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Verifier computes the buffersize, useful for streaming 

Close #3898
This commit is contained in:
BogDan Vatra 2016-07-14 20:15:44 +03:00
parent 7a3f1cf78e
commit 4b53762cf2
2 changed files with 48 additions and 1 deletions
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31
include/flatbuffers/flatbuffers.h
View File

@ -1216,6 +1216,9 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
size_t _max_tables = 1000000)
: buf_(buf), end_(buf + buf_len), depth_(0), max_depth_(_max_depth),
num_tables_(0), max_tables_(_max_tables)
#ifdef FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
, upper_bound_(buf)
#endif
{}
// Central location where any verification failures register.
@ -1223,11 +1226,20 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
#ifdef FLATBUFFERS_DEBUG_VERIFICATION_FAILURE
assert(ok);
#endif
#ifdef FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
if (!ok)
upper_bound_ = buf_;
#endif
return ok;
}
// Verify any range within the buffer.
bool Verify(const void *elem, size_t elem_len) const {
#ifdef FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
auto upper_bound = reinterpret_cast<const uint8_t *>(elem) + elem_len;
if (upper_bound_ < upper_bound)
upper_bound_ = upper_bound;
#endif
return Check(elem_len <= (size_t) (end_ - buf_) &&
elem >= buf_ &&
elem <= end_ - elem_len);
@ -1306,7 +1318,11 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
// Call T::Verify, which must be in the generated code for this type.
return Verify<uoffset_t>(buf_) &&
reinterpret_cast<const T *>(buf_ + ReadScalar<uoffset_t>(buf_))->
Verify(*this);
Verify(*this)
#ifdef FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
&& GetComputedSize()
#endif
;
}
// Called at the start of a table to increase counters measuring data
@ -1325,6 +1341,16 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
return true;
}
#ifdef FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
// Returns the message size in bytes
size_t GetComputedSize() const {
uintptr_t size = upper_bound_ - buf_;
// Align the size to uoffset_t
size = (size - 1 + sizeof(uoffset_t)) & -uintptr_t(sizeof(uoffset_t));
return (buf_ + size > end_) ? 0 : size;
}
#endif
private:
const uint8_t *buf_;
const uint8_t *end_;
@ -1332,6 +1358,9 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
size_t max_depth_;
size_t num_tables_;
size_t max_tables_;
#ifdef FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
mutable const uint8_t *upper_bound_;
#endif
};
// Convenient way to bundle a buffer and its length, to pass it around

18
tests/test.cpp
View File

@ -15,6 +15,7 @@
*/
#define FLATBUFFERS_DEBUG_VERIFICATION_FAILURE 1
#define FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE
#include "flatbuffers/flatbuffers.h"
#include "flatbuffers/idl.h"
@ -160,6 +161,23 @@ void AccessFlatBufferTest(const uint8_t *flatbuf, size_t length) {
flatbuffers::Verifier verifier(flatbuf, length);
TEST_EQ(VerifyMonsterBuffer(verifier), true);
std::vector<uint8_t> test_buff;
test_buff.resize(length * 2);
std::memcpy(&test_buff[0], flatbuf , length);
std::memcpy(&test_buff[length], flatbuf , length);
flatbuffers::Verifier verifierl(&test_buff[0], length - 1);
TEST_EQ(VerifyMonsterBuffer(verifierl), false);
TEST_EQ(verifierl.GetComputedSize(), 0);
flatbuffers::Verifier verifier1(&test_buff[0], length);
TEST_EQ(VerifyMonsterBuffer(verifier1), true);
TEST_EQ(verifier1.GetComputedSize(), length);
flatbuffers::Verifier verifier2(&test_buff[length], length);
TEST_EQ(VerifyMonsterBuffer(verifier2), true);
TEST_EQ(verifier2.GetComputedSize(), length);
TEST_EQ(strcmp(MonsterIdentifier(), "MONS"), 0);
TEST_EQ(MonsterBufferHasIdentifier(flatbuf), true);
TEST_EQ(strcmp(MonsterExtension(), "mon"), 0);