Only allow .scl files to load other .scl files

.scl files are starlark configuraiont language files, which is starlark
without any of the bazel buildin symbols.

This is to match bazel's behavior, and it doesn't make sense for
scl files to load bzl files.

We should change all the release config bzl files to scl, and then
also make it so that when using executionModeScl you can only load
scl files.

Test: go test
Change-Id: I196bcf3a4548118791ed1d47c2d37e46a1ef86c4

7 files changed, 84 insertions, 15 deletions

diff --git a/tools/rbcrun/host.go b/tools/rbcrun/host.go
index 1d68d43fb5..7f5e3327c0 100644
--- a/tools/rbcrun/host.go
+++ b/tools/rbcrun/host.go
@@ -31,11 +31,11 @@ import (
 type ExecutionMode int
 const (
 	ExecutionModeRbc ExecutionMode = iota
-	ExecutionModeMake ExecutionMode = iota
+	ExecutionModeScl ExecutionMode = iota
 )
 
 const allowExternalEntrypointKey = "allowExternalEntrypoint"
-const callerDirKey = "callerDir"
+const callingFileKey = "callingFile"
 const executionModeKey = "executionMode"
 const shellKey = "shell"
 
@@ -58,7 +58,7 @@ var rbcBuiltins starlark.StringDict = starlark.StringDict{
 	"rblf_wildcard": starlark.NewBuiltin("rblf_wildcard", wildcard),
 }
 
-var makeBuiltins starlark.StringDict = starlark.StringDict{
+var sclBuiltins starlark.StringDict = starlark.StringDict{
 	"struct":   starlark.NewBuiltin("struct", starlarkstruct.Make),
 	"json": starlarkjson.Module,
 }
@@ -128,7 +128,8 @@ func loader(thread *starlark.Thread, module string) (starlark.StringDict, error)
 			module = module[:pipePos]
 		}
 	}
-	modulePath, err := cleanModuleName(module, thread.Local(callerDirKey).(string), allowExternalEntrypoint)
+	callingFile := thread.Local(callingFileKey).(string)
+	modulePath, err := cleanModuleName(module, filepath.Dir(callingFile), allowExternalEntrypoint)
 	if err != nil {
 		return nil, err
 	}
@@ -150,6 +151,13 @@ func loader(thread *starlark.Thread, module string) (starlark.StringDict, error)
 
 		// Load or return default
 		if mustLoad {
+			if strings.HasSuffix(callingFile, ".scl") && !strings.HasSuffix(modulePath, ".scl") {
+				return nil, fmt.Errorf(".scl files can only load other .scl files: %q loads %q", callingFile, modulePath)
+			}
+			// Switch into scl mode from here on
+			if strings.HasSuffix(modulePath, ".scl") {
+				mode = ExecutionModeScl
+			}
 			childThread := &starlark.Thread{Name: "exec " + module, Load: thread.Load}
 			// Cheating for the sake of testing:
 			// propagate starlarktest's Reporter key, otherwise testing
@@ -161,14 +169,14 @@ func loader(thread *starlark.Thread, module string) (starlark.StringDict, error)
 
 			// Only the entrypoint starlark file allows external loads.
 			childThread.SetLocal(allowExternalEntrypointKey, false)
-			childThread.SetLocal(callerDirKey, filepath.Dir(modulePath))
+			childThread.SetLocal(callingFileKey, modulePath)
 			childThread.SetLocal(executionModeKey, mode)
 			childThread.SetLocal(shellKey, thread.Local(shellKey))
 			if mode == ExecutionModeRbc {
 				globals, err := starlark.ExecFile(childThread, modulePath, nil, rbcBuiltins)
 				e = &modentry{globals, err}
-			} else if mode == ExecutionModeMake {
-				globals, err := starlark.ExecFile(childThread, modulePath, nil, makeBuiltins)
+			} else if mode == ExecutionModeScl {
+				globals, err := starlark.ExecFile(childThread, modulePath, nil, sclBuiltins)
 				e = &modentry{globals, err}
 			} else {
 				return nil, fmt.Errorf("unknown executionMode %d", mode)
@@ -338,7 +346,7 @@ func Run(filename string, src interface{}, mode ExecutionMode, allowExternalEntr
 			if mode == ExecutionModeRbc {
 				// In rbc mode, rblf_log is used to print to stderr
 				fmt.Println(msg)
-			} else if mode == ExecutionModeMake {
+			} else if mode == ExecutionModeScl {
 				fmt.Fprintln(os.Stderr, msg)
 			}
 		},
@@ -365,13 +373,13 @@ func Run(filename string, src interface{}, mode ExecutionMode, allowExternalEntr
 
 	var results starlark.StringDict
 	mainThread.SetLocal(allowExternalEntrypointKey, allowExternalEntrypoint)
-	mainThread.SetLocal(callerDirKey, filepath.Dir(filename))
+	mainThread.SetLocal(callingFileKey, filename)
 	mainThread.SetLocal(executionModeKey, mode)
 	mainThread.SetLocal(shellKey, shellPath)
 	if mode == ExecutionModeRbc {
 		results, err = starlark.ExecFile(mainThread, filename, src, rbcBuiltins)
-	} else if mode == ExecutionModeMake {
-		results, err = starlark.ExecFile(mainThread, filename, src, makeBuiltins)
+	} else if mode == ExecutionModeScl {
+		results, err = starlark.ExecFile(mainThread, filename, src, sclBuiltins)
 	} else {
 		return results, nil, fmt.Errorf("unknown executionMode %d", mode)
 	}
diff --git a/tools/rbcrun/host_test.go b/tools/rbcrun/host_test.go
index 10ce55ec2f..468a620b51 100644
--- a/tools/rbcrun/host_test.go
+++ b/tools/rbcrun/host_test.go
@@ -19,6 +19,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 
 	"go.starlark.net/resolve"
@@ -126,7 +127,7 @@ func TestLoad(t *testing.T) {
 		t.Fatal(err)
 	}
 	thread.SetLocal(allowExternalEntrypointKey, false)
-	thread.SetLocal(callerDirKey, dir)
+	thread.SetLocal(callingFileKey, "testdata/load.star")
 	thread.SetLocal(executionModeKey, ExecutionModeRbc)
 	if _, err := starlark.ExecFile(thread, "testdata/load.star", nil, rbcBuiltins); err != nil {
 		if err, ok := err.(*starlark.EvalError); ok {
@@ -136,6 +137,55 @@ func TestLoad(t *testing.T) {
 	}
 }
 
