Forms: improve cpp/c interface regarding exceptions

Three alterations:
We were previously being careful to avoid throwing exceptions in
the DOM-implementation callbacks because these were being called
directly from C++. This commit adds three veneers that turn exceptions
into warnings, hence allowing the callbacks to be written in usual
mupdf style.

Protect the "field" callbacks from executing with a NULL field.

Ensure that the event object is set up before executing A actions

5 files changed, 95 insertions, 41 deletions

diff --git a/pdf/pdf_form.c b/pdf/pdf_form.c
index 2fb8114c..76e28058 100644
--- a/pdf/pdf_form.c
+++ b/pdf/pdf_form.c
@@ -1737,9 +1737,13 @@ void pdf_update_appearance(pdf_document *doc, pdf_obj *obj)
 
 static void execute_action_chain(pdf_document *doc, pdf_obj *obj)
 {
-	pdf_obj *a;
+	pdf_obj *a = pdf_dict_gets(obj, "A");
+	pdf_js_event e;
+
+	e.target = obj;
+	e.value = "";
+	pdf_js_setup_event(doc->js, &e);
 
-	a = pdf_dict_gets(obj, "A");
 	while (a)
 	{
 		execute_action(doc, obj, a);
diff --git a/pdf/pdf_js.c b/pdf/pdf_js.c
index 2443e667..fa33c44c 100644
--- a/pdf/pdf_js.c
+++ b/pdf/pdf_js.c
@@ -70,21 +70,9 @@ static pdf_jsimp_obj *field_buttonSetCaption(void *jsctx, void *obj, int argc, p
 static pdf_jsimp_obj *field_getDisplay(void *jsctx, void *obj)
 {
 	pdf_js *js = (pdf_js *)jsctx;
-	fz_context *ctx = js->doc->ctx;
 	pdf_obj *field = (pdf_obj *)obj;
-	pdf_jsimp_obj *res = NULL;
 
-	fz_try(ctx)
-	{
-		int d = pdf_field_display(js->doc, field);
-		res = pdf_jsimp_from_number(js->imp, (double)d);
-	}
-	fz_catch(ctx)
-	{
-		fz_warn(ctx, "%s", ctx->error->message);
-	}
-
-	return res;
+	return field ? pdf_jsimp_from_number(js->imp, (double)pdf_field_display(js->doc, field)) : NULL;
 }
 
 static void field_setDisplay(void *jsctx, void *obj, pdf_jsimp_obj *val)
@@ -93,15 +81,8 @@ static void field_setDisplay(void *jsctx, void *obj, pdf_jsimp_obj *val)
 	fz_context *ctx = js->doc->ctx;
 	pdf_obj *field = (pdf_obj *)obj;
 
-	fz_try(ctx)
-	{
-		int ival = (int)pdf_jsimp_to_number(js->imp, val);
-		pdf_field_set_display(js->doc, field, ival);
-	}
-	fz_catch(ctx)
-	{
-		fz_warn(ctx, "%s", ctx->error->message);
-	}
+	if (field)
+		pdf_field_set_display(js->doc, field, (int)pdf_jsimp_to_number(js->imp, val));
 }
 
 static pdf_jsimp_obj *field_getFillColor(void *jsctx, void *obj)
@@ -114,8 +95,12 @@ static void field_setFillColor(void *jsctx, void *obj, pdf_jsimp_obj *val)
 	pdf_js *js = (pdf_js *)jsctx;
 	fz_context *ctx = js->doc->ctx;
 	pdf_obj *field = (pdf_obj *)obj;
-	pdf_obj *col = load_color(js->doc->ctx, js->imp, val);
+	pdf_obj *col;
 
+	if (!field)
+		return;
+
+	col = load_color(js->doc->ctx, js->imp, val);
 	fz_try(ctx)
 	{
 		pdf_field_set_fill_color(js->doc, field, col);
@@ -140,8 +125,12 @@ static void field_setTextColor(void *jsctx, void *obj, pdf_jsimp_obj *val)
 	pdf_js *js = (pdf_js *)jsctx;
 	fz_context *ctx = js->doc->ctx;
 	pdf_obj *field = (pdf_obj *)obj;
-	pdf_obj *col = load_color(js->doc->ctx, js->imp, val);
+	pdf_obj *col;
+
+	if (!field)
+		return;
 
+	col = load_color(js->doc->ctx, js->imp, val);
 	fz_try(ctx)
 	{
 		pdf_field_set_text_color(js->doc, field, col);
@@ -161,7 +150,7 @@ static pdf_jsimp_obj *field_getBorderStyle(void *jsctx, void *obj)
 	pdf_js *js = (pdf_js *)jsctx;
 	pdf_obj *field = (pdf_obj *)obj;
 
-	return pdf_jsimp_from_string(js->imp, pdf_field_border_style(js->doc, field));
+	return field ? pdf_jsimp_from_string(js->imp, pdf_field_border_style(js->doc, field)) : NULL;
 }
 
 static void field_setBorderStyle(void *jsctx, void *obj, pdf_jsimp_obj *val)
@@ -169,15 +158,20 @@ static void field_setBorderStyle(void *jsctx, void *obj, pdf_jsimp_obj *val)
 	pdf_js *js = (pdf_js *)jsctx;
 	pdf_obj *field = (pdf_obj *)obj;
 
