Allow reading zipfile list from a file.

Android build generates 180K+ zip files that are to be merged and the
result passed to the indexing pipeline to generate the source code
cross-reference. Their names cannot be passed on the command line,
hence the need for this change. That required extensive changes to
the code as it no longer can be assumed that all the input files can
be kept open.

Bug: 121267023
Test: internal + treehugger + combine index files
Change-Id: I0a829f96ff7187ad967fb6b8cede387501ec57cc

cmd/merge_zips/Android.bp

@@ -18,6 +18,7 @@ blueprint_go_binary {
       "android-archive-zip",
       "blueprint-pathtools",
       "soong-jar",
+      "soong-zip",
     ],
     srcs: [
         "merge_zips.go",

cmd/merge_zips/merge_zips_test.go

@@ -51,6 +51,39 @@ var (
 	moduleInfoFile = testZipEntry{jar.ModuleInfoClass, 0755, []byte("module-info")}
 )
 
+type testInputZip struct {
+	name    string
+	entries []testZipEntry
+	reader  *zip.Reader
+}
+
+func (tiz *testInputZip) Name() string {
+	return tiz.name
+}
+
+func (tiz *testInputZip) Open() error {
+	if tiz.reader == nil {
+		tiz.reader = testZipEntriesToZipReader(tiz.entries)
+	}
+	return nil
+}
+
+func (tiz *testInputZip) Close() error {
+	tiz.reader = nil
+	return nil
+}
+
+func (tiz *testInputZip) Entries() []*zip.File {
+	if tiz.reader == nil {
+		panic(fmt.Errorf("%s: should be open to get entries", tiz.Name()))
+	}
+	return tiz.reader.File
+}
+
+func (tiz *testInputZip) IsOpen() bool {
+	return tiz.reader != nil
+}
+
 func TestMergeZips(t *testing.T) {
 	testCases := []struct {
 		name             string
@@ -207,13 +240,9 @@ func TestMergeZips(t *testing.T) {
 
 	for _, test := range testCases {
 		t.Run(test.name, func(t *testing.T) {
-			var readers []namedZipReader
+			inputZips := make([]InputZip, len(test.in))
 			for i, in := range test.in {
-				r := testZipEntriesToZipReader(in)
+				inputZips[i] = &testInputZip{name: "in" + strconv.Itoa(i), entries: in}
-				readers = append(readers, namedZipReader{
-					path:   "in" + strconv.Itoa(i),
-					reader: r,
-				})
 			}
 
 			want := testZipEntriesToBuf(test.out)
@@ -221,7 +250,7 @@ func TestMergeZips(t *testing.T) {
 			out := &bytes.Buffer{}
 			writer := zip.NewWriter(out)
 
-			err := mergeZips(readers, writer, "", "",
+			err := mergeZips(inputZips, writer, "", "",
 				test.sort, test.jar, false, test.stripDirEntries, test.ignoreDuplicates,
 				test.stripFiles, test.stripDirs, test.zipsToNotStrip)
 
@@ -304,3 +333,60 @@ func dumpZip(buf []byte) string {
 
 	return ret
 }
+
+type DummyInpuZip struct {
+	isOpen bool
+}
+
+func (diz *DummyInpuZip) Name() string {
+	return "dummy"
+}
+
+func (diz *DummyInpuZip) Open() error {
+	diz.isOpen = true
+	return nil
+}
+
+func (diz *DummyInpuZip) Close() error {
+	diz.isOpen = false
+	return nil
+}
+
+func (DummyInpuZip) Entries() []*zip.File {
+	panic("implement me")
+}
+
+func (diz *DummyInpuZip) IsOpen() bool {
+	return diz.isOpen
+}
+
+func TestInputZipsManager(t *testing.T) {
+	const nInputZips = 20
+	const nMaxOpenZips = 10
+	izm := NewInputZipsManager(20, 10)
+	managedZips := make([]InputZip, nInputZips)
+	for i := 0; i < nInputZips; i++ {
+		managedZips[i] = izm.Manage(&DummyInpuZip{})
+	}
+
+	t.Run("InputZipsManager", func(t *testing.T) {
+		for i, iz := range managedZips {
+			if err := iz.Open(); err != nil {
+				t.Fatalf("Step %d: open failed: %s", i, err)
+				return
+			}
+			if izm.nOpenZips > nMaxOpenZips {
+				t.Errorf("Step %d: should be <=%d open zips", i, nMaxOpenZips)
+			}
+		}
+		if !managedZips[nInputZips-1].IsOpen() {
+			t.Error("The last input should stay open")
+		}
+		for _, iz := range managedZips {
+			iz.Close()
+		}
+		if izm.nOpenZips > 0 {
+			t.Error("Some input zips are still open")
+		}
+	})
+}