external_libraries/boost/libs/filesystem/v3/src/unique_path.cpp

   1 //  filesystem system_crypt_random.cpp  ------------------------------------------------//
   2
   3 //  Copyright Beman Dawes 2010
   4
   5 //  Distributed under the Boost Software License, Version 1.0.
   6 //  See http://www.boost.org/LICENSE_1_0.txt
   7
   8 //  Library home page: http://www.boost.org/libs/filesystem
   9
  10 //--------------------------------------------------------------------------------------//
  11
  12 #include <boost/config.hpp>
  13 #if !defined( BOOST_NO_STD_WSTRING )
  14 // Boost.Filesystem V3 and later requires std::wstring support.
  15 // During the transition to V3, libraries are compiled with both V2 and V3 sources.
  16 // On old compilers that don't support V3 anyhow, we just skip everything so the compile
  17 // will succeed and the library can be built.
  18
  19 // define BOOST_FILESYSTEM_SOURCE so that <boost/filesystem/config.hpp> knows
  20 // the library is being built (possibly exporting rather than importing code)
  21 #define BOOST_FILESYSTEM_SOURCE
  22
  23 #ifndef BOOST_SYSTEM_NO_DEPRECATED
  24 # define BOOST_SYSTEM_NO_DEPRECATED
  25 #endif
  26
  27 #include <boost/filesystem/v3/operations.hpp>
  28
  29 # ifdef BOOST_POSIX_API
  30 #   include <fcntl.h>
  31 # else // BOOST_WINDOWS_API
  32 #   include <windows.h>
  33 #   include <wincrypt.h>
  34 #   pragma comment(lib, "Advapi32.lib")
  35 # endif
  36
  37 namespace {
  38
  39 void fail(int err, boost::system::error_code* ec)
  40 {
  41   if (ec == 0)
  42     BOOST_FILESYSTEM_THROW( boost::system::system_error(err,
  43       boost::system::system_category(),
  44       "boost::filesystem::unique_path"));
  45
  46   ec->assign(err, boost::system::system_category());
  47   return;
  48 }
  49
  50 void system_crypt_random(void* buf, std::size_t len, boost::system::error_code* ec)
  51 {
  52 # ifdef BOOST_POSIX_API
  53
  54   int file = open("/dev/urandom", O_RDONLY);
  55   if (file == -1)
  56   {
  57     file = open("/dev/random", O_RDONLY);
  58     if (file == -1)
  59     {
  60       fail(errno, ec);
  61       return;
  62     }
  63   }
  64
  65   size_t bytes_read = 0;
  66   while (bytes_read < len)
  67   {
  68     ssize_t n = read(file, buf, len - bytes_read);
  69     if (n == -1)
  70     {
  71       close(file);
  72       fail(errno, ec);
  73       return;
  74     }
  75     bytes_read += n;
  76     buf = static_cast<char*>(buf) + n;
  77   }
  78
  79   close(file);
  80
  81 # else // BOOST_WINDOWS_API
  82
  83   HCRYPTPROV handle;
  84   int errval = 0;
  85
  86   if (!::CryptAcquireContextW(&handle, 0, 0, PROV_RSA_FULL, 0))
  87   {
  88     errval = ::GetLastError();
  89     if (errval == NTE_BAD_KEYSET)
  90     {
  91       if (!::CryptAcquireContextW(&handle, 0, 0, PROV_RSA_FULL, CRYPT_NEWKEYSET))
  92       {
  93         errval = ::GetLastError();
  94       }
  95       else errval = 0;
  96     }
  97   }
  98
  99   if (!errval)
 100   {
 101     BOOL gen_ok = ::CryptGenRandom(handle, len, static_cast<unsigned char*>(buf));
 102     if (!gen_ok)
 103       errval = ::GetLastError();
 104     ::CryptReleaseContext(handle, 0);
 105   }
 106
 107   if (!errval) return;
 108
 109   fail(errval, ec);
 110 # endif
 111 }
 112
 113 }  // unnamed namespace
 114
 115 namespace boost { namespace filesystem3 { namespace detail {
 116
 117 BOOST_FILESYSTEM_DECL
 118 path unique_path(const path& model, system::error_code* ec)
 119 {
 120   std::wstring s (model.wstring());  // std::string ng for MBCS encoded POSIX
 121   const wchar_t hex[] = L"0123456789abcdef";
 122   const int n_ran = 16;
 123   const int max_nibbles = 2 * n_ran;   // 4-bits per nibble
 124   char ran[n_ran];
 125
 126   int nibbles_used = max_nibbles;
 127   for(std::wstring::size_type i=0; i < s.size(); ++i)
 128   {
 129     if (s[i] == L'%')                        // digit request
 130     {
 131       if (nibbles_used == max_nibbles)
 132       {
 133         system_crypt_random(ran, sizeof(ran), ec);
 134         if (ec != 0 && *ec)
 135           return "";
 136         nibbles_used = 0;
 137       }
 138       int c = ran[nibbles_used/2];
 139       c >>= 4 * (nibbles_used++ & 1);  // if odd, shift right 1 nibble
 140       s[i] = hex[c & 0xf];             // convert to hex digit and replace
 141     }
 142   }
 143
 144   if (ec != 0) ec->clear();
 145
 146   return s;
 147 }
 148
 149 }}}
 150
 151 #endif  // no wide character support