/*

* Copyright 2015 Google Inc. All rights reserved.

*

* 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.

*/

#include "flatbuffers/reflection.h"

#include "flatbuffers/util.h"

// Helper functionality for reflection.

namespace flatbuffers {

int64_t GetAnyValueI(reflection::BaseType type, const uint8_t *data) {

# define FLATBUFFERS_GET(T) static_cast<int64_t>(ReadScalar<T>(data))

switch (type) {

case reflection::UType:

case reflection::Bool:

case reflection::UByte: return FLATBUFFERS_GET(uint8_t);

case reflection::Byte: return FLATBUFFERS_GET(int8_t);

case reflection::Short: return FLATBUFFERS_GET(int16_t);

case reflection::UShort: return FLATBUFFERS_GET(uint16_t);

case reflection::Int: return FLATBUFFERS_GET(int32_t);

case reflection::UInt: return FLATBUFFERS_GET(uint32_t);

case reflection::Long: return FLATBUFFERS_GET(int64_t);

case reflection::ULong: return FLATBUFFERS_GET(uint64_t);

case reflection::Float: return FLATBUFFERS_GET(float);

case reflection::Double: return FLATBUFFERS_GET(double);

case reflection::String: {

auto s = reinterpret_cast<const String *>(ReadScalar<uoffset_t>(data) +

data);

return s ? StringToInt(s->c_str()) : 0;

}

default: return 0; // Tables & vectors do not make sense.

}

# undef FLATBUFFERS_GET

}

double GetAnyValueF(reflection::BaseType type, const uint8_t *data) {

switch (type) {

case reflection::Float: return static_cast<double>(ReadScalar<float>(data));

case reflection::Double: return ReadScalar<double>(data);

case reflection::String: {

auto s = reinterpret_cast<const String *>(ReadScalar<uoffset_t>(data) +

data);

return s ? strtod(s->c_str(), nullptr) : 0.0;

}

default: return static_cast<double>(GetAnyValueI(type, data));

}

}

std::string GetAnyValueS(reflection::BaseType type, const uint8_t *data,

const reflection::Schema *schema, int type_index) {

switch (type) {

case reflection::Float:

case reflection::Double: return NumToString(GetAnyValueF(type, data));

case reflection::String: {

auto s = reinterpret_cast<const String *>(ReadScalar<uoffset_t>(data) +

data);

return s ? s->c_str() : "";

}

case reflection::Obj:

if (schema) {

// Convert the table to a string. This is mostly for debugging purposes,

// and does NOT promise to be JSON compliant.

// Also prefixes the type.

auto &objectdef = *schema->objects()->Get(type_index);

auto s = objectdef.name()->str();

if (objectdef.is_struct()) {

s += "(struct)"; // TODO: implement this as well.

} else {

auto table_field = reinterpret_cast<const Table *>(

ReadScalar<uoffset_t>(data) + data);

s += " { ";

auto fielddefs = objectdef.fields();

for (auto it = fielddefs->begin(); it != fielddefs->end(); ++it) {

auto &fielddef = **it;

if (!table_field->CheckField(fielddef.offset())) continue;

auto val = GetAnyFieldS(*table_field, fielddef, schema);

if (fielddef.type()->base_type() == reflection::String)

val = "\"" + val + "\""; // Doesn't deal with escape codes etc.

s += fielddef.name()->str();

s += ": ";

s += val;

s += ", ";

}

s += "}";

}

return s;

} else {

return "(table)";

}

case reflection::Vector:

return "[(elements)]"; // TODO: implement this as well.

case reflection::Union:

return "(union)"; // TODO: implement this as well.

default: return NumToString(GetAnyValueI(type, data));

}

}

void SetAnyValueI(reflection::BaseType type, uint8_t *data, int64_t val) {

# define FLATBUFFERS_SET(T) WriteScalar(data, static_cast<T>(val))

switch (type) {

case reflection::UType:

case reflection::Bool:

case reflection::UByte: FLATBUFFERS_SET(uint8_t ); break;

case reflection::Byte: FLATBUFFERS_SET(int8_t ); break;

case reflection::Short: FLATBUFFERS_SET(int16_t ); break;

case reflection::UShort: FLATBUFFERS_SET(uint16_t); break;

case reflection::Int: FLATBUFFERS_SET(int32_t ); break;

case reflection::UInt: FLATBUFFERS_SET(uint32_t); break;

case reflection::Long: FLATBUFFERS_SET(int64_t ); break;

case reflection::ULong: FLATBUFFERS_SET(uint64_t); break;

case reflection::Float: FLATBUFFERS_SET(float ); break;

case reflection::Double: FLATBUFFERS_SET(double ); break;

// TODO: support strings

default: break;

