[NaCl SDK] httpfs now sets errno to an appropriate value on non-200 response.

native_client_sdk/src/libraries/nacl_io/mount_node_http.cc

Index: native_client_sdk/src/libraries/nacl_io/mount_node_http.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/mount_node_http.cc b/native_client_sdk/src/libraries/nacl_io/mount_node_http.cc
index 5005ff48d30c292b81b345f80164497f10c55b49..29058d461d8539b194423d43e6854e500fe37ed0 100644
--- a/native_client_sdk/src/libraries/nacl_io/mount_node_http.cc
+++ b/native_client_sdk/src/libraries/nacl_io/mount_node_http.cc
@@ -27,6 +27,8 @@ namespace {
 const size_t MAX_READ_BUFFER_SIZE = 64 * 1024;
 const int32_t STATUSCODE_OK = 200;
 const int32_t STATUSCODE_PARTIAL_CONTENT = 206;
+const int32_t STATUSCODE_FORBIDDEN = 403;
+const int32_t STATUSCODE_NOT_FOUND = 404;
 
 StringMap_t ParseHeaders(const char* headers, int32_t headers_length) {
   enum State {
@@ -124,6 +126,22 @@ bool ParseContentRange(const StringMap_t& headers,
   return false;
 }
 
+// Maps an HTTP |status_code| onto the appropriate errno code.
+int HTTPStatusCodeToErrno(int status_code) {
+  switch (status_code) {
+    case STATUSCODE_OK:
+    case STATUSCODE_PARTIAL_CONTENT:
+      return 0;
+    case STATUSCODE_FORBIDDEN:
+      return EACCES;
+    case STATUSCODE_NOT_FOUND:
+      return ENOENT;
+  }
+  if (status_code >= 400 && status_code < 500)
+    return EINVAL;
+  return EIO;
+}
+
 }  // namespace
 
 void MountNodeHttp::SetCachedSize(off_t size) {
@@ -298,10 +316,9 @@ Error MountNodeHttp::OpenUrl(const char* method,
   *out_statuscode = statuscode.value.as_int;
 
   // Only accept OK or Partial Content.
-  if (*out_statuscode != STATUSCODE_OK &&
-      *out_statuscode != STATUSCODE_PARTIAL_CONTENT) {
-    return EINVAL;
-  }
+  Error error = HTTPStatusCodeToErrno(*out_statuscode);
+  if (error)
+    return error;
 
   // Get response headers.
   PP_Var response_headers_var = response_interface->GetProperty(