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      1 //===- ObjectFile.h - File format independent object file -------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file declares a file format independent ObjectFile class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_OBJECT_OBJECT_FILE_H
     15 #define LLVM_OBJECT_OBJECT_FILE_H
     16 
     17 #include "llvm/Object/Binary.h"
     18 #include "llvm/ADT/StringRef.h"
     19 #include "llvm/Support/DataTypes.h"
     20 #include "llvm/Support/ErrorHandling.h"
     21 #include "llvm/Support/MemoryBuffer.h"
     22 #include <cstring>
     23 
     24 namespace llvm {
     25 namespace object {
     26 
     27 class ObjectFile;
     28 
     29 union DataRefImpl {
     30   struct {
     31     // ELF needs this for relocations. This entire union should probably be a
     32     // char[max(8, sizeof(uintptr_t))] and require the impl to cast.
     33     uint16_t a, b;
     34     uint32_t c;
     35   } w;
     36   struct {
     37     uint32_t a, b;
     38   } d;
     39   uintptr_t p;
     40 };
     41 
     42 template<class content_type>
     43 class content_iterator {
     44   content_type Current;
     45 public:
     46   content_iterator(content_type symb)
     47     : Current(symb) {}
     48 
     49   const content_type* operator->() const {
     50     return &Current;
     51   }
     52 
     53   const content_type &operator*() const {
     54     return Current;
     55   }
     56 
     57   bool operator==(const content_iterator &other) const {
     58     return Current == other.Current;
     59   }
     60 
     61   bool operator!=(const content_iterator &other) const {
     62     return !(*this == other);
     63   }
     64 
     65   content_iterator& increment(error_code &err) {
     66     content_type next;
     67     if (error_code ec = Current.getNext(next))
     68       err = ec;
     69     else
     70       Current = next;
     71     return *this;
     72   }
     73 };
     74 
     75 static bool operator ==(const DataRefImpl &a, const DataRefImpl &b) {
     76   // Check bitwise identical. This is the only legal way to compare a union w/o
     77   // knowing which member is in use.
     78   return std::memcmp(&a, &b, sizeof(DataRefImpl)) == 0;
     79 }
     80 
     81 class SymbolRef;
     82 
     83 /// RelocationRef - This is a value type class that represents a single
     84 /// relocation in the list of relocations in the object file.
     85 class RelocationRef {
     86   DataRefImpl RelocationPimpl;
     87   const ObjectFile *OwningObject;
     88 
     89 public:
     90   RelocationRef() : OwningObject(NULL) {
     91     std::memset(&RelocationPimpl, 0, sizeof(RelocationPimpl));
     92   }
     93 
     94   RelocationRef(DataRefImpl RelocationP, const ObjectFile *Owner);
     95 
     96   bool operator==(const RelocationRef &Other) const;
     97 
     98   error_code getNext(RelocationRef &Result) const;
     99 
    100   error_code getAddress(uint64_t &Result) const;
    101   error_code getSymbol(SymbolRef &Result) const;
    102   error_code getType(uint32_t &Result) const;
    103 
    104   /// @brief Get a string that represents the type of this relocation.
    105   ///
    106   /// This is for display purposes only.
    107   error_code getTypeName(SmallVectorImpl<char> &Result) const;
    108   error_code getAdditionalInfo(int64_t &Result) const;
    109 
    110   /// @brief Get a string that represents the calculation of the value of this
    111   ///        relocation.
    112   ///
    113   /// This is for display purposes only.
    114   error_code getValueString(SmallVectorImpl<char> &Result) const;
    115 };
    116 typedef content_iterator<RelocationRef> relocation_iterator;
    117 
    118 /// SectionRef - This is a value type class that represents a single section in
    119 /// the list of sections in the object file.
