make -seed=random use the same random seed for all packages

Otherwise, a different random seed per package will break imported names.

crypto.go

@@ -6,6 +6,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	mathrand "math/rand"
+	"strings"
 )
 
 // If math/rand.Seed() is not called, the generator behaves as if seeded by rand.Seed(1),
@@ -25,7 +26,7 @@ func genNonce() []byte {
 func genRandBytes(size int) []byte {
 	buffer := make([]byte, size)
 
-	if envGarbleSeed == "random" {
+	if strings.HasPrefix(envGarbleSeed, "random;") {
 		_, err := rand.Read(buffer)
 		if err != nil {
 			panic(fmt.Sprintf("couldn't generate random key:  %v", err))

main.go

@@ -195,6 +195,17 @@ func mainErr(args []string) error {
 		}
 		os.Setenv("GARBLE_DIR", wd)
 		os.Setenv("GARBLE_LITERALS", fmt.Sprint(flagGarbleLiterals))
+
+		if flagSeed == "random" {
+			seed = make([]byte, 16) // random 128 bit seed
+
+			_, err = rand.Read(seed)
+			if err != nil {
+				return fmt.Errorf("Error generating random seed: %v", err)
+			}
+
+			flagSeed = "random;" + base64.StdEncoding.EncodeToString(seed)
+		}
 		os.Setenv("GARBLE_SEED", flagSeed)
 
 		if flagDebugDir != "" {
@@ -349,20 +360,15 @@ func transformCompile(args []string) ([]string, error) {
 		files = append(files, file)
 	}
 
-	if envGarbleSeed == "random" {
+	if envGarbleSeed != "" {
-		seed = make([]byte, 16) // random 128 bit seed
+		seed, err = base64.StdEncoding.DecodeString(strings.TrimPrefix(envGarbleSeed, "random;"))
-
-		_, err = rand.Read(seed)
-		if err != nil {
-			return nil, fmt.Errorf("Error generating random seed: %v", err)
-		}
-	} else if envGarbleSeed != "" {
-		seed, err = base64.StdEncoding.DecodeString(envGarbleSeed)
 		if err != nil {
 			return nil, fmt.Errorf("Error decoding base64 encoded seed: %v", err)
 		}
 
 		mathrand.Seed(int64(binary.BigEndian.Uint64(seed)))
+	} else {
+		mathrand.Seed(int64(binary.BigEndian.Uint64([]byte(buildInfo.buildID))))
 	}
 
 	if envGarbleLiterals {

strings.go

@@ -240,17 +240,3 @@ func keyStmt(key []byte) *ast.GenDecl {
 		}},
 	}
 }
-
-var cryptoAesImportSpec = &ast.GenDecl{
-	Tok: token.IMPORT,
-	Specs: []ast.Spec{
-		&ast.ImportSpec{Path: &ast.BasicLit{
-			Kind:  token.STRING,
-			Value: `"crypto/aes"`,
-		}},
-		&ast.ImportSpec{Path: &ast.BasicLit{
-			Kind:  token.STRING,
-			Value: `"crypto/cipher"`,
-		}},
-	},
-}

testdata/scripts/seed.txt

@@ -1,43 +1,53 @@
 # Check the binary with a given base64 encoded seed
-garble -literals -seed=OQg9kACEECQ= build main.go
+garble -literals -seed=OQg9kACEECQ= build
 exec ./main$exe
 cmp stderr main.stdout   
-! binsubstr  main$exe 'teststring' 'teststringVar'
+! binsubstr  main$exe 'teststring' 'teststringVar' 'imported var value' 'ImportedVar'
 
 [short] stop # checking that the build is reproducible and random is slow
 
 # Also check that the binary is reproducible.
 cp main$exe main_old$exe
 rm main$exe
-garble -literals -seed=OQg9kACEECQ= build main.go
+garble -literals -seed=OQg9kACEECQ= build
 bincmp main$exe main_old$exe
 
 # Also check that a different seed leads to a different binary
 cp main$exe main_old$exe
 rm main$exe
-garble -literals -seed=NruiDmVz6/s= build main.go
+garble -literals -seed=NruiDmVz6/s= build
 ! bincmp main$exe main_old$exe
 
 # Check the random binary
-garble -literals -seed=random build main.go
+garble -literals -seed=random build
 exec ./main$exe
 cmp stderr main.stdout
-! binsubstr  main$exe 'teststring' 'teststringVar'
+! binsubstr  main$exe 'teststring' 'teststringVar' 'imported var value' 'ImportedVar'
 
 # Also check that the random binary is not reproducible.
 cp main$exe main_old$exe
 rm main$exe
-garble -literals -seed=random build main.go
+garble -literals -seed=random build
 ! bincmp main$exe main_old$exe
 
+-- go.mod --
+module test/main
 -- main.go --
 package main
 
+import "test/main/imported"
+
 var teststringVar = "teststring"
 
 func main() {
 	println(teststringVar)
+	println(imported.ImportedVar)
 }
+-- imported/imported.go --
+package imported
+
+var ImportedVar = "imported var value"
 
 -- main.stdout --
-teststring
+teststring
+imported var value