1 files changed, 326 insertions, 0 deletions
diff --git a/vendor/github.com/containerd/continuity/fs/diff.go b/vendor/github.com/containerd/continuity/fs/diff.go
new file mode 100644
index 000000000..e64f9e73d
--- /dev/null
+++ b/vendor/github.com/containerd/continuity/fs/diff.go
@@ -0,0 +1,326 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package fs
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/sync/errgroup"
+
+	"github.com/sirupsen/logrus"
+)
+
+// ChangeKind is the type of modification that
+// a change is making.
+type ChangeKind int
+
+const (
+	// ChangeKindUnmodified represents an unmodified
+	// file
+	ChangeKindUnmodified = iota
+
+	// ChangeKindAdd represents an addition of
+	// a file
+	ChangeKindAdd
+
+	// ChangeKindModify represents a change to
+	// an existing file
+	ChangeKindModify
+
+	// ChangeKindDelete represents a delete of
+	// a file
+	ChangeKindDelete
+)
+
+func (k ChangeKind) String() string {
+	switch k {
+	case ChangeKindUnmodified:
+		return "unmodified"
+	case ChangeKindAdd:
+		return "add"
+	case ChangeKindModify:
+		return "modify"
+	case ChangeKindDelete:
+		return "delete"
+	default:
+		return ""
+	}
+}
+
+// Change represents single change between a diff and its parent.
+type Change struct {
+	Kind ChangeKind
+	Path string
+}
+
+// ChangeFunc is the type of function called for each change
+// computed during a directory changes calculation.
+type ChangeFunc func(ChangeKind, string, os.FileInfo, error) error
+
+// Changes computes changes between two directories calling the
+// given change function for each computed change. The first
+// directory is intended to the base directory and second
+// directory the changed directory.
+//
+// The change callback is called by the order of path names and
+// should be appliable in that order.
+//  Due to this apply ordering, the following is true
+//  - Removed directory trees only create a single change for the root
+//    directory removed. Remaining changes are implied.
+//  - A directory which is modified to become a file will not have
+//    delete entries for sub-path items, their removal is implied
+//    by the removal of the parent directory.
+//
+// Opaque directories will not be treated specially and each file
+// removed from the base directory will show up as a removal.
+//
+// File content comparisons will be done on files which have timestamps
+// which may have been truncated. If either of the files being compared
+// has a zero value nanosecond value, each byte will be compared for
+// differences. If 2 files have the same seconds value but different
+// nanosecond values where one of those values is zero, the files will
+// be considered unchanged if the content is the same. This behavior
+// is to account for timestamp truncation during archiving.
+func Changes(ctx context.Context, a, b string, changeFn ChangeFunc) error {
+	if a == "" {
+		logrus.Debugf("Using single walk diff for %s", b)
+		return addDirChanges(ctx, changeFn, b)
+	} else if diffOptions := detectDirDiff(b, a); diffOptions != nil {
+		logrus.Debugf("Using single walk diff for %s from %s", diffOptions.diffDir, a)
+		return diffDirChanges(ctx, changeFn, a, diffOptions)
+	}
+
+	logrus.Debugf("Using double walk diff for %s from %s", b, a)
+	return doubleWalkDiff(ctx, changeFn, a, b)
+}
+
+func addDirChanges(ctx context.Context, changeFn ChangeFunc, root string) error {
+	return filepath.Walk(root, func(path string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Rebase path
+		path, err = filepath.Rel(root, path)
+		if err != nil {
+			return err
+		}
+
+		path = filepath.Join(string(os.PathSeparator), path)
+
+		// Skip root
+		if path == string(os.PathSeparator) {
+			return nil
+		}
+
+		return changeFn(ChangeKindAdd, path, f, nil)
+	})
+}
+
+// diffDirOptions is used when the diff can be directly calculated from
+// a diff directory to its base, without walking both trees.
+type diffDirOptions struct {
+	diffDir      string
+	skipChange   func(string) (bool, error)
+	deleteChange func(string, string, os.FileInfo) (string, error)
+}
+
+// diffDirChanges walks the diff directory and compares changes against the base.
