Import globbing from Soong

Add globbing with dependency checking to blueprint.  Calling
ModuleContext.GlobWithDeps or SingletonContext.GlobWithDeps will return
a list of files that match the globs, while also adding efficient
dependencies to rerun the primary builder if a file that matches the
glob is added or removed.

Also use the globbing support for optional_subdirs=, subdirs= and build=
lines in blueprints files.  The globbing slightly changes the behavior
of subname= lines, it no longer falls back to looking for a file called
"Blueprints".  Blueprint files that need to include a subdirectory with
a different name can use build= instead of subdir= to directly include
them.  The Blueprints file is updated to reset subname="Blueprints" in
case we want to include subdirectories inside blueprint and the primary
builder has changed the subname.

Also adds a new test directory that contains a simple primary builder
tree to test regeneration for globbing, and runs the tests in travis.

Change-Id: I83ce525fd11e11579cc58ba5308d01ca8eea7bc6

18 files changed, 1012 insertions, 109 deletions

diff --git a/.gitignore b/.gitignore
index de99854..3a9ef96 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 out.test
+src.test
diff --git a/.travis.yml b/.travis.yml
index ecb8c5c..2824056 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -23,3 +23,4 @@ script:
     - ./blueprint.bash
     - diff -us ../build.ninja.in .minibootstrap/build.ninja.in
     - ../tests/test.sh
+    - ../tests/test_tree_tests.sh
diff --git a/Blueprints b/Blueprints
index f0a0f87..702d0de 100644
--- a/Blueprints
+++ b/Blueprints
@@ -9,6 +9,7 @@ bootstrap_go_package(
     srcs = [
         "context.go",
         "fs.go",
+        "glob.go",
         "live_tracker.go",
         "mangle.go",
         "module_ctx.go",
@@ -55,6 +56,9 @@ bootstrap_go_package(
 bootstrap_go_package(
     name = "blueprint-pathtools",
     pkgPath = "github.com/google/blueprint/pathtools",
+    deps = [
+        "blueprint-deptools",
+    ],
     srcs = [
         "pathtools/lists.go",
         "pathtools/glob.go",
@@ -97,6 +101,7 @@ bootstrap_go_package(
         "bootstrap/command.go",
         "bootstrap/config.go",
         "bootstrap/doc.go",
+        "bootstrap/glob.go",
         "bootstrap/writedocs.go",
     ],
 )
@@ -122,6 +127,12 @@ bootstrap_core_go_binary(
     srcs = ["bootstrap/minibp/main.go"],
 )
 
+bootstrap_core_go_binary(
+    name = "bpglob",
+    deps = ["blueprint-pathtools"],
+    srcs = ["bootstrap/bpglob/bpglob.go"],
+)
+
 blueprint_go_binary(
     name = "bpfmt",
     deps = ["blueprint-parser"],
diff --git a/bootstrap/bpglob/bpglob.go b/bootstrap/bpglob/bpglob.go
new file mode 100644
index 0000000..cb6633b
--- /dev/null
+++ b/bootstrap/bpglob/bpglob.go
@@ -0,0 +1,77 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// 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.
+
+// bpglob is the command line tool that checks if the list of files matching a glob has
+// changed, and only updates the output file list if it has changed.  It is used to optimize
+// out build.ninja regenerations when non-matching files are added.  See
+// github.com/google/blueprint/bootstrap/glob.go for a longer description.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/google/blueprint/pathtools"
+)
+
+var (
+	out = flag.String("o", "", "file to write list of files that match glob")
+
+	excludes multiArg
+)
+
+func init() {
+	flag.Var(&excludes, "e", "pattern to exclude from results")
+}
+
+type multiArg []string
+
+func (m *multiArg) String() string {
+	return `""`
+}
+
+func (m *multiArg) Set(s string) error {
+	*m = append(*m, s)
+	return nil
+}
+
+func (m *multiArg) Get() interface{} {
+	return m
+}
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: bpglob -o out glob\n")
+	flag.PrintDefaults()
+	os.Exit(2)
+}
+
+func main() {
+	flag.Parse()
+
+	if *out == "" {
+		fmt.Fprintf(os.Stderr, "error: -o is required\n")
+		usage()
+	}
+
+	if flag.NArg() != 1 {
+		usage()
+	}
+
+	_, err := pathtools.GlobWithDepFile(flag.Arg(0), *out, *out+".d", excludes)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %s\n", err.Error())
+		os.Exit(1)
+	}
+}
diff --git a/bootstrap/command.go b/bootstrap/command.go
index cc55b28..7c220e5 100644
--- a/bootstrap/command.go
+++ b/bootstrap/command.go
@@ -117,6 +117,8 @@ func Main(ctx *blueprint.Context, config interface{}, extraNinjaFileDeps ...stri
 	ctx.RegisterTopDownMutator("bootstrap_stage", propagateStageBootstrap)
 	ctx.RegisterSingletonType("bootstrap", newSingletonFactory(bootstrapConfig))
 
