moved code in examples directory, modified README

oss-internship-2020/sapi_lodepng/CMakeLists.txt

@@ -19,69 +19,51 @@ project(lodepng_sapi CXX)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED 17)
 
-add_library(lodepng STATIC lodepng/lodepng.cpp lodepng/lodepng.h)
+# Build static library
+add_library(lodepng STATIC
+  lodepng/lodepng.cpp
+  lodepng/lodepng.h
+)
 
-
-# unsandboxed main
-add_executable(lodepng_normal main.cc)
-target_link_libraries(lodepng_normal PRIVATE lodepng)
-
-# sandboxed main
+# Build SAPI library
 set(SAPI_ROOT "/usr/local/google/home/amedar/internship/sandboxed-api" CACHE PATH "Path to the Sandboxed API source tree")
 
 add_subdirectory("${SAPI_ROOT}"
-                 "${CMAKE_BINARY_DIR}/sandboxed-api-build"
-                 # Omit this to have the full Sandboxed API in IDE
-                 EXCLUDE_FROM_ALL)
-
-add_sapi_library(
-    lodepng_sapi
-    FUNCTIONS lodepng_decode32_file
-    lodepng_encode32_file
-    lodepng_encode32
-    lodepng_save_file
-    lodepng_load_file
-    lodepng_decode32
-    INPUTS lodepng/lodepng.h
-    LIBRARY lodepng
-    LIBRARY_NAME Lodepng
-    NAMESPACE ""
+  "${CMAKE_BINARY_DIR}/sandboxed-api-build"
+  EXCLUDE_FROM_ALL
 )
 
+add_sapi_library(
+  lodepng_sapi
+  
+  FUNCTIONS
+  lodepng_decode_memory
+  lodepng_decode32
+  lodepng_decode24
+
+  lodepng_decode_file
+  lodepng_decode32_file
+  lodepng_decode24_file
+
+  lodepng_encode_memory
+  lodepng_encode32
+  lodepng_encode24
+
+  lodepng_encode_file
+  lodepng_encode32_file
+  lodepng_encode24_file
+
+  lodepng_save_file
+  lodepng_load_file
+  
+  INPUTS lodepng/lodepng.h
+  LIBRARY lodepng
+  LIBRARY_NAME Lodepng
+  NAMESPACE ""
+)
 
 target_include_directories(lodepng_sapi INTERFACE
   "${PROJECT_BINARY_DIR}"  # To find the generated SAPI header
 )
 
-add_executable(lodepng_sandboxed main_sandboxed.cc sandbox.h)
-
-target_link_libraries(lodepng_sandboxed PRIVATE
-  lodepng_sapi
-  sapi::sapi
-  sapi::vars
-  sapi::status
-  glog::glog
-)
-
-# gtest
-
-include(GoogleTest)
-enable_testing()
-
-add_executable(main_unit_test
-  main_unit_test.cc
-  )
-
-target_link_libraries(main_unit_test PRIVATE
-  lodepng_sapi
-  absl::memory
-  absl::strings
-  absl::time
-  glog::glog
-  sapi::flags
-  sapi::sapi
-  sapi::status
-  sapi::test_main
-  sapi::vars
-)
-gtest_discover_tests(main_unit_test)
+add_subdirectory(examples)