+func TestBzlLoadsScl(t *testing.T) {
+	moduleCache = make(map[string]*modentry)
+	dir := dataDir()
+	if err := os.Chdir(filepath.Dir(dir)); err != nil {
+		t.Fatal(err)
+	}
+	vars, _, err := Run("testdata/bzl_loads_scl.bzl", nil, ExecutionModeScl, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if val, ok := vars["foo"]; !ok {
+		t.Fatalf("Failed to load foo variable")
+	} else if val.(starlark.String) != "bar" {
+		t.Fatalf("Expected \"bar\", got %q", val)
+	}
+}
+
+func TestNonEntrypointBzlLoadsScl(t *testing.T) {
+	moduleCache = make(map[string]*modentry)
+	dir := dataDir()
+	if err := os.Chdir(filepath.Dir(dir)); err != nil {
+		t.Fatal(err)
+	}
+	vars, _, err := Run("testdata/bzl_loads_scl_2.bzl", nil, ExecutionModeScl, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if val, ok := vars["foo"]; !ok {
+		t.Fatalf("Failed to load foo variable")
+	} else if val.(starlark.String) != "bar" {
+		t.Fatalf("Expected \"bar\", got %q", val)
+	}
+}
+
+func TestSclLoadsBzl(t *testing.T) {
+	moduleCache = make(map[string]*modentry)
+	dir := dataDir()
+	if err := os.Chdir(filepath.Dir(dir)); err != nil {
+		t.Fatal(err)
+	}
+	_, _, err := Run("testdata/scl_incorrectly_loads_bzl.scl", nil, ExecutionModeScl, false)
+	if err == nil {
+		t.Fatal("Expected failure")
+	}
+	if !strings.Contains(err.Error(), ".scl files can only load other .scl files") {
+		t.Fatalf("Expected error to contain \".scl files can only load other .scl files\": %q", err.Error())
+	}
+}
+
 func TestShell(t *testing.T) {
 	exerciseStarlarkTestFile(t, "testdata/shell.star")
 }
diff --git a/tools/rbcrun/rbcrun/rbcrun.go b/tools/rbcrun/rbcrun/rbcrun.go
index a15b867b60..8c372c71d3 100644
--- a/tools/rbcrun/rbcrun/rbcrun.go
+++ b/tools/rbcrun/rbcrun/rbcrun.go
@@ -55,13 +55,13 @@ func getMode() rbcrun.ExecutionMode {
 	case "rbc":
 		return rbcrun.ExecutionModeRbc
 	case "make":
-		return rbcrun.ExecutionModeMake
+		return rbcrun.ExecutionModeScl
 	case "":
 		quit("-mode flag is required.")
 	default:
 		quit("Unknown -mode value %q, expected 1 of \"rbc\", \"make\"", *modeFlag)
 	}
-	return rbcrun.ExecutionModeMake
+	return rbcrun.ExecutionModeScl
 }
 
 var makeStringReplacer = strings.NewReplacer("#", "\\#", "$", "$$")
@@ -175,7 +175,7 @@ func main() {
 			quit("%s\n", err)
 		}
 	}
-	if mode == rbcrun.ExecutionModeMake {
+	if mode == rbcrun.ExecutionModeScl {
 		if err := printVarsInMakeFormat(variables); err != nil {
 			quit("%s\n", err)
 		}
diff --git a/tools/rbcrun/testdata/bzl_loads_scl.bzl b/tools/rbcrun/testdata/bzl_loads_scl.bzl
new file mode 100644
index 0000000000..e8deca3d9c
--- /dev/null
+++ b/tools/rbcrun/testdata/bzl_loads_scl.bzl
@@ -0,0 +1,3 @@
+load(":test_scl.scl", _foo = "foo")
+
+foo = _foo
diff --git a/tools/rbcrun/testdata/bzl_loads_scl_2.bzl b/tools/rbcrun/testdata/bzl_loads_scl_2.bzl
new file mode 100644
index 0000000000..9a680edc03
--- /dev/null
+++ b/tools/rbcrun/testdata/bzl_loads_scl_2.bzl
@@ -0,0 +1,3 @@
+load(":bzl_loads_scl.bzl", _foo = "foo")
+
+foo = _foo
diff --git a/tools/rbcrun/testdata/scl_incorrectly_loads_bzl.scl b/tools/rbcrun/testdata/scl_incorrectly_loads_bzl.scl
new file mode 100644
index 0000000000..9a680edc03
--- /dev/null
+++ b/tools/rbcrun/testdata/scl_incorrectly_loads_bzl.scl
@@ -0,0 +1,3 @@
+load(":bzl_loads_scl.bzl", _foo = "foo")
+
+foo = _foo
diff --git a/tools/rbcrun/testdata/test_scl.scl b/tools/rbcrun/testdata/test_scl.scl
new file mode 100644
index 0000000000..6360ccb715
--- /dev/null
+++ b/tools/rbcrun/testdata/test_scl.scl
@@ -0,0 +1,2 @@
+
+foo = "bar"