+	ctx.RegisterSingletonType("glob", globSingletonFactory(ctx))
+
 	deps, errs := ctx.ParseBlueprintsFiles(bootstrapConfig.topLevelBlueprintsFile)
 	if len(errs) > 0 {
 		fatalErrors(errs)
diff --git a/bootstrap/glob.go b/bootstrap/glob.go
new file mode 100644
index 0000000..2e209d9
--- /dev/null
+++ b/bootstrap/glob.go
@@ -0,0 +1,144 @@
+// Copyright 2016 Google Inc. All rights reserved.
+//
+// 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 bootstrap
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/deptools"
+	"github.com/google/blueprint/pathtools"
+)
+
+// This file supports globbing source files in Blueprints files.
+//
+// The build.ninja file needs to be regenerated any time a file matching the glob is added
+// or removed.  The naive solution is to have the build.ninja file depend on all the
+// traversed directories, but this will cause the regeneration step to run every time a
+// non-matching file is added to a traversed directory, including backup files created by
+// editors.
+//
+// The solution implemented here optimizes out regenerations when the directory modifications
+// don't match the glob by having the build.ninja file depend on an intermedate file that
+// is only updated when a file matching the glob is added or removed.  The intermediate file
+// depends on the traversed directories via a depfile.  The depfile is used to avoid build
+// errors if a directory is deleted - a direct dependency on the deleted directory would result
+// in a build failure with a "missing and no known rule to make it" error.
+
+var (
+	globCmd = filepath.Join("$BinDir", "bpglob")
+
+	// globRule rule traverses directories to produce a list of files that match $glob
+	// and writes it to $out if it has changed, and writes the directories to $out.d
+	GlobRule = pctx.StaticRule("GlobRule",
+		blueprint.RuleParams{
+			Command:     fmt.Sprintf(`%s -o $out $excludes "$glob"`, globCmd),
+			CommandDeps: []string{globCmd},
+			Description: "glob $glob",
+
+			Restat:  true,
+			Deps:    blueprint.DepsGCC,
+			Depfile: "$out.d",
+		},
+		"glob", "excludes")
+)
+
+// GlobFileContext is the subset of ModuleContext and SingletonContext needed by GlobFile
+type GlobFileContext interface {
+	Build(pctx blueprint.PackageContext, params blueprint.BuildParams)
+}
+
+// GlobFile creates a rule to write to fileListFile a list of the files that match the specified
+// pattern but do not match any of the patterns specified in excludes.  The file will include
+// appropriate dependencies written to depFile to regenerate the file if and only if the list of
+// matching files has changed.
+func GlobFile(ctx GlobFileContext, pattern string, excludes []string,
+	fileListFile, depFile string) {
+
+	ctx.Build(pctx, blueprint.BuildParams{
+		Rule:    GlobRule,
+		Outputs: []string{fileListFile},
+		Args: map[string]string{
+			"glob":     pattern,
+			"excludes": joinWithPrefixAndQuote(excludes, "-e "),
+		},
+	})
+}
+
+func joinWithPrefixAndQuote(strs []string, prefix string) string {
+	if len(strs) == 0 {
+		return ""
+	}
+
+	if len(strs) == 1 {
+		return prefix + `"` + strs[0] + `"`
+	}
+
+	n := len(" ") * (len(strs) - 1)
+	for _, s := range strs {
+		n += len(prefix) + len(s) + len(`""`)
+	}
+
+	ret := make([]byte, 0, n)
+	for i, s := range strs {
+		if i != 0 {
+			ret = append(ret, ' ')
+		}
+		ret = append(ret, prefix...)
+		ret = append(ret, '"')
+		ret = append(ret, s...)
+		ret = append(ret, '"')
+	}
+	return string(ret)
+}
+
+// globSingleton collects any glob patterns that were seen by Context and writes out rules to
+// re-evaluate them whenever the contents of the searched directories change, and retrigger the
+// primary builder if the results change.
+type globSingleton struct {
+	globLister func() []blueprint.GlobPath
+}
+
+func globSingletonFactory(ctx *blueprint.Context) func() blueprint.Singleton {
+	return func() blueprint.Singleton {
+		return &globSingleton{
+			globLister: ctx.Globs,
+		}
+	}
+}
+
+func (s *globSingleton) GenerateBuildActions(ctx blueprint.SingletonContext) {
+	if config, ok := ctx.Config().(ConfigInterface); ok && config.GeneratingBootstrapper() {
+		// Skip singleton for bootstrap.bash -r case to avoid putting unnecessary glob lines into
+		// the bootstrap manifest
+		return
+	}
+
+	for _, g := range s.globLister() {
+		fileListFile := filepath.Join(BuildDir, ".glob", g.Name)
+		depFile := fileListFile + ".d"
+
+		fileList := strings.Join(g.Files, "\n") + "\n"
+		pathtools.WriteFileIfChanged(fileListFile, []byte(fileList), 0666)
+		deptools.WriteDepFile(depFile, fileListFile, g.Deps)
+
+		GlobFile(ctx, g.Pattern, g.Excludes, fileListFile, depFile)
+
+		// Make build.ninja depend on the fileListFile
+		ctx.AddNinjaFileDeps(fileListFile)
+	}
+}
diff --git a/build.ninja.in b/build.ninja.in
index 8b3fe98..ec32fcf 100644
--- a/build.ninja.in
+++ b/build.ninja.in
@@ -58,8 +58,9 @@ rule g.bootstrap.link
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a $
         : g.bootstrap.compile ${g.bootstrap.srcDir}/context.go $
-        ${g.bootstrap.srcDir}/fs.go ${g.bootstrap.srcDir}/live_tracker.go $
-        ${g.bootstrap.srcDir}/mangle.go ${g.bootstrap.srcDir}/module_ctx.go $
+        ${g.bootstrap.srcDir}/fs.go ${g.bootstrap.srcDir}/glob.go $
+        ${g.bootstrap.srcDir}/live_tracker.go ${g.bootstrap.srcDir}/mangle.go $
+        ${g.bootstrap.srcDir}/module_ctx.go $
         ${g.bootstrap.srcDir}/ninja_defs.go $
         ${g.bootstrap.srcDir}/ninja_strings.go $
         ${g.bootstrap.srcDir}/ninja_writer.go $
@@ -67,9 +68,10 @@ build $
         ${g.bootstrap.srcDir}/singleton_ctx.go ${g.bootstrap.srcDir}/unpack.go $
         | ${g.bootstrap.compileCmd} $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a
-    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg
     pkgPath = github.com/google/blueprint
 default $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a
@@ -79,7 +81,7 @@ default $
 # Variant:
 # Type:    bootstrap_go_package
 # Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
-# Defined: Blueprints:85:1
+# Defined: Blueprints:89:1
 
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg/github.com/google/blueprint/bootstrap.a $
@@ -88,15 +90,16 @@ build $
         ${g.bootstrap.srcDir}/bootstrap/command.go $
         ${g.bootstrap.srcDir}/bootstrap/config.go $
         ${g.bootstrap.srcDir}/bootstrap/doc.go $
+        ${g.bootstrap.srcDir}/bootstrap/glob.go $
         ${g.bootstrap.srcDir}/bootstrap/writedocs.go | $
         ${g.bootstrap.compileCmd} $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a $
-        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a
-    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg
     pkgPath = github.com/google/blueprint/bootstrap
 default $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg/github.com/google/blueprint/bootstrap.a
@@ -106,17 +109,18 @@ default $
 # Variant:
 # Type:    bootstrap_go_package
 # Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
-# Defined: Blueprints:104:1
+# Defined: Blueprints:109:1
 
