Translate cpp_wrapper.py to C to try to improve build speed (#5)

Author: Jason Mobarak

Dockerfile

@@ -41,7 +41,7 @@ RUN    apt-get update \
                           python \
     && mkdir -p cmake-build && cd cmake-build \
     && wget https://cmake.org/files/v3.10/cmake-3.10.1.tar.gz \
-    && tar -xvzf cmake-3.10.1.tar.gz \
+    && tar -xzf cmake-3.10.1.tar.gz \
     && cd cmake-3.10.1 \
     && ./configure \
     && make -j4 \
@@ -51,7 +51,4 @@ RUN    apt-get update \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
-COPY cpp_wrapper.py /bin
-RUN chmod +x /bin/cpp_wrapper.py
-
 # EOF

Makefile

@@ -6,6 +6,9 @@ SCRIPTS := .travis.sh \
 					 run_build_shell.bash \
 					 stage_sysroot.bash \
 
+cpp_wrapper: cpp_wrapper.c
+	gcc -O3 -std=c99 -Wall cpp_wrapper.c -o cpp_wrapper
+
 check:
 	docker run -v $(CURDIR):/mnt koalaman/shellcheck -x $(SCRIPTS)
 

build.bash

@@ -49,7 +49,7 @@ CMAKE_COMMAND="\
         -DLLVM_TARGETS_TO_BUILD=$ARCH \
         -DCMAKE_CXX_FLAGS='-DENDIAN_LITTLE=1' \
         -DCMAKE_C_COMPILER=/usr/bin/gcc \
-        -DCMAKE_CXX_COMPILER=/bin/cpp_wrapper.py \
+        -DCMAKE_CXX_COMPILER=/bin/cpp_wrapper \
         -DCMAKE_BUILD_TYPE=Release \
         -DLLVM_BINUTILS_INCDIR=/usr/include \
         -DLLVM_INCLUDE_TESTS=OFF"
@@ -66,6 +66,7 @@ fi
 docker run ${INTERACTIVE[@]:-} --rm \
     -v "$PWD/output/opt:/opt" \
     -v "$PWD/patches:/patches" \
+    -v "$PWD:/this_dir" \
     -v obfuscator-llvm:/work/obfuscator-llvm \
     -v obfuscator-llvm-build:/work/build \
     "$DOCKER_NAMETAG" \
@@ -76,6 +77,8 @@ docker run ${INTERACTIVE[@]:-} --rm \
                   else \
                     (cd /work/obfuscator-llvm && git pull); \
                   fi \
+                  && cp -v /this_dir/cpp_wrapper.c /work/cpp_wrapper.c \
+                  && gcc -std=c99 -O3 -Wall /work/cpp_wrapper.c -o /bin/cpp_wrapper \
                   && cd /work/obfuscator-llvm \
                   && $PATCH_COMMAND \
                   && cd /work/build \

cpp_wrapper.c

@@ -0,0 +1,106 @@
+/* Copyright (C) 2017 Swift Navigation Inc.
+ * Contact: Swift Navigation <[email protected]>
+ *
+ * This source is subject to the license found in the file 'LICENSE' which must
+ * be be distributed together with this source. All other rights reserved.
+ *
+ * THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+ * EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+//#define DEBUG
+
+const char* real_cpp_path = "/usr/bin/g++";
+const char* new_argv_entry = "lib/libLLVMTransformUtils.a";
+
+int main(int argc, const char* argv[]) {
+
+  size_t args_str_size = 0;
+  size_t* lengths = (size_t*) malloc(argc*sizeof(size_t));
+
+  for (int x = 0; x < argc; x++) {
+    lengths[x] = strlen(argv[x]);
+    args_str_size += lengths[x];
+  }
+
+#ifdef DEBUG
+  printf("%zu\n", args_str_size);
+#endif
+
+  // Make space for spaces in between argument values + null terminator
+  args_str_size += (argc - 1) + 1;
+
+  char* all_args_buf = (char*) malloc(args_str_size);
+  char* p = all_args_buf;
+
+  for (int x = 0; x < argc; x++) {
+    memcpy(p, argv[x], lengths[x]);
+    p += lengths[x];
+    *p++ = ' ';
+  }
+
+  // Null terminate the string
+  *p = '\0';
+
+#ifdef DEBUG
+  printf("All args: %s\n", all_args_buf);
+#endif
+
+  bool append_new_arg = false;
+
+  if ( (strstr(all_args_buf, "-o lib/libLTO.so.4.0.1")   != NULL &&
+        strstr(all_args_buf, "lib/libLLVMObfuscation.a") != NULL    )
+      ||
+       (strstr(all_args_buf, "-o bin/llvm-lto")          != NULL &&
+        strstr(all_args_buf, "lib/libLLVMObfuscation.a") != NULL    ) )
+  {
+    fprintf(stderr, "********************** HACK IMMINENT **************************\n");
+    fprintf(stderr, "********************** HACK IMMINENT **************************\n");
+    fprintf(stderr, "********************** HACK IMMINENT **************************\n");
+
+    append_new_arg = true;
+  }
+
+  argv[0] = real_cpp_path;
+
+  if (append_new_arg) {
+
+    int new_argc = argc + 1;
+    const char** new_argv = malloc( (new_argc+1) * sizeof(char*) );
+
+    for (int x = 0; x < argc; x++) {
+
+      size_t length = (lengths[x] + 1);
+
+      new_argv[x] = (char*) malloc(length * sizeof(char));
+      memcpy((void*) new_argv[x], argv[x], length * sizeof(char));
+    }
+
+    size_t new_argv_len = strlen(new_argv_entry) + 1;
+    new_argv[new_argc - 1] = malloc(new_argv_len * sizeof(char));
+
+    memcpy((void*) new_argv[new_argc - 1], new_argv_entry, new_argv_len);
+
+    new_argv[new_argc] = NULL; 
+    
+    argc = new_argc;
+    argv = new_argv;
+  }
+
+#if 0 // This causes a heap corruption error trigger?
+  free(lengths);
+  free(all_args_buf);
+#endif
+
+  int execv_ret = execv(real_cpp_path, (char*const*)argv);
+
+  fprintf(stderr, "execv() failure: %d\n", execv_ret);
+  return -42;
+}

cpp_wrapper.py

@@ -1 +1 @@
-swiftnav/arm-llvm-obf:4.0-ubuntu1404
+swiftnav/arm-llvm-obf:4.0-ubuntu1404-2017.12.22