From bf786f4cc6f4d6b9dd3b63c6b8030a34b3409366 Mon Sep 17 00:00:00 2001
From: Kevin Backhouse <kevinbackhouse@github.com>
Date: Sun, 11 Jul 2021 21:14:08 +0100
Subject: [PATCH] Updates to make fuzzing work.

---
 CMakeLists.txt            |  2 +-
 cmake/compilerFlags.cmake |  4 +++-
 fuzz/CMakeLists.txt       |  2 +-
 fuzz/read-metadata.cpp    | 21 +++++++++++++--------
 src/iptc.cpp              |  4 ++--
 src/jpgimage.cpp          |  2 +-
 src/tiffvisitor_int.cpp   |  2 ++
 7 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e4f0093d..474c6d4c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -92,7 +92,7 @@ if( EXIV2_BUILD_UNIT_TESTS )
     add_subdirectory ( unitTests )
 endif()
 
-if( EXIV2_BUILD_FUZZ_TESTS)
+if( EXIV2_BUILD_FUZZ_TESTS )
     if ((NOT COMPILER_IS_CLANG) OR (NOT EXIV2_TEAM_USE_SANITIZERS))
         message(FATAL_ERROR "You need to build with Clang and sanitizers for the fuzzers to work. "
                 "Use Clang and -DEXIV2_TEAM_USE_SANITIZERS=ON")
diff --git a/cmake/compilerFlags.cmake b/cmake/compilerFlags.cmake
index 20f6ac53..8459fa0e 100644
--- a/cmake/compilerFlags.cmake
+++ b/cmake/compilerFlags.cmake
@@ -82,7 +82,9 @@ if ( MINGW OR UNIX OR MSYS ) # MINGW, Linux, APPLE, CYGWIN
                     set(SANITIZER_FLAGS "-fno-omit-frame-pointer -fsanitize=address")
                 endif()
             elseif( COMPILER_IS_CLANG )
-                if ( CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 4.9 )
+                if ( EXIV2_BUILD_FUZZ_TESTS )
+                    set(SANITIZER_FLAGS "-fsanitize=fuzzer-no-link")
+                elseif ( CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 4.9 )
                     set(SANITIZER_FLAGS "-fno-omit-frame-pointer -fsanitize=address,undefined -fno-sanitize-recover=all")
                 elseif ( CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 3.4 )
                     set(SANITIZER_FLAGS "-fno-omit-frame-pointer -fsanitize=address,undefined")
diff --git a/fuzz/CMakeLists.txt b/fuzz/CMakeLists.txt
index 281ff570..86209e9c 100644
--- a/fuzz/CMakeLists.txt
+++ b/fuzz/CMakeLists.txt
@@ -11,4 +11,4 @@ macro(fuzzer name)
             )
 endmacro()
 
-fuzzer(read-metadata)
\ No newline at end of file
+fuzzer(read-metadata)
diff --git a/fuzz/read-metadata.cpp b/fuzz/read-metadata.cpp
index 9f0b5979..088b3ef8 100644
--- a/fuzz/read-metadata.cpp
+++ b/fuzz/read-metadata.cpp
@@ -4,21 +4,26 @@
 #include <iomanip>
 #include <cassert>
 
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t * Data, size_t Size) {
+  // Invalid files generate a lot of warnings, so switch off logging.
+  Exiv2::LogMsg::setLevel(Exiv2::LogMsg::mute);
 
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t * Data, size_t Size)
-try {
+  Exiv2::XmpParser::initialize();
+  ::atexit(Exiv2::XmpParser::terminate);
+
+  try {
     Exiv2::Image::UniquePtr image = Exiv2::ImageFactory::open(Data, Size);
     assert(image.get() != 0);
+
     image->readMetadata();
 
     Exiv2::ExifData &exifData = image->exifData();
     if (exifData.empty()) {
-        return -1;
+      return -1;
     }
+  } catch(...) {
+    // Exiv2 throws an exception if the metadata is invalid.
+  }
 
-
-    return 0;
-}
-catch (Exiv2::Error& e) {
-    return -1;
+  return 0;
 }
diff --git a/src/iptc.cpp b/src/iptc.cpp
index 9ae64d81..4252a988 100644
--- a/src/iptc.cpp
+++ b/src/iptc.cpp
@@ -474,13 +474,13 @@ namespace Exiv2 {
 #endif
                 }
             }
-#ifndef SUPPRESS_WARNINGS
             else {
+#ifndef SUPPRESS_WARNINGS
                 EXV_WARNING << "IPTC dataset " << IptcKey(dataSet, record)
                             << " has invalid size " << sizeData << "; skipped.\n";
+#endif
                 return 7;
             }
-#endif
             pRead += sizeData;
         }
 
diff --git a/src/jpgimage.cpp b/src/jpgimage.cpp
index e722a797..6e6f0f96 100644
--- a/src/jpgimage.cpp
+++ b/src/jpgimage.cpp
@@ -181,7 +181,7 @@ namespace Exiv2 {
 #endif
                 return -2;
             }
-#ifndef EXIV2_DEBUG_MESSAGES
+#ifdef EXIV2_DEBUG_MESSAGES
             if (   (dataSize & 1)
                 && position + dataSize == static_cast<uint32_t>(sizePsData)) {
                 std::cerr << "Warning: "
diff --git a/src/tiffvisitor_int.cpp b/src/tiffvisitor_int.cpp
index 063cd250..ccf12a4d 100644
--- a/src/tiffvisitor_int.cpp
+++ b/src/tiffvisitor_int.cpp
@@ -1335,7 +1335,9 @@ namespace Exiv2 {
                 tc->setStart(p);
                 object->addChild(std::move(tc));
             } else {
+#ifndef SUPPRESS_WARNINGS
                EXV_WARNING << "Unable to handle tag " << tag << ".\n";
+#endif
             }
             p += 12;
         }