    120 class SectionRef {
    121   friend class SymbolRef;
    122   DataRefImpl SectionPimpl;
    123   const ObjectFile *OwningObject;
    124 
    125 public:
    126   SectionRef() : OwningObject(NULL) {
    127     std::memset(&SectionPimpl, 0, sizeof(SectionPimpl));
    128   }
    129 
    130   SectionRef(DataRefImpl SectionP, const ObjectFile *Owner);
    131 
    132   bool operator==(const SectionRef &Other) const;
    133 
    134   error_code getNext(SectionRef &Result) const;
    135 
    136   error_code getName(StringRef &Result) const;
    137   error_code getAddress(uint64_t &Result) const;
    138   error_code getSize(uint64_t &Result) const;
    139   error_code getContents(StringRef &Result) const;
    140 
    141   /// @brief Get the alignment of this section as the actual value (not log 2).
    142   error_code getAlignment(uint64_t &Result) const;
    143 
    144   // FIXME: Move to the normalization layer when it's created.
    145   error_code isText(bool &Result) const;
    146   error_code isData(bool &Result) const;
    147   error_code isBSS(bool &Result) const;
    148 
    149   error_code containsSymbol(SymbolRef S, bool &Result) const;
    150 
    151   relocation_iterator begin_relocations() const;
    152   relocation_iterator end_relocations() const;
    153 };
    154 typedef content_iterator<SectionRef> section_iterator;
    155 
    156 /// SymbolRef - This is a value type class that represents a single symbol in
    157 /// the list of symbols in the object file.
    158 class SymbolRef {
    159   friend class SectionRef;
    160   DataRefImpl SymbolPimpl;
    161   const ObjectFile *OwningObject;
    162 
    163 public:
    164   SymbolRef() : OwningObject(NULL) {
    165     std::memset(&SymbolPimpl, 0, sizeof(SymbolPimpl));
    166   }
    167 
    168   enum Type {
    169     ST_Data,
    170     ST_Debug,
    171     ST_External,    // Defined in another object file
    172     ST_File,
    173     ST_Function,
    174     ST_Other
    175   };
    176 
    177   SymbolRef(DataRefImpl SymbolP, const ObjectFile *Owner);
    178 
    179   bool operator==(const SymbolRef &Other) const;
    180 
    181   error_code getNext(SymbolRef &Result) const;
    182 
    183   error_code getName(StringRef &Result) const;
    184   error_code getAddress(uint64_t &Result) const;
    185   error_code getOffset(uint64_t &Result) const;
    186   error_code getSize(uint64_t &Result) const;
    187   error_code getType(SymbolRef::Type &Result) const;
    188 
    189   /// Returns the ascii char that should be displayed in a symbol table dump via
    190   /// nm for this symbol.
    191   error_code getNMTypeChar(char &Result) const;
    192 
    193   /// Returns true for symbols that are internal to the object file format such
    194   /// as section symbols.
    195   error_code isInternal(bool &Result) const;
    196 
    197   /// Returns true for symbols that can be used in another objects,
    198   /// such as library functions
    199   error_code isGlobal(bool &Result) const;
    200 
    201   /// Returns true for weak symbols.
    202   error_code isWeak(bool &Result) const;
    203 
    204   /// @brief Return true for absolute symbols.
    205   error_code isAbsolute(bool &Result) const;
    206 
    207   /// @brief Get section this symbol is defined in reference to. Result is
    208   /// end_sections() if it is undefined or is an absolute symbol.
    209   error_code getSection(section_iterator &Result) const;
    210 
    211   DataRefImpl getRawDataRefImpl() const;
    212 };
    213 typedef content_iterator<SymbolRef> symbol_iterator;
    214 
    215 const uint64_t UnknownAddressOrSize = ~0ULL;
    216 
    217 /// ObjectFile - This class is the base class for all object file types.
    218 /// Concrete instances of this object are created by createObjectFile, which
    219 /// figure out which type to create.
    220 class ObjectFile : public Binary {
    221 private:
    222   ObjectFile(); // = delete
    223   ObjectFile(const ObjectFile &other); // = delete
    224 
    225 protected:
    226   ObjectFile(unsigned int Type, MemoryBuffer *source, error_code &ec);
    227 
    228   const uint8_t *base() const {
    229     return reinterpret_cast<const uint8_t *>(Data->getBufferStart());
    230   }
    231 
    232   // These functions are for SymbolRef to call internally. The main goal of
    233   // this is to allow SymbolRef::SymbolPimpl to point directly to the symbol
    234   // entry in the memory mapped object file. SymbolPimpl cannot contain any
    235   // virtual functions because then it could not point into the memory mapped
    236   // file.
