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  1. //===- DWARFDataExtractor.h -------------------------------------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8.  
  9. #ifndef LLVM_DEBUGINFO_DWARF_DWARFDATAEXTRACTOR_H
  10. #define LLVM_DEBUGINFO_DWARF_DWARFDATAEXTRACTOR_H
  11.  
  12. #include "llvm/BinaryFormat/Dwarf.h"
  13. #include "llvm/DebugInfo/DWARF/DWARFSection.h"
  14. #include "llvm/Support/DataExtractor.h"
  15.  
  16. namespace llvm {
  17. class DWARFObject;
  18.  
  19. /// A DataExtractor (typically for an in-memory copy of an object-file section)
  20. /// plus a relocation map for that section, if there is one.
  21. class DWARFDataExtractor : public DataExtractor {
  22.   const DWARFObject *Obj = nullptr;
  23.   const DWARFSection *Section = nullptr;
  24.  
  25. public:
  26.   /// Constructor for the normal case of extracting data from a DWARF section.
  27.   /// The DWARFSection's lifetime must be at least as long as the extractor's.
  28.   DWARFDataExtractor(const DWARFObject &Obj, const DWARFSection &Section,
  29.                      bool IsLittleEndian, uint8_t AddressSize)
  30.       : DataExtractor(Section.Data, IsLittleEndian, AddressSize), Obj(&Obj),
  31.         Section(&Section) {}
  32.  
  33.   /// Constructor for cases when there are no relocations.
  34.   DWARFDataExtractor(StringRef Data, bool IsLittleEndian, uint8_t AddressSize)
  35.     : DataExtractor(Data, IsLittleEndian, AddressSize) {}
  36.   DWARFDataExtractor(ArrayRef<uint8_t> Data, bool IsLittleEndian,
  37.                      uint8_t AddressSize)
  38.       : DataExtractor(
  39.             StringRef(reinterpret_cast<const char *>(Data.data()), Data.size()),
  40.             IsLittleEndian, AddressSize) {}
  41.  
  42.   /// Truncating constructor
  43.   DWARFDataExtractor(const DWARFDataExtractor &Other, size_t Length)
  44.       : DataExtractor(Other.getData().substr(0, Length), Other.isLittleEndian(),
  45.                       Other.getAddressSize()),
  46.         Obj(Other.Obj), Section(Other.Section) {}
  47.  
  48.   /// Extracts the DWARF "initial length" field, which can either be a 32-bit
  49.   /// value smaller than 0xfffffff0, or the value 0xffffffff followed by a
  50.   /// 64-bit length. Returns the actual length, and the DWARF format which is
  51.   /// encoded in the field. In case of errors, it returns {0, DWARF32} and
  52.   /// leaves the offset unchanged.
  53.   std::pair<uint64_t, dwarf::DwarfFormat>
  54.   getInitialLength(uint64_t *Off, Error *Err = nullptr) const;
  55.  
  56.   std::pair<uint64_t, dwarf::DwarfFormat> getInitialLength(Cursor &C) const {
  57.     return getInitialLength(&getOffset(C), &getError(C));
  58.   }
  59.  
  60.   /// Extracts a value and applies a relocation to the result if
  61.   /// one exists for the given offset.
  62.   uint64_t getRelocatedValue(uint32_t Size, uint64_t *Off,
  63.                              uint64_t *SectionIndex = nullptr,
  64.                              Error *Err = nullptr) const;
  65.   uint64_t getRelocatedValue(Cursor &C, uint32_t Size,
  66.                              uint64_t *SectionIndex = nullptr) const {
  67.     return getRelocatedValue(Size, &getOffset(C), SectionIndex, &getError(C));
  68.   }
  69.  
  70.   /// Extracts an address-sized value and applies a relocation to the result if
  71.   /// one exists for the given offset.
  72.   uint64_t getRelocatedAddress(uint64_t *Off, uint64_t *SecIx = nullptr) const {
  73.     return getRelocatedValue(getAddressSize(), Off, SecIx);
  74.   }
  75.   uint64_t getRelocatedAddress(Cursor &C, uint64_t *SecIx = nullptr) const {
  76.     return getRelocatedValue(getAddressSize(), &getOffset(C), SecIx,
  77.                              &getError(C));
  78.   }
  79.  
  80.   /// Extracts a DWARF-encoded pointer in \p Offset using \p Encoding.
  81.   /// There is a DWARF encoding that uses a PC-relative adjustment.
  82.   /// For these values, \p AbsPosOffset is used to fix them, which should
  83.   /// reflect the absolute address of this pointer.
  84.   std::optional<uint64_t> getEncodedPointer(uint64_t *Offset, uint8_t Encoding,
  85.                                             uint64_t AbsPosOffset = 0) const;
  86. };
  87.  
  88. } // end namespace llvm
  89.  
  90. #endif // LLVM_DEBUGINFO_DWARF_DWARFDATAEXTRACTOR_H
  91.