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Fix misalignment of small structs in a Vector (C++) (#7883)

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* Rare fix: kick fix test

* Rare fix: real fix

* Rare fix: separate test

* Rare fix: remove comments

* Rare fix: updates

* Rare fix: less

* Rare fix: size_t switch to uoffset_t

* Rare fix: swap exp/val

* Rare fix: add annotated before/after

* Rare fix: remove unnecessary changes

---------

Co-authored-by: Derek Bailey <derekbailey@google.com>
This commit is contained in:
Pavlo Bashmakov
2023-09-28 22:53:50 -07:00
committed by GitHub
parent 053d39adaf
commit 15f16f149e
8 changed files with 138 additions and 6 deletions
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47
tests/alignment_test.cpp
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@@ -2,6 +2,7 @@
#include "tests/alignment_test_generated.h"
#include "flatbuffers/flatbuffer_builder.h"
#include "flatbuffers/util.h"
#include "test_assert.h"
namespace flatbuffers {
@@ -24,7 +25,51 @@ void AlignmentTest() {
builder.Finish(root);
Verifier verifier(builder.GetBufferPointer(), builder.GetSize());
TEST_ASSERT(VerifyBadAlignmentRootBuffer(verifier));
TEST_ASSERT(verifier.VerifyBuffer<BadAlignmentRoot>(nullptr));
// ============= Test Small Structs Vector misalignment ========
builder.Clear();
// creating 5 structs with 2 bytes each
// 10 bytes in total for Vector data is needed
std::vector<JustSmallStruct> small_vector = {
{ 2, 1 }, { 3, 1 }, { 4, 1 }
};
// CreateVectorOfStructs is used in the generated CreateSmallStructsDirect()
// method, but we test it directly
Offset<Vector<const JustSmallStruct *>> small_structs_offset =
builder.CreateVectorOfStructs<JustSmallStruct>(small_vector);
Offset<SmallStructs> small_structs_root =
CreateSmallStructs(builder, small_structs_offset);
builder.Finish(small_structs_root);
// Save the binary that we later can annotate with `flatc --annotate` command
// NOTE: the conversion of the JSON data to --binary via `flatc --binary`
// command is not changed with that fix and was always producing the
// correct binary data.
// SaveFile("alignment_test_{before,after}_fix.bin",
// reinterpret_cast<char *>(builder.GetBufferPointer()),
// builder.GetSize(), true);
Verifier verifier_small_structs(builder.GetBufferPointer(),
builder.GetSize());
TEST_ASSERT(verifier_small_structs.VerifyBuffer<SmallStructs>(nullptr));
// Reading SmallStructs vector values back and compare with original
auto root_msg =
flatbuffers::GetRoot<SmallStructs>(builder.GetBufferPointer());
TEST_EQ(root_msg->small_structs()->size(), small_vector.size());
for (flatbuffers::uoffset_t i = 0; i < root_msg->small_structs()->size();
++i) {
TEST_EQ(small_vector[i].var_0(),
root_msg->small_structs()->Get(i)->var_0());
TEST_EQ(small_vector[i].var_1(),
root_msg->small_structs()->Get(i)->var_1());
}
}
} // namespace tests