}

# undef FLATBUFFERS_SET

}

void SetAnyValueF(reflection::BaseType type, uint8_t *data, double val) {

switch (type) {

case reflection::Float: WriteScalar(data, static_cast<float>(val)); break;

case reflection::Double: WriteScalar(data, val); break;

// TODO: support strings.

default: SetAnyValueI(type, data, static_cast<int64_t>(val)); break;

}

}

void SetAnyValueS(reflection::BaseType type, uint8_t *data, const char *val) {

switch (type) {

case reflection::Float:

case reflection::Double:

SetAnyValueF(type, data, strtod(val, nullptr));

break;

// TODO: support strings.

default: SetAnyValueI(type, data, StringToInt(val)); break;

}

}

// Resize a FlatBuffer in-place by iterating through all offsets in the buffer

// and adjusting them by "delta" if they straddle the start offset.

// Once that is done, bytes can now be inserted/deleted safely.

// "delta" may be negative (shrinking).

// Unless "delta" is a multiple of the largest alignment, you'll create a small

// amount of garbage space in the buffer (usually 0..7 bytes).

// If your FlatBuffer's root table is not the schema's root table, you should

// pass in your root_table type as well.

class ResizeContext {

public:

ResizeContext(const reflection::Schema &schema, uoffset_t start, int delta,

std::vector<uint8_t> *flatbuf,

const reflection::Object *root_table = nullptr)

: schema_(schema), startptr_(flatbuf->data() + start),

delta_(delta), buf_(*flatbuf),

dag_check_(flatbuf->size() / sizeof(uoffset_t), false) {

auto mask = static_cast<int>(sizeof(largest_scalar_t) - 1);

delta_ = (delta_ + mask) & ~mask;

if (!delta_) return; // We can't shrink by less than largest_scalar_t.

// Now change all the offsets by delta_.

auto root = GetAnyRoot(buf_.data());

Straddle<uoffset_t, 1>(buf_.data(), root, buf_.data());

ResizeTable(root_table ? *root_table : *schema.root_table(), root);

// We can now add or remove bytes at start.

if (delta_ > 0) buf_.insert(buf_.begin() + start, delta_, 0);

else buf_.erase(buf_.begin() + start, buf_.begin() + start - delta_);

}

// Check if the range between first (lower address) and second straddles

// the insertion point. If it does, change the offset at offsetloc (of

// type T, with direction D).

template<typename T, int D> void Straddle(void *first, void *second,

void *offsetloc) {

if (first <= startptr_ && second >= startptr_) {

WriteScalar<T>(offsetloc, ReadScalar<T>(offsetloc) + delta_ * D);

DagCheck(offsetloc) = true;

}

}

// This returns a boolean that records if the corresponding offset location

// has been modified already. If so, we can't even read the corresponding

// offset, since it is pointing to a location that is illegal until the

// resize actually happens.

// This must be checked for every offset, since we can't know which offsets

// will straddle and which won't.

uint8_t &DagCheck(void *offsetloc) {

auto dag_idx = reinterpret_cast<uoffset_t *>(offsetloc) -

reinterpret_cast<uoffset_t *>(buf_.data());

return dag_check_[dag_idx];

}

void ResizeTable(const reflection::Object &objectdef, Table *table) {

if (DagCheck(table))

return; // Table already visited.

auto vtable = table->GetVTable();

// Check if the vtable offset points beyond the insertion point.

Straddle<soffset_t, -1>(table, vtable, table);

// This direction shouldn't happen because vtables that sit before tables

// are always directly adjacent, but check just in case we ever change the

// way flatbuffers are built.

Straddle<soffset_t, -1>(vtable, table, table);

// Early out: since all fields inside the table must point forwards in

// memory, if the insertion point is before the table we can stop here.

auto tableloc = reinterpret_cast<uint8_t *>(table);

if (startptr_ <= tableloc) return;

// Check each field.

auto fielddefs = objectdef.fields();

for (auto it = fielddefs->begin(); it != fielddefs->end(); ++it) {

auto &fielddef = **it;

auto base_type = fielddef.type()->base_type();

// Ignore scalars.

if (base_type <= reflection::Double) continue;

// Ignore fields that are not stored.

auto offset = table->GetOptionalFieldOffset(fielddef.offset());

if (!offset) continue;

// Ignore structs.

auto subobjectdef = base_type == reflection::Obj ?

schema_.objects()->Get(fielddef.type()->index()) : nullptr;

if (subobjectdef && subobjectdef->is_struct()) continue;

// Get this fields' offset, and read it if safe.

auto offsetloc = tableloc + offset;

if (DagCheck(offsetloc))

continue; // This offset already visited.

auto ref = offsetloc + ReadScalar<uoffset_t>(offsetloc);