-	pdf_field_set_border_style(js->doc, field, pdf_jsimp_to_string(js->imp, val));
+	if (field)
+		pdf_field_set_border_style(js->doc, field, pdf_jsimp_to_string(js->imp, val));
 }
 
 static pdf_jsimp_obj *field_getValue(void *jsctx, void *obj)
 {
 	pdf_js *js = (pdf_js *)jsctx;
 	pdf_obj *field = (pdf_obj *)obj;
-	char *fval = pdf_field_value(js->doc, field);
+	char *fval;
+
+	if (!field)
+		return NULL;
 
+	fval = pdf_field_value(js->doc, field);
 	return pdf_jsimp_from_string(js->imp, fval?fval:"");
 }
 
@@ -186,7 +180,8 @@ static void field_setValue(void *jsctx, void *obj, pdf_jsimp_obj *val)
 	pdf_js *js = (pdf_js *)jsctx;
 	pdf_obj *field = (pdf_obj *)obj;
 
-	(void)pdf_field_set_value(js->doc, field, pdf_jsimp_to_string(js->imp, val));
+	if (field)
+		(void)pdf_field_set_value(js->doc, field, pdf_jsimp_to_string(js->imp, val));
 }
 
 static pdf_jsimp_obj *event_getTarget(void *jsctx, void *obj)
diff --git a/pdf/pdf_jsimp_cpp.c b/pdf/pdf_jsimp_cpp.c
index 5ac449ee..90f2a6e8 100644
--- a/pdf/pdf_jsimp_cpp.c
+++ b/pdf/pdf_jsimp_cpp.c
@@ -166,3 +166,52 @@ void pdf_jsimp_execute_count(pdf_jsimp *imp, char *code, int count)
 	if (err != NULL)
 		fz_throw(pdf_jsimp_ctx_cpp(imp), "%s", err);
 }
+pdf_jsimp_obj *pdf_jsimp_call_method(pdf_jsimp *imp, pdf_jsimp_method *meth, void *jsctx, void *obj, int argc, pdf_jsimp_obj *args[])
+{
+	fz_context *ctx = pdf_jsimp_ctx_cpp(imp);
+	pdf_jsimp_obj *res;
+
+	fz_try(ctx)
+	{
+		res = meth(jsctx, obj, argc, args);
+	}
+	fz_catch(ctx)
+	{
+		res = NULL;
+		fz_warn(ctx, "%s", ctx->error->message);
+	}
+
+	return res;
+}
+
+pdf_jsimp_obj *pdf_jsimp_call_getter(pdf_jsimp *imp, pdf_jsimp_getter *get, void *jsctx, void *obj)
+{
+	fz_context *ctx = pdf_jsimp_ctx_cpp(imp);
+	pdf_jsimp_obj *res;
+
+	fz_try(ctx)
+	{
+		res = get(jsctx, obj);
+	}
+	fz_catch(ctx)
+	{
+		res = NULL;
+		fz_warn(ctx, "%s", ctx->error->message);
+	}
+
+	return res;
+}
+
+void pdf_jsimp_call_setter(pdf_jsimp *imp, pdf_jsimp_setter *set, void *jsctx, void *obj, pdf_jsimp_obj *val)
+{
+	fz_context *ctx = pdf_jsimp_ctx_cpp(imp);
+
+	fz_try(ctx)
+	{
+		set(jsctx, obj, val);
+	}
+	fz_catch(ctx)
+	{
+		fz_warn(ctx, "%s", ctx->error->message);
+	}
+}
diff --git a/pdf/pdf_jsimp_cpp.h b/pdf/pdf_jsimp_cpp.h
index b794d02d..01b87edd 100644
--- a/pdf/pdf_jsimp_cpp.h
+++ b/pdf/pdf_jsimp_cpp.h
@@ -21,3 +21,9 @@ const char *pdf_jsimp_array_len_cpp(pdf_jsimp *imp, pdf_jsimp_obj *obj, int *len
 const char *pdf_jsimp_array_item_cpp(pdf_jsimp *imp, pdf_jsimp_obj *obj, int i, pdf_jsimp_obj **item);
 const char *pdf_jsimp_execute_cpp(pdf_jsimp *imp, char *code);
 const char *pdf_jsimp_execute_count_cpp(pdf_jsimp *imp, char *code, int count);
+
+/* Also when calling back into mupdf, all exceptions must be caught. The functions bellow
+ * wrap these calls */
+pdf_jsimp_obj *pdf_jsimp_call_method(pdf_jsimp *imp, pdf_jsimp_method *meth, void *jsctx, void *obj, int argc, pdf_jsimp_obj *args[]);
+pdf_jsimp_obj *pdf_jsimp_call_getter(pdf_jsimp *imp, pdf_jsimp_getter *get, void *jsctx, void *obj);
+void pdf_jsimp_call_setter(pdf_jsimp *imp, pdf_jsimp_setter *set, void *jsctx, void *obj, pdf_jsimp_obj *val);
diff --git a/pdf/pdf_jsimp_v8.cpp b/pdf/pdf_jsimp_v8.cpp
index 4e38a9b3..78a14eac 100644
--- a/pdf/pdf_jsimp_v8.cpp
+++ b/pdf/pdf_jsimp_v8.cpp
@@ -17,29 +17,29 @@ extern "C" {
 using namespace v8;
 using namespace std;
 