    237   //
    238   // Implementations assume that the DataRefImpl is valid and has not been
    239   // modified externally. It's UB otherwise.
    240   friend class SymbolRef;
    241   virtual error_code getSymbolNext(DataRefImpl Symb, SymbolRef &Res) const = 0;
    242   virtual error_code getSymbolName(DataRefImpl Symb, StringRef &Res) const = 0;
    243   virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const =0;
    244   virtual error_code getSymbolOffset(DataRefImpl Symb, uint64_t &Res) const =0;
    245   virtual error_code getSymbolSize(DataRefImpl Symb, uint64_t &Res) const = 0;
    246   virtual error_code getSymbolType(DataRefImpl Symb,
    247                                    SymbolRef::Type &Res) const = 0;
    248   virtual error_code getSymbolNMTypeChar(DataRefImpl Symb, char &Res) const = 0;
    249   virtual error_code isSymbolInternal(DataRefImpl Symb, bool &Res) const = 0;
    250   virtual error_code isSymbolGlobal(DataRefImpl Symb, bool &Res) const = 0;
    251   virtual error_code isSymbolWeak(DataRefImpl Symb, bool &Res) const = 0;
    252   virtual error_code isSymbolAbsolute(DataRefImpl Symb, bool &Res) const = 0;
    253   virtual error_code getSymbolSection(DataRefImpl Symb,
    254                                       section_iterator &Res) const = 0;
    255 
    256   // Same as above for SectionRef.
    257   friend class SectionRef;
    258   virtual error_code getSectionNext(DataRefImpl Sec, SectionRef &Res) const = 0;
    259   virtual error_code getSectionName(DataRefImpl Sec, StringRef &Res) const = 0;
    260   virtual error_code getSectionAddress(DataRefImpl Sec, uint64_t &Res) const =0;
    261   virtual error_code getSectionSize(DataRefImpl Sec, uint64_t &Res) const = 0;
    262   virtual error_code getSectionContents(DataRefImpl Sec, StringRef &Res)const=0;
    263   virtual error_code getSectionAlignment(DataRefImpl Sec, uint64_t &Res)const=0;
    264   virtual error_code isSectionText(DataRefImpl Sec, bool &Res) const = 0;
    265   virtual error_code isSectionData(DataRefImpl Sec, bool &Res) const = 0;
    266   virtual error_code isSectionBSS(DataRefImpl Sec, bool &Res) const = 0;
    267   virtual error_code sectionContainsSymbol(DataRefImpl Sec, DataRefImpl Symb,
    268                                            bool &Result) const = 0;
    269   virtual relocation_iterator getSectionRelBegin(DataRefImpl Sec) const = 0;
    270   virtual relocation_iterator getSectionRelEnd(DataRefImpl Sec) const = 0;
    271 
    272 
    273   // Same as above for RelocationRef.
    274   friend class RelocationRef;
    275   virtual error_code getRelocationNext(DataRefImpl Rel,
    276                                        RelocationRef &Res) const = 0;
    277   virtual error_code getRelocationAddress(DataRefImpl Rel,
    278                                           uint64_t &Res) const =0;
    279   virtual error_code getRelocationSymbol(DataRefImpl Rel,
    280                                          SymbolRef &Res) const = 0;
    281   virtual error_code getRelocationType(DataRefImpl Rel,
    282                                        uint32_t &Res) const = 0;
    283   virtual error_code getRelocationTypeName(DataRefImpl Rel,
    284                                        SmallVectorImpl<char> &Result) const = 0;
    285   virtual error_code getRelocationAdditionalInfo(DataRefImpl Rel,
    286                                                  int64_t &Res) const = 0;
    287   virtual error_code getRelocationValueString(DataRefImpl Rel,
    288                                        SmallVectorImpl<char> &Result) const = 0;
    289 
    290 public:
    291 
    292   virtual symbol_iterator begin_symbols() const = 0;
    293   virtual symbol_iterator end_symbols() const = 0;
    294 
    295   virtual section_iterator begin_sections() const = 0;
    296   virtual section_iterator end_sections() const = 0;
    297 
    298   /// @brief The number of bytes used to represent an address in this object
    299   ///        file format.
