mozglue/linker/Mappable.h

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   3  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #ifndef Mappable_h
   6 #define Mappable_h
   7
   8 #include <optional>
   9 #include "mozilla/RefCounted.h"
  10 #include "Utils.h"
  11
  12 /**
  13  * Helper class to mmap plain files.
  14  */
  15 class Mappable : public mozilla::RefCounted<Mappable> {
  16  public:
  17   MOZ_DECLARE_REFCOUNTED_TYPENAME(Mappable)
  18   ~Mappable() {}
  19
  20   MemoryRange mmap(const void* addr, size_t length, int prot, int flags,
  21                    off_t offset);
  22
  23  private:
  24   void munmap(void* addr, size_t length) { ::munmap(addr, length); }
  25   /* Limit use of Mappable::munmap to classes that keep track of the address
  26    * and size of the mapping. This allows to ignore ::munmap return value. */
  27   friend class Mappable1stPagePtr;
  28   friend class LibHandle;
  29
  30  public:
  31   /**
  32    * Indicate to a Mappable instance that no further mmap is going to happen.
  33    */
  34   void finalize();
  35
  36   /**
  37    * Returns the maximum length that can be mapped from this Mappable for
  38    * offset = 0.
  39    */
  40   size_t GetLength() const;
  41
  42   /**
  43    * Create a Mappable instance for the given file path.
  44    */
  45   static Mappable* Create(const char* path);
  46
  47  protected:
  48   explicit Mappable(int fd) : fd(fd) {}
  49
  50  private:
  51   /* File descriptor */
  52   std::optional<AutoCloseFD> fd;
  53 };
  54
  55 #endif /* Mappable_h */