is being copied to match the
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// originally requested name.
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rebaseName = filepath.Base(path)
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}
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return resolvedPath, rebaseName
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}
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