cmd/link: don't mangle string symbol names

String symbol names could contain weird characters as we put the
string literal into the symbol name. So it may appear to need
mangling. However, as string symbols are grouped into a single
"go:string.*" symbol, the individual symbol names actually don't
matter. So don't mangle them.

Also make the mangling code more defensive in case of weird
symbol names.

Fixes #62098.

Change-Id: I533012567a9fffab69debda934f426421c7abb04
Reviewed-on: https://go-review.googlesource.com/c/go/+/520856
Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/cgo/internal/testplugin/plugin_test.go

@@ -380,9 +380,11 @@ func TestForkExec(t *testing.T) {
 	}
 }
 
-func TestGeneric(t *testing.T) {
+func TestSymbolNameMangle(t *testing.T) {
 	// Issue 58800: generic function name may contain weird characters
 	// that confuse the external linker.
+	// Issue 62098: the name mangling code doesn't handle some string
+	// symbols correctly.
 	globalSkip(t)
-	goCmd(t, "build", "-buildmode=plugin", "-o", "generic.so", "./generic/plugin.go")
+	goCmd(t, "build", "-buildmode=plugin", "-o", "mangle.so", "./mangle/plugin.go")
 }

src/cmd/cgo/internal/testplugin/testdata/mangle/plugin.go

@@ -2,21 +2,37 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Instantiated function name may contain weird characters
-// that confuse the external linker, so it needs to be
-// mangled.
+// Test cases for symbol name mangling.
 
 package main
 
-//go:noinline
-func F[T any]() {}
+import (
+	"fmt"
+	"strings"
+)
 
+// Issue 58800:
+// Instantiated function name may contain weird characters
+// that confuse the external linker, so it needs to be
+// mangled.
 type S struct {
 	X int `parser:"|@@)"`
 }
 
+//go:noinline
+func F[T any]() {}
+
 func P() {
 	F[S]()
 }
 
+// Issue 62098: the name mangling code doesn't handle some string
+// symbols correctly.
+func G(id string) error {
+	if strings.ContainsAny(id, "&$@;/:+,?\\{^}%`]\">[~<#|") {
+		return fmt.Errorf("invalid")
+	}
+	return nil
+}
+
 func main() {}

src/cmd/link/internal/ld/lib.go

@@ -993,6 +993,11 @@ func typeSymbolMangle(name string) string {
 	if strings.HasPrefix(name, "type:runtime.") {
 		return name
 	}
+	if strings.HasPrefix(name, "go:string.") {
+		// String symbols will be grouped to a single go:string.* symbol.
+		// No need to mangle individual symbol names.
+		return name
+	}
 	if len(name) <= 14 && !strings.Contains(name, "@") { // Issue 19529
 		return name
 	}
@@ -1007,7 +1012,7 @@ func typeSymbolMangle(name string) string {
 	// instantiated symbol, replace type name in []
 	i := strings.IndexByte(name, '[')
 	j := strings.LastIndexByte(name, ']')
-	if j == -1 {
+	if j == -1 || j <= i {
 		j = len(name)
 	}
 	hash := notsha256.Sum256([]byte(name[i+1 : j]))