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a $
         : g.bootstrap.compile ${g.bootstrap.srcDir}/bootstrap/bpdoc/bpdoc.go | $
         ${g.bootstrap.compileCmd} $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a
-    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg
     pkgPath = github.com/google/blueprint/bootstrap/bpdoc
 default $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a
@@ -126,7 +130,7 @@ default $
 # Variant:
 # Type:    bootstrap_go_package
 # Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
-# Defined: Blueprints:49:1
+# Defined: Blueprints:50:1
 
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
@@ -141,7 +145,7 @@ default $
 # Variant:
 # Type:    bootstrap_go_package
 # Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
-# Defined: Blueprints:33:1
+# Defined: Blueprints:34:1
 
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
@@ -159,12 +163,14 @@ default $
 # Variant:
 # Type:    bootstrap_go_package
 # Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
-# Defined: Blueprints:55:1
+# Defined: Blueprints:56:1
 
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
         : g.bootstrap.compile ${g.bootstrap.srcDir}/pathtools/lists.go $
-        ${g.bootstrap.srcDir}/pathtools/glob.go | ${g.bootstrap.compileCmd}
+        ${g.bootstrap.srcDir}/pathtools/glob.go | ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg
     pkgPath = github.com/google/blueprint/pathtools
 default $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a
@@ -174,7 +180,7 @@ default $
 # Variant:
 # Type:    bootstrap_go_package
 # Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
-# Defined: Blueprints:67:1
+# Defined: Blueprints:71:1
 
 build $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
@@ -189,11 +195,37 @@ default $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a
 
 # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  bpglob
+# Variant:
+# Type:    bootstrap_core_go_binary
+# Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
+# Defined: Blueprints:130:1
+
+build ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/bpglob.a: $
+        g.bootstrap.compile ${g.bootstrap.srcDir}/bootstrap/bpglob/bpglob.go | $
+        ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg
+    pkgPath = bpglob
+default ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/bpglob.a
+
+build ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/a.out: g.bootstrap.link $
+        ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/bpglob.a | $
+        ${g.bootstrap.linkCmd}
+    libDirFlags = -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg
+default ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/a.out
+
+build ${g.bootstrap.BinDir}/bpglob: g.bootstrap.cp $
+        ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/a.out
+default ${g.bootstrap.BinDir}/bpglob
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
 # Module:  gotestmain
 # Variant:
 # Type:    bootstrap_core_go_binary
 # Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
-# Defined: Blueprints:137:1
+# Defined: Blueprints:148:1
 
 build ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/gotestmain.a: $
         g.bootstrap.compile ${g.bootstrap.srcDir}/gotestmain/gotestmain.go | $
@@ -216,7 +248,7 @@ default ${g.bootstrap.BinDir}/gotestmain
 # Variant:
 # Type:    bootstrap_core_go_binary
 # Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
-# Defined: Blueprints:142:1
+# Defined: Blueprints:153:1
 
 build ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/gotestrunner.a: $
         g.bootstrap.compile ${g.bootstrap.srcDir}/gotestrunner/gotestrunner.go $
@@ -239,26 +271,26 @@ default ${g.bootstrap.BinDir}/gotestrunner
 # Variant:
 # Type:    bootstrap_core_go_binary
 # Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
-# Defined: Blueprints:116:1
+# Defined: Blueprints:121:1
 
 build ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/minibp.a: $
         g.bootstrap.compile ${g.bootstrap.srcDir}/bootstrap/minibp/main.go | $
         ${g.bootstrap.compileCmd} $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a $
-        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a $
         ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg/github.com/google/blueprint/bootstrap.a
-    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg
     pkgPath = minibp
 default ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/minibp.a
 
 build ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/a.out: g.bootstrap.link $
         ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/minibp.a | $
         ${g.bootstrap.linkCmd}
-    libDirFlags = -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg
+    libDirFlags = -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg
 default ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/a.out
 
 build ${g.bootstrap.BinDir}/minibp: g.bootstrap.cp $
diff --git a/context.go b/context.go
index 48856cf..7e54150 100644
--- a/context.go
+++ b/context.go
@@ -25,6 +25,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"text/scanner"
 	"text/template"
@@ -105,6 +106,9 @@ type Context struct {
 	renames      []rename
 	replacements []replace
 
+	globs    map[string]GlobPath
+	globLock sync.Mutex
+
 	fs fileSystem
 }
 
@@ -270,6 +274,7 @@ func NewContext() *Context {
 		moduleNames:      make(map[string]*moduleGroup),
 		moduleInfo:       make(map[Module]*moduleInfo),
 		moduleNinjaNames: make(map[string]*moduleGroup),
+		globs:            make(map[string]GlobPath),
 		fs:               fs,
 	}
 
@@ -524,12 +529,11 @@ func (c *Context) SetAllowMissingDependencies(allowMissingDependencies bool) {
 // filename specifies the path to the Blueprints file.  These paths are used for
 // error reporting and for determining the module's directory.
 func (c *Context) parse(rootDir, filename string, r io.Reader,
-	scope *parser.Scope) (file *parser.File, subBlueprints []stringAndScope, deps []string,
-	errs []error) {
+	scope *parser.Scope) (file *parser.File, subBlueprints []stringAndScope, errs []error) {
 
 	relBlueprintsFile, err := filepath.Rel(rootDir, filename)
 	if err != nil {
-		return nil, nil, nil, []error{err}
+		return nil, nil, []error{err}
 	}
 
 	scope = parser.NewScope(scope)
@@ -550,7 +554,7 @@ func (c *Context) parse(rootDir, filename string, r io.Reader,
 
 		// If there were any parse errors don't bother trying to interpret the
 		// result.
-		return nil, nil, nil, errs
+		return nil, nil, errs
 	}
 	file.Name = relBlueprintsFile
 
@@ -570,24 +574,28 @@ func (c *Context) parse(rootDir, filename string, r io.Reader,
 	}
 
 	subBlueprintsName, _, err := getStringFromScope(scope, "subname")
+	if err != nil {
+		errs = append(errs, err)
+	}
+
+	if subBlueprintsName == "" {
+		subBlueprintsName = "Blueprints"
+	}
 
 	var blueprints []string
 
-	newBlueprints, newDeps, newErrs := c.findBuildBlueprints(filepath.Dir(filename), build, buildPos)
+	newBlueprints, newErrs := c.findBuildBlueprints(filepath.Dir(filename), build, buildPos)
 	blueprints = append(blueprints, newBlueprints...)
-	deps = append(deps, newDeps...)
 	errs = append(errs, newErrs...)
 
