externals: Update fmt to 6.2.0

Merge commit 'c9dec5da8c'

externals/fmt/test/fuzzing/sprintf.cpp

@@ -0,0 +1,116 @@
+// Copyright (c) 2019, Paul Dreik
+// License: see LICENSE.rst in the fmt root directory
+#include <fmt/format.h>
+#include <fmt/printf.h>
+#include <cstdint>
+#include <stdexcept>
+
+#include "fuzzer_common.h"
+
+using fmt_fuzzer::Nfixed;
+
+template <typename Item1, typename Item2>
+void invoke_fmt(const uint8_t* Data, std::size_t Size) {
+  constexpr auto N1 = sizeof(Item1);
+  constexpr auto N2 = sizeof(Item2);
+  static_assert(N1 <= Nfixed, "size1 exceeded");
+  static_assert(N2 <= Nfixed, "size2 exceeded");
+  if (Size <= Nfixed + Nfixed) {
+    return;
+  }
+  Item1 item1 = fmt_fuzzer::assignFromBuf<Item1>(Data);
+  Data += Nfixed;
+  Size -= Nfixed;
+
+  Item2 item2 = fmt_fuzzer::assignFromBuf<Item2>(Data);
+  Data += Nfixed;
+  Size -= Nfixed;
+
+  auto fmtstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
+
+#if FMT_FUZZ_FORMAT_TO_STRING
+  std::string message = fmt::format(fmtstring, item1, item2);
+#else
+  fmt::memory_buffer message;
+  fmt::format_to(message, fmtstring, item1, item2);
+#endif
+}
+
+// for dynamic dispatching to an explicit instantiation
+template <typename Callback> void invoke(int index, Callback callback) {
+  switch (index) {
+  case 0:
+    callback(bool{});
+    break;
+  case 1:
+    callback(char{});
+    break;
+  case 2:
+    using sc = signed char;
+    callback(sc{});
+    break;
+  case 3:
+    using uc = unsigned char;
+    callback(uc{});
+    break;
+  case 4:
+    callback(short{});
+    break;
+  case 5:
+    using us = unsigned short;
+    callback(us{});
+    break;
+  case 6:
+    callback(int{});
+    break;
+  case 7:
+    callback(unsigned{});
+    break;
+  case 8:
+    callback(long{});
+    break;
+  case 9:
+    using ul = unsigned long;
+    callback(ul{});
+    break;
+  case 10:
+    callback(float{});
+    break;
+  case 11:
+    callback(double{});
+    break;
+  case 12:
+    using LD = long double;
+    callback(LD{});
+    break;
+  case 13:
+    using ptr = void*;
+    callback(ptr{});
+    break;
+  }
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, std::size_t Size) {
+  if (Size <= 3) {
+    return 0;
+  }
+
+  // switch types depending on the first byte of the input
+  const auto first = Data[0] & 0x0F;
+  const auto second = (Data[0] & 0xF0) >> 4;
+  Data++;
+  Size--;
+
+  auto outer = [=](auto param1) {
+    auto inner = [=](auto param2) {
+      invoke_fmt<decltype(param1), decltype(param2)>(Data, Size);
+    };
+    invoke(second, inner);
+  };
+
+  try {
+    invoke(first, outer);
+  } catch (std::exception& /*e*/) {
+  }
+  return 0;
+}