1b21067cf2
Previously when objcopy generated section headers, it padded the LEB that encodes the section size out to 5 bytes, matching the behavior of clang. This is correct, but results in a binary that differs from the input. This can sometimes have undesirable consequences (e.g. breaking source maps). This change makes the object reader remember the size of the LEB encoding in the section header, so that llvm-objcopy can reproduce it exactly. For sections not read from an object file (e.g. that llvm-objcopy is adding itself), pad to 5 bytes. Reviewed By: jhenderson Differential Revision: https://reviews.llvm.org/D155535
40 lines
1.4 KiB
C++
40 lines
1.4 KiB
C++
//===- WasmReader.cpp -----------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "WasmReader.h"
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namespace llvm {
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namespace objcopy {
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namespace wasm {
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using namespace object;
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using namespace llvm::wasm;
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Expected<std::unique_ptr<Object>> Reader::create() const {
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auto Obj = std::make_unique<Object>();
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Obj->Header = WasmObj.getHeader();
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std::vector<Section> Sections;
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Obj->Sections.reserve(WasmObj.getNumSections());
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for (const SectionRef &Sec : WasmObj.sections()) {
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const WasmSection &WS = WasmObj.getWasmSection(Sec);
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Obj->Sections.push_back({static_cast<uint8_t>(WS.Type),
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WS.HeaderSecSizeEncodingLen, WS.Name, WS.Content});
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// Give known sections standard names to allow them to be selected. (Custom
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// sections already have their names filled in by the parser).
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Section &ReaderSec = Obj->Sections.back();
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if (ReaderSec.SectionType > WASM_SEC_CUSTOM &&
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ReaderSec.SectionType <= WASM_SEC_LAST_KNOWN)
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ReaderSec.Name = sectionTypeToString(ReaderSec.SectionType);
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}
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return std::move(Obj);
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}
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} // end namespace wasm
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} // end namespace objcopy
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} // end namespace llvm
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