oss-internship-2020/sapi_lodepng/README.md

@@ -1,15 +1,40 @@
+# LodePng Sandboxed
+
+Sandboxed version of the [lodepng](https://github.com/lvandeve/lodepng) library, using [Sandboxed API](https://github.com/google/sandboxed-api)
+
+## Details
+
+With Sandboxed API, many of the library's functions can be sandboxed. However, they need the `extern "C"` keyword defined so that name mangling does not happen, which is why a fork of the **lodepng** library is used. The only differences are found in the header file. An alternative to this is to define another library that wraps every needed function, specifying the required keyword.
+
+Even if many of the functions from the library can be sandboxed, there are some that are not supported (those which have `std::vector` parameters, overloaded functions etc.). If you really need these functions, a solution is to implement a custom library that wraps around these functions in order to make them compatible.
+
+## Examples
+
+The code found in the **examples** folder features a basic use case of the library. An image is generated, encoded into a file and then decoded to check that the values are the same. The encoding part was based on [this example](https://github.com/lvandeve/lodepng/blob/master/examples/example_encode.c) while decoding was based on [this](https://github.com/lvandeve/lodepng/blob/master/examples/example_decode.c).
+
+This folder is structured as:
+- `main.cc` - unsandboxed example
+- `sandbox.h` - custom sandbox policy
+- `main_sandboxed.cc` - sandboxed version of the example
+- `main_unit_test.cc` - testing file using [Google Test](https://github.com/google/googletest).
+
+The executables generated from these files will create the png files in the current directory. However, for the 
+`main_sandboxed.cc` file there is also the `images_path` flag which can be used to specify a different directory.
+
+<!-- 
 TODO
 
 - ~~check return value of functions~~
 - ~~integrate unit testing~~
 - add more functions
 - this readme
-- remove path from CMakeLists.txt
 - include abseil flags for unit testing
 - ~~improve tests (images, generating images etc.)~~
 - clear redundant includes
-- check if security policy can be stricter
+- ~~check if security policy can be stricter~~
 - ~~use addDirectoryAt instead of addDirectory~~
 - ~~modify tests assertions~~
-- ``add useful prints to unit tests``
-
+- ~~add useful prints to unit tests~~
+- ~~move examples to examples folder~~
+  
+ -->

oss-internship-2020/sapi_lodepng/examples/CMakeLists.txt

@@ -0,0 +1,58 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Build the unsandboxed main
+add_executable(lodepng_normal
+  main.cc
+
+  )
+target_link_libraries(lodepng_normal PRIVATE
+  lodepng
+)
+
+# Build the sandboxed main
+add_executable(lodepng_sandboxed
+  main_sandboxed.cc
+  sandbox.h
+)
+
+target_link_libraries(lodepng_sandboxed PRIVATE
+  lodepng_sapi
+  sapi::sapi
+  sapi::vars
+  sapi::status
+  glog::glog
+)
+
+# Build the unit tests
+include(GoogleTest)
+enable_testing()
+
+add_executable(main_unit_test
+  main_unit_test.cc
+)
+
+target_link_libraries(main_unit_test PRIVATE
+  lodepng_sapi
+  absl::memory
+  absl::strings
+  absl::time
+  glog::glog
+  sapi::flags
+  sapi::sapi
+  sapi::status
+  sapi::test_main
+  sapi::vars
+)
+gtest_discover_tests(main_unit_test)

oss-internship-2020/sapi_lodepng/examples/main.cc

@@ -12,22 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <stdio.h>
-#include <stdlib.h>
-
 #include <cassert>
 #include <filesystem>
 #include <iostream>
 
-#include "lodepng/lodepng.h"
-
-constexpr unsigned int img_len(unsigned int width, unsigned int height) {
-  return width * height * 4;
-}
+#include "../lodepng/lodepng.h"
 
 void generate_one_step(const std::string &images_path) {
-  unsigned int width = 512, height = 512;
-  std::vector<unsigned char> image(img_len(width, height));
+  constexpr unsigned int width = 512, height = 512,
+                         img_len = width * height * 4;
+  std::vector<unsigned char> image(img_len);
 
   for (int y = 0; y < height; ++y) {
     for (int x = 0; x < width; ++x) {
@@ -59,15 +53,16 @@ void generate_one_step(const std::string &images_path) {
   assert(height2 == height);
 
