[Go] Fixes for Go 1.6: avoid returning Go pointers from

directors that return string values; add a trailing 0 byte
when treating Go string as C char*.

CHANGES.current

@@ -5,6 +5,11 @@ See the RELEASENOTES file for a summary of changes in each release.
 Version 3.0.9 (in progress)
 ===========================
 
+2016-04-17: ianlancetaylor
+	    [Go] Fixes for Go 1.6: avoid returning Go pointers from
+	    directors that return string values; add a trailing 0 byte
+	    when treating Go string as C char*.
+
 2016-04-06: smarchetto
             [Scilab] #552 Make Scilab runtime keep track of pointer types
             Instead of a Scilab pointer which has no type, SWIG Scilab maps a

Examples/test-suite/apply_strings.i

@@ -68,6 +68,10 @@ TAscii *DigitsGlobalC;
 // Director test
 %feature("director");
 
+#if defined(SWIGGO)
+%typemap(godirectorout) CharPtr, CCharPtr ""
+#endif
+
 %inline %{
   struct DirectorTest {
     virtual UCharPtr UCharFunction(UCharPtr str) { return str; }

Examples/test-suite/go_inout.i

@@ -23,7 +23,7 @@ struct RetStruct {
 
 // Write a typemap that calls C++ by converting in and out of JSON.
 
-%go_import("encoding/json", "bytes", "encoding/binary")
+%go_import("encoding/json", "bytes", "encoding/binary", "reflect", "unsafe")
 
 %insert(go_header)
 %{
@@ -87,6 +87,10 @@ struct MyArray {
   std::vector<std::string> strings;
 };
 
+void* Allocate(int n) {
+  return new char[n];
+}
+
 static uint64_t getuint64(const char* s) {
   uint64_t ret = 0;
   for (int i = 0; i < 8; i++, s++) {
@@ -121,7 +125,12 @@ static void putuint64(std::string *s, size_t off, uint64_t v) {
 			buf.Write(b[:])
 			buf.WriteString(s)
 		}
-		str := buf.String()
+		bb := buf.Bytes()
+		p := Allocate(len(bb))
+		copy((*[1<<15]byte)(unsafe.Pointer(p))[:len(bb)], bb)
+		var str string
+		(*reflect.StringHeader)(unsafe.Pointer(&str)).Data = uintptr(unsafe.Pointer(p))
+		(*reflect.StringHeader)(unsafe.Pointer(&str)).Len = len(bb)
 		$result = &str
 	}
 %}

Examples/test-suite/namespace_typemap.i

@@ -109,7 +109,11 @@ namespace test {
 #ifdef SWIGGO
 	%typemap(gotype) string_class * "string"
 	%typemap(in) string_class * {
-            $1 = new string_class($input.p);
+	    char* buf = new char[$input.n + 1];
+	    memcpy(buf, $input.p, $input.n);
+	    buf[$input.n] = '\0';
+	    $1 = new string_class(buf);
+	    delete[] buf;
 	}
 	%typemap(freearg) string_class * {
 	    delete $1;

Lib/go/go.swg

@@ -435,10 +435,22 @@
 
 %typemap(in)
 	char *, char[ANY], char[]
-%{ $1 = ($1_ltype)$input.p; %}
+%{
+  $1 = ($1_ltype)malloc($input.n + 1);
+  memcpy($1, $input.p, $input.n);
+  $1[$input.n] = '\0';
+%}
 
 %typemap(in) char *&
-%{ $1 = ($1_ltype)$input.p; %}
+%{
+  $1 = ($1_ltype)malloc($input.n + 1);
+  memcpy($1, $input.p, $input.n);
+  $1[$input.n] = '\0';
+%}
+
+%typemap(freearg)
+	char *, char *&, char[ANY], char[]
+%{ free($1); %}
 
 %typemap(out,fragment="AllocateString")
 	char *, char *&, char[ANY], char[]
@@ -460,7 +472,19 @@
   $result = swigCopyString($input)
 %}
 
-%typemap(directorout)
+%typemap(godirectorout)
+	char *, char *&, char[ANY], char[]
+%{
+  {
+    p := Swig_malloc(len($input) + 1)
+    s := (*[1<<30]byte)(unsafe.Pointer(p))[:len($input) + 1]
+    copy(s, $input)
+    s[len($input)] = 0
+    $result = *(*string)(unsafe.Pointer(&s))
+  }
+%}
+
+%typemap(directorout, warning=SWIGWARN_TYPEMAP_DIRECTOROUT_PTR_MSG)
 	char *, char *&, char[ANY], char[]
 %{ $result = ($1_ltype)$input.p; %}
 

Lib/go/goruntime.swg

@@ -8,6 +8,10 @@
 static void Swig_free(void* p) {
   free(p);
 }
+
+static void* Swig_malloc(int c) {
+  return malloc(c);
+}
 %}
 
 %insert(runtime) %{

Lib/go/std_string.i

@@ -24,8 +24,21 @@ class string;
 %typemap(in) string
 %{ $1.assign($input.p, $input.n); %}
 
+%typemap(godirectorout) string
+%{
+  {
+    p := Swig_malloc(len($input))
+    s := (*[1<<30]byte)(unsafe.Pointer(p))[:len($input)]
+    copy(s, $input)
+    $result = *(*string)(unsafe.Pointer(&s))
+  }
+%}
+
 %typemap(directorout) string
-%{ $result.assign($input.p, $input.n); %}
+%{
+  $result.assign($input.p, $input.n);
+  free($input.p);
+%}
 
 %typemap(out,fragment="AllocateString") string
 %{ $result = Swig_AllocateString($1.data(), $1.length()); %}
@@ -45,10 +58,21 @@ class string;
   $1 = &$1_str;
 %}
 
+%typemap(godirectorout) const string &
+%{
+  {
+    p := Swig_malloc(len($input))
+    s := (*[1<<30]byte)(unsafe.Pointer(p))[:len($input)]
+    copy(s, $input)
+    $result = *(*string)(unsafe.Pointer(&s))
+  }
+%}
+
 %typemap(directorout,warning=SWIGWARN_TYPEMAP_THREAD_UNSAFE_MSG) const string &
 %{
   static $*1_ltype $1_str;
   $1_str.assign($input.p, $input.n);
+  free($input.p);
   $result = &$1_str;
 %}