compliance package: dumpresolutions

package to read, consume, and analyze license metadata and dependency
graph.

Includes the below command-line tool:

dumpresolutions outputs the resulting set of resolutions after the
bottom-up and top-down resolves, or after joining 1 or more condition
walks.

Bug: 68860345
Bug: 151177513
Bug: 151953481

Test: m all
Test: m systemlicense
Test: m dumpgraph; out/soong/host/linux-x86/dumpgraph ...
Test: m dumpresolutions; out/soong/host/linux-x86/dumpresolutions ...

where ... is the path to the .meta_lic file for the system image. In my
case if

$ export PRODUCT=$(realpath $ANDROID_PRODUCT_OUT --relative-to=$PWD)

... can be expressed as:

${PRODUCT}/gen/META/lic_intermediates/${PRODUCT}/system.img.meta_lic

Change-Id: I9869400126cd7ad4b7376b0bab31b46aad732f5d
diff --git a/tools/compliance/cmd/dumpresolutions.go b/tools/compliance/cmd/dumpresolutions.go
new file mode 100644
index 0000000..36fbb7d
--- /dev/null
+++ b/tools/compliance/cmd/dumpresolutions.go
@@ -0,0 +1,284 @@
+// Copyright 2021 Google LLC
+//
+// 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 main
+
+import (
+	"compliance"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+var (
+	conditions      = newMultiString("c", "License condition to resolve. (may be given multiple times)")
+	graphViz        = flag.Bool("dot", false, "Whether to output graphviz (i.e. dot) format.")
+	labelConditions = flag.Bool("label_conditions", false, "Whether to label target nodes with conditions.")
+	stripPrefix     = flag.String("strip_prefix", "", "Prefix to remove from paths. i.e. path to root")
+
+	failNoneRequested = fmt.Errorf("\nNo license metadata files requested")
+	failNoLicenses = fmt.Errorf("No licenses found")
+)
+
+type context struct {
+	conditions      []string
+	graphViz        bool
+	labelConditions bool
+	stripPrefix     string
+}
+
+func init() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, `Usage: %s {options} file.meta_lic {file.meta_lic...}
+
+Outputs a space-separated Target ActsOn Origin Condition tuple for each
+resolution in the graph. When -dot flag given, outputs nodes and edges
+in graphviz directed graph format.
+
+If one or more '-c condition' conditions are given, outputs the joined
+set of resolutions for all of the conditions. Otherwise, outputs the
+result of the bottom-up and top-down resolve only.
+
+In plain text mode, when '-label_conditions' is requested, the Target
+and Origin have colon-separated license conditions appended:
+i.e. target:condition1:condition2 etc.
+
+Options:
+`, filepath.Base(os.Args[0]))
+		flag.PrintDefaults()
+	}
+}
+
+// newMultiString creates a flag that allows multiple values in an array.
+func newMultiString(name, usage string) *multiString {
+	var f multiString
+	flag.Var(&f, name, usage)
+	return &f
+}
+
+// multiString implements the flag `Value` interface for multiple strings.
+type multiString []string
+
+func (ms *multiString) String() string     { return strings.Join(*ms, ", ") }
+func (ms *multiString) Set(s string) error { *ms = append(*ms, s); return nil }
+
+func main() {
+	flag.Parse()
+
+	// Must specify at least one root target.
+	if flag.NArg() == 0 {
+		flag.Usage()
+		os.Exit(2)
+	}
+
+	ctx := &context{
+		conditions:      append([]string{}, *conditions...),
+		graphViz:        *graphViz,
+		labelConditions: *labelConditions,
+		stripPrefix:     *stripPrefix,
+	}
+	err := dumpResolutions(ctx, os.Stdout, os.Stderr, flag.Args()...)
+	if err != nil {
+		if err == failNoneRequested {
+			flag.Usage()
+		}
+		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
+		os.Exit(1)
+	}
+	os.Exit(0)
+}
+
+// dumpResolutions implements the dumpresolutions utility.
+func dumpResolutions(ctx *context, stdout, stderr io.Writer, files ...string) error {
+	if len(files) < 1 {
+		return failNoneRequested
+	}
+
+	// Read the license graph from the license metadata files (*.meta_lic).
+	licenseGraph, err := compliance.ReadLicenseGraph(os.DirFS("."), stderr, files)
+	if err != nil {
+		return fmt.Errorf("Unable to read license metadata file(s) %q: %v\n", files, err)
+	}
+	if licenseGraph == nil {
+		return failNoLicenses
+	}
+
+	// resolutions will contain the requested set of resolutions.
+	var resolutions *compliance.ResolutionSet
+
+	resolutions = compliance.ResolveTopDownConditions(licenseGraph)
+	if len(ctx.conditions) > 0 {
+		rlist := make([]*compliance.ResolutionSet, 0, len(ctx.conditions))
+		for _, c := range ctx.conditions {
+			rlist = append(rlist, compliance.WalkResolutionsForCondition(licenseGraph, resolutions, compliance.ConditionNames{c}))
+		}
+		if len(rlist) == 1 {
+			resolutions = rlist[0]
+		} else {
+			resolutions = compliance.JoinResolutionSets(rlist...)
+		}
+	}
+
