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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CRAZY_LINKER_PROC_MAPS_H
      6 #define CRAZY_LINKER_PROC_MAPS_H
      7 
      8 // Helper classes and functions to extract useful information out of
      9 // /proc/self/maps.
     10 
     11 #include <stdint.h>
     12 #include <sys/mman.h>  // for PROT_READ etc...
     13 
     14 namespace crazy {
     15 
     16 class ProcMapsInternal;
     17 
     18 class ProcMaps {
     19  public:
     20   // Used to open /proc/self/maps.
     21   // There is no error reporting. If the file can't be opened, then
     22   // GetNextEntry() will return false on the first call.
     23   ProcMaps();
     24 
     25   // Used to open /proc/$PID/maps.
     26   // There is also no error reporting.
     27   explicit ProcMaps(pid_t pid);
     28 
     29   ~ProcMaps();
     30 
     31   // Small structure to model an entry.
     32   struct Entry {
     33     size_t vma_start;
     34     size_t vma_end;
     35     int prot_flags;
     36     size_t load_offset;
     37     const char* path;  // can be NULL, not always zero-terminated.
     38     size_t path_len;   // 0 if |path| is NULL.
     39   };
     40 
     41   void Rewind();
     42 
     43   // Get next entry in maps, return NULL on failure.
     44   // On success, return true and set |entry| to valid values.
     45   // Note that the |entry->path| field can be NULL or will point to
     46   // an address which content may change on the next call to this method.
     47   bool GetNextEntry(Entry* entry);
     48 
     49   int GetProtectionFlagsForAddress(void* address);
     50 
     51  private:
     52   ProcMapsInternal* internal_;
     53 };
     54 
     55 // Find which loaded ELF binary contains |address|.
     56 // On success, returns true and sets |*load_address| to its load address,
     57 // and fills |path_buffer| with the path to the corresponding file.
     58 bool FindElfBinaryForAddress(void* address,
     59                              uintptr_t* load_address,
     60                              char* path_buffer,
     61                              size_t path_buffer_len);
     62 
     63 // Returns the current protection bit flags for the page holding a given
     64 // |address|. On success, returns true and sets |*prot_flags|.
     65 bool FindProtectionFlagsForAddress(void* address, int* prot_flags);
     66 
     67 // Return the load address of a given ELF binary.
     68 // If |file_name| contains a slash, this will try to perform an
     69 // exact match with the content of /proc/self/maps. Otherwise,
     70 // it will be taken as a base name, and the load address of the first
     71 // matching entry will be returned.
     72 // On success, returns true and sets |*load_address| to the load address,
     73 // and |*load_offset| to the load offset.
     74 bool FindLoadAddressForFile(const char* file_name,
     75                             uintptr_t* load_address,
     76                             uintptr_t* load_offset);
     77 
     78 }  // namespace crazy
     79 
     80 #endif  // CRAZY_LINKER_PROC_MAPS_H
     81