1 files changed, 165 insertions, 0 deletions
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/loops.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/loops.go
new file mode 100644
index 0000000..e76985c
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/loops.go
@@ -0,0 +1,165 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package graph
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/datawire/dlib/derror"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
+	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
+	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
+)
+
+func (g Graph) ShowLoops(out io.Writer) {
+	orphans := make(containers.Set[btrfsvol.LogicalAddr])
+	for node := range g.Nodes {
+		if len(g.EdgesTo[node]) == 0 {
+			orphans.Insert(node)
+		}
+	}
+
+	loopWalk(out, g, 0)
+	for _, orphan := range maps.SortedKeys(orphans) {
+		loopWalk(out, g, orphan)
+	}
+}
+
+func loopWalk(out io.Writer, scanData Graph, stack ...btrfsvol.LogicalAddr) {
+	for _, kp := range scanData.EdgesFrom[stack[len(stack)-1]] {
+		childStack := append(stack, kp.ToNode)
+		if slices.Contains(kp.ToNode, stack) {
+			loopRender(out, scanData, childStack...)
+		} else {
+			loopWalk(out, scanData, childStack...)
+		}
+	}
+}
+
+func nodeRender(scanData Graph, node btrfsvol.LogicalAddr) []string {
+	if node == 0 {
+		return []string{"root"}
+	} else if nodeData, ok := scanData.Nodes[node]; ok {
+		return []string{
+			fmt.Sprintf("{addr:      %v,", node),
+			fmt.Sprintf(" level:     %v,", nodeData.Level),
+			fmt.Sprintf(" gen:       %v,", nodeData.Generation),
+			fmt.Sprintf(" num_items: %v,", nodeData.NumItems),
+			fmt.Sprintf(" min_item:  {%d,%v,%d},",
+				nodeData.MinItem.ObjectID,
+				nodeData.MinItem.ItemType,
+				nodeData.MinItem.Offset),
+			fmt.Sprintf(" max_item:  {%d,%v,%d}}",
+				nodeData.MaxItem.ObjectID,
+				nodeData.MaxItem.ItemType,
+				nodeData.MaxItem.Offset),
+		}
+	} else if nodeErr, ok := scanData.BadNodes[node]; ok {
+		return []string{
+			fmt.Sprintf("{addr:%v,", node),
+			fmt.Sprintf(" err:%q}", nodeErr.Error()),
+		}
+	} else {
+		panic("should not happen")
+	}
+}
+
+func edgeRender(scanData Graph, kp Edge) []string {
+	a := fmt.Sprintf("[%d]={", kp.FromItem)
+	b := strings.Repeat(" ", len(a))
+	ret := []string{
+		a + fmt.Sprintf("ToNode:  %v,", kp.ToNode),
+		b + fmt.Sprintf("ToLevel: %v,", kp.ToLevel),
+		b + fmt.Sprintf("ToGen:   %v,", kp.ToGeneration),
+		b + fmt.Sprintf("ToKey:   {%d,%v,%d}}",
+			kp.ToKey.ObjectID,
+			kp.ToKey.ItemType,
+			kp.ToKey.Offset),
+	}
+
+	var err error
+	if toNode, ok := scanData.Nodes[kp.ToNode]; !ok {
+		err = scanData.BadNodes[kp.ToNode]
+	} else {
+		err = checkNodeExpectations(kp, toNode)
+	}
+	if err != nil {
+		c := strings.Repeat(" ", len(a)-1)
+		ret = append(ret,
+			c+"^",
+			c+"`-err="+strings.ReplaceAll(err.Error(), "\n", "\n"+c+"      "),
+		)
+	}
+	return ret
+}
+
+func loopRender(out io.Writer, scanData Graph, stack ...btrfsvol.LogicalAddr) {
+	var lines []string
+	add := func(suffixes []string) {
+		curLen := 0
+		for _, line := range lines {
+			if len(line) > curLen {
+				curLen = len(line)
+			}
+		}
+		for i, suffix := range suffixes {
+			if len(lines) <= i {
+				lines = append(lines, "")
+			}
+			if len(lines[i]) < curLen {
+				if i == 0 {
+					lines[i] += strings.Repeat("-", curLen-len(lines[i])-1) + ">"
+				} else {
+					lines[i] += strings.Repeat(" ", curLen-len(lines[i]))
+				}
+			}
+			lines[i] += suffix
+		}
+	}
+
+	for i, node := range stack {
+		if i > 0 {
+			for _, kp := range scanData.EdgesTo[node] {
+				if kp.FromNode == stack[i-1] {
+					add(edgeRender(scanData, *kp))
+					break
+				}
+			}
+		}
+		add(nodeRender(scanData, node))
+	}
+
+	fmt.Fprintln(out, "loop:")
+	for _, line := range lines {
+		fmt.Fprintln(out, "    "+line)
+	}
+}
+
+func checkNodeExpectations(kp Edge, toNode Node) error {
+	var errs derror.MultiError
+	if toNode.Level != kp.ToLevel {
+		errs = append(errs, fmt.Errorf("kp.level=%v != node.level=%v",
+			kp.ToLevel, toNode.Level))
+	}
+	if toNode.Generation != kp.ToGeneration {
+		errs = append(errs, fmt.Errorf("kp.generation=%v != node.generation=%v",
+			kp.ToGeneration, toNode.Generation))
+	}
+	if toNode.NumItems == 0 {
+		errs = append(errs, fmt.Errorf("node.num_items=0"))
+	} else if kp.ToKey != (btrfsprim.Key{}) && toNode.MinItem != kp.ToKey {
+		errs = append(errs, fmt.Errorf("kp.key=%v != node.items[0].key=%v",
+			kp.ToKey, toNode.MinItem))
+	}
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
+}