    300   virtual uint8_t getBytesInAddress() const = 0;
    301 
    302   virtual StringRef getFileFormatName() const = 0;
    303   virtual /* Triple::ArchType */ unsigned getArch() const = 0;
    304 
    305   /// @returns Pointer to ObjectFile subclass to handle this type of object.
    306   /// @param ObjectPath The path to the object file. ObjectPath.isObject must
    307   ///        return true.
    308   /// @brief Create ObjectFile from path.
    309   static ObjectFile *createObjectFile(StringRef ObjectPath);
    310   static ObjectFile *createObjectFile(MemoryBuffer *Object);
    311 
    312   static inline bool classof(const Binary *v) {
    313     return v->getType() >= isObject &&
    314            v->getType() < lastObject;
    315   }
    316   static inline bool classof(const ObjectFile *v) { return true; }
    317 
    318 public:
    319   static ObjectFile *createCOFFObjectFile(MemoryBuffer *Object);
    320   static ObjectFile *createELFObjectFile(MemoryBuffer *Object);
    321   static ObjectFile *createMachOObjectFile(MemoryBuffer *Object);
    322 };
    323 
    324 // Inline function definitions.
    325 inline SymbolRef::SymbolRef(DataRefImpl SymbolP, const ObjectFile *Owner)
    326   : SymbolPimpl(SymbolP)
    327   , OwningObject(Owner) {}
    328 
    329 inline bool SymbolRef::operator==(const SymbolRef &Other) const {
    330   return SymbolPimpl == Other.SymbolPimpl;
    331 }
    332 
    333 inline error_code SymbolRef::getNext(SymbolRef &Result) const {
    334   return OwningObject->getSymbolNext(SymbolPimpl, Result);
    335 }
    336 
    337 inline error_code SymbolRef::getName(StringRef &Result) const {
    338   return OwningObject->getSymbolName(SymbolPimpl, Result);
    339 }
    340 
    341 inline error_code SymbolRef::getAddress(uint64_t &Result) const {
    342   return OwningObject->getSymbolAddress(SymbolPimpl, Result);
    343 }
    344 
    345 inline error_code SymbolRef::getOffset(uint64_t &Result) const {
    346   return OwningObject->getSymbolOffset(SymbolPimpl, Result);
    347 }
    348 
    349 inline error_code SymbolRef::getSize(uint64_t &Result) const {
    350   return OwningObject->getSymbolSize(SymbolPimpl, Result);
    351 }
    352 
    353 inline error_code SymbolRef::getNMTypeChar(char &Result) const {
    354   return OwningObject->getSymbolNMTypeChar(SymbolPimpl, Result);
    355 }
    356 
    357 inline error_code SymbolRef::isInternal(bool &Result) const {
    358   return OwningObject->isSymbolInternal(SymbolPimpl, Result);
    359 }
    360 
    361 inline error_code SymbolRef::isGlobal(bool &Result) const {
    362   return OwningObject->isSymbolGlobal(SymbolPimpl, Result);
    363 }
    364 
    365 inline error_code SymbolRef::isWeak(bool &Result) const {
    366   return OwningObject->isSymbolWeak(SymbolPimpl, Result);
    367 }
    368 
    369 inline error_code SymbolRef::isAbsolute(bool &Result) const {
    370   return OwningObject->isSymbolAbsolute(SymbolPimpl, Result);
    371 }
    372 
    373 inline error_code SymbolRef::getSection(section_iterator &Result) const {
    374   return OwningObject->getSymbolSection(SymbolPimpl, Result);
    375 }
    376 
    377 inline error_code SymbolRef::getType(SymbolRef::Type &Result) const {
    378   return OwningObject->getSymbolType(SymbolPimpl, Result);
    379 }
    380 
    381 inline DataRefImpl SymbolRef::getRawDataRefImpl() const {
    382   return SymbolPimpl;
    383 }
    384 
    385 
    386 /// SectionRef
    387 inline SectionRef::SectionRef(DataRefImpl SectionP,
    388                               const ObjectFile *Owner)
    389   : SectionPimpl(SectionP)
    390   , OwningObject(Owner) {}
    391 
    392 inline bool SectionRef::operator==(const SectionRef &Other) const {
    393   return SectionPimpl == Other.SectionPimpl;
