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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_SYSTEM_H
      6 #define CRAZY_LINKER_SYSTEM_H
      7 
      8 #include <errno.h>
      9 #include <stdio.h>
     10 #include <stdlib.h>
     11 #include <sys/mman.h>
     12 #include <unistd.h>
     13 
     14 #include "crazy_linker_util.h"  // for String
     15 
     16 // System abstraction used by the crazy linker.
     17 // This is used to make unit testing easier without using tons of
     18 // dependency injection in the rest of the code base.
     19 //
     20 // In a nutshell: in a normal build, this will wrap normal open() / read()
     21 // calls. During unit testing, everything is mocked, see
     22 // crazy_linker_system_mock.cpp
     23 
     24 namespace crazy {
     25 
     26 enum FileOpenMode {
     27   FILE_OPEN_READ_ONLY = 0,
     28   FILE_OPEN_READ_WRITE,
     29   FILE_OPEN_WRITE
     30 };
     31 
     32 // Scoping file descriptor class.
     33 class FileDescriptor {
     34  public:
     35 #ifdef UNIT_TESTS
     36 #define kEmptyFD NULL
     37   typedef void* HandleType;
     38 #else
     39 #define kEmptyFD (-1)
     40   typedef int HandleType;
     41 #endif
     42 
     43   FileDescriptor() : fd_(kEmptyFD) {}
     44 
     45   FileDescriptor(const char* path) : fd_(kEmptyFD) { OpenReadOnly(path); }
     46 
     47   ~FileDescriptor() { Close(); }
     48 
     49   bool IsOk() const { return fd_ != kEmptyFD; }
     50   HandleType Get() const { return fd_; }
     51   bool OpenReadOnly(const char* path);
     52   bool OpenReadWrite(const char* path);
     53   int Read(void* buffer, size_t buffer_size);
     54   int SeekTo(off_t offset);
     55   void* Map(void* address,
     56             size_t length,
     57             int prot_flags,
     58             int flags,
     59             off_t offset);
     60   void Close();
     61 
     62  private:
     63   HandleType fd_;
     64 };
     65 
     66 // Returns true iff a given file path exists.
     67 bool PathExists(const char* path_name);
     68 
     69 // Returns true iff a given path is a regular file (or link to a regular
     70 // file).
     71 bool PathIsFile(const char* path_name);
     72 
     73 // Returns the current directory, as a string.
     74 String GetCurrentDirectory();
     75 
     76 // Returns the value of a given environment variable.
     77 const char* GetEnv(const char* var_name);
     78 
     79 // Returns true iff |lib_name| corresponds to one of the NDK-exposed
     80 // system libraries.
     81 bool IsSystemLibrary(const char* lib_name);
     82 
     83 }  // namespace crazy
     84 
     85 #endif  // CRAZY_LINKER_SYSTEM_H
     86