   // now, we can compare the values
-  for (size_t i = 0; i < img_len(width, height); ++i) {
+  for (size_t i = 0; i < img_len; ++i) {
     assert(image2[i] == image[i]);
   }
 }
 
 void generate_two_steps(const std::string &images_path) {
   // generate the values
-  unsigned int width = 512, height = 512;
-  std::vector<unsigned char> image(img_len(width, height));
+  constexpr unsigned int width = 512, height = 512,
+                         img_len = width * height * 4;
+  std::vector<unsigned char> image(img_len);
 
   for (int y = 0; y < height; ++y) {
     for (int x = 0; x < width; ++x) {
@@ -112,7 +107,7 @@ void generate_two_steps(const std::string &images_path) {
   assert(height2 == height);
 
   // compare values
-  for (size_t i = 0; i < img_len(width, height); ++i) {
+  for (size_t i = 0; i < img_len; ++i) {
     assert(image2[i] == image[i]);
   }
 }

oss-internship-2020/sapi_lodepng/examples/main_sandboxed.cc

@@ -12,15 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <stdio.h>
-#include <stdlib.h>
-
 #include <cassert>
-#include <cstdlib>
 #include <filesystem>
 #include <iostream>
 
-#include "lodepng_sapi.sapi.h"
 #include "sandbox.h"
 #include "sandboxed_api/util/flag.h"
 
@@ -29,13 +24,10 @@ ABSL_DECLARE_FLAG(string, sandbox2_danger_danger_permit_all_and_log);
 ABSL_FLAG(string, images_path, std::filesystem::current_path().string(),
           "path to the folder containing test images");
 
-constexpr unsigned int img_len(unsigned int width, unsigned int height) {
-  return width * height * 4;
-}
-
 void generate_one_step(SapiLodepngSandbox &sandbox, LodepngApi &api) {
-  unsigned int width = 512, height = 512;
-  std::vector<unsigned char> image(img_len(width, height));
+  constexpr unsigned int width = 512, height = 512,
+                         img_len = width * height * 4;
+  std::vector<unsigned char> image(img_len);
 
   for (int y = 0; y < height; ++y) {
     for (int x = 0; x < width; ++x) {
@@ -47,8 +39,7 @@ void generate_one_step(SapiLodepngSandbox &sandbox, LodepngApi &api) {
   }
 
   // encode the image
-  sapi::v::Array<unsigned char> sapi_image(image.data(),
-                                           img_len(width, height));
+  sapi::v::Array<unsigned char> sapi_image(image.data(), img_len);
   sapi::v::UInt sapi_width(width), sapi_height(height);
   std::string filename = "/output/out_generated1.png";
   sapi::v::ConstCStr sapi_filename(filename.c_str());
@@ -86,8 +77,7 @@ void generate_one_step(SapiLodepngSandbox &sandbox, LodepngApi &api) {
   // 4) transfer the memory to this process (this step is why we need
   // the pointer and the length)
   sapi::v::RemotePtr sapi_remote_out_ptr(sapi_image_ptr.GetValue());
-  sapi::v::Array<unsigned char> sapi_pixels(
-      img_len(sapi_width2.GetValue(), sapi_height2.GetValue()));
+  sapi::v::Array<unsigned char> sapi_pixels(img_len);
   sapi_pixels.SetRemote(sapi_remote_out_ptr.GetValue());
 
   assert(sandbox.TransferFromSandboxee(&sapi_pixels).ok());
@@ -97,15 +87,16 @@ void generate_one_step(SapiLodepngSandbox &sandbox, LodepngApi &api) {
   unsigned char *pixels_ptr = sapi_pixels.GetData();
 
   // now, we can compare the values
-  for (size_t i = 0; i < img_len(width, height); ++i) {
+  for (size_t i = 0; i < img_len; ++i) {
     assert(pixels_ptr[i] == image[i]);
   }
 }
 
 void generate_two_steps(SapiLodepngSandbox &sandbox, LodepngApi &api) {
   // generate the values
-  unsigned int width = 512, height = 512;
-  std::vector<unsigned char> image(img_len(width, height));
+  constexpr unsigned int width = 512, height = 512,
+                         img_len = width * height * 4;
+  std::vector<unsigned char> image(img_len);
 
   for (int y = 0; y < height; ++y) {
     for (int x = 0; x < width; ++x) {
@@ -117,8 +108,7 @@ void generate_two_steps(SapiLodepngSandbox &sandbox, LodepngApi &api) {
   }
 