-	newBlueprints, newDeps, newErrs = c.findSubdirBlueprints(filepath.Dir(filename), subdirs, subdirsPos,
+	newBlueprints, newErrs = c.findSubdirBlueprints(filepath.Dir(filename), subdirs, subdirsPos,
 		subBlueprintsName, false)
 	blueprints = append(blueprints, newBlueprints...)
-	deps = append(deps, newDeps...)
 	errs = append(errs, newErrs...)
 
-	newBlueprints, newDeps, newErrs = c.findSubdirBlueprints(filepath.Dir(filename), optionalSubdirs,
+	newBlueprints, newErrs = c.findSubdirBlueprints(filepath.Dir(filename), optionalSubdirs,
 		optionalSubdirsPos, subBlueprintsName, true)
 	blueprints = append(blueprints, newBlueprints...)
-	deps = append(deps, newDeps...)
 	errs = append(errs, newErrs...)
 
 	subBlueprintsAndScope := make([]stringAndScope, len(blueprints))
@@ -595,7 +603,7 @@ func (c *Context) parse(rootDir, filename string, r io.Reader,
 		subBlueprintsAndScope[i] = stringAndScope{b, scope}
 	}
 
-	return file, subBlueprintsAndScope, deps, errs
+	return file, subBlueprintsAndScope, errs
 }
 
 type stringAndScope struct {
@@ -790,7 +798,7 @@ func (c *Context) parseBlueprintsFile(filename string, scope *parser.Scope, root
 		}
 	}()
 
-	file, subBlueprints, deps, errs := c.parse(rootDir, filename, f, scope)
+	file, subBlueprints, errs := c.parse(rootDir, filename, f, scope)
 	if len(errs) > 0 {
 		errsCh <- errs
 	} else {
@@ -799,22 +807,31 @@ func (c *Context) parseBlueprintsFile(filename string, scope *parser.Scope, root
 
 	for _, b := range subBlueprints {
 		blueprintsCh <- b
-	}
-
-	for _, d := range deps {
-		depsCh <- d
+		depsCh <- b.string
 	}
 }
 
 func (c *Context) findBuildBlueprints(dir string, build []string,
-	buildPos scanner.Position) (blueprints, deps []string, errs []error) {
+	buildPos scanner.Position) ([]string, []error) {
+
+	var blueprints []string
+	var errs []error
 
 	for _, file := range build {
-		globPattern := filepath.Join(dir, file)
-		matches, matchedDirs, err := pathtools.Glob(globPattern)
+		pattern := filepath.Join(dir, file)
+		var matches []string
+		var err error
+
+		if pathtools.IsGlob(pattern) {
+			matches, err = c.glob(pattern, nil)
+		} else {
+			// Not a glob, but use filepath.Glob to check if it exists
+			matches, err = filepath.Glob(pattern)
+		}
+
 		if err != nil {
 			errs = append(errs, &BlueprintError{
-				Err: fmt.Errorf("%q: %s", globPattern, err.Error()),
+				Err: fmt.Errorf("%q: %s", pattern, err.Error()),
 				Pos: buildPos,
 			})
 			continue
@@ -822,47 +839,40 @@ func (c *Context) findBuildBlueprints(dir string, build []string,
 
 		if len(matches) == 0 {
 			errs = append(errs, &BlueprintError{
-				Err: fmt.Errorf("%q: not found", globPattern),
+				Err: fmt.Errorf("%q: not found", pattern),
 				Pos: buildPos,
 			})
 		}
 
-		// Depend on all searched directories so we pick up future changes.
-		deps = append(deps, matchedDirs...)
-
 		for _, foundBlueprints := range matches {
-			exists, dir, err := c.fs.Exists(foundBlueprints)
-			if err != nil {
-				errs = append(errs, err)
-			} else if !exists {
-				errs = append(errs, &BlueprintError{
-					Err: fmt.Errorf("%q not found", foundBlueprints),
-				})
-				continue
-			} else if dir {
-				errs = append(errs, &BlueprintError{
-					Err: fmt.Errorf("%q is a directory", foundBlueprints),
-				})
-				continue
-			}
-
 			blueprints = append(blueprints, foundBlueprints)
-			deps = append(deps, foundBlueprints)
 		}
 	}
 
-	return blueprints, deps, errs
+	return blueprints, errs
 }
 
 func (c *Context) findSubdirBlueprints(dir string, subdirs []string, subdirsPos scanner.Position,
-	subBlueprintsName string, optional bool) (blueprints, deps []string, errs []error) {
+	subBlueprintsName string, optional bool) ([]string, []error) {
+
+	var blueprints []string
+	var errs []error
 
 	for _, subdir := range subdirs {
-		globPattern := filepath.Join(dir, subdir)
-		matches, matchedDirs, err := pathtools.Glob(globPattern)
+		pattern := filepath.Join(dir, subdir, subBlueprintsName)
+		var matches []string
+		var err error
+
+		if pathtools.IsGlob(pattern) {
+			matches, err = c.glob(pattern, nil)
+		} else {
+			// Not a glob, but use filepath.Glob to check if it exists
+			matches, err = filepath.Glob(pattern)
+		}
+
 		if err != nil {
 			errs = append(errs, &BlueprintError{
-				Err: fmt.Errorf("%q: %s", globPattern, err.Error()),
+				Err: fmt.Errorf("%q: %s", pattern, err.Error()),
 				Pos: subdirsPos,
 			})
 			continue
@@ -870,56 +880,17 @@ func (c *Context) findSubdirBlueprints(dir string, subdirs []string, subdirsPos
 
 		if len(matches) == 0 && !optional {
 			errs = append(errs, &BlueprintError{
-				Err: fmt.Errorf("%q: not found", globPattern),
+				Err: fmt.Errorf("%q: not found", pattern),
 				Pos: subdirsPos,
 			})
 		}
 
