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vendor/github.com/vbatts/go-mtree/update.go

@@ -0,0 +1,154 @@
+package mtree
+
+import (
+	"container/heap"
+	"os"
+	"sort"
+
+	"github.com/sirupsen/logrus"
+)
+
+// DefaultUpdateKeywords is the default set of keywords that can take updates to the files on disk
+var DefaultUpdateKeywords = []Keyword{
+	"uid",
+	"gid",
+	"mode",
+	"xattr",
+	"link",
+	"time",
+}
+
+// Update attempts to set the attributes of root directory path, given the values of `keywords` in dh DirectoryHierarchy.
+func Update(root string, dh *DirectoryHierarchy, keywords []Keyword, fs FsEval) ([]InodeDelta, error) {
+	creator := dhCreator{DH: dh}
+	curDir, err := os.Getwd()
+	if err == nil {
+		defer os.Chdir(curDir)
+	}
+
+	if err := os.Chdir(root); err != nil {
+		return nil, err
+	}
+	sort.Sort(byPos(creator.DH.Entries))
+
+	// This is for deferring the update of mtimes of directories, to unwind them
+	// in a most specific path first
+	h := &pathUpdateHeap{}
+	heap.Init(h)
+
+	results := []InodeDelta{}
+	for i, e := range creator.DH.Entries {
+		switch e.Type {
+		case SpecialType:
+			if e.Name == "/set" {
+				creator.curSet = &creator.DH.Entries[i]
+			} else if e.Name == "/unset" {
+				creator.curSet = nil
+			}
+			logrus.Debugf("%#v", e)
+			continue
+		case RelativeType, FullType:
+			e.Set = creator.curSet
+			pathname, err := e.Path()
+			if err != nil {
+				return nil, err
+			}
+
+			// filter the keywords to update on the file, from the keywords available for this entry:
+			var kvToUpdate []KeyVal
+			kvToUpdate = keyvalSelector(e.AllKeys(), keywords)
+			logrus.Debugf("kvToUpdate(%q): %#v", pathname, kvToUpdate)
+
+			for _, kv := range kvToUpdate {
+				if !InKeywordSlice(kv.Keyword().Prefix(), keywordPrefixes(keywords)) {
+					continue
+				}
+				logrus.Debugf("finding function for %q (%q)", kv.Keyword(), kv.Keyword().Prefix())
+				ukFunc, ok := UpdateKeywordFuncs[kv.Keyword().Prefix()]
+				if !ok {
+					logrus.Debugf("no UpdateKeywordFunc for %s; skipping", kv.Keyword())
+					continue
+				}
+
+				// TODO check for the type=dir of the entry as well
+				if kv.Keyword().Prefix() == "time" && e.IsDir() {
+					heap.Push(h, pathUpdate{
+						Path: pathname,
+						E:    e,
+						KV:   kv,
+						Func: ukFunc,
+					})
+
+					continue
+				}
+
+				if _, err := ukFunc(pathname, kv); err != nil {
+					results = append(results, InodeDelta{
+						diff: ErrorDifference,
+						path: pathname,
+						old:  e,
+						keys: []KeyDelta{
+							{
+								diff: ErrorDifference,
+								name: kv.Keyword(),
+								err:  err,
+							},
+						}})
+				}
+				// XXX really would be great to have a Check() or Compare() right here,
+				// to compare each entry as it is encountered, rather than just running
+				// Check() on this path after the whole update is finished.
+			}
+		}
+	}
+
+	for h.Len() > 0 {
+		pu := heap.Pop(h).(pathUpdate)
+		if _, err := pu.Func(pu.Path, pu.KV); err != nil {
+			results = append(results, InodeDelta{
+				diff: ErrorDifference,
+				path: pu.Path,
+				old:  pu.E,
+				keys: []KeyDelta{
+					{
+						diff: ErrorDifference,
+						name: pu.KV.Keyword(),
+						err:  err,
+					},
+				}})
+		}
+	}
+	return results, nil
+}
+
+type pathUpdateHeap []pathUpdate
+
+func (h pathUpdateHeap) Len() int      { return len(h) }
+func (h pathUpdateHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
+
+// This may end up looking backwards, but for container/heap, Less evaluates
+// the negative priority. So when popping members of the array, it will be
+// sorted by least. For this use-case, we want the most-qualified-name popped
+// first (the longest path name), such that "." is the last entry popped.
+func (h pathUpdateHeap) Less(i, j int) bool {
+	return len(h[i].Path) > len(h[j].Path)
+}
+
+func (h *pathUpdateHeap) Push(x interface{}) {
+	*h = append(*h, x.(pathUpdate))
+}
+
+func (h *pathUpdateHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}
+
+type pathUpdate struct {
+	Path string
+	E    Entry
+	KV   KeyVal
+	Func UpdateKeywordFunc
+}