01033dba23
this avoids e.g. on macOS:
In file included from abseil-cpp/absl/debugging/internal/elf_mem_image.cc:18:
abseil-cpp/absl/debugging/internal/elf_mem_image.h:37:5: error: 'ABSL_HAVE_ELF_MEM_IMAGE' is not defined, evaluates to 0 [-Werror,-Wundef]
^
1 error generated.
130 lines
4.5 KiB
C++
130 lines
4.5 KiB
C++
/*
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* Copyright 2017 The Abseil Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// Allow dynamic symbol lookup for in-memory Elf images.
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#ifndef ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
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#define ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
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// Including this will define the __GLIBC__ macro if glibc is being
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// used.
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#include <climits>
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// Maybe one day we can rewrite this file not to require the elf
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// symbol extensions in glibc, but for right now we need them.
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#ifdef ABSL_HAVE_ELF_MEM_IMAGE
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#error ABSL_HAVE_ELF_MEM_IMAGE cannot be directly set
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#endif
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#if defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) && \
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!defined(__asmjs__) && !defined(__wasm__)
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#define ABSL_HAVE_ELF_MEM_IMAGE 1
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#endif
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#ifdef ABSL_HAVE_ELF_MEM_IMAGE
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#include <link.h> // for ElfW
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namespace absl {
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namespace debugging_internal {
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// An in-memory ELF image (may not exist on disk).
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class ElfMemImage {
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private:
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// Sentinel: there could never be an elf image at &kInvalidBaseSentinel.
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static const int kInvalidBaseSentinel;
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public:
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// Sentinel: there could never be an elf image at this address.
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static constexpr const void *const kInvalidBase =
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static_cast<const void*>(&kInvalidBaseSentinel);
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// Information about a single vdso symbol.
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// All pointers are into .dynsym, .dynstr, or .text of the VDSO.
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// Do not free() them or modify through them.
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struct SymbolInfo {
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const char *name; // E.g. "__vdso_getcpu"
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const char *version; // E.g. "LINUX_2.6", could be ""
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// for unversioned symbol.
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const void *address; // Relocated symbol address.
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const ElfW(Sym) *symbol; // Symbol in the dynamic symbol table.
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};
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// Supports iteration over all dynamic symbols.
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class SymbolIterator {
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public:
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friend class ElfMemImage;
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const SymbolInfo *operator->() const;
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const SymbolInfo &operator*() const;
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SymbolIterator& operator++();
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bool operator!=(const SymbolIterator &rhs) const;
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bool operator==(const SymbolIterator &rhs) const;
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private:
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SymbolIterator(const void *const image, int index);
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void Update(int incr);
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SymbolInfo info_;
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int index_;
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const void *const image_;
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};
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explicit ElfMemImage(const void *base);
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void Init(const void *base);
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bool IsPresent() const { return ehdr_ != nullptr; }
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const ElfW(Phdr)* GetPhdr(int index) const;
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const ElfW(Sym)* GetDynsym(int index) const;
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const ElfW(Versym)* GetVersym(int index) const;
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const ElfW(Verdef)* GetVerdef(int index) const;
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const ElfW(Verdaux)* GetVerdefAux(const ElfW(Verdef) *verdef) const;
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const char* GetDynstr(ElfW(Word) offset) const;
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const void* GetSymAddr(const ElfW(Sym) *sym) const;
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const char* GetVerstr(ElfW(Word) offset) const;
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int GetNumSymbols() const;
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SymbolIterator begin() const;
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SymbolIterator end() const;
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// Look up versioned dynamic symbol in the image.
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// Returns false if image is not present, or doesn't contain given
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// symbol/version/type combination.
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// If info_out is non-null, additional details are filled in.
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bool LookupSymbol(const char *name, const char *version,
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int symbol_type, SymbolInfo *info_out) const;
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// Find info about symbol (if any) which overlaps given address.
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// Returns true if symbol was found; false if image isn't present
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// or doesn't have a symbol overlapping given address.
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// If info_out is non-null, additional details are filled in.
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bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
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private:
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const ElfW(Ehdr) *ehdr_;
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const ElfW(Sym) *dynsym_;
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const ElfW(Versym) *versym_;
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const ElfW(Verdef) *verdef_;
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const ElfW(Word) *hash_;
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const char *dynstr_;
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size_t strsize_;
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size_t verdefnum_;
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ElfW(Addr) link_base_; // Link-time base (p_vaddr of first PT_LOAD).
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};
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} // namespace debugging_internal
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} // namespace absl
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#endif // ABSL_HAVE_ELF_MEM_IMAGE
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#endif // ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
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