refactor

test/fuzzing/CMakeLists.txt

@@ -12,7 +12,7 @@ set(FMT_FUZZ_LDFLAGS "" CACHE STRING "LDFLAGS for the fuzz targets")
 
 #find all fuzzers.
 set(SOURCES
-chrono_duration.cpp # this triggers integer overflows I yet not know how to fix
+chrono_duration.cpp
 named_arg.cpp
 one_arg.cpp
 sprintf.cpp
@@ -26,7 +26,7 @@ endif()
 macro(implement_fuzzer sourcefile)
   get_filename_component(basename ${sourcefile} NAME_WE)
   set(name fuzzer_${basename})
-  add_executable(${name} ${sourcefile})
+  add_executable(${name} ${sourcefile} fuzzer_common.h)
   target_link_libraries(${name}  PRIVATE fmt)
 if(FMT_FUZZ_LDFLAGS)
   target_link_libraries(${name} PRIVATE ${FMT_FUZZ_LDFLAGS})

test/fuzzing/chrono_duration.cpp

@@ -8,17 +8,13 @@
 #include <stdexcept>
 #include <type_traits>
 #include <vector>
+#include "fuzzer_common.h"
 
 template <typename Item, typename Ratio>
 void invoke_inner(fmt::string_view formatstring, const Item item) {
   const std::chrono::duration<Item, Ratio> value(item);
   try {
-    // Don't switch these two dynamically,
-    // there is already a large combinatoric explosion
-    // of type and ratio, causing afl to suffer and the corpus
-    // getting enormous. Occasionally, flip this switch and
-    // try manually.
-#if 0
+#if FMT_FUZZ_FORMAT_TO_STRING
     std::string message = fmt::format(formatstring, value);
 #else
     fmt::memory_buffer buf;
@@ -31,21 +27,16 @@ void invoke_inner(fmt::string_view formatstring, const Item item) {
 // Item is the underlying type for duration (int, long etc)
 template <typename Item>
 void invoke_outer(const uint8_t* Data, std::size_t Size, const int scaling) {
-  // always use a fixed location of the data, so different cases will
-  // cooperate better. the same bit pattern, interpreted as another type,
-  // is likely interesting.
-  // won't work on travis.
-  //constexpr auto Nfixed = std::max(sizeof(long double), sizeof(std::intmax_t));
-  constexpr auto Nfixed=16;
+  // always use a fixed location of the data
+  using fmt_fuzzer::Nfixed;
 
   constexpr auto N = sizeof(Item);
   static_assert(N <= Nfixed, "fixed size is too small");
   if (Size <= Nfixed + 1) {
     return;
   }
 
-  // travis doesn't handle this
-#if 0
+#if __cplusplus >= 201402L
   static_assert(std::is_trivially_copyable<Item>::value,
                 "Item must be blittable");
 #endif

test/fuzzing/fuzzer_common.h

@@ -0,0 +1,37 @@
+#ifndef FUZZER_COMMON_H
+#define FUZZER_COMMON_H
+// Copyright (c) 2019, Paul Dreik
+// License: see LICENSE.rst in the fmt root directory
+
+// one can format to either a string, or a buf. buf is faster,
+// but one may be interested in formatting to a string instead to
+// verify it works as intended. to avoid a combinatoric explosion,
+// select this at compile time instead of dynamically from the fuzz data
+#define FMT_FUZZ_FORMAT_TO_STRING 1
+
+// if fmt is given a buffer that is separately allocated,
+// chances that address sanitizer detects out of bound reads is
+// much higher. However, it slows down the fuzzing.
+#define FMT_FUZZ_SEPARATE_ALLOCATION 1
+
+
+
+// To let the the fuzzer mutation be efficient at cross pollinating
+// between different types, use a fixed size format.
+// The same bit pattern, interpreted as another type,
+// is likely interesting.
+// For this, we must know the size of the largest possible type in use.
+// There are some problems on old compilers, hence the C++ version check
+#if __cplusplus >= 201402L
+# include <algorithm>
+# include <cstdint>
+namespace fmt_fuzzer {
+  constexpr auto Nfixed = std::max(sizeof(long double), sizeof(std::intmax_t));
+}
+#else
+namespace fmt_fuzzer {
+  constexpr auto Nfixed=16;
+}
+#endif
+
+#endif // FUZZER_COMMON_H

test/fuzzing/named_arg.cpp

@@ -7,6 +7,7 @@
 #include <stdexcept>
 #include <type_traits>
 #include <vector>
+#include "fuzzer_common.h"
 
 template <typename Item1>
 void invoke_fmt(const uint8_t* Data, std::size_t Size, int argsize) {
@@ -30,8 +31,7 @@ void invoke_fmt(const uint8_t* Data, std::size_t Size, int argsize) {
 
   // allocating buffers separately is slower, but increases chances
   // of detecting memory errors
-#define SEPARATE_ALLOCATION 1
-#if SEPARATE_ALLOCATION
+#if FMT_FUZZ_SEPARATE_ALLOCATION
   std::vector<char> argnamebuffer(argsize);
   std::memcpy(argnamebuffer.data(), Data, argsize);
   auto argname = fmt::string_view(argnamebuffer.data(), argsize);
@@ -41,7 +41,7 @@ void invoke_fmt(const uint8_t* Data, std::size_t Size, int argsize) {
   Data += argsize;
   Size -= argsize;
 
