Serialize and deserialize null (#783)

* Build (grpc's) nanopb with -DPB_FIELD_16BIT

We require (at least) 16 bit fields. (By default, nanopb uses 8 bit
fields, ie allowing up to 256 field tags.)

Also note that this patch adds this to grpc's nanopb, rather than to our
nanopb. We'll need to eventually either:
a) we instruct grpc to use our nanopb
b) we rely on grpc's nanopb instead of using our own.

(^ marked as a TODO for now.)

* Add some dependant protos

Imported from protobuf. Nanopb requires these to be present (though
anything using libprotobuf does not, as these are already built into
that.)

* Add generated nanopb protos based off of newly added proto definitions

* Build the nanopb protos

* Serialize and deserialize null

6 files changed, 433 insertions, 0 deletions

diff --git a/Firestore/Protos/nanopb/google/protobuf/any.pb.c b/Firestore/Protos/nanopb/google/protobuf/any.pb.c
new file mode 100644
index 0000000..b28d0ba
--- /dev/null
+++ b/Firestore/Protos/nanopb/google/protobuf/any.pb.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Automatically generated nanopb constant definitions */
+/* Generated by nanopb-0.3.8 at Mon Feb 12 11:03:06 2018. */
+
+#include "any.pb.h"
+
+/* @@protoc_insertion_point(includes) */
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+
+
+const pb_field_t google_protobuf_Any_fields[3] = {
+    PB_FIELD(  1, STRING  , SINGULAR, CALLBACK, FIRST, google_protobuf_Any, type_url, type_url, 0),
+    PB_FIELD(  2, BYTES   , SINGULAR, CALLBACK, OTHER, google_protobuf_Any, value, type_url, 0),
+    PB_LAST_FIELD
+};
+
+
+/* @@protoc_insertion_point(eof) */
diff --git a/Firestore/Protos/nanopb/google/protobuf/any.pb.h b/Firestore/Protos/nanopb/google/protobuf/any.pb.h
new file mode 100644
index 0000000..10a722e
--- /dev/null
+++ b/Firestore/Protos/nanopb/google/protobuf/any.pb.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Automatically generated nanopb header */
+/* Generated by nanopb-0.3.8 at Mon Feb 12 11:03:06 2018. */
+
+#ifndef PB_GOOGLE_PROTOBUF_ANY_PB_H_INCLUDED
+#define PB_GOOGLE_PROTOBUF_ANY_PB_H_INCLUDED
+#include <pb.h>
+
+/* @@protoc_insertion_point(includes) */
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Struct definitions */
+typedef struct _google_protobuf_Any {
+    pb_callback_t type_url;
+    pb_callback_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_Any) */
+} google_protobuf_Any;
+
+/* Default values for struct fields */
+
+/* Initializer values for message structs */
+#define google_protobuf_Any_init_default         {{{NULL}, NULL}, {{NULL}, NULL}}
+#define google_protobuf_Any_init_zero            {{{NULL}, NULL}, {{NULL}, NULL}}
+
+/* Field tags (for use in manual encoding/decoding) */
+#define google_protobuf_Any_type_url_tag         1
+#define google_protobuf_Any_value_tag            2
+
+/* Struct field encoding specification for nanopb */
+extern const pb_field_t google_protobuf_Any_fields[3];
+
+/* Maximum encoded size of messages (where known) */
+/* google_protobuf_Any_size depends on runtime parameters */
+
+/* Message IDs (where set with "msgid" option) */
+#ifdef PB_MSGID
+
+#define ANY_MESSAGES \
+
+
+#endif
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+/* @@protoc_insertion_point(eof) */
+
+#endif
diff --git a/Firestore/Protos/nanopb/google/protobuf/empty.pb.c b/Firestore/Protos/nanopb/google/protobuf/empty.pb.c
new file mode 100644
index 0000000..050af9c
--- /dev/null
+++ b/Firestore/Protos/nanopb/google/protobuf/empty.pb.c
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Automatically generated nanopb constant definitions */
+/* Generated by nanopb-0.3.8 at Mon Feb 12 11:03:06 2018. */
+
+#include "empty.pb.h"
+
+/* @@protoc_insertion_point(includes) */
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+
+
+const pb_field_t google_protobuf_Empty_fields[1] = {
+    PB_LAST_FIELD
+};
+
+
+/* @@protoc_insertion_point(eof) */
diff --git a/Firestore/Protos/nanopb/google/protobuf/empty.pb.h b/Firestore/Protos/nanopb/google/protobuf/empty.pb.h
new file mode 100644
index 0000000..466e1fd
--- /dev/null
+++ b/Firestore/Protos/nanopb/google/protobuf/empty.pb.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Automatically generated nanopb header */
+/* Generated by nanopb-0.3.8 at Mon Feb 12 11:03:06 2018. */
+