-		// Depend on all searched directories so we pick up future changes.
-		deps = append(deps, matchedDirs...)
-
-		for _, foundSubdir := range matches {
-			exists, dir, subdirStatErr := c.fs.Exists(foundSubdir)
-			if subdirStatErr != nil {
-				errs = append(errs, subdirStatErr)
-				continue
-			}
-
-			// Skip files
-			if !dir {
-				continue
-			}
-
-			var subBlueprints string
-			if subBlueprintsName != "" {
-				subBlueprints = filepath.Join(foundSubdir, subBlueprintsName)
-				exists, _, err = c.fs.Exists(subBlueprints)
-			}
-
-			if err == nil && (!exists || subBlueprints == "") {
-				subBlueprints = filepath.Join(foundSubdir, "Blueprints")
-				exists, _, err = c.fs.Exists(subBlueprints)
-			}
-
-			if err != nil {
-				errs = append(errs, err)
-				continue
-			}
-
-			if !exists {
-				// There is no Blueprints file in this subdirectory.  We
-				// need to add the directory to the list of dependencies
-				// so that if someone adds a Blueprints file in the
-				// future we'll pick it up.
-				deps = append(deps, foundSubdir)
-			} else {
-				deps = append(deps, subBlueprints)
-				blueprints = append(blueprints, subBlueprints)
-			}
+		for _, subBlueprints := range matches {
+			blueprints = append(blueprints, subBlueprints)
 		}
 	}
 
-	return blueprints, deps, errs
+	return blueprints, errs
 }
 
 func getLocalStringListFromScope(scope *parser.Scope, v string) ([]string, scanner.Position, error) {
diff --git a/context_test.go b/context_test.go
index 5d9f4bc..b05c541 100644
--- a/context_test.go
+++ b/context_test.go
@@ -95,7 +95,7 @@ func TestContextParse(t *testing.T) {
 		}
 	`)
 
-	_, _, _, errs := ctx.parse(".", "Blueprint", r, nil)
+	_, _, errs := ctx.parse(".", "Blueprint", r, nil)
 	if len(errs) > 0 {
 		t.Errorf("unexpected parse errors:")
 		for _, err := range errs {
diff --git a/glob.go b/glob.go
new file mode 100644
index 0000000..dad5edf
--- /dev/null
+++ b/glob.go
@@ -0,0 +1,116 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// 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 blueprint
+
+import (
+	"fmt"
+	"reflect"
+	"sort"
+
+	"github.com/google/blueprint/pathtools"
+)
+
+type GlobPath struct {
+	Pattern  string
+	Excludes []string
+	Files    []string
+	Deps     []string
+	Name     string
+}
+
+func verifyGlob(fileName, pattern string, excludes []string, g GlobPath) {
+	if pattern != g.Pattern {
+		panic(fmt.Errorf("Mismatched patterns %q and %q for glob file %q", pattern, g.Pattern, fileName))
+	}
+	if !reflect.DeepEqual(g.Excludes, excludes) {
+		panic(fmt.Errorf("Mismatched excludes %v and %v for glob file %q", excludes, g.Excludes, fileName))
+	}
+}
+
+func (c *Context) glob(pattern string, excludes []string) ([]string, error) {
+	fileName := globToFileName(pattern, excludes)
+
+	// Try to get existing glob from the stored results
+	c.globLock.Lock()
+	g, exists := c.globs[fileName]
+	c.globLock.Unlock()
+
+	if exists {
+		// Glob has already been done, double check it is identical
+		verifyGlob(fileName, pattern, excludes, g)
+		return g.Files, nil
+	}
+
+	// Get a globbed file list
+	files, deps, err := pathtools.GlobWithExcludes(pattern, excludes)
+	if err != nil {
+		return nil, err
+	}
+
+	// Store the results
+	c.globLock.Lock()
+	if g, exists = c.globs[fileName]; !exists {
+		c.globs[fileName] = GlobPath{pattern, excludes, files, deps, fileName}
+	}
+	c.globLock.Unlock()
+
+	// Getting the list raced with another goroutine, throw away the results and use theirs
+	if exists {
+		verifyGlob(fileName, pattern, excludes, g)
+		return g.Files, nil
+	}
+
+	return files, nil
+}
+
+func (c *Context) Globs() []GlobPath {
+	fileNames := make([]string, 0, len(c.globs))
+	for k := range c.globs {
+		fileNames = append(fileNames, k)
+	}
+	sort.Strings(fileNames)
+
+	globs := make([]GlobPath, len(fileNames))
+	for i, fileName := range fileNames {
+		globs[i] = c.globs[fileName]
+	}
+
+	return globs
+}
+
+func globToString(pattern string) string {
+	ret := ""
+	for _, c := range pattern {
+		switch {
+		case c >= 'a' && c <= 'z',
+			c >= 'A' && c <= 'Z',
+			c >= '0' && c <= '9',
+			c == '_', c == '-', c == '/':
+			ret += string(c)
+		default:
+			ret += "_"
+		}
+	}
+
+	return ret
+}
+
+func globToFileName(pattern string, excludes []string) string {
+	ret := globToString(pattern)
+	for _, e := range excludes {
+		ret += "__" + globToString(e)
+	}
+	return ret + ".glob"
+}
diff --git a/module_ctx.go b/module_ctx.go
index cfbb2db..f8a42f0 100644
--- a/module_ctx.go
+++ b/module_ctx.go
@@ -128,6 +128,12 @@ type BaseModuleContext interface {
 	PropertyErrorf(property, fmt string, args ...interface{})
 	Failed() bool
 
+	// GlobWithDeps returns a list of files that match the specified pattern but do not match any
+	// of the patterns in excludes.  It also adds efficient dependencies to rerun the primary
+	// builder whenever a file matching the pattern as added or removed, without rerunning if a
+	// file that does not match the pattern is added to a searched directory.
+	GlobWithDeps(pattern string, excludes []string) ([]string, error)
+
 	moduleInfo() *moduleInfo
 	error(err error)
 }
@@ -246,6 +252,11 @@ func (d *baseModuleContext) Failed() bool {
 	return len(d.errs) > 0
 }
 
+func (d *baseModuleContext) GlobWithDeps(pattern string,
+	excludes []string) ([]string, error) {
+	return d.context.glob(pattern, excludes)
+}
+
 var _ ModuleContext = (*moduleContext)(nil)
 
 type moduleContext struct {
diff --git a/pathtools/glob.go b/pathtools/glob.go
index 5541643..8e0a7e0 100644
--- a/pathtools/glob.go
+++ b/pathtools/glob.go
@@ -16,9 +16,12 @@ package pathtools
 
 import (
 	"errors"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/google/blueprint/deptools"
 )
 