   // encode the image into memory first
-  sapi::v::Array<unsigned char> sapi_image(image.data(),
-                                           img_len(width, height));
+  sapi::v::Array<unsigned char> sapi_image(image.data(), img_len);
   sapi::v::UInt sapi_width(width), sapi_height(height);
   std::string filename = "/output/out_generated2.png";
   sapi::v::ConstCStr sapi_filename(filename.c_str());
@@ -190,8 +180,7 @@ void generate_two_steps(SapiLodepngSandbox &sandbox, LodepngApi &api) {
 
   // transfer the pixels so they can be used
   sapi::v::RemotePtr sapi_remote_out_ptr3(sapi_png_ptr3.GetValue());
-  sapi::v::Array<unsigned char> sapi_pixels(
-      img_len(sapi_width2.GetValue(), sapi_height2.GetValue()));
+  sapi::v::Array<unsigned char> sapi_pixels(img_len);
 
   sapi_pixels.SetRemote(sapi_remote_out_ptr3.GetValue());
 
@@ -200,24 +189,18 @@ void generate_two_steps(SapiLodepngSandbox &sandbox, LodepngApi &api) {
   unsigned char *pixels_ptr = sapi_pixels.GetData();
 
   // compare values
-  for (size_t i = 0; i < img_len(width, height); ++i) {
+  for (size_t i = 0; i < img_len; ++i) {
     assert(pixels_ptr[i] == image[i]);
   }
 }
 
 int main(int argc, char *argv[]) {
   gflags::ParseCommandLineFlags(&argc, &argv, true);
-  absl::Status ret;
 
   std::string images_path(absl::GetFlag(FLAGS_images_path));
 
   SapiLodepngSandbox sandbox(images_path);
-  ret = sandbox.Init();
-  if (!ret.ok()) {
-    std::cerr << "error code: " << ret.code() << std::endl
-              << "message: " << ret.message() << std::endl;
-    exit(1);
-  }
+  assert(sandbox.Init().ok());
 
   LodepngApi api(&sandbox);
 
@@ -225,4 +208,4 @@ int main(int argc, char *argv[]) {
   generate_two_steps(sandbox, api);
 
   return EXIT_SUCCESS;
-}
+}

oss-internship-2020/sapi_lodepng/examples/main_unit_test.cc

@@ -12,15 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <stdlib.h>
-
 #include <filesystem>
 
-#include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "lodepng_sapi.sapi.h"
 #include "sandbox.h"
-#include "sandboxed_api/util/flag.h"
 #include "sandboxed_api/util/status_matchers.h"
 
 using sapi::IsOk;
@@ -29,10 +24,6 @@ using testing::NotNull;
 
 namespace {
 
-constexpr unsigned int img_len(unsigned int width, unsigned int height) {
-  return width * height * 4;
-}
-
 // use the current path
 std::string images_path = std::filesystem::current_path().string();
 
@@ -49,8 +40,9 @@ TEST(generate_image, encode_decode_compare_one_step) {
   LodepngApi api(&sandbox);
 
   // generate the values
-  unsigned int width = 512, height = 512;
-  std::vector<unsigned char> image(img_len(width, height));
+  constexpr unsigned int width = 512, height = 512,
+                         img_len = width * height * 4;
+  std::vector<unsigned char> image(img_len);
 
   for (int y = 0; y < height; ++y) {
     for (int x = 0; x < width; ++x) {
@@ -62,8 +54,7 @@ TEST(generate_image, encode_decode_compare_one_step) {
   }
 