Straddle<uoffset_t, 1>(offsetloc, ref, offsetloc);

// Recurse.

switch (base_type) {

case reflection::Obj: {

ResizeTable(*subobjectdef, reinterpret_cast<Table *>(ref));

break;

}

case reflection::Vector: {

auto elem_type = fielddef.type()->element();

if (elem_type != reflection::Obj && elem_type != reflection::String)

break;

auto vec = reinterpret_cast<Vector<uoffset_t> *>(ref);

auto elemobjectdef = elem_type == reflection::Obj

? schema_.objects()->Get(fielddef.type()->index())

: nullptr;

if (elemobjectdef && elemobjectdef->is_struct()) break;

for (uoffset_t i = 0; i < vec->size(); i++) {

auto loc = vec->Data() + i * sizeof(uoffset_t);

if (DagCheck(loc))

continue; // This offset already visited.

auto dest = loc + vec->Get(i);

Straddle<uoffset_t, 1>(loc, dest ,loc);

if (elemobjectdef)

ResizeTable(*elemobjectdef, reinterpret_cast<Table *>(dest));

}

break;

}

case reflection::Union: {

ResizeTable(GetUnionType(schema_, objectdef, fielddef, *table),

reinterpret_cast<Table *>(ref));

break;

}

case reflection::String:

break;

default:

assert(false);

}

}

}

void operator=(const ResizeContext &rc);

private:

const reflection::Schema &schema_;

uint8_t *startptr_;

int delta_;

std::vector<uint8_t> &buf_;

std::vector<uint8_t> dag_check_;

};

void SetString(const reflection::Schema &schema, const std::string &val,

const String *str, std::vector<uint8_t> *flatbuf,

const reflection::Object *root_table) {

auto delta = static_cast<int>(val.size()) - static_cast<int>(str->Length());

auto str_start = static_cast<uoffset_t>(

reinterpret_cast<const uint8_t *>(str) - flatbuf->data());

auto start = str_start + static_cast<uoffset_t>(sizeof(uoffset_t));

if (delta) {

// Clear the old string, since we don't want parts of it remaining.

memset(flatbuf->data() + start, 0, str->Length());

// Different size, we must expand (or contract).

ResizeContext(schema, start, delta, flatbuf, root_table);

// Set the new length.

WriteScalar(flatbuf->data() + str_start,

static_cast<uoffset_t>(val.size()));

}

// Copy new data. Safe because we created the right amount of space.

memcpy(flatbuf->data() + start, val.c_str(), val.size() + 1);

}

uint8_t *ResizeAnyVector(const reflection::Schema &schema, uoffset_t newsize,

const VectorOfAny *vec, uoffset_t num_elems,

uoffset_t elem_size, std::vector<uint8_t> *flatbuf,

const reflection::Object *root_table) {

auto delta_elem = static_cast<int>(newsize) - static_cast<int>(num_elems);

auto delta_bytes = delta_elem * static_cast<int>(elem_size);

auto vec_start = reinterpret_cast<const uint8_t *>(vec) - flatbuf->data();

auto start = static_cast<uoffset_t>(vec_start + sizeof(uoffset_t) +

elem_size * num_elems);

if (delta_bytes) {

if (delta_elem < 0) {

// Clear elements we're throwing away, since some might remain in the

// buffer.

auto size_clear = -delta_elem * elem_size;

memset(flatbuf->data() + start - size_clear, 0, size_clear);

}

ResizeContext(schema, start, delta_bytes, flatbuf, root_table);

WriteScalar(flatbuf->data() + vec_start, newsize); // Length field.

// Set new elements to 0.. this can be overwritten by the caller.

if (delta_elem > 0) {

memset(flatbuf->data() + start, 0, delta_elem * elem_size);

}

}

return flatbuf->data() + start;

}

const uint8_t *AddFlatBuffer(std::vector<uint8_t> &flatbuf,

const uint8_t *newbuf, size_t newlen) {

// Align to sizeof(uoffset_t) past sizeof(largest_scalar_t) since we're

// going to chop off the root offset.

while ((flatbuf.size() & (sizeof(uoffset_t) - 1)) ||

!(flatbuf.size() & (sizeof(largest_scalar_t) - 1))) {

flatbuf.push_back(0);

}

auto insertion_point = static_cast<uoffset_t>(flatbuf.size());

// Insert the entire FlatBuffer minus the root pointer.

flatbuf.insert(flatbuf.end(), newbuf + sizeof(uoffset_t), newbuf + newlen);

auto root_offset = ReadScalar<uoffset_t>(newbuf) - sizeof(uoffset_t);

return flatbuf.data() + insertion_point + root_offset;

