libstdc++-v3/src/c++11/snprintf_lite.cc

   1 // Debugging support -*- C++ -*-
   2
   3 // Copyright (C) 2013-2015 Free Software Foundation, Inc.
   4 //
   5 // This file is part of GCC.
   6 //
   7 // GCC is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // GCC is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 #include <stdarg.h>
  27 #include <bits/functexcept.h>
  28 #include <bits/locale_facets.h>
  29
  30 namespace std {
  31 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  32   template<typename _CharT, typename _ValueT>
  33   int
  34   __int_to_char(_CharT* __bufend, _ValueT __v, const _CharT* __lit,
  35                 ios_base::fmtflags __flags, bool __dec);
  36 _GLIBCXX_END_NAMESPACE_VERSION
  37 }
  38
  39 namespace __gnu_cxx {
  40
  41   // Private helper to throw logic error if snprintf_lite runs out
  42   // of space (which is not expected to ever happen).
  43   // NUL-terminates __buf.
  44   void
  45   __throw_insufficient_space(const char *__buf, const char *__bufend)
  46     __attribute__((__noreturn__));
  47
  48   void
  49   __throw_insufficient_space(const char *__buf, const char *__bufend)
  50   {
  51     // Include space for trailing NUL.
  52     const size_t __len = __bufend - __buf + 1;
  53
  54     const char __err[] = "not enough space for format expansion "
  55       "(Please submit full bug report at http://gcc.gnu.org/bugs.html):\n    ";
  56     const size_t __errlen = sizeof(__err) - 1;
  57
  58     char *const __e
  59       = static_cast<char*>(__builtin_alloca(__errlen + __len));
  60
  61     __builtin_memcpy(__e, __err, __errlen);
  62     __builtin_memcpy(__e + __errlen, __buf, __len - 1);
  63     __e[__errlen + __len - 1] = '\0';
  64     std::__throw_logic_error(__e);
  65   }
  66
  67
  68   // Private routine to append decimal representation of VAL to the given
  69   // BUFFER, but not more than BUFSIZE characters.
  70   // Does not NUL-terminate the output buffer.
  71   // Returns number of characters appended, or -1 if BUFSIZE is too small.
  72   int __concat_size_t(char *__buf, size_t __bufsize, size_t __val)
  73   {
  74     // __int_to_char is explicitly instantiated and available only for
  75     // some, but not all, types. See locale-inst.cc.
  76 #ifdef _GLIBCXX_USE_LONG_LONG
  77     unsigned long long __val2 = __val;
  78 #else
  79     unsigned long __val2 = __val;
  80 #endif
  81     // Long enough for decimal representation.
  82     int __ilen = 3 * sizeof(__val2);
  83     char *__cs = static_cast<char*>(__builtin_alloca(__ilen));
  84     size_t __len = std::__int_to_char(__cs + __ilen, __val2,
  85                                       std::__num_base::_S_atoms_out,
  86                                       std::ios_base::dec, true);
  87     if (__bufsize < __len)
  88       return -1;
  89
  90     __builtin_memcpy(__buf, __cs + __ilen - __len, __len);
  91     return __len;
  92   }
  93
  94
  95   // Private routine to print into __buf arguments according to format,
  96   // not to exceed __bufsize.
  97   // Only '%%', '%s' and '%zu' format specifiers are understood.
  98   // Returns number of characters printed (excluding terminating NUL).
  99   // Always NUL-terminates __buf.
 100   // Throws logic_error on insufficient space.
 101   int __snprintf_lite(char *__buf, size_t __bufsize, const char *__fmt,
 102                       va_list __ap)
 103   {
 104     char *__d = __buf;
 105     const char *__s = __fmt;
 106     const char *const __limit = __d + __bufsize - 1;  // Leave space for NUL.
 107
 108     while (__s[0] != '\0' && __d < __limit)
 109       {
 110         if (__s[0] == '%')
 111           switch (__s[1])
 112             {
 113             default:  // Stray '%'. Just print it.
 114               break;
 115             case '%':  // '%%'
 116               __s += 1;
 117               break;
 118             case 's':  // '%s'.
 119               {
 120                 const char *__v = va_arg(__ap, const char *);
 121
 122                 while (__v[0] != '\0' && __d < __limit)
 123                   *__d++ = *__v++;
 124
 125                 if (__v[0] != '\0')
 126                   // Not enough space for __fmt expansion.
 127                   __throw_insufficient_space(__buf, __d);
 128
 129                 __s += 2;  // Step over %s.
 130                 continue;
 131               }
 132               break;
 133             case 'z':
 134               if (__s[2] == 'u')  // '%zu' -- expand next size_t arg.
 135                 {
 136                   const int __len = __concat_size_t(__d, __limit - __d,
 137                                                     va_arg(__ap, size_t));
 138                   if (__len > 0)
 139                     __d += __len;
 140                   else
 141                     // Not enough space for __fmt expansion.
 142                     __throw_insufficient_space(__buf, __d);
 143
 144                   __s += 3;  // Step over %zu
 145                   continue;
 146                 }
 147               // Stray '%zX'. Just print it.
 148               break;
 149             }
 150         *__d++ = *__s++;
 151       }
 152
 153     if (__s[0] != '\0')
 154       // Not enough space for __fmt expansion.
 155       __throw_insufficient_space(__buf, __d);
 156
 157     *__d = '\0';
 158     return __d - __buf;
 159   }
 160
 161 }  // __gnu_cxx