 var GlobMultipleRecursiveErr = errors.New("pattern contains multiple **")
@@ -28,7 +31,12 @@ var GlobLastRecursiveErr = errors.New("pattern ** as last path element")
 // list of directories that were searched to construct the file list.
 // The supported glob patterns are equivalent to filepath.Glob, with an
 // extension that recursive glob (** matching zero or more complete path
-// entries) is supported.
+// entries) is supported. Glob also returns a list of directories that were
+// searched.
+//
+// In general ModuleContext.GlobWithDeps or SingletonContext.GlobWithDeps
+// should be used instead, as they will automatically set up dependencies
+// to rerun the primary builder when the list of matching files changes.
 func Glob(pattern string) (matches, dirs []string, err error) {
 	return GlobWithExcludes(pattern, nil)
 }
@@ -38,6 +46,11 @@ func Glob(pattern string) (matches, dirs []string, err error) {
 // that were searched to construct the file list.  The supported glob and
 // exclude patterns are equivalent to filepath.Glob, with an extension that
 // recursive glob (** matching zero or more complete path entries) is supported.
+// GlobWIthExcludes also returns a list of directories that were searched.
+//
+// In general ModuleContext.GlobWithDeps or SingletonContext.GlobWithDeps
+// should be used instead, as they will automatically set up dependencies
+// to rerun the primary builder when the list of matching files changes.
 func GlobWithExcludes(pattern string, excludes []string) (matches, dirs []string, err error) {
 	if filepath.Base(pattern) == "**" {
 		return nil, nil, GlobLastRecursiveErr
@@ -287,3 +300,98 @@ func GlobPatternList(patterns []string, prefix string) (globedList []string, dep
 	}
 	return globedList, depDirs, nil
 }
+
+// IsGlob returns true if the pattern contains any glob characters (*, ?, or [).
+func IsGlob(pattern string) bool {
+	return strings.IndexAny(pattern, "*?[") >= 0
+}
+
+// HasGlob returns true if any string in the list contains any glob characters (*, ?, or [).
+func HasGlob(in []string) bool {
+	for _, s := range in {
+		if IsGlob(s) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// GlobWithDepFile finds all files that match glob.  It compares the list of files
+// against the contents of fileListFile, and rewrites fileListFile if it has changed.  It also
+// writes all of the the directories it traversed as a depenencies on fileListFile to depFile.
+//
+// The format of glob is either path/*.ext for a single directory glob, or path/**/*.ext
+// for a recursive glob.
+//
+// Returns a list of file paths, and an error.
+//
+// In general ModuleContext.GlobWithDeps or SingletonContext.GlobWithDeps
+// should be used instead, as they will automatically set up dependencies
+// to rerun the primary builder when the list of matching files changes.
+func GlobWithDepFile(glob, fileListFile, depFile string, excludes []string) (files []string, err error) {
+	files, dirs, err := GlobWithExcludes(glob, excludes)
+	if err != nil {
+		return nil, err
+	}
+
+	fileList := strings.Join(files, "\n") + "\n"
+
+	WriteFileIfChanged(fileListFile, []byte(fileList), 0666)
+	deptools.WriteDepFile(depFile, fileListFile, dirs)
+
+	return
+}
+
+// WriteFileIfChanged wraps ioutil.WriteFile, but only writes the file if
+// the files does not already exist with identical contents.  This can be used
+// along with ninja restat rules to skip rebuilding downstream rules if no
+// changes were made by a rule.
+func WriteFileIfChanged(filename string, data []byte, perm os.FileMode) error {
+	var isChanged bool
+
+	dir := filepath.Dir(filename)
+	err := os.MkdirAll(dir, 0777)
+	if err != nil {
+		return err
+	}
+
+	info, err := os.Stat(filename)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// The file does not exist yet.
+			isChanged = true
+		} else {
+			return err
+		}
+	} else {
+		if info.Size() != int64(len(data)) {
+			isChanged = true
+		} else {
+			oldData, err := ioutil.ReadFile(filename)
+			if err != nil {
+				return err
+			}
+
+			if len(oldData) != len(data) {
+				isChanged = true
+			} else {
+				for i := range data {
+					if oldData[i] != data[i] {
+						isChanged = true
+						break
+					}
+				}
+			}
+		}
+	}
+
+	if isChanged {
+		err = ioutil.WriteFile(filename, data, perm)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
diff --git a/singleton_ctx.go b/singleton_ctx.go
index 007e180..fc4a781 100644
--- a/singleton_ctx.go
+++ b/singleton_ctx.go
@@ -62,6 +62,12 @@ type SingletonContext interface {
 	FinalModule(module Module) Module
 
 	AddNinjaFileDeps(deps ...string)
+
+	// GlobWithDeps returns a list of files that match the specified pattern but do not match any
+	// of the patterns in excludes.  It also adds efficient dependencies to rerun the primary
+	// builder whenever a file matching the pattern as added or removed, without rerunning if a
+	// file that does not match the pattern is added to a searched directory.
+	GlobWithDeps(pattern string, excludes []string) ([]string, error)
 }
 
