func TarWithOptions()

in pkg/archive/archive.go [483:657]
112 lines of code
32 McCabe index (conditional complexity)

func TarWithOptions(srcPath string, options *TarOptions) (io.ReadCloser, error) {

	// Fix the source path to work with long path names. This is a no-op
	// on platforms other than Windows.
	srcPath = fixVolumePathPrefix(srcPath)

	patterns, patDirs, exceptions, err := fileutils.CleanPatterns(options.ExcludePatterns)

	if err != nil {
		return nil, err
	}

	pipeReader, pipeWriter := io.Pipe()

	compressWriter, err := CompressStream(pipeWriter, options.Compression)
	if err != nil {
		return nil, err
	}

	go func() {
		ta := &tarAppender{
			TarWriter: tar.NewWriter(compressWriter),
			Buffer:    pools.BufioWriter32KPool.Get(nil),
			SeenFiles: make(map[uint64]string),
			UIDMaps:   options.UIDMaps,
			GIDMaps:   options.GIDMaps,
		}

		defer func() {
			// Make sure to check the error on Close.
			if err := ta.TarWriter.Close(); err != nil {
				logrus.Errorf("Can't close tar writer: %s", err)
			}
			if err := compressWriter.Close(); err != nil {
				logrus.Errorf("Can't close compress writer: %s", err)
			}
			if err := pipeWriter.Close(); err != nil {
				logrus.Errorf("Can't close pipe writer: %s", err)
			}
		}()

		// this buffer is needed for the duration of this piped stream
		defer pools.BufioWriter32KPool.Put(ta.Buffer)

		// In general we log errors here but ignore them because
		// during e.g. a diff operation the container can continue
		// mutating the filesystem and we can see transient errors
		// from this

		stat, err := os.Lstat(srcPath)
		if err != nil {
			return
		}

		if !stat.IsDir() {
			// We can't later join a non-dir with any includes because the
			// 'walk' will error if "file/." is stat-ed and "file" is not a
			// directory. So, we must split the source path and use the
			// basename as the include.
			if len(options.IncludeFiles) > 0 {
				logrus.Warn("Tar: Can't archive a file with includes")
			}

			dir, base := SplitPathDirEntry(srcPath)
			srcPath = dir
			options.IncludeFiles = []string{base}
		}

		if len(options.IncludeFiles) == 0 {
			options.IncludeFiles = []string{"."}
		}

		seen := make(map[string]bool)

		for _, include := range options.IncludeFiles {
			rebaseName := options.RebaseNames[include]

			walkRoot := getWalkRoot(srcPath, include)
			filepath.Walk(walkRoot, func(filePath string, f os.FileInfo, err error) error {
				if err != nil {
					logrus.Errorf("Tar: Can't stat file %s to tar: %s", srcPath, err)
					return nil
				}

				relFilePath, err := filepath.Rel(srcPath, filePath)
				if err != nil || (!options.IncludeSourceDir && relFilePath == "." && f.IsDir()) {
					// Error getting relative path OR we are looking
					// at the source directory path. Skip in both situations.
					return nil
				}

				if options.IncludeSourceDir && include == "." && relFilePath != "." {
					relFilePath = strings.Join([]string{".", relFilePath}, string(filepath.Separator))
				}

				skip := false

				// If "include" is an exact match for the current file
				// then even if there's an "excludePatterns" pattern that
				// matches it, don't skip it. IOW, assume an explicit 'include'
				// is asking for that file no matter what - which is true
				// for some files, like .dockerignore and Dockerfile (sometimes)
				if include != relFilePath {
					skip, err = fileutils.OptimizedMatches(relFilePath, patterns, patDirs)
					if err != nil {
						logrus.Errorf("Error matching %s: %v", relFilePath, err)
						return err
					}
				}

				if skip {
					// If we want to skip this file and its a directory
					// then we should first check to see if there's an
					// excludes pattern (eg !dir/file) that starts with this
					// dir. If so then we can't skip this dir.

					// Its not a dir then so we can just return/skip.
					if !f.IsDir() {
						return nil
					}

					// No exceptions (!...) in patterns so just skip dir
					if !exceptions {
						return filepath.SkipDir
					}

					dirSlash := relFilePath + string(filepath.Separator)

					for _, pat := range patterns {
						if pat[0] != '!' {
							continue
						}
						pat = pat[1:] + string(filepath.Separator)
						if strings.HasPrefix(pat, dirSlash) {
							// found a match - so can't skip this dir
							return nil
						}
					}

					// No matching exclusion dir so just skip dir
					return filepath.SkipDir
				}

				if seen[relFilePath] {
					return nil
				}
				seen[relFilePath] = true

				// Rename the base resource.
				if rebaseName != "" {
					var replacement string
					if rebaseName != string(filepath.Separator) {
						// Special case the root directory to replace with an
						// empty string instead so that we don't end up with
						// double slashes in the paths.
						replacement = rebaseName
					}

					relFilePath = strings.Replace(relFilePath, include, replacement, 1)
				}

				if err := ta.addTarFile(filePath, relFilePath); err != nil {
					logrus.Errorf("Can't add file %s to tar: %s", filePath, err)
					// if pipe is broken, stop writing tar stream to it
					if err == io.ErrClosedPipe {
						return err
					}
				}
				return nil
			})
		}
	}()

	return pipeReader, nil
}