added some comments in main_unit_test.cc and .gitignore

oss-internship-2020/sapi_lodepng/.gitignore

@@ -0,0 +1 @@
+build/

oss-internship-2020/sapi_lodepng/main_unit_test.cc