properly remove all filenames when -tiny is passed (#160)

* properly remove all filenames when -tiny is passed

* document filename symbol removal

import_obfuscation.go

@@ -291,6 +291,15 @@ func stripPCLinesAndNames(am *goobj2.ArchiveMember) {
 	lists := [][]*goobj2.Sym{am.SymDefs, am.NonPkgSymDefs, am.NonPkgSymRefs}
 	for _, list := range lists {
 		for _, s := range list {
+			// remove filename symbols when -tiny is passed as they
+			// are only used for printing panics, and -tiny removes
+			// panic printing; we need to set the symbol names to
+			// 'gofile..', otherwise the linker will expect to see
+			// filename symbols and panic
+			if strings.HasPrefix(s.Name, "gofile..") {
+				s.Name = "gofile.."
+			}
+
 			if s.Func == nil {
 				continue
 			}
@@ -495,6 +504,13 @@ func garbleSymbolName(symName string, privImports privateImports, garbledImports
 		return symName
 	}
 
+	// remove filename symbols when -tiny is passed
+	// as they are only used for printing panics,
+	// and -tiny removes panic printing
+	if envGarbleTiny && prefix == "gofile.." {
+		return prefix
+	}
+
 	var namedataSym bool
 	if prefix == "type..namedata." {
 		namedataSym = true

testdata/scripts/tiny.txt

@@ -2,6 +2,7 @@ env GOPRIVATE=test/main
 
 # Tiny mode
 garble -tiny build
+! binsubstr main$exe 'main.go' 'fmt/print.go'
 env GODEBUG='allocfreetrace=1,gcpacertrace=1,gctrace=1,scavenge=1,scavtrace=1,scheddetail=1,schedtrace=10'
 ! exec ./main$exe
 cmp stdout main.stdout