C bindings: Implement _Validate(), and some pre-requisites

mojo/public/c/bindings/lib/message.c

Index: mojo/public/c/bindings/lib/message.c
diff --git a/mojo/public/c/bindings/lib/message.c b/mojo/public/c/bindings/lib/message.c
index 9b2d27dce004f9b4f9e8c5fad1d8d3e04c960e17..cceffb87cc45c0dd93850f9b990fb07c18fbac17 100644
--- a/mojo/public/c/bindings/lib/message.c
+++ b/mojo/public/c/bindings/lib/message.c
@@ -12,10 +12,10 @@ MojomValidationResult MojomMessage_ValidateHeader(const void* in_buf,
                                                   uint32_t in_buf_size) {
   const struct MojomStructHeader* header =
     (const struct MojomStructHeader*)in_buf;
+
   if (in_buf_size < sizeof(struct MojomStructHeader) ||

[viettrungluu, 2016/07/28 23:03:01]

For arrays, you return "illegal memory range" for the first check, but
"unexpected ... header" for the second. Should you do the same here? (Or should
you do there what you do here?)

[vardhan, 2016/07/29 21:29:21]

True -- this should be split up (but i guess the validation tests don't exercise
this enough)

neither :( there is an inconsistency here -- struct and message headers are this
way (since message headers are structs), but arrays are for some reason
different.  we should fix this later, I'll open up a bug for it

-      in_buf_size < header->num_bytes) {
-    return MOJOM_VALIDATION_UNEXPECTED_STRUCT_HEADER;
-  }
+      in_buf_size < header->num_bytes)
+    return MOJOM_VALIDATION_ILLEGAL_MEMORY_RANGE;
 
   const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
   if (header->version == 0u) {
@@ -47,3 +47,28 @@ MojomValidationResult MojomMessage_ValidateHeader(const void* in_buf,
   // Accept unknown versions of the message header to be future-proof.
   return MOJOM_VALIDATION_ERROR_NONE;
 }
+
+MojomValidationResult MojomMessage_ValidateRequestExpectingResponse(
+    const void* in_buf) {
+  const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
+  return (msg->flags & MOJOM_MESSAGE_FLAGS_EXPECTS_RESPONSE)
+             ? MOJOM_VALIDATION_ERROR_NONE
+             : MOJOM_VALIDATION_MESSAGE_HEADER_INVALID_FLAGS;
+}
+
+MojomValidationResult MojomMessage_ValidateRequestWithoutResponse(
+    const void* in_buf) {
+  const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
+  return !(msg->flags & MOJOM_MESSAGE_FLAGS_EXPECTS_RESPONSE) &&

[viettrungluu, 2016/07/28 23:03:01]

nit: I'd suggest always putting (...) around the entire condition when you're
using ?: (unless the condition is just one thing (like a single function call or
a single variable name).

[vardhan, 2016/07/29 21:29:21]

Done.

+                 !(msg->flags & MOJOM_MESSAGE_FLAGS_IS_RESPONSE)
+             ? MOJOM_VALIDATION_ERROR_NONE
+             : MOJOM_VALIDATION_MESSAGE_HEADER_INVALID_FLAGS;
+}
+
+MojomValidationResult MojomMessage_ValidateResponse(
+    const void* in_buf) {
+  const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
+  return msg->flags & MOJOM_MESSAGE_FLAGS_IS_RESPONSE

[viettrungluu, 2016/07/28 23:03:01]

"

[vardhan, 2016/07/29 21:29:21]

Done.

+             ? MOJOM_VALIDATION_ERROR_NONE
+             : MOJOM_VALIDATION_MESSAGE_HEADER_INVALID_FLAGS;
+}