src/sim/fd_array.hh

   1 /*
   2  * Copyright (c) 2016 Advanced Micro Devices, Inc.
   3  * All rights reserved.
   4  *
   5  * For use for simulation and test purposes only
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright notice,
  11  * this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright notice,
  14  * this list of conditions and the following disclaimer in the documentation
  15  * and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the copyright holder nor the names of its
  18  * contributors may be used to endorse or promote products derived from this
  19  * software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  22  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  25  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  *
  33  * Author: Brandon Potter
  34  */
  35
  36 #ifndef __FD_ARRAY_HH__
  37 #define __FD_ARRAY_HH__
  38
  39 #include <array>
  40 #include <memory>
  41 #include <string>
  42
  43 #include "sim/fd_entry.hh"
  44
  45 class FDArray
  46 {
  47   private:
  48     static const int NUM_FDS = 1024;
  49
  50   public:
  51     /**
  52      * Initialize the file descriptor array and set the standard file
  53      * descriptors to defaults or values passed in with the process
  54      * params.
  55      * @param input Used to initialize the stdin file descriptor
  56      * @param output Used to initialize the stdout file descriptor
  57      * @param errout Used to initialize the stderr file descriptor
  58      */
  59     FDArray(std::string const& input, std::string const& output,
  60             std::string const& errout);
  61
  62     std::string _input;
  63     std::string _output;
  64     std::string _errout;
  65
  66     /**
  67      * Figure out the file offsets for all currently open files and save them
  68      * the offsets during the calls to drain by the owning process.
  69      */
  70     void updateFileOffsets();
  71
  72     /**
  73      * Restore all offsets for currently open files during the unserialize
  74      * phase for the owning process class.
  75      */
  76     void restoreFileOffsets();
  77
  78     /**
  79      * Treat this object like a normal array in using the subscript operator
  80      * to pull entries out of it.
  81      * @param tgt_fd Use target file descriptors to index the array.
  82      */
  83     inline std::shared_ptr<FDEntry>
  84     operator[](int tgt_fd)
  85     {
  86         return getFDEntry(tgt_fd);
  87     }
  88
  89     /**
  90      * Step through the file descriptor array and find the first available
  91      * entry which is denoted as being free by being a 'nullptr'. That file
  92      * descriptor entry is the new target file descriptor entry that we
  93      * return as the return parameter.
  94      * @param fdp Allocated beforehand and passed into this method;
  95      * the fdp is meant to be a generic pointer capable of pointing to
  96      * different types of file descriptors. Must cast the pointer to the
  97      * correct type before dereferencing to access the needed fields.
  98      */
  99     int allocFD(std::shared_ptr<FDEntry> fdp);
 100
 101     /**
 102      * Return the size of the _fdArray field
 103      */
 104     int getSize() const { return _fdArray.size(); }
 105
 106     /**
 107      * Try to close the host file descriptor. If successful, set the
 108      * specified file descriptor entry object pointer to nullptr.
 109      * Used to "close" the target file descriptor.
 110      * @param tgt_fd Use target file descriptors to index the array.
 111      */
 112     int closeFDEntry(int tgt_fd);
 113
 114   private:
 115     /**
 116      * Help clarify our intention when opening files in the init and
 117      * restoration code. These are helper functions which are not meant to
 118      * be exposed to other objects or files.
 119      */
 120     int openFile(std::string const& file_name, int flags, mode_t mode) const;
 121     int openInputFile(std::string const& file_name) const;
 122     int openOutputFile(std::string const& file_name) const;
 123
 124     /**
 125      * Return the file descriptor entry object associated with the index
 126      * provided. (The index is protected with bounds checking on the array
 127      * size without the use of the array's at operator.)
 128      * @param tgt_fd Use target file descriptors to index the array.
 129      */
 130     std::shared_ptr<FDEntry> getFDEntry(int tgt_fd);
 131
 132     /**
 133      * Hold pointers to the file descriptor entries. The array size is
 134      * statically defined by the operating system.
 135      */
 136     std::array<std::shared_ptr<FDEntry>, NUM_FDS> _fdArray;
 137
 138     /**
 139      * Hold strings which represent the default values which are checked
 140      * against to initialize the standard file descriptors. If the string
 141      * provided doesn't hit against these maps, then a file is opened on the
 142      * host instead of using the host's standard file descriptors.
 143      */
 144     std::map<std::string, int> imap;
 145     std::map<std::string, int> oemap;
 146 };
 147
 148 #endif // __FD_ARRAY_HH__