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      1 /* Copyright (C) 2007-2010 The Android Open Source Project
      2 **
      3 ** This software is licensed under the terms of the GNU General Public
      4 ** License version 2, as published by the Free Software Foundation, and
      5 ** may be copied, distributed, and modified under those terms.
      6 **
      7 ** This program is distributed in the hope that it will be useful,
      8 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
      9 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     10 ** GNU General Public License for more details.
     11 */
     12 
     13 /*
     14  * Contains declaration of a class ElfMappedSection, that encapsulates
     15  * a section of an ELF file, mapped to memory.
     16  */
     17 
     18 #ifndef ELFF_ELF_MAPPED_SECTION_H_
     19 #define ELFF_ELF_MAPPED_SECTION_H_
     20 
     21 #include "elf_defs.h"
     22 #include "mapfile.h"
     23 
     24 /* Encapsulates a section of an ELF file, mapped to memory. */
     25 class ElfMappedSection {
     26  public:
     27   /* Constructs ElfMappedSection instance. */
     28   ElfMappedSection();
     29 
     30   /* Destructs ElfMappedSection instance. */
     31   ~ElfMappedSection();
     32 
     33   /* Maps ELF file section to memory.
     34    * Param:
     35    *  handle - Handle to an opened ELF file.
     36    *  offset - Offset of the beginning of the section data in ELF file.
     37    *    NOTE: we explicitly use 64-bit type for this parameter, since we may
     38    *    still allow 32-bit library to process 64 bits ELF/DWARF formats. We
     39    *    really only care about section size being small enough to fit in 32
     40    *    bits value in this case (which seems to be always true for ELF files,
     41    *    as section size is encoded with 32-bit value even in 64-bit ELF file).
     42    *  size - Section byte size in ELF file.
     43    * Return:
     44    *  true on success, or false on failure, with errno providing extended
     45    *  error information.
     46    *  NOTE: if section has already been mapped, this method immediately
     47    *  returns with success.
     48    */
     49   bool map(MapFile* handle, Elf_Xword offset, Elf_Word size);
     50 
     51   /* Checks if section has been mapped. */
     52   bool is_mapped() const {
     53     return mapped_at_ != NULL;
     54   }
     55 
     56   /* Gets address of the beginning of the mapped section. */
     57   const void* data() const {
     58     assert(is_mapped());
     59     return data_;
     60   }
     61 
     62   /* Gets section size. */
     63   Elf_Word size() const {
     64     assert(is_mapped());
     65     return size_;
     66   }
     67 
     68   /* Checks if an address range is fully contained in this section. */
     69   bool is_contained(const void* ptr, size_t rsize) const {
     70     assert(is_mapped());
     71     return is_mapped() && is_in_section(ptr, rsize, data(), size());
     72   }
     73 
     74  protected:
     75   /* Beginning of the memory mapping, containing the section.
     76    * NOTE: due to page alignment requirements of the mapping API, mapping
     77    * address may differ from the address where the actual section data
     78    * starts inside that mapping.
     79    */
     80   void*         mapped_at_;
     81 
     82   /* Address of the beginning of the mapped section. */
     83   const void*   data_;
     84 
     85   /* Section size. */
     86   Elf_Word      size_;
     87 };
     88 
     89 #endif  // ELFF_ELF_MAPPED_SECTION_H_
     90