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

   1 // Debugging support -*- C++ -*-
   2
   3 // Copyright (C) 2013-2017 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 https://gcc.gnu.org/bugs/):\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     // Long enough for decimal representation.
  75     int __ilen = 3 * sizeof(__val);
  76     char *__cs = static_cast<char*>(__builtin_alloca(__ilen));
  77     char* __out = __cs + __ilen;
  78     do
  79       {
  80         *--__out = "0123456789"[__val % 10];
  81         __val /= 10;
  82       }
  83     while (__val != 0);
  84     size_t __len = __cs + __ilen - __out;
  85     if (__bufsize < __len)
  86       return -1;
  87
  88     __builtin_memcpy(__buf, __cs + __ilen - __len, __len);
  89     return __len;
  90   }
  91
  92
  93   // Private routine to print into __buf arguments according to format,
  94   // not to exceed __bufsize.
  95   // Only '%%', '%s' and '%zu' format specifiers are understood.
  96   // Returns number of characters printed (excluding terminating NUL).
  97   // Always NUL-terminates __buf.
  98   // Throws logic_error on insufficient space.
  99   int __snprintf_lite(char *__buf, size_t __bufsize, const char *__fmt,
 100                       va_list __ap)
 101   {
 102     char *__d = __buf;
 103     const char *__s = __fmt;
 104     const char *const __limit = __d + __bufsize - 1;  // Leave space for NUL.
 105
 106     while (__s[0] != '\0' && __d < __limit)
 107       {
 108         if (__s[0] == '%')
 109           switch (__s[1])
 110             {
 111             default:  // Stray '%'. Just print it.
 112               break;
 113             case '%':  // '%%'
 114               __s += 1;
 115               break;
 116             case 's':  // '%s'.
 117               {
 118                 const char *__v = va_arg(__ap, const char *);
 119
 120                 while (__v[0] != '\0' && __d < __limit)
 121                   *__d++ = *__v++;
 122
 123                 if (__v[0] != '\0')
 124                   // Not enough space for __fmt expansion.
 125                   __throw_insufficient_space(__buf, __d);
 126
 127                 __s += 2;  // Step over %s.
 128                 continue;
 129               }
 130               break;
 131             case 'z':
 132               if (__s[2] == 'u')  // '%zu' -- expand next size_t arg.
 133                 {
 134                   const int __len = __concat_size_t(__d, __limit - __d,
 135                                                     va_arg(__ap, size_t));
 136                   if (__len > 0)
 137                     __d += __len;
 138                   else
 139                     // Not enough space for __fmt expansion.
 140                     __throw_insufficient_space(__buf, __d);
 141
 142                   __s += 3;  // Step over %zu
 143                   continue;
 144                 }
 145               // Stray '%zX'. Just print it.
 146               break;
 147             }
 148         *__d++ = *__s++;
 149       }
 150
 151     if (__s[0] != '\0')
 152       // Not enough space for __fmt expansion.
 153       __throw_insufficient_space(__buf, __d);
 154
 155     *__d = '\0';
 156     return __d - __buf;
 157   }
 158
 159 }  // __gnu_cxx