 var _ SingletonContext = (*singletonContext)(nil)
@@ -228,3 +234,8 @@ func (s *singletonContext) VisitAllModuleVariants(module Module, visit func(Modu
 func (s *singletonContext) AddNinjaFileDeps(deps ...string) {
 	s.ninjaFileDeps = append(s.ninjaFileDeps, deps...)
 }
+
+func (s *singletonContext) GlobWithDeps(pattern string,
+	excludes []string) ([]string, error) {
+	return s.context.glob(pattern, excludes)
+}
diff --git a/tests/test_tree/Blueprints b/tests/test_tree/Blueprints
new file mode 100644
index 0000000..d5e1358
--- /dev/null
+++ b/tests/test_tree/Blueprints
@@ -0,0 +1,3 @@
+// Root Blueprints file for test_tree
+
+subdirs=["*"]
diff --git a/tests/test_tree/a/Blueprints b/tests/test_tree/a/Blueprints
new file mode 100644
index 0000000..836d6ba
--- /dev/null
+++ b/tests/test_tree/a/Blueprints
@@ -0,0 +1 @@
+// a/Blueprints
diff --git a/tests/test_tree/blueprint b/tests/test_tree/blueprint
new file mode 120000
index 0000000..c25bddb
--- /dev/null
+++ b/tests/test_tree/blueprint
@@ -0,0 +1 @@
+../..
\ No newline at end of file
diff --git a/tests/test_tree/build.ninja.in b/tests/test_tree/build.ninja.in
new file mode 100644
index 0000000..5604b40
--- /dev/null
+++ b/tests/test_tree/build.ninja.in
@@ -0,0 +1,335 @@
+# ******************************************************************************
+# ***            This file is generated and should not be edited             ***
+# ******************************************************************************
+#
+# This file contains variables, rules, and pools with name prefixes indicating
+# they were generated by the following Go packages:
+#
+#     bootstrap [from Go package github.com/google/blueprint/bootstrap]
+#
+ninja_required_version = 1.7.0
+
+g.bootstrap.buildDir = @@BuildDir@@
+
+g.bootstrap.BinDir = ${g.bootstrap.buildDir}/.bootstrap/bin
+
+g.bootstrap.bootstrapCmd = @@Bootstrap@@
+
+g.bootstrap.compileCmd = @@GoCompile@@
+
+g.bootstrap.goRoot = @@GoRoot@@
+
+g.bootstrap.linkCmd = @@GoLink@@
+
+g.bootstrap.srcDir = @@SrcDir@@
+
+builddir = ${g.bootstrap.buildDir}/.minibootstrap
+
+rule g.bootstrap.bootstrap
+    command = BUILDDIR=${g.bootstrap.buildDir} ${g.bootstrap.bootstrapCmd} -i ${in}
+    description = bootstrap ${in}
+    generator = true
+
+rule g.bootstrap.build.ninja
+    command = ${builder} ${extra} -b ${g.bootstrap.buildDir} -d ${out}.d -o ${out} ${in}
+    depfile = ${out}.d
+    description = ${builder} ${out}
+    restat = true
+
+rule g.bootstrap.compile
+    command = GOROOT='${g.bootstrap.goRoot}' ${g.bootstrap.compileCmd} -o ${out} -p ${pkgPath} -complete ${incFlags} -pack ${in}
+    description = compile ${out}
+
+rule g.bootstrap.cp
+    command = cp ${in} ${out}
+    description = cp ${out}
+
+rule g.bootstrap.link
+    command = GOROOT='${g.bootstrap.goRoot}' ${g.bootstrap.linkCmd} -o ${out} ${libDirFlags} ${in}
+    description = link ${out}
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:1:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a $
+        : g.bootstrap.compile ${g.bootstrap.srcDir}/blueprint/context.go $
+        ${g.bootstrap.srcDir}/blueprint/fs.go $
+        ${g.bootstrap.srcDir}/blueprint/glob.go $
+        ${g.bootstrap.srcDir}/blueprint/live_tracker.go $
+        ${g.bootstrap.srcDir}/blueprint/mangle.go $
+        ${g.bootstrap.srcDir}/blueprint/module_ctx.go $
+        ${g.bootstrap.srcDir}/blueprint/ninja_defs.go $
+        ${g.bootstrap.srcDir}/blueprint/ninja_strings.go $
+        ${g.bootstrap.srcDir}/blueprint/ninja_writer.go $
+        ${g.bootstrap.srcDir}/blueprint/package_ctx.go $
+        ${g.bootstrap.srcDir}/blueprint/scope.go $
+        ${g.bootstrap.srcDir}/blueprint/singleton_ctx.go $
+        ${g.bootstrap.srcDir}/blueprint/unpack.go | ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg
+    pkgPath = github.com/google/blueprint
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint-bootstrap
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:89:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg/github.com/google/blueprint/bootstrap.a $
+        : g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/bootstrap.go $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/cleanup.go $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/command.go $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/config.go $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/doc.go $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/glob.go $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/writedocs.go | $
+        ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg
+    pkgPath = github.com/google/blueprint/bootstrap
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg/github.com/google/blueprint/bootstrap.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint-bootstrap-bpdoc
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:109:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a $
+        : g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/bpdoc/bpdoc.go | $
+        ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg
+    pkgPath = github.com/google/blueprint/bootstrap/bpdoc
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint-deptools
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:50:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        : g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/deptools/depfile.go | $
+        ${g.bootstrap.compileCmd}
+    pkgPath = github.com/google/blueprint/deptools
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint-parser
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:34:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        : g.bootstrap.compile ${g.bootstrap.srcDir}/blueprint/parser/ast.go $
+        ${g.bootstrap.srcDir}/blueprint/parser/modify.go $
+        ${g.bootstrap.srcDir}/blueprint/parser/parser.go $
+        ${g.bootstrap.srcDir}/blueprint/parser/printer.go $
+        ${g.bootstrap.srcDir}/blueprint/parser/sort.go | $
+        ${g.bootstrap.compileCmd}
+    pkgPath = github.com/google/blueprint/parser
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint-pathtools
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:56:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
+        : g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/pathtools/lists.go $
+        ${g.bootstrap.srcDir}/blueprint/pathtools/glob.go | $
+        ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg
+    pkgPath = github.com/google/blueprint/pathtools
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  blueprint-proptools
+# Variant:
+# Type:    bootstrap_go_package
+# Factory: github.com/google/blueprint/bootstrap.newGoPackageModuleFactory.func1
+# Defined: blueprint/Blueprints:71:1
+
+build $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
+        : g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/proptools/clone.go $
+        ${g.bootstrap.srcDir}/blueprint/proptools/escape.go $
+        ${g.bootstrap.srcDir}/blueprint/proptools/extend.go $
+        ${g.bootstrap.srcDir}/blueprint/proptools/proptools.go $
+        ${g.bootstrap.srcDir}/blueprint/proptools/typeequal.go | $
+        ${g.bootstrap.compileCmd}
+    pkgPath = github.com/google/blueprint/proptools
+default $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  bpglob
+# Variant:
+# Type:    bootstrap_core_go_binary
+# Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
+# Defined: blueprint/Blueprints:130:1
+
+build ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/bpglob.a: $