+struct PDFJSImp;
+
 /* Object we pass to FunctionTemplate::New, which v8 passes back to us in
  * callMethod, allowing us to call our client's, passed-in method. */
 struct PDFJSImpMethod
 {
-	void             *jsctx;
+	PDFJSImp *imp;
 	pdf_jsimp_method *meth;
 
-	PDFJSImpMethod(void *jsctx, pdf_jsimp_method *meth) : jsctx(jsctx), meth(meth) {}
+	PDFJSImpMethod(PDFJSImp *imp, pdf_jsimp_method *meth) : imp(imp), meth(meth) {}
 };
 
 /* Object we pass to ObjectTemplate::SetAccessor, which v8 passes back to us in
  * setProp and getProp, allowing us to call our client's, passed-in set/get methods. */
 struct PDFJSImpProperty
 {
-	void             *jsctx;
+	PDFJSImp *imp;
 	pdf_jsimp_getter *get;
 	pdf_jsimp_setter *set;
 
-	PDFJSImpProperty(void *jsctx, pdf_jsimp_getter *get, pdf_jsimp_setter *set) : jsctx(jsctx), get(get), set(set) {}
+	PDFJSImpProperty(PDFJSImp *imp, pdf_jsimp_getter *get, pdf_jsimp_setter *set) : imp(imp), get(get), set(set) {}
 };
 
-struct PDFJSImp;
-
 /* Internal representation of the pdf_jsimp_type object */
 struct PDFJSImpType
 {
@@ -239,7 +239,7 @@ static Handle<Value> callMethod(const Arguments &args)
 	for (int i = 0; i < c; i++)
 		native_args[i] = new PDFJSImpObject(args[i]);
 
-	PDFJSImpObject *obj = reinterpret_cast<PDFJSImpObject *>(m->meth(m->jsctx, nself, c, reinterpret_cast<pdf_jsimp_obj **>(native_args)));
+	PDFJSImpObject *obj = reinterpret_cast<PDFJSImpObject *>(pdf_jsimp_call_method(reinterpret_cast<pdf_jsimp *>(m->imp), m->meth, m->imp->jsctx, nself, c, reinterpret_cast<pdf_jsimp_obj **>(native_args)));
 	Handle<Value> val;
 	if (obj)
 		val = obj->toValue();
@@ -258,7 +258,7 @@ extern "C" const char *pdf_jsimp_addmethod_cpp(pdf_jsimp *imp, pdf_jsimp_type *t
 	PDFJSImpType *vType = reinterpret_cast<PDFJSImpType *>(type);
 	HandleScope scope;
 
-	PDFJSImpMethod *pmeth = new PDFJSImpMethod(vType->imp->jsctx, meth);
+	PDFJSImpMethod *pmeth = new PDFJSImpMethod(vType->imp, meth);
 	vType->templ->Set(String::New(name), FunctionTemplate::New(callMethod, External::New(pmeth)));
 	vType->methods.push_back(pmeth);
 	return NULL;
@@ -283,7 +283,7 @@ static Handle<Value> getProp(Local<String> property, const AccessorInfo &info)
 		}
 	}
 
-	PDFJSImpObject *obj = reinterpret_cast<PDFJSImpObject *>(p->get(p->jsctx, nself));
+	PDFJSImpObject *obj = reinterpret_cast<PDFJSImpObject *>(pdf_jsimp_call_getter(reinterpret_cast<pdf_jsimp *>(p->imp), p->get, p->imp->jsctx, nself));
 	Handle<Value> val;
 	if (obj)
 		val = obj->toValue();
@@ -308,7 +308,7 @@ static void setProp(Local<String> property, Local<Value> value, const AccessorIn
 
 	PDFJSImpObject *obj = new PDFJSImpObject(value);
 
-	p->set(p->jsctx, nself, reinterpret_cast<pdf_jsimp_obj *>(obj));
+	pdf_jsimp_call_setter(reinterpret_cast<pdf_jsimp *>(p->imp), p->set, p->imp->jsctx, nself, reinterpret_cast<pdf_jsimp_obj *>(obj));
 	delete obj;
 }
 
@@ -317,7 +317,7 @@ extern "C" const char *pdf_jsimp_addproperty_cpp(pdf_jsimp *imp, pdf_jsimp_type
 	PDFJSImpType *vType = reinterpret_cast<PDFJSImpType *>(type);
 	HandleScope scope;
 
-	PDFJSImpProperty *prop = new PDFJSImpProperty(vType->imp->jsctx, get, set);
+	PDFJSImpProperty *prop = new PDFJSImpProperty(vType->imp, get, set);
 	vType->templ->SetAccessor(String::New(name), getProp, setProp, External::New(prop));
 	vType->properties.push_back(prop);
 	return NULL;