Adding SAN option to CMakeLists.txt, to make it easier to use clang's…

… address/undefined behavior sanitizer on codebase

Fixing overflow issue on extreme colors in color_distance().
Explicitly disabling unaligned addressing in miniz and transcoder when UBSAN is enabled
Disabling a needless optimization in transcoder causing ubsan issues (that could have easily been worked around in a different way, but it was an unnecessary optimization to begin with)
Rebuild wasm builds

CMakeLists.txt

@@ -2,6 +2,7 @@ project(basisu)
 
 cmake_minimum_required(VERSION 3.0)
 option(STATIC "static linking" FALSE)
+option(SAN "sanitize" FALSE)
 
 # For MSVC builds default to SSE enabled, and determine if it's a 64-bit (-A x64) vs. 32-bit (-A Win32) build.
 if (MSVC)
@@ -24,6 +25,7 @@ message("Initial CMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}")
 message("Initial SSE=${SSE}")
 message("Initial ZSTD=${ZSTD}")
 message("Initial OPENCL=${OPENCL}")
+message("Initial SAN=${SAN}")
 
 if (NOT MSVC)
 	# With MSVC builds we use the Khronos lib/include files in the project's "OpenCL" directory, to completely avoid requiring fiddly to install vendor SDK's.
@@ -60,10 +62,15 @@ endif()
 
 if (NOT MSVC)
    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g")
-   set(CMAKE_C_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g")
-
+   set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -g")
+   
    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
-   set(CMAKE_C_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
+   set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
+
+   if (SAN)
+      set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined")
+      set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined")
+   endif()
 
    set(CMAKE_CXX_FLAGS -std=c++11)
    set(GCC_COMPILE_FLAGS "-fvisibility=hidden -fPIC -fno-strict-aliasing -D_LARGEFILE64_SOURCE=1 -D_FILE_OFFSET_BITS=64 -Wall -Wextra -Wno-unused-local-typedefs -Wno-unused-value -Wno-unused-parameter -Wno-unused-variable")

encoder/basisu_enc.h

@@ -990,17 +990,28 @@ namespace basisu
 			int dg = e1.g - e2.g;
 			int db = e1.b - e2.b;
 
+#if 0
 			int delta_l = dr * 27 + dg * 92 + db * 9;
 			int delta_cr = dr * 128 - delta_l;
 			int delta_cb = db * 128 - delta_l;
-
+															
 			uint32_t id = ((uint32_t)(delta_l * delta_l) >> 7U) +
 				((((uint32_t)(delta_cr * delta_cr) >> 7U) * 26U) >> 7U) +
 				((((uint32_t)(delta_cb * delta_cb) >> 7U) * 3U) >> 7U);
+#else
+			int64_t delta_l = dr * 27 + dg * 92 + db * 9;
+			int64_t delta_cr = dr * 128 - delta_l;
+			int64_t delta_cb = db * 128 - delta_l;
+
+			uint32_t id = ((uint32_t)((delta_l * delta_l) >> 7U)) +
+				((((uint32_t)((delta_cr * delta_cr) >> 7U)) * 26U) >> 7U) +
+				((((uint32_t)((delta_cb * delta_cb) >> 7U)) * 3U) >> 7U);
+#endif
 
 			if (alpha)
 			{
 				int da = (e1.a - e2.a) << 7;
+				// This shouldn't overflow if da is 255 or -255: 29.99 bits after squaring.
 				id += ((uint32_t)(da * da) >> 7U);
 			}
 

encoder/basisu_miniz.h

@@ -76,6 +76,14 @@
 #define MINIZ_USE_UNALIGNED_LOADS_AND_STORES 1
 #endif
 
+// Using unaligned loads and stores causes errors when using UBSan. Jam it off.
+#if defined(__has_feature)
+#if __has_feature(undefined_behavior_sanitizer)
+#undef MINIZ_USE_UNALIGNED_LOADS_AND_STORES
+#define MINIZ_USE_UNALIGNED_LOADS_AND_STORES 0
+#endif
+#endif
+
 #if defined(_M_X64) || defined(_WIN64) || defined(__MINGW64__) || defined(_LP64) || defined(__LP64__) || defined(__ia64__) || defined(__x86_64__)
 // Set MINIZ_HAS_64BIT_REGISTERS to 1 if operations on 64-bit integers are reasonably fast (and don't involve compiler generated calls to helper functions).
 #define MINIZ_HAS_64BIT_REGISTERS 1

transcoder/basisu_containers.h

@@ -285,7 +285,10 @@ namespace basisu
          m_size = other.m_size;
 
          if (BASISU_IS_BITWISE_COPYABLE(T))
-            memcpy(m_p, other.m_p, m_size * sizeof(T));
+         {
+             if ((m_p) && (other.m_p))
+                memcpy(m_p, other.m_p, m_size * sizeof(T));
+         }
          else
          {
             T* pDst = m_p;
@@ -326,7 +329,10 @@ namespace basisu
          }
 
          if (BASISU_IS_BITWISE_COPYABLE(T))
-            memcpy(m_p, other.m_p, other.m_size * sizeof(T));
+         {
+             if ((m_p) && (other.m_p))
+                memcpy(m_p, other.m_p, other.m_size * sizeof(T));
+         }
          else
          {
             T* pDst = m_p;

transcoder/basisu_transcoder.cpp

@@ -37,6 +37,14 @@
 	#endif
 #endif
 
+// Using unaligned loads and stores causes errors when using UBSan. Jam it off.
+#if defined(__has_feature)
+#if __has_feature(undefined_behavior_sanitizer)
+#undef BASISD_USE_UNALIGNED_WORD_READS
+#define BASISD_USE_UNALIGNED_WORD_READS 0
+#endif
+#endif
+
 #define BASISD_SUPPORTED_BASIS_VERSION (0x13)
 
 #ifndef BASISD_SUPPORT_KTX2
@@ -12440,12 +12448,8 @@ namespace basist
 				bits = read_bits64(blk.m_bytes, bit_ofs, basisu::minimum<int>(64, 128 - (int)bit_ofs));
 			else
 			{
-#ifdef __EMSCRIPTEN__
 				bits = blk.m_dwords[2];
 				bits |= (((uint64_t)blk.m_dwords[3]) << 32U);
-#else
-				bits = blk.m_qwords[1];
-#endif
 
 				if (bit_ofs >= 64U)
 					bits >>= (bit_ofs - 64U);

transcoder/basisu_transcoder_uastc.h

@@ -205,10 +205,6 @@ namespace basist
 		{
 			uint8_t m_bytes[16];
 			uint32_t m_dwords[4];
-
-#ifndef __EMSCRIPTEN__
-			uint64_t m_qwords[2];
-#endif
 		};
 	};