+func diffDirChanges(ctx context.Context, changeFn ChangeFunc, base string, o *diffDirOptions) error {
+	changedDirs := make(map[string]struct{})
+	return filepath.Walk(o.diffDir, func(path string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Rebase path
+		path, err = filepath.Rel(o.diffDir, path)
+		if err != nil {
+			return err
+		}
+
+		path = filepath.Join(string(os.PathSeparator), path)
+
+		// Skip root
+		if path == string(os.PathSeparator) {
+			return nil
+		}
+
+		// TODO: handle opaqueness, start new double walker at this
+		// location to get deletes, and skip tree in single walker
+
+		if o.skipChange != nil {
+			if skip, err := o.skipChange(path); skip {
+				return err
+			}
+		}
+
+		var kind ChangeKind
+
+		deletedFile, err := o.deleteChange(o.diffDir, path, f)
+		if err != nil {
+			return err
+		}
+
+		// Find out what kind of modification happened
+		if deletedFile != "" {
+			path = deletedFile
+			kind = ChangeKindDelete
+			f = nil
+		} else {
+			// Otherwise, the file was added
+			kind = ChangeKindAdd
+
+			// ...Unless it already existed in a base, in which case, it's a modification
+			stat, err := os.Stat(filepath.Join(base, path))
+			if err != nil && !os.IsNotExist(err) {
+				return err
+			}
+			if err == nil {
+				// The file existed in the base, so that's a modification
+
+				// However, if it's a directory, maybe it wasn't actually modified.
+				// If you modify /foo/bar/baz, then /foo will be part of the changed files only because it's the parent of bar
+				if stat.IsDir() && f.IsDir() {
+					if f.Size() == stat.Size() && f.Mode() == stat.Mode() && sameFsTime(f.ModTime(), stat.ModTime()) {
+						// Both directories are the same, don't record the change
+						return nil
+					}
+				}
+				kind = ChangeKindModify
+			}
+		}
+
+		// If /foo/bar/file.txt is modified, then /foo/bar must be part of the changed files.
+		// This block is here to ensure the change is recorded even if the
+		// modify time, mode and size of the parent directory in the rw and ro layers are all equal.
+		// Check https://github.com/docker/docker/pull/13590 for details.
+		if f.IsDir() {
+			changedDirs[path] = struct{}{}
+		}
+		if kind == ChangeKindAdd || kind == ChangeKindDelete {
+			parent := filepath.Dir(path)
+			if _, ok := changedDirs[parent]; !ok && parent != "/" {
+				pi, err := os.Stat(filepath.Join(o.diffDir, parent))
+				if err := changeFn(ChangeKindModify, parent, pi, err); err != nil {
+					return err
+				}
+				changedDirs[parent] = struct{}{}
+			}
+		}
+
+		return changeFn(kind, path, f, nil)
+	})
+}
+
+// doubleWalkDiff walks both directories to create a diff
+func doubleWalkDiff(ctx context.Context, changeFn ChangeFunc, a, b string) (err error) {
+	g, ctx := errgroup.WithContext(ctx)
+
+	var (
+		c1 = make(chan *currentPath)
+		c2 = make(chan *currentPath)
+
+		f1, f2 *currentPath
+		rmdir  string
+	)
+	g.Go(func() error {
+		defer close(c1)
+		return pathWalk(ctx, a, c1)
+	})
+	g.Go(func() error {
+		defer close(c2)
+		return pathWalk(ctx, b, c2)
+	})
+	g.Go(func() error {
+		for c1 != nil || c2 != nil {
+			if f1 == nil && c1 != nil {
+				f1, err = nextPath(ctx, c1)
+				if err != nil {
+					return err
+				}
+				if f1 == nil {
+					c1 = nil
+				}
+			}
+
+			if f2 == nil && c2 != nil {
+				f2, err = nextPath(ctx, c2)
+				if err != nil {
+					return err
+				}
+				if f2 == nil {
+					c2 = nil
+				}
+			}
+			if f1 == nil && f2 == nil {
+				continue
+			}
+
+			var f os.FileInfo
+			k, p := pathChange(f1, f2)
+			switch k {
+			case ChangeKindAdd:
+				if rmdir != "" {
+					rmdir = ""
+				}
+				f = f2.f
+				f2 = nil
+			case ChangeKindDelete:
+				// Check if this file is already removed by being
+				// under of a removed directory
+				if rmdir != "" && strings.HasPrefix(f1.path, rmdir) {
+					f1 = nil
+					continue
+				} else if f1.f.IsDir() {
+					rmdir = f1.path + string(os.PathSeparator)
+				} else if rmdir != "" {
+					rmdir = ""
+				}
+				f1 = nil
+			case ChangeKindModify:
+				same, err := sameFile(f1, f2)
+				if err != nil {
+					return err
+				}
+				if f1.f.IsDir() && !f2.f.IsDir() {
+					rmdir = f1.path + string(os.PathSeparator)
+				} else if rmdir != "" {
+					rmdir = ""
+				}
+				f = f2.f
+				f1 = nil
+				f2 = nil
+				if same {
+					if !isLinked(f) {
+						continue
+					}
+					k = ChangeKindUnmodified
+				}
+			}
+			if err := changeFn(k, p, f, nil); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+
+	return g.Wait()
+}