RhodeCode

#include <fstream>

#ifndef WIN32

#include <sys/time.h>

#include <ctime>

#include <sys/types.h>

#include <unistd.h>

#else

#include <windows.h>

#endif

    ///\name Initialization

    ///

    /// @{

    /// \brief Seeding from file or from process id and time

    ///

    /// By default, this function calls the \c seedFromFile() member

    /// function with the <tt>/dev/urandom</tt> file. If it is not success,

    /// it uses the \c seedFromTime().

    /// \return Currently always true.

    bool seed() {

#ifndef WIN32

      if (seedFromFile("/dev/urandom", 0)) return true;

#endif

      if (seedFromTime()) return true;

      return false;

    }

    /// \brief Seeding from file

    ///

    /// Seeding the random sequence from file. The linux kernel has two

    /// devices, <tt>/dev/random</tt> and <tt>/dev/urandom</tt> which

    /// could give good seed values for pseudo random generators (The

    /// difference between two devices is that the <tt>random</tt> may

    /// block the reading operation while the kernel can give good

    /// source of randomness, while the <tt>urandom</tt> does not

    /// block the input, but it could give back bytes with worse

    /// entropy).

    /// \param file The source file

    /// \param offset The offset, from the file read.

    /// \return True when the seeding is success.

#ifndef WIN32

    bool seedFromFile(const std::string& file = "/dev/urandom", int offset = 0) 

#else

    bool seedFromFile(const std::string& file = "", int offset = 0) 

#endif

    {

      std::ifstream rs(file.c_str());

      const int size = 4;

      Word buf[size];

      if (offset != 0 && !rs.seekg(offset)) return false;

      if (!rs.read(reinterpret_cast<char*>(buf), sizeof(buf))) return false;

      seed(buf, buf + size);

      return true;

    }

    /// \brief Seding from process id and time

    ///

    /// Seding from process id and time. This function uses the

    /// current process id and the current time for initialize the

    /// random sequence.

    /// \return Currently always true.

    bool seedFromTime() { 	

#ifndef WIN32

      timeval tv;

      gettimeofday(&tv, 0);

      seed(getpid() + tv.tv_sec + tv.tv_usec);

#else

      FILETIME time;

      GetSystemTimeAsFileTime(&time);

      seed(GetCurrentProcessId() + time.dwHighDateTime + time.dwLowDateTime);

#endif

      return true;

    }

    /// @}

    ///\name Uniform distributions

    ///

    /// @{

    /// @}