   // encode the image
-  sapi::v::Array<unsigned char> sapi_image(image.data(),
-                                           img_len(width, height));
+  sapi::v::Array<unsigned char> sapi_image(image.data(), img_len);
   sapi::v::UInt sapi_width(width), sapi_height(height);
   std::string filename = "/output/out_generated1.png";
   sapi::v::ConstCStr sapi_filename(filename.c_str());
@@ -102,8 +93,7 @@ TEST(generate_image, encode_decode_compare_one_step) {
   // 4) transfer the memory to this process (this step is why we need
   // the pointer and the length)
   sapi::v::RemotePtr sapi_remote_out_ptr(sapi_image_ptr.GetValue());
-  sapi::v::Array<unsigned char> sapi_pixels(
-      img_len(sapi_width2.GetValue(), sapi_height2.GetValue()));
+  sapi::v::Array<unsigned char> sapi_pixels(img_len);
   sapi_pixels.SetRemote(sapi_remote_out_ptr.GetValue());
 
   ASSERT_THAT(sandbox.TransferFromSandboxee(&sapi_pixels), IsOk())
@@ -114,7 +104,7 @@ TEST(generate_image, encode_decode_compare_one_step) {
   unsigned char *pixels_ptr = sapi_pixels.GetData();
 
   // now, we can compare the values
-  for (size_t i = 0; i < img_len(width, height); ++i) {
+  for (size_t i = 0; i < img_len; ++i) {
     EXPECT_THAT(pixels_ptr[i], Eq(image[i])) << "Pixels values differ";
   }
 }
@@ -128,8 +118,9 @@ TEST(generate_image, encode_decode_compare_two_steps) {
   LodepngApi api(&sandbox);
 
   // generate the values
-  unsigned int width = 512, height = 512;
-  std::vector<unsigned char> image(img_len(width, height));
+  constexpr unsigned int width = 512, height = 512,
+                         img_len = width * height * 4;
+  std::vector<unsigned char> image(img_len);
 
   for (int y = 0; y < height; ++y) {
     for (int x = 0; x < width; ++x) {
@@ -141,8 +132,7 @@ TEST(generate_image, encode_decode_compare_two_steps) {
   }
 
   // encode the image into memory first
-  sapi::v::Array<unsigned char> sapi_image(image.data(),
-                                           img_len(width, height));
+  sapi::v::Array<unsigned char> sapi_image(image.data(), img_len);
   sapi::v::UInt sapi_width(width), sapi_height(height);
   std::string filename = "/output/out_generated2.png";
   sapi::v::ConstCStr sapi_filename(filename.c_str());
@@ -219,8 +209,7 @@ TEST(generate_image, encode_decode_compare_two_steps) {
 
   // transfer the pixels so they can be used
   sapi::v::RemotePtr sapi_remote_out_ptr3(sapi_png_ptr3.GetValue());
-  sapi::v::Array<unsigned char> sapi_pixels(
-      img_len(sapi_width2.GetValue(), sapi_height2.GetValue()));
+  sapi::v::Array<unsigned char> sapi_pixels(img_len);
 
   sapi_pixels.SetRemote(sapi_remote_out_ptr3.GetValue());
 
@@ -230,7 +219,7 @@ TEST(generate_image, encode_decode_compare_two_steps) {
   unsigned char *pixels_ptr = sapi_pixels.GetData();
 
   // compare values
-  for (size_t i = 0; i < img_len(width, height); ++i) {
+  for (size_t i = 0; i < img_len; ++i) {
     EXPECT_THAT(pixels_ptr[i], Eq(image[i])) << "Pixel values differ";
   }
 }

oss-internship-2020/sapi_lodepng/examples/sandbox.h

@@ -16,7 +16,6 @@
 #define SAPI_LODEPNG_SANDBOX_H_
 
 #include <syscall.h>
-#include <unistd.h>
 
 #include "lodepng_sapi.sapi.h"