+#ifndef PB_GOOGLE_PROTOBUF_EMPTY_PB_H_INCLUDED
+#define PB_GOOGLE_PROTOBUF_EMPTY_PB_H_INCLUDED
+#include <pb.h>
+
+/* @@protoc_insertion_point(includes) */
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Struct definitions */
+typedef struct _google_protobuf_Empty {
+    char dummy_field;
+/* @@protoc_insertion_point(struct:google_protobuf_Empty) */
+} google_protobuf_Empty;
+
+/* Default values for struct fields */
+
+/* Initializer values for message structs */
+#define google_protobuf_Empty_init_default       {0}
+#define google_protobuf_Empty_init_zero          {0}
+
+/* Field tags (for use in manual encoding/decoding) */
+
+/* Struct field encoding specification for nanopb */
+extern const pb_field_t google_protobuf_Empty_fields[1];
+
+/* Maximum encoded size of messages (where known) */
+#define google_protobuf_Empty_size               0
+
+/* Message IDs (where set with "msgid" option) */
+#ifdef PB_MSGID
+
+#define EMPTY_MESSAGES \
+
+
+#endif
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+/* @@protoc_insertion_point(eof) */
+
+#endif
diff --git a/Firestore/Protos/nanopb/google/protobuf/wrappers.pb.c b/Firestore/Protos/nanopb/google/protobuf/wrappers.pb.c
new file mode 100644
index 0000000..41ab3c6
--- /dev/null
+++ b/Firestore/Protos/nanopb/google/protobuf/wrappers.pb.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Automatically generated nanopb constant definitions */
+/* Generated by nanopb-0.3.8 at Mon Feb 12 11:03:06 2018. */
+
+#include "wrappers.pb.h"
+
+/* @@protoc_insertion_point(includes) */
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+
+
+const pb_field_t google_protobuf_DoubleValue_fields[2] = {
+    PB_FIELD(  1, DOUBLE  , SINGULAR, STATIC  , FIRST, google_protobuf_DoubleValue, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_FloatValue_fields[2] = {
+    PB_FIELD(  1, FLOAT   , SINGULAR, STATIC  , FIRST, google_protobuf_FloatValue, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_Int64Value_fields[2] = {
+    PB_FIELD(  1, INT64   , SINGULAR, STATIC  , FIRST, google_protobuf_Int64Value, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_UInt64Value_fields[2] = {
+    PB_FIELD(  1, UINT64  , SINGULAR, STATIC  , FIRST, google_protobuf_UInt64Value, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_Int32Value_fields[2] = {
+    PB_FIELD(  1, INT32   , SINGULAR, STATIC  , FIRST, google_protobuf_Int32Value, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_UInt32Value_fields[2] = {
+    PB_FIELD(  1, UINT32  , SINGULAR, STATIC  , FIRST, google_protobuf_UInt32Value, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_BoolValue_fields[2] = {
+    PB_FIELD(  1, BOOL    , SINGULAR, STATIC  , FIRST, google_protobuf_BoolValue, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_StringValue_fields[2] = {
+    PB_FIELD(  1, STRING  , SINGULAR, CALLBACK, FIRST, google_protobuf_StringValue, value, value, 0),
+    PB_LAST_FIELD
+};
+
+const pb_field_t google_protobuf_BytesValue_fields[2] = {
+    PB_FIELD(  1, BYTES   , SINGULAR, CALLBACK, FIRST, google_protobuf_BytesValue, value, value, 0),
+    PB_LAST_FIELD
+};
+
+
+/* On some platforms (such as AVR), double is really float.
+ * These are not directly supported by nanopb, but see example_avr_double.
+ * To get rid of this error, remove any double fields from your .proto.
+ */
+PB_STATIC_ASSERT(sizeof(double) == 8, DOUBLE_MUST_BE_8_BYTES)
+
+/* @@protoc_insertion_point(eof) */
diff --git a/Firestore/Protos/nanopb/google/protobuf/wrappers.pb.h b/Firestore/Protos/nanopb/google/protobuf/wrappers.pb.h
new file mode 100644
index 0000000..0e98785
--- /dev/null
+++ b/Firestore/Protos/nanopb/google/protobuf/wrappers.pb.h
@@ -0,0 +1,147 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Automatically generated nanopb header */
+/* Generated by nanopb-0.3.8 at Mon Feb 12 11:03:06 2018. */
+
+#ifndef PB_GOOGLE_PROTOBUF_WRAPPERS_PB_H_INCLUDED
+#define PB_GOOGLE_PROTOBUF_WRAPPERS_PB_H_INCLUDED
+#include <pb.h>
+
+/* @@protoc_insertion_point(includes) */
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Struct definitions */
+typedef struct _google_protobuf_BytesValue {
+    pb_callback_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_BytesValue) */
+} google_protobuf_BytesValue;
+
+typedef struct _google_protobuf_StringValue {