+        g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/bpglob/bpglob.go | $
+        ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg
+    pkgPath = bpglob
+default ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/bpglob.a
+
+build ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/a.out: g.bootstrap.link $
+        ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/bpglob.a | $
+        ${g.bootstrap.linkCmd}
+    libDirFlags = -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg
+default ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/a.out
+
+build ${g.bootstrap.BinDir}/bpglob: g.bootstrap.cp $
+        ${g.bootstrap.buildDir}/.bootstrap/bpglob/obj/a.out
+default ${g.bootstrap.BinDir}/bpglob
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  gotestmain
+# Variant:
+# Type:    bootstrap_core_go_binary
+# Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
+# Defined: blueprint/Blueprints:148:1
+
+build ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/gotestmain.a: $
+        g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/gotestmain/gotestmain.go | $
+        ${g.bootstrap.compileCmd}
+    pkgPath = gotestmain
+default ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/gotestmain.a
+
+build ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/a.out: $
+        g.bootstrap.link $
+        ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/gotestmain.a | $
+        ${g.bootstrap.linkCmd}
+default ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/a.out
+
+build ${g.bootstrap.BinDir}/gotestmain: g.bootstrap.cp $
+        ${g.bootstrap.buildDir}/.bootstrap/gotestmain/obj/a.out
+default ${g.bootstrap.BinDir}/gotestmain
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  gotestrunner
+# Variant:
+# Type:    bootstrap_core_go_binary
+# Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
+# Defined: blueprint/Blueprints:153:1
+
+build ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/gotestrunner.a: $
+        g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/gotestrunner/gotestrunner.go | $
+        ${g.bootstrap.compileCmd}
+    pkgPath = gotestrunner
+default ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/gotestrunner.a
+
+build ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/a.out: $
+        g.bootstrap.link $
+        ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/gotestrunner.a | $
+        ${g.bootstrap.linkCmd}
+default ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/a.out
+
+build ${g.bootstrap.BinDir}/gotestrunner: g.bootstrap.cp $
+        ${g.bootstrap.buildDir}/.bootstrap/gotestrunner/obj/a.out
+default ${g.bootstrap.BinDir}/gotestrunner
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Module:  minibp
+# Variant:
+# Type:    bootstrap_core_go_binary
+# Factory: github.com/google/blueprint/bootstrap.newGoBinaryModuleFactory.func1
+# Defined: blueprint/Blueprints:121:1
+
+build ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/minibp.a: $
+        g.bootstrap.compile $
+        ${g.bootstrap.srcDir}/blueprint/bootstrap/minibp/main.go | $
+        ${g.bootstrap.compileCmd} $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg/github.com/google/blueprint/parser.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg/github.com/google/blueprint/deptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg/github.com/google/blueprint/pathtools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg/github.com/google/blueprint/proptools.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg/github.com/google/blueprint.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg/github.com/google/blueprint/bootstrap/bpdoc.a $
+        ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg/github.com/google/blueprint/bootstrap.a
+    incFlags = -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg -I ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg
+    pkgPath = minibp
+default ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/minibp.a
+
+build ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/a.out: g.bootstrap.link $
+        ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/minibp.a | $
+        ${g.bootstrap.linkCmd}
+    libDirFlags = -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-parser/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-deptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-pathtools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-proptools/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap-bpdoc/pkg -L ${g.bootstrap.buildDir}/.bootstrap/blueprint-bootstrap/pkg
+default ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/a.out
+
+build ${g.bootstrap.BinDir}/minibp: g.bootstrap.cp $
+        ${g.bootstrap.buildDir}/.bootstrap/minibp/obj/a.out
+default ${g.bootstrap.BinDir}/minibp
+
+# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
+# Singleton: bootstrap
+# Factory:   github.com/google/blueprint/bootstrap.newSingletonFactory.func1
+
+build ${g.bootstrap.buildDir}/.bootstrap/build.ninja: g.bootstrap.build.ninja $
+        ${g.bootstrap.srcDir}/Blueprints | ${builder}
+    builder = ${g.bootstrap.BinDir}/minibp
+    extra = --build-primary
+default ${g.bootstrap.buildDir}/.bootstrap/build.ninja
+
+build ${g.bootstrap.buildDir}/.minibootstrap/build.ninja.in: $
+        g.bootstrap.build.ninja ${g.bootstrap.srcDir}/Blueprints | ${builder}
+    builder = ${g.bootstrap.BinDir}/minibp
+    extra = 
+default ${g.bootstrap.buildDir}/.minibootstrap/build.ninja.in
+
+build ${g.bootstrap.buildDir}/.minibootstrap/build.ninja: $
+        g.bootstrap.bootstrap $
+        ${g.bootstrap.buildDir}/.minibootstrap/build.ninja.in | $
+        ${g.bootstrap.bootstrapCmd}
+default ${g.bootstrap.buildDir}/.minibootstrap/build.ninja
+
diff --git a/tests/test_tree_tests.sh b/tests/test_tree_tests.sh
new file mode 100755
index 0000000..a269fdf
--- /dev/null
+++ b/tests/test_tree_tests.sh
@@ -0,0 +1,78 @@
+#!/bin/bash -ex
+
+function mtime() {
+    stat -c %Y $1
+}
+
+# Go to top of blueprint tree
+TOP=$(dirname ${BASH_SOURCE[0]})/..
+cd ${TOP}
+
+rm -rf out.test
+mkdir out.test
+
+rm -rf src.test
+mkdir src.test
+cp -r tests/test_tree src.test/test_tree
+
+cd out.test
+export SRCDIR=../src.test/test_tree
+${SRCDIR}/blueprint/bootstrap.bash
+./blueprint.bash
+
+if ! cmp -s ${SRCDIR}/build.ninja.in .minibootstrap/build.ninja.in; then
+    echo "tests/test_tree/build.ninja.in and .minibootstrap/build.ninja.in should be the same" >&2
+    exit 1
+fi
+
+OLDTIME=$(mtime build.ninja)
+
+sleep 2
+./blueprint.bash
+
+if [ ${OLDTIME} != $(mtime build.ninja) ]; then
+    echo "unnecessary build.ninja regeneration for null build" >&2
+    exit 1
+fi
+
+mkdir ${SRCDIR}/newglob
+
+sleep 2
+./blueprint.bash
+
+if [ ${OLDTIME} != $(mtime build.ninja) ]; then
+    echo "unnecessary build.ninja regeneration for glob addition" >&2
+    exit 1
+fi
+
+touch ${SRCDIR}/newglob/Blueprints
+
+sleep 2
+./blueprint.bash
+
+if [ ${OLDTIME} = $(mtime build.ninja) ]; then
+    echo "Failed to rebuild for glob addition" >&2
+    exit 1
+fi
+
+OLDTIME=$(mtime build.ninja)
+rm ${SRCDIR}/newglob/Blueprints
+
+sleep 2
+./blueprint.bash
+
+if [ ${OLDTIME} = $(mtime build.ninja) ]; then
+    echo "Failed to rebuild for glob removal" >&2
+    exit 1
+fi
+
+OLDTIME=$(mtime build.ninja)
+rmdir ${SRCDIR}/newglob
+
+sleep 2
+./blueprint.bash
+
+if [ ${OLDTIME} != $(mtime build.ninja) ]; then
+    echo "unnecessary build.ninja regeneration for glob removal" >&2
+    exit 1
+fi