mozglue/misc/Sprintf.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Provides a safer sprintf for printing to fixed-size character arrays. */
   8
   9 #ifndef mozilla_Sprintf_h_
  10 #define mozilla_Sprintf_h_
  11
  12 #include <stdio.h>
  13 #include <stdarg.h>
  14 #include <algorithm>
  15
  16 #include "mozilla/Assertions.h"
  17 #include "mozilla/Attributes.h"
  18 #include "mozilla/Printf.h"
  19
  20 #ifdef __cplusplus
  21
  22 #  ifndef SPRINTF_H_USES_VSNPRINTF
  23 namespace mozilla {
  24 namespace detail {
  25
  26 struct MOZ_STACK_CLASS SprintfAppend final : public mozilla::PrintfTarget {
  27   explicit SprintfAppend(char* aBuf, size_t aBufLen)
  28       : mBuf(aBuf), mBufLen(aBufLen) {}
  29
  30   bool append(const char* aStr, size_t aLen) override {
  31     if (aLen == 0) {
  32       return true;
  33     }
  34     // Don't copy more than what's left to use.
  35     size_t copy = std::min(mBufLen, aLen);
  36     if (copy > 0) {
  37       memcpy(mBuf, aStr, copy);
  38       mBuf += copy;
  39       mBufLen -= copy;
  40     }
  41     return true;
  42   }
  43
  44  private:
  45   char* mBuf;
  46   size_t mBufLen;
  47 };
  48
  49 }  // namespace detail
  50 }  // namespace mozilla
  51 #  endif  // SPRINTF_H_USES_VSNPRINTF
  52
  53 MOZ_FORMAT_PRINTF(3, 0)
  54 MOZ_MAYBE_UNUSED
  55 static int VsprintfBuf(char* buffer, size_t bufsize, const char* format,
  56                        va_list args) {
  57   MOZ_ASSERT(format != buffer);
  58 #  ifdef SPRINTF_H_USES_VSNPRINTF
  59   int result = vsnprintf(buffer, bufsize, format, args);
  60   buffer[bufsize - 1] = '\0';
  61   return result;
  62 #  else
  63   mozilla::detail::SprintfAppend ss(buffer, bufsize);
  64   ss.vprint(format, args);
  65   size_t len = ss.emitted();
  66   buffer[std::min(len, bufsize - 1)] = '\0';
  67   return len;
  68 #  endif
  69 }
  70
  71 MOZ_FORMAT_PRINTF(3, 4)
  72 MOZ_MAYBE_UNUSED
  73 static int SprintfBuf(char* buffer, size_t bufsize, const char* format, ...) {
  74   va_list args;
  75   va_start(args, format);
  76   int result = VsprintfBuf(buffer, bufsize, format, args);
  77   va_end(args);
  78   return result;
  79 }
  80
  81 template <size_t N>
  82 MOZ_FORMAT_PRINTF(2, 0)
  83 int VsprintfLiteral(char (&buffer)[N], const char* format, va_list args) {
  84   return VsprintfBuf(buffer, N, format, args);
  85 }
  86
  87 template <size_t N>
  88 MOZ_FORMAT_PRINTF(2, 3)
  89 int SprintfLiteral(char (&buffer)[N], const char* format, ...) {
  90   va_list args;
  91   va_start(args, format);
  92   int result = VsprintfLiteral(buffer, format, args);
  93   va_end(args);
  94   return result;
  95 }
  96
  97 #endif
  98 #endif /* mozilla_Sprintf_h_ */