+    pb_callback_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_StringValue) */
+} google_protobuf_StringValue;
+
+typedef struct _google_protobuf_BoolValue {
+    bool value;
+/* @@protoc_insertion_point(struct:google_protobuf_BoolValue) */
+} google_protobuf_BoolValue;
+
+typedef struct _google_protobuf_DoubleValue {
+    double value;
+/* @@protoc_insertion_point(struct:google_protobuf_DoubleValue) */
+} google_protobuf_DoubleValue;
+
+typedef struct _google_protobuf_FloatValue {
+    float value;
+/* @@protoc_insertion_point(struct:google_protobuf_FloatValue) */
+} google_protobuf_FloatValue;
+
+typedef struct _google_protobuf_Int32Value {
+    int32_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_Int32Value) */
+} google_protobuf_Int32Value;
+
+typedef struct _google_protobuf_Int64Value {
+    int64_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_Int64Value) */
+} google_protobuf_Int64Value;
+
+typedef struct _google_protobuf_UInt32Value {
+    uint32_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_UInt32Value) */
+} google_protobuf_UInt32Value;
+
+typedef struct _google_protobuf_UInt64Value {
+    uint64_t value;
+/* @@protoc_insertion_point(struct:google_protobuf_UInt64Value) */
+} google_protobuf_UInt64Value;
+
+/* Default values for struct fields */
+
+/* Initializer values for message structs */
+#define google_protobuf_DoubleValue_init_default {0}
+#define google_protobuf_FloatValue_init_default  {0}
+#define google_protobuf_Int64Value_init_default  {0}
+#define google_protobuf_UInt64Value_init_default {0}
+#define google_protobuf_Int32Value_init_default  {0}
+#define google_protobuf_UInt32Value_init_default {0}
+#define google_protobuf_BoolValue_init_default   {0}
+#define google_protobuf_StringValue_init_default {{{NULL}, NULL}}
+#define google_protobuf_BytesValue_init_default  {{{NULL}, NULL}}
+#define google_protobuf_DoubleValue_init_zero    {0}
+#define google_protobuf_FloatValue_init_zero     {0}
+#define google_protobuf_Int64Value_init_zero     {0}
+#define google_protobuf_UInt64Value_init_zero    {0}
+#define google_protobuf_Int32Value_init_zero     {0}
+#define google_protobuf_UInt32Value_init_zero    {0}
+#define google_protobuf_BoolValue_init_zero      {0}
+#define google_protobuf_StringValue_init_zero    {{{NULL}, NULL}}
+#define google_protobuf_BytesValue_init_zero     {{{NULL}, NULL}}
+
+/* Field tags (for use in manual encoding/decoding) */
+#define google_protobuf_BytesValue_value_tag     1
+#define google_protobuf_StringValue_value_tag    1
+#define google_protobuf_BoolValue_value_tag      1
+#define google_protobuf_DoubleValue_value_tag    1
+#define google_protobuf_FloatValue_value_tag     1
+#define google_protobuf_Int32Value_value_tag     1
+#define google_protobuf_Int64Value_value_tag     1
+#define google_protobuf_UInt32Value_value_tag    1
+#define google_protobuf_UInt64Value_value_tag    1
+
+/* Struct field encoding specification for nanopb */
+extern const pb_field_t google_protobuf_DoubleValue_fields[2];
+extern const pb_field_t google_protobuf_FloatValue_fields[2];
+extern const pb_field_t google_protobuf_Int64Value_fields[2];
+extern const pb_field_t google_protobuf_UInt64Value_fields[2];
+extern const pb_field_t google_protobuf_Int32Value_fields[2];
+extern const pb_field_t google_protobuf_UInt32Value_fields[2];
+extern const pb_field_t google_protobuf_BoolValue_fields[2];
+extern const pb_field_t google_protobuf_StringValue_fields[2];
+extern const pb_field_t google_protobuf_BytesValue_fields[2];
+
+/* Maximum encoded size of messages (where known) */
+#define google_protobuf_DoubleValue_size         9
+#define google_protobuf_FloatValue_size          5
+#define google_protobuf_Int64Value_size          11
+#define google_protobuf_UInt64Value_size         11
+#define google_protobuf_Int32Value_size          11
+#define google_protobuf_UInt32Value_size         6
+#define google_protobuf_BoolValue_size           2
+/* google_protobuf_StringValue_size depends on runtime parameters */
+/* google_protobuf_BytesValue_size depends on runtime parameters */
+
+/* Message IDs (where set with "msgid" option) */
+#ifdef PB_MSGID
+
+#define WRAPPERS_MESSAGES \
+
+
+#endif
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+/* @@protoc_insertion_point(eof) */
+
+#endif