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+/*
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+ * llvm C frontend for perf. Support dynamically compile C file
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+ *
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+ * Inspired by clang example code:
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+ * http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
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+ *
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+ * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
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+ * Copyright (C) 2016 Huawei Inc.
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+ */
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+
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+#include "clang/CodeGen/CodeGenAction.h"
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+#include "clang/Frontend/CompilerInvocation.h"
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+#include "clang/Frontend/CompilerInstance.h"
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+#include "clang/Frontend/TextDiagnosticPrinter.h"
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+#include "clang/Tooling/Tooling.h"
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+#include "llvm/IR/LegacyPassManager.h"
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+#include "llvm/IR/Module.h"
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+#include "llvm/Option/Option.h"
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+#include "llvm/Support/FileSystem.h"
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+#include "llvm/Support/ManagedStatic.h"
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+#include "llvm/Support/TargetRegistry.h"
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+#include "llvm/Support/TargetSelect.h"
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+#include "llvm/Target/TargetMachine.h"
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+#include "llvm/Target/TargetOptions.h"
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+#include <memory>
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+
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+#include "clang.h"
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+#include "clang-c.h"
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+
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+namespace perf {
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+
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+static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
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+
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+using namespace clang;
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+
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+static CompilerInvocation *
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+createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
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+ DiagnosticsEngine& Diags)
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+{
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+ llvm::opt::ArgStringList CCArgs {
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+ "-cc1",
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+ "-triple", "bpf-pc-linux",
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+ "-fsyntax-only",
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+ "-ferror-limit", "19",
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+ "-fmessage-length", "127",
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+ "-O2",
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+ "-nostdsysteminc",
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+ "-nobuiltininc",
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+ "-vectorize-loops",
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+ "-vectorize-slp",
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+ "-Wno-unused-value",
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+ "-Wno-pointer-sign",
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+ "-x", "c"};
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+
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+ CCArgs.append(CFlags.begin(), CFlags.end());
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+ CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
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+
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+ FrontendOptions& Opts = CI->getFrontendOpts();
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+ Opts.Inputs.clear();
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+ Opts.Inputs.emplace_back(Path, IK_C);
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+ return CI;
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+}
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+
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+static std::unique_ptr<llvm::Module>
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+getModuleFromSource(llvm::opt::ArgStringList CFlags,
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+ StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
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+{
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+ CompilerInstance Clang;
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+ Clang.createDiagnostics();
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+
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+ Clang.setVirtualFileSystem(&*VFS);
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+
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+ IntrusiveRefCntPtr<CompilerInvocation> CI =
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+ createCompilerInvocation(std::move(CFlags), Path,
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+ Clang.getDiagnostics());
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+ Clang.setInvocation(&*CI);
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+
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+ std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
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+ if (!Clang.ExecuteAction(*Act))
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+ return std::unique_ptr<llvm::Module>(nullptr);
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+
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+ return Act->takeModule();
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+}
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+
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+std::unique_ptr<llvm::Module>
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+getModuleFromSource(llvm::opt::ArgStringList CFlags,
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+ StringRef Name, StringRef Content)
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+{
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+ using namespace vfs;
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+
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+ llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
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+ new OverlayFileSystem(getRealFileSystem()));
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+ llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
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+ new InMemoryFileSystem(true));
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+
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+ /*
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+ * pushOverlay helps setting working dir for MemFS. Must call
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+ * before addFile.
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+ */
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+ OverlayFS->pushOverlay(MemFS);
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+ MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
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+
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+ return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
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+}
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+
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+std::unique_ptr<llvm::Module>
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+getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
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+{
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+ IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
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+ return getModuleFromSource(std::move(CFlags), Path, VFS);
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+}
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+
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+std::unique_ptr<llvm::SmallVectorImpl<char>>
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+getBPFObjectFromModule(llvm::Module *Module)
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+{
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+ using namespace llvm;
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+
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+ std::string TargetTriple("bpf-pc-linux");
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+ std::string Error;
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+ const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
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+ if (!Target) {
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+ llvm::errs() << Error;
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+ return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
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+ }
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+
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+ llvm::TargetOptions Opt;
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+ TargetMachine *TargetMachine =
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+ Target->createTargetMachine(TargetTriple,
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+ "generic", "",
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+ Opt, Reloc::Static);
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+
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+ Module->setDataLayout(TargetMachine->createDataLayout());
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+ Module->setTargetTriple(TargetTriple);
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+
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+ std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
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+ raw_svector_ostream ostream(*Buffer);
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+
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+ legacy::PassManager PM;
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+ if (TargetMachine->addPassesToEmitFile(PM, ostream,
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+ TargetMachine::CGFT_ObjectFile)) {
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+ llvm::errs() << "TargetMachine can't emit a file of this type\n";
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+ return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);;
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+ }
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+ PM.run(*Module);
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+
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+ return std::move(Buffer);
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+}
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+
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+}
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+
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+extern "C" {
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+void perf_clang__init(void)
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+{
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+ perf::LLVMCtx.reset(new llvm::LLVMContext());
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+ LLVMInitializeBPFTargetInfo();
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+ LLVMInitializeBPFTarget();
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+ LLVMInitializeBPFTargetMC();
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+ LLVMInitializeBPFAsmPrinter();
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+}
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+
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+void perf_clang__cleanup(void)
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+{
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+ perf::LLVMCtx.reset(nullptr);
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+ llvm::llvm_shutdown();
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+}
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+
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+int perf_clang__compile_bpf(const char *filename,
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+ void **p_obj_buf,
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+ size_t *p_obj_buf_sz)
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+{
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+ using namespace perf;
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+
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+ if (!p_obj_buf || !p_obj_buf_sz)
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+ return -EINVAL;
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+
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+ llvm::opt::ArgStringList CFlags;
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+ auto M = getModuleFromSource(std::move(CFlags), filename);
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+ if (!M)
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+ return -EINVAL;
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+ auto O = getBPFObjectFromModule(&*M);
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+ if (!O)
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+ return -EINVAL;
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+
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+ size_t size = O->size_in_bytes();
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+ void *buffer;
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+
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+ buffer = malloc(size);
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+ if (!buffer)
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+ return -ENOMEM;
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+ memcpy(buffer, O->data(), size);
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+ *p_obj_buf = buffer;
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+ *p_obj_buf_sz = size;
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+ return 0;
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+}
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+}
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