+var ErrNotInOutputDir = fmt.Errorf("Must point to path within the output directory")
+
+func (runner *ContainerRunner) derefOutputSymlink(path string, startinfo os.FileInfo) (tgt string, readlinktgt string, info os.FileInfo, err error) {
+ // Follow symlinks if necessary
+ info = startinfo
+ tgt = path
+ readlinktgt = ""
+ nextlink := path
+ for followed := 0; info.Mode()&os.ModeSymlink != 0; followed++ {
+ if followed >= limitFollowSymlinks {
+ // Got stuck in a loop or just a pathological number of links, give up.
+ err = fmt.Errorf("Followed more than %v symlinks from path %q", limitFollowSymlinks, path)
+ return
+ }
+
+ readlinktgt, err = os.Readlink(nextlink)
+ if err != nil {
+ return
+ }
+
+ tgt = readlinktgt
+ if !strings.HasPrefix(tgt, "/") {
+ // Relative symlink, resolve it to host path
+ tgt = filepath.Join(filepath.Dir(path), tgt)
+ }
+ if strings.HasPrefix(tgt, runner.Container.OutputPath+"/") && !strings.HasPrefix(tgt, runner.HostOutputDir+"/") {
+ // Absolute symlink to container output path, adjust it to host output path.
+ tgt = filepath.Join(runner.HostOutputDir, tgt[len(runner.Container.OutputPath):])
+ }
+ if !strings.HasPrefix(tgt, runner.HostOutputDir+"/") {
+ // After dereferencing, symlink target must either be
+ // within output directory, or must point to a
+ // collection mount.
+ err = ErrNotInOutputDir
+ return
+ }
+
+ info, err = os.Lstat(tgt)
+ if err != nil {
+ // tgt
+ err = fmt.Errorf("Symlink in output %q points to invalid location %q: %v",
+ path[len(runner.HostOutputDir):], readlinktgt, err)
+ return
+ }
+
+ nextlink = tgt
+ }
+
+ return
+}
+
+var limitFollowSymlinks = 10
+
+// UploadFile uploads files within the output directory, with special handling
+// for symlinks. If the symlink leads to a keep mount, copy the manifest text
+// from the keep mount into the output manifestText. Ensure that whether
+// symlinks are relative or absolute, every symlink target (even targets that
+// are symlinks themselves) must point to a path in either the output directory
+// or a collection mount.
+//
+// Assumes initial value of "path" is absolute, and located within runner.HostOutputDir.
+func (runner *ContainerRunner) UploadOutputFile(
+ path string,
+ info os.FileInfo,
+ infoerr error,
+ binds []string,
+ walkUpload *WalkUpload,
+ relocateFrom string,
+ relocateTo string,
+ followed int) (manifestText string, err error) {
+
+ if infoerr != nil {
+ return "", infoerr
+ }
+
+ if info.Mode().IsDir() {
+ // if empty, need to create a .keep file
+ dir, direrr := os.Open(path)
+ if direrr != nil {
+ return "", direrr
+ }
+ defer dir.Close()
+ names, eof := dir.Readdirnames(1)
+ if len(names) == 0 && eof == io.EOF && path != runner.HostOutputDir {
+ containerPath := runner.OutputPath + path[len(runner.HostOutputDir):]
+ for _, bind := range binds {
+ mnt := runner.Container.Mounts[bind]
+ // Check if there is a bind for this
+ // directory, in which case assume we don't need .keep
+ if (containerPath == bind || strings.HasPrefix(containerPath, bind+"/")) && mnt.PortableDataHash != "d41d8cd98f00b204e9800998ecf8427e+0" {
+ return
+ }
+ }
+ outputSuffix := path[len(runner.HostOutputDir)+1:]
+ return fmt.Sprintf("./%v d41d8cd98f00b204e9800998ecf8427e+0 0:0:.keep\n", outputSuffix), nil
+ }
+ return
+ }
+
+ if followed >= limitFollowSymlinks {
+ // Got stuck in a loop or just a pathological number of
+ // directory links, give up.
+ err = fmt.Errorf("Followed more than %v symlinks from path %q", limitFollowSymlinks, path)
+ return
+ }
+
+ // "path" is the actual path we are visiting
+ // "tgt" is the target of "path" (a non-symlink) after following symlinks
+ // "relocated" is the path in the output manifest where the file should be placed,
+ // but has HostOutputDir as a prefix.
+
+ // The destination path in the output manifest may need to be
+ // logically relocated to some other path in order to appear
+ // in the correct location as a result of following a symlink.
+ // Remove the relocateFrom prefix and replace it with
+ // relocateTo.
+ relocated := relocateTo + path[len(relocateFrom):]
+
+ tgt, readlinktgt, info, derefErr := runner.derefOutputSymlink(path, info)
+ if derefErr != nil && derefErr != ErrNotInOutputDir {
+ return "", derefErr
+ }
+
+ // go through mounts and try reverse map to collection reference
+ for _, bind := range binds {
+ mnt := runner.Container.Mounts[bind]
+ if tgt == bind || strings.HasPrefix(tgt, bind+"/") {
+ // get path relative to bind
+ targetSuffix := tgt[len(bind):]
+
+ // Copy mount and adjust the path to add path relative to the bind
+ adjustedMount := mnt
+ adjustedMount.Path = filepath.Join(adjustedMount.Path, targetSuffix)
+
+ // Terminates in this keep mount, so add the
+ // manifest text at appropriate location.
+ outputSuffix := relocated[len(runner.HostOutputDir):]
+ manifestText, err = runner.getCollectionManifestForPath(adjustedMount, outputSuffix)
+ return
+ }
+ }
+
+ // If target is not a collection mount, it must be located within the
+ // output directory, otherwise it is an error.
+ if derefErr == ErrNotInOutputDir {
+ err = fmt.Errorf("Symlink in output %q points to invalid location %q, must point to path within the output directory.",
+ path[len(runner.HostOutputDir):], readlinktgt)
+ return
+ }
+
+ if info.Mode().IsRegular() {
+ return "", walkUpload.UploadFile(relocated, tgt)
+ }
+
+ if info.Mode().IsDir() {
+ // Symlink leads to directory. Walk() doesn't follow
+ // directory symlinks, so we walk the target directory
+ // instead. Within the walk, file paths are relocated
+ // so they appear under the original symlink path.
+ err = filepath.Walk(tgt, func(walkpath string, walkinfo os.FileInfo, walkerr error) error {
+ var m string
+ m, walkerr = runner.UploadOutputFile(walkpath, walkinfo, walkerr,
+ binds, walkUpload, tgt, relocated, followed+1)
+ if walkerr == nil {
+ manifestText = manifestText + m
+ }
+ return walkerr
+ })
+ return
+ }
+
+ return
+}
+