Update README.md

Author: beduin23

README.md

@@ -1 +1,80 @@
-HexVASAN repo
+# HexVASAN: Venerable Variadic Vulnerabilities Vanquished
+
+## To build:
+### Step 1: `git clone https://github.com/HexHive/HexVASAN.git`
+### Step 2: Now in your llvm working directory, do the following steps
+
+```
+  - rm /path/to/llvm/tools/clang/lib/Driver/Tools.cpp 
+    ln -s /path/to/HexVASAN/src/Tools.cpp /path/to/llvm/tools/clang/lib/Driver/Tools.cpp 
+    
+  - rm /path/to/llvm/tools/clang/include/clang/Basic/Sanitizers.def
+    ln -s /path/to/HexVASAN/src/Sanitizers.def /path/to/llvm/tools/clang/include/clang/Basic/Sanitizers.def
+    
+  - rm /path/to/llvm/tools/clang/include/clang/Driver/SanitizerArgs.h
+    ln -s /path/to/HexVASAN/src/SanitizerArgs.h /path/to/llvm/tools/clang/include/clang/Driver/SanitizerArgs.h
+    
+  - rm /path/to/llvm/include/llvm/Transforms/Instrumentation.h 
+    ln -s /path/to/HexVASAN/src/Instrumentation.h /path/to/llvm/include/llvm/Transforms/Instrumentation.h
+    
+  - rm /path/to/llvm/include/llvm/InitializePasses.h
+    ln -s /path/to/HexVASAN/src/InitializePasses.h /path/to/llvm/include/llvm/InitializePasses.h
+    
+  - rm /path/to/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp
+    ln -s /path/to/HexVASAN/src/BackendUtil.cpp /path/to/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp
+ ```
+    
+ ### Step 3: 
+ a. Now link the two compiler passes
+ 
+ ```
+ ln -s /path/to/HexVASAN/lib/Transforms/Instrumentation/VASAN.cpp path/to/llvm/lib/Transforms/Instrumentation/VASAN.cpp
+ ln -s /path/to/HexVASAN/lib/Transforms/Instrumentation/VASANCaller.cpp path/to/llvm/lib/Transforms/Instrumentation/VASANCaller.cpp
+ ```
+ 
+ b. Now add VASAN.cpp and VASANCaller.cpp in the CMakeLists.txt in path/to/llvm/lib/Transforms/Instrumentation/
+    
+ ### Step 4: 
+ a. Now add the runtime library
+ ```
+ ln -s /path/to/HexVASAN/runtime/vasan  /path/to/llvm/projects/compiler-rt/lib/vasan
+ ```
+ b. Add the following line in the  CMakeLists.txt at /path/to/llvm/projects/compiler-rt/lib/
+  ```
+  add_subdirectory(vasan)
+  ```
+ ### Step 5: cmake option for build 
+ ```
+ cmake -GNinja \
+-DCMAKE_BUILD_TYPE=Release \
+-DCMAKE_C_COMPILER=clang \
+-DCMAKE_CXX_COMPILER=clang++ \
+-DLLVM_ENABLE_ASSERTIONS=ON \
+-DLLVM_BUILD_TESTS=OFF \
+-DLLVM_BUILD_EXAMPLES=OFF \
+-DLLVM_INCLUDE_TESTS=OFF \
+-DLLVM_INCLUDE_EXAMPLES=OFF \
+-DBUILD_SHARED_LIBS=on \
+-DLLVM_TARGETS_TO_BUILD="X86" \
+-DCMAKE_C_FLAGS="-fstandalone-debug" \
+-DCMAKE_CXX_FLAGS="-fstandalone-debug" \
+ ../llvm
+```
+### Step 6: 
+Build command
+```
+ninja
+```
+
+## Run
+a. To run, give the following command:
+```
+$BUILD_DIR/bin/clang++ test.cpp -fsanitize=vasan
+./a.out
+```
+b. Alternatively, you can set the error log file and run with backtracing enabled
+```
+export VASAN_ERR_LOG_PATH="/tmp/vasan/"
+$BUILD_DIR/bin/clang++ test.cpp -fsanitize=vasan-backtrace
+./a.out
+```