}

void CopyInline(FlatBufferBuilder &fbb, const reflection::Field &fielddef,

const Table &table, size_t align, size_t size) {

fbb.Align(align);

fbb.PushBytes(table.GetStruct<const uint8_t *>(fielddef.offset()), size);

fbb.TrackField(fielddef.offset(), fbb.GetSize());

}

Offset<const Table *> CopyTable(FlatBufferBuilder &fbb,

const reflection::Schema &schema,

const reflection::Object &objectdef,

const Table &table,

bool use_string_pooling) {

// Before we can construct the table, we have to first generate any

// subobjects, and collect their offsets.

std::vector<uoffset_t> offsets;

auto fielddefs = objectdef.fields();

for (auto it = fielddefs->begin(); it != fielddefs->end(); ++it) {

auto &fielddef = **it;

// Skip if field is not present in the source.

if (!table.CheckField(fielddef.offset())) continue;

uoffset_t offset = 0;

switch (fielddef.type()->base_type()) {

case reflection::String: {

offset = use_string_pooling

? fbb.CreateSharedString(GetFieldS(table, fielddef)).o

: fbb.CreateString(GetFieldS(table, fielddef)).o;

break;

}

case reflection::Obj: {

auto &subobjectdef = *schema.objects()->Get(fielddef.type()->index());

if (!subobjectdef.is_struct()) {

offset = CopyTable(fbb, schema, subobjectdef,

*GetFieldT(table, fielddef)).o;

}

break;

}

case reflection::Union: {

auto &subobjectdef = GetUnionType(schema, objectdef, fielddef, table);

offset = CopyTable(fbb, schema, subobjectdef,

*GetFieldT(table, fielddef)).o;

break;

}

case reflection::Vector: {

auto vec = table.GetPointer<const Vector<Offset<Table>> *>(

fielddef.offset());

auto element_base_type = fielddef.type()->element();

auto elemobjectdef = element_base_type == reflection::Obj

? schema.objects()->Get(fielddef.type()->index())

: nullptr;

switch (element_base_type) {

case reflection::String: {

std::vector<Offset<const String *>> elements(vec->size());

auto vec_s = reinterpret_cast<const Vector<Offset<String>> *>(vec);

for (uoffset_t i = 0; i < vec_s->size(); i++) {

elements[i] = use_string_pooling

? fbb.CreateSharedString(vec_s->Get(i)).o

: fbb.CreateString(vec_s->Get(i)).o;

}

offset = fbb.CreateVector(elements).o;

break;

}

case reflection::Obj: {

if (!elemobjectdef->is_struct()) {

std::vector<Offset<const Table *>> elements(vec->size());

for (uoffset_t i = 0; i < vec->size(); i++) {

elements[i] =

CopyTable(fbb, schema, *elemobjectdef, *vec->Get(i));

}

offset = fbb.CreateVector(elements).o;

break;

}

// FALL-THRU:

}

default: { // Scalars and structs.

auto element_size = GetTypeSize(element_base_type);

if (elemobjectdef && elemobjectdef->is_struct())

element_size = elemobjectdef->bytesize();

fbb.StartVector(element_size, vec->size());

fbb.PushBytes(vec->Data(), element_size * vec->size());

offset = fbb.EndVector(vec->size());

break;

}

}

break;

}

default: // Scalars.

break;

}

if (offset) {

offsets.push_back(offset);

}

}

// Now we can build the actual table from either offsets or scalar data.

auto start = objectdef.is_struct()

? fbb.StartStruct(objectdef.minalign())

: fbb.StartTable();

size_t offset_idx = 0;

for (auto it = fielddefs->begin(); it != fielddefs->end(); ++it) {

auto &fielddef = **it;

if (!table.CheckField(fielddef.offset())) continue;

auto base_type = fielddef.type()->base_type();

switch (base_type) {

case reflection::Obj: {

auto &subobjectdef = *schema.objects()->Get(fielddef.type()->index());

if (subobjectdef.is_struct()) {

CopyInline(fbb, fielddef, table, subobjectdef.minalign(),

subobjectdef.bytesize());

break;

}

// else: FALL-THRU:

}

case reflection::Union:

case reflection::String:

case reflection::Vector:

fbb.AddOffset(fielddef.offset(), Offset<void>(offsets[offset_idx++]));

break;

default: { // Scalars.

auto size = GetTypeSize(base_type);

CopyInline(fbb, fielddef, table, size, size);

break;

}

}

}

assert(offset_idx == offsets.size());

if (objectdef.is_struct()) {

fbb.ClearOffsets();

return fbb.EndStruct();

} else {

return fbb.EndTable(start, static_cast<voffset_t>(fielddefs->size()));

}

}

} // namespace flatbuffers