+	// nodes maps license metadata file names to graphViz node names when graphViz requested.
+	nodes := make(map[string]string)
+	n := 0
+
+	// targetOut calculates the string to output for `target` adding `sep`-separated conditions as needed.
+	targetOut := func(target *compliance.TargetNode, sep string) string {
+		tOut := strings.TrimPrefix(target.Name(), ctx.stripPrefix)
+		if ctx.labelConditions {
+			conditions := make([]string, 0, target.LicenseConditions().Count())
+			for _, lc := range target.LicenseConditions().AsList() {
+				conditions = append(conditions, lc.Name())
+			}
+			sort.Strings(conditions)
+			if len(conditions) > 0 {
+				tOut += sep + strings.Join(conditions, sep)
+			}
+		}
+		return tOut
+	}
+
+	// makeNode maps `target` to a graphViz node name.
+	makeNode := func(target *compliance.TargetNode) {
+		tName := target.Name()
+		if _, ok := nodes[tName]; !ok {
+			nodeName := fmt.Sprintf("n%d", n)
+			nodes[tName] = nodeName
+			fmt.Fprintf(stdout, "\t%s [label=\"%s\"];\n", nodeName, targetOut(target, "\\n"))
+			n++
+		}
+	}
+
+	// outputResolution prints a resolution in the requested format to `stdout`, where one can read
+	// a resolution as `tname` resolves `oname`'s conditions named in `cnames`.
+	// `tname` is the name of the target the resolution applies to.
+	// `oname` is the name of the target where the conditions originate.
+	// `cnames` is the list of conditions to resolve.
+	outputResolution := func(tname, aname, oname string, cnames []string) {
+		if ctx.graphViz {
+			// ... one edge per line labelled with \\n-separated annotations.
+			tNode := nodes[tname]
+			aNode := nodes[aname]
+			oNode := nodes[oname]
+			fmt.Fprintf(stdout, "\t%s -> %s; %s -> %s [label=\"%s\"];\n", tNode, aNode, aNode, oNode, strings.Join(cnames, "\\n"))
+		} else {
+			// ... one edge per line with names in a colon-separated tuple.
+			fmt.Fprintf(stdout, "%s %s %s %s\n", tname, aname, oname, strings.Join(cnames, ":"))
+		}
+	}
+
+	// outputSingleton prints `tname` to plain text in the unexpected event that `tname` is the name of
+	// a target in `resolutions.AppliesTo()` but has no conditions to resolve.
+	outputSingleton := func(tname, aname string) {
+		if !ctx.graphViz {
+			fmt.Fprintf(stdout, "%s %s\n", tname, aname)
+		}
+	}
+
+	// Sort the resolutions by targetname for repeatability/stability.
+	targets := resolutions.AttachesTo()
+	sort.Sort(targets)
+
+	// If graphviz output, start the directed graph.
+	if ctx.graphViz {
+		fmt.Fprintf(stdout, "strict digraph {\n\trankdir=LR;\n")
+		for _, target := range targets {
+			makeNode(target)
+			rl := compliance.ResolutionList(resolutions.Resolutions(target))
+			sort.Sort(rl)
+			for _, r := range rl {
+				makeNode(r.ActsOn())
+			}
+			conditions := rl.AllConditions().AsList()
+			sort.Sort(conditions)
+			for _, lc := range conditions {
+				makeNode(lc.Origin())
+			}
+		}
+	}
+
+	// Output the sorted targets.
+	for _, target := range targets {
+		var tname string
+		if ctx.graphViz {
+			tname = target.Name()
+		} else {
+			tname = targetOut(target, ":")
+		}
+
+		rl := compliance.ResolutionList(resolutions.Resolutions(target))
+		sort.Sort(rl)
+		for _, r := range rl {
+			var aname string
+			if ctx.graphViz {
+				aname = r.ActsOn().Name()
+			} else {
+				aname = targetOut(r.ActsOn(), ":")
+			}
+
+			conditions := r.Resolves().AsList()
+			sort.Sort(conditions)
+
+			// poname is the previous origin name or "" if no previous
+			poname := ""
+
+			// cnames accumulates the list of condition names originating at a single origin that apply to `target`.
+			cnames := make([]string, 0, len(conditions))
+
+			// Output 1 line for each attachesTo+actsOn+origin combination.
+			for _, condition := range conditions {
+				var oname string
+				if ctx.graphViz {
+					oname = condition.Origin().Name()
+				} else {
+					oname = targetOut(condition.Origin(), ":")
+				}
+
+				// Detect when origin changes and output prior origin's conditions.
+				if poname != oname && poname != "" {
+					outputResolution(tname, aname, poname, cnames)
+					cnames = cnames[:0]
+				}
+				poname = oname
+				cnames = append(cnames, condition.Name())
+			}
+			// Output last origin's conditions or a singleton if no origins.
+			if poname == "" {
+				outputSingleton(tname, aname)
+			} else {
+				outputResolution(tname, aname, poname, cnames)
+			}
+		}
+	}
+	// If graphViz output, rank the root nodes together, and complete the directed graph.
+	if ctx.graphViz {
+		fmt.Fprintf(stdout, "\t{rank=same;")
+		for _, f := range files {
+			fName := f
+			if !strings.HasSuffix(fName, ".meta_lic") {
+				fName += ".meta_lic"
+			}
+			if fNode, ok := nodes[fName]; ok {
+				fmt.Fprintf(stdout, " %s", fNode)
+			}
+		}
+		fmt.Fprintf(stdout, "}\n}\n")
+	}
+	return nil
+}