-#if SEPARATE_ALLOCATION
+#if FMT_FUZZ_SEPARATE_ALLOCATION
   // allocates as tight as possible, making it easier to catch buffer overruns.
   std::vector<char> fmtstringbuffer(Size);
   std::memcpy(fmtstringbuffer.data(), Data, Size);
@@ -50,7 +50,6 @@ void invoke_fmt(const uint8_t* Data, std::size_t Size, int argsize) {
   auto fmtstring = fmt::string_view((const char*)Data, Size);
 #endif
   std::string message = fmt::format(fmtstring, fmt::arg(argname, item1));
-#undef SEPARATE_ALLOCATION
 }
 
 // for dynamic dispatching to an explicit instantiation

test/fuzzing/one_arg.cpp

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include <fmt/chrono.h>
+#include "fuzzer_common.h"
 
 template <typename Item>
 void invoke_fmt(const uint8_t* Data, std::size_t Size) {
@@ -24,17 +25,16 @@ void invoke_fmt(const uint8_t* Data, std::size_t Size) {
   Data += N;
   Size -= N;
 
-#define SEPARATE_ALLOCATION 0
-#if SEPARATE_ALLOCATION
+#if FMT_FUZZ_SEPARATE_ALLOCATION
   // allocates as tight as possible, making it easier to catch buffer overruns.
   std::vector<char> fmtstringbuffer(Size);
   std::memcpy(fmtstringbuffer.data(), Data, Size);
   auto fmtstring = fmt::string_view(fmtstringbuffer.data(), Size);
 #else
   auto fmtstring = fmt::string_view((const char*)Data, Size);
 #endif
-#define ALLOCATE_RESULT_IN_STRING 0
-#if ALLOCATE_RESULT_IN_STRING
+
+#if FMT_FUZZ_FORMAT_TO_STRING
   std::string message = fmt::format(fmtstring, item);
 #else
   fmt::memory_buffer message;
@@ -52,7 +52,7 @@ void invoke_fmt_time(const uint8_t* Data, std::size_t Size) {
   std::memcpy(&item, Data, N);
   Data += N;
   Size -= N;
-#if SEPARATE_ALLOCATION
+#if FMT_FUZZ_SEPARATE_ALLOCATION
   // allocates as tight as possible, making it easier to catch buffer overruns.
   std::vector<char> fmtstringbuffer(Size);
   std::memcpy(fmtstringbuffer.data(), Data, Size);
@@ -62,7 +62,7 @@ void invoke_fmt_time(const uint8_t* Data, std::size_t Size) {
 #endif
   auto* b = std::localtime(&item);
   if (b) {
-#if ALLOCATE_RESULT_IN_STRING
+#if FMT_FUZZ_FORMAT_TO_STRING
     std::string message = fmt::format(fmtstring, *b);
 #else
     fmt::memory_buffer message;

test/fuzzing/sprintf.cpp

@@ -5,10 +5,9 @@
 #include <cstdint>
 #include <stdexcept>
 
+#include "fuzzer_common.h"
 
-// won't work on travis.
-//constexpr auto Nmax = std::max(sizeof(long double), sizeof(std::intmax_t));
-constexpr auto Nmax=16;
+constexpr auto Nmax=fmt_fuzzer::Nfixed;
 
 template <class Item>
 Item assignFromBuf(const uint8_t* Data, std::size_t Size) {
@@ -40,8 +39,7 @@ void invoke_fmt(const uint8_t* Data, std::size_t Size) {
 
   auto fmtstring = fmt::string_view((const char*)Data, Size);
 
-#define ALLOCATE_RESULT_IN_STRING 0
-#if ALLOCATE_RESULT_IN_STRING
+#if FMT_FUZZ_FORMAT_TO_STRING
   std::string message = fmt::format(fmtstring, item1, item2);
 #else
   fmt::memory_buffer message;

test/fuzzing/two_args.cpp

@@ -5,9 +5,9 @@
 #include <stdexcept>
 #include <type_traits>
 
-// won't work on travis.
-//constexpr auto Nmax = std::max(sizeof(long double), sizeof(std::intmax_t));
-constexpr auto Nmax=16;
+#include "fuzzer_common.h"
+
+constexpr auto Nmax=fmt_fuzzer::Nfixed;
 
 template <typename Item1, typename Item2>
 void invoke_fmt(const uint8_t* Data, std::size_t Size) {
@@ -38,8 +38,7 @@ void invoke_fmt(const uint8_t* Data, std::size_t Size) {
 
   auto fmtstring = fmt::string_view((const char*)Data, Size);
 
-#define ALLOCATE_RESULT_IN_STRING 0
-#if ALLOCATE_RESULT_IN_STRING
+#if FMT_FUZZ_FORMAT_TO_STRING
   std::string message = fmt::format(fmtstring, item1, item2);
 #else
   fmt::memory_buffer message;