Move AllowMissingDependencies check from PathsForSource to PathForSource

PathsForSource was handling the AllowMissingDependencies case, but
PathForSource was not.  Refactor PathForSource and
ExistentPathForSource, and add logic to PathForSource to fall back
to behavior similar to ExistentPathForSource when
AllowMissingDependencies is set.

Test: paths_test.go
Change-Id: Id7925999a27ea75a05e9301bbf1eb9f9a6bc4652

android/paths.go

@@ -195,20 +195,6 @@ type Paths []Path
 
 // PathsForSource returns Paths rooted from SrcDir
 func PathsForSource(ctx PathContext, paths []string) Paths {
-	if ctx.Config().AllowMissingDependencies() {
-		if modCtx, ok := ctx.(ModuleContext); ok {
-			ret := make(Paths, 0, len(paths))
-			for _, path := range paths {
-				p := ExistentPathForSource(ctx, path)
-				if p.Valid() {
-					ret = append(ret, p.Path())
-				} else {
-					modCtx.AddMissingDependencies([]string{path})
-				}
-			}
-			return ret
-		}
-	}
 	ret := make(Paths, len(paths))
 	for i, path := range paths {
 		ret[i] = PathForSource(ctx, path)
@@ -507,100 +493,100 @@ func safePathForSource(ctx PathContext, path string) SourcePath {
 	return ret
 }
 
-// PathForSource joins the provided path components and validates that the result
-// neither escapes the source dir nor is in the out dir.
-// On error, it will return a usable, but invalid SourcePath, and report a ModuleError.
-func PathForSource(ctx PathContext, pathComponents ...string) SourcePath {
+// pathForSource creates a SourcePath from pathComponents, but does not check that it exists.
+func pathForSource(ctx PathContext, pathComponents ...string) (SourcePath, error) {
 	p, err := validatePath(pathComponents...)
 	ret := SourcePath{basePath{p, ctx.Config(), ""}}
 	if err != nil {
-		reportPathError(ctx, err)
-		return ret
+		return ret, err
 	}
 
 	abs, err := filepath.Abs(ret.String())
 	if err != nil {
-		reportPathError(ctx, err)
-		return ret
+		return ret, err
 	}
 	buildroot, err := filepath.Abs(ctx.Config().buildDir)
 	if err != nil {
-		reportPathError(ctx, err)
-		return ret
+		return ret, err
 	}
 	if strings.HasPrefix(abs, buildroot) {
-		reportPathErrorf(ctx, "source path %s is in output", abs)
-		return ret
+		return ret, fmt.Errorf("source path %s is in output", abs)
 	}
 
-	if exists, _, err := ctx.Fs().Exists(ret.String()); err != nil {
-		reportPathErrorf(ctx, "%s: %s", ret, err.Error())
-	} else if !exists {
-		reportPathErrorf(ctx, "source path %s does not exist", ret)
+	if pathtools.IsGlob(ret.String()) {
+		return ret, fmt.Errorf("path may not contain a glob: %s", ret.String())
 	}
-	return ret
+
+	return ret, nil
+}
+
+// existsWithDependencies returns true if the path exists, and adds appropriate dependencies to rerun if the
+// path does not exist.
+func existsWithDependencies(ctx PathContext, path SourcePath) (exists bool, err error) {
+	var files []string
+
+	if gctx, ok := ctx.(PathGlobContext); ok {
+		// Use glob to produce proper dependencies, even though we only want
+		// a single file.
+		files, err = gctx.GlobWithDeps(path.String(), nil)
+	} else {
+		var deps []string
+		// We cannot add build statements in this context, so we fall back to
+		// AddNinjaFileDeps
+		files, deps, err = pathtools.Glob(path.String(), nil)
+		ctx.AddNinjaFileDeps(deps...)
+	}
+
+	if err != nil {
+		return false, fmt.Errorf("glob: %s", err.Error())
+	}
+
+	return len(files) > 0, nil
+}
+
+// PathForSource joins the provided path components and validates that the result
+// neither escapes the source dir nor is in the out dir.
+// On error, it will return a usable, but invalid SourcePath, and report a ModuleError.
+func PathForSource(ctx PathContext, pathComponents ...string) SourcePath {
+	path, err := pathForSource(ctx, pathComponents...)
+	if err != nil {
+		reportPathError(ctx, err)
+	}
+
+	if modCtx, ok := ctx.(ModuleContext); ok && ctx.Config().AllowMissingDependencies() {
+		exists, err := existsWithDependencies(ctx, path)
+		if err != nil {
+			reportPathError(ctx, err)
+		}
+		if !exists {
+			modCtx.AddMissingDependencies([]string{path.String()})
+		}
+	} else if exists, _, err := ctx.Fs().Exists(path.String()); err != nil {
+		reportPathErrorf(ctx, "%s: %s", path, err.Error())
+	} else if !exists {
+		reportPathErrorf(ctx, "source path %s does not exist", path)
+	}
+	return path
 }
 
 // ExistentPathForSource returns an OptionalPath with the SourcePath if the
 // path exists, or an empty OptionalPath if it doesn't exist. Dependencies are added
 // so that the ninja file will be regenerated if the state of the path changes.
 func ExistentPathForSource(ctx PathContext, pathComponents ...string) OptionalPath {
-	p, err := validatePath(pathComponents...)
+	path, err := pathForSource(ctx, pathComponents...)
 	if err != nil {
 		reportPathError(ctx, err)
 		return OptionalPath{}
 	}
-	path := SourcePath{basePath{p, ctx.Config(), ""}}
 
-	abs, err := filepath.Abs(path.String())
+	exists, err := existsWithDependencies(ctx, path)
 	if err != nil {
 		reportPathError(ctx, err)
 		return OptionalPath{}
 	}
-	buildroot, err := filepath.Abs(ctx.Config().buildDir)
-	if err != nil {
-		reportPathError(ctx, err)
+	if !exists {
 		return OptionalPath{}
 	}
-	if strings.HasPrefix(abs, buildroot) {
-		reportPathErrorf(ctx, "source path %s is in output", abs)
-		return OptionalPath{}
-	}
-
-	if pathtools.IsGlob(path.String()) {
-		reportPathErrorf(ctx, "path may not contain a glob: %s", path.String())
-		return OptionalPath{}
-	}
-
-	if gctx, ok := ctx.(PathGlobContext); ok {
-		// Use glob to produce proper dependencies, even though we only want
-		// a single file.
-		files, err := gctx.GlobWithDeps(path.String(), nil)
-		if err != nil {
-			reportPathErrorf(ctx, "glob: %s", err.Error())
-			return OptionalPath{}
-		}
-
-		if len(files) == 0 {
-			return OptionalPath{}
-		}
-	} else {
-		// We cannot add build statements in this context, so we fall back to
-		// AddNinjaFileDeps
-		files, dirs, err := pathtools.Glob(path.String(), nil)
-		if err != nil {
-			reportPathErrorf(ctx, "glob: %s", err.Error())
-			return OptionalPath{}
-		}
-
-		ctx.AddNinjaFileDeps(dirs...)
-
-		if len(files) == 0 {
-			return OptionalPath{}
-		}
-
-		ctx.AddNinjaFileDeps(path.String())
-	}
 	return OptionalPathForPath(path)
 }