    394 }
    395 
    396 inline error_code SectionRef::getNext(SectionRef &Result) const {
    397   return OwningObject->getSectionNext(SectionPimpl, Result);
    398 }
    399 
    400 inline error_code SectionRef::getName(StringRef &Result) const {
    401   return OwningObject->getSectionName(SectionPimpl, Result);
    402 }
    403 
    404 inline error_code SectionRef::getAddress(uint64_t &Result) const {
    405   return OwningObject->getSectionAddress(SectionPimpl, Result);
    406 }
    407 
    408 inline error_code SectionRef::getSize(uint64_t &Result) const {
    409   return OwningObject->getSectionSize(SectionPimpl, Result);
    410 }
    411 
    412 inline error_code SectionRef::getContents(StringRef &Result) const {
    413   return OwningObject->getSectionContents(SectionPimpl, Result);
    414 }
    415 
    416 inline error_code SectionRef::getAlignment(uint64_t &Result) const {
    417   return OwningObject->getSectionAlignment(SectionPimpl, Result);
    418 }
    419 
    420 inline error_code SectionRef::isText(bool &Result) const {
    421   return OwningObject->isSectionText(SectionPimpl, Result);
    422 }
    423 
    424 inline error_code SectionRef::isData(bool &Result) const {
    425   return OwningObject->isSectionData(SectionPimpl, Result);
    426 }
    427 
    428 inline error_code SectionRef::isBSS(bool &Result) const {
    429   return OwningObject->isSectionBSS(SectionPimpl, Result);
    430 }
    431 
    432 inline error_code SectionRef::containsSymbol(SymbolRef S, bool &Result) const {
    433   return OwningObject->sectionContainsSymbol(SectionPimpl, S.SymbolPimpl,
    434                                              Result);
    435 }
    436 
    437 inline relocation_iterator SectionRef::begin_relocations() const {
    438   return OwningObject->getSectionRelBegin(SectionPimpl);
    439 }
    440 
    441 inline relocation_iterator SectionRef::end_relocations() const {
    442   return OwningObject->getSectionRelEnd(SectionPimpl);
    443 }
    444 
    445 
    446 /// RelocationRef
    447 inline RelocationRef::RelocationRef(DataRefImpl RelocationP,
    448                               const ObjectFile *Owner)
    449   : RelocationPimpl(RelocationP)
    450   , OwningObject(Owner) {}
    451 
    452 inline bool RelocationRef::operator==(const RelocationRef &Other) const {
    453   return RelocationPimpl == Other.RelocationPimpl;
    454 }
    455 
    456 inline error_code RelocationRef::getNext(RelocationRef &Result) const {
    457   return OwningObject->getRelocationNext(RelocationPimpl, Result);
    458 }
    459 
    460 inline error_code RelocationRef::getAddress(uint64_t &Result) const {
    461   return OwningObject->getRelocationAddress(RelocationPimpl, Result);
    462 }
    463 
    464 inline error_code RelocationRef::getSymbol(SymbolRef &Result) const {
    465   return OwningObject->getRelocationSymbol(RelocationPimpl, Result);
    466 }
    467 
    468 inline error_code RelocationRef::getType(uint32_t &Result) const {
    469   return OwningObject->getRelocationType(RelocationPimpl, Result);
    470 }
    471 
    472 inline error_code RelocationRef::getTypeName(SmallVectorImpl<char> &Result)
    473   const {
    474   return OwningObject->getRelocationTypeName(RelocationPimpl, Result);
    475 }
    476 
    477 inline error_code RelocationRef::getAdditionalInfo(int64_t &Result) const {
    478   return OwningObject->getRelocationAdditionalInfo(RelocationPimpl, Result);
    479 }
    480 
    481 inline error_code RelocationRef::getValueString(SmallVectorImpl<char> &Result)
    482   const {
    483   return OwningObject->getRelocationValueString(RelocationPimpl, Result);
    484 }
    485 
    486 } // end namespace object
    487 } // end namespace llvm
    488 
    489 #endif
    490