| 1 | //===- FuzzerExtFunctionsWeak.cpp - Interface to external functions -------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // Implementation for Linux. This relies on the linker's support for weak |
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| 9 | // symbols. We don't use this approach on Apple platforms because it requires |
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| 10 | // clients of LibFuzzer to pass ``-U _<symbol_name>`` to the linker to allow |
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| 11 | // weak symbols to be undefined. That is a complication we don't want to expose |
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| 12 | // to clients right now. |
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| 13 | //===----------------------------------------------------------------------===// |
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| 14 | #include "FuzzerPlatform.h" |
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| 15 | #if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FUCHSIA || \ |
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| 16 | LIBFUZZER_FREEBSD || LIBFUZZER_EMSCRIPTEN |
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| 17 | |
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| 18 | #include "FuzzerExtFunctions.h" |
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| 19 | #include "FuzzerIO.h" |
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| 20 | |
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| 21 | extern "C" { |
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| 22 | // Declare these symbols as weak to allow them to be optionally defined. |
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| 23 | #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ |
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| 24 | __attribute__((weak, visibility("default"))) RETURN_TYPE NAME FUNC_SIG |
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| 25 | |
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| 26 | #include "FuzzerExtFunctions.def" |
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| 27 | |
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| 28 | #undef EXT_FUNC |
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| 29 | } |
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| 30 | |
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| 31 | using namespace fuzzer; |
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| 32 | |
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| 33 | static void CheckFnPtr(void *FnPtr, const char *FnName, bool WarnIfMissing) { |
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| 34 | if (FnPtr == nullptr && WarnIfMissing) { |
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| 35 | Printf(Fmt: "WARNING: Failed to find function \"%s\".\n" , FnName); |
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| 36 | } |
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| 37 | } |
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| 38 | |
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| 39 | namespace fuzzer { |
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| 40 | |
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| 41 | ExternalFunctions::ExternalFunctions() { |
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| 42 | #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \ |
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| 43 | this->NAME = ::NAME; \ |
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| 44 | CheckFnPtr(reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(::NAME)), \ |
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| 45 | #NAME, WARN); |
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| 46 | |
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| 47 | #include "FuzzerExtFunctions.def" |
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| 48 | |
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| 49 | #undef EXT_FUNC |
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| 50 | } |
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| 51 | |
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| 52 | } // namespace fuzzer |
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| 53 | |
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| 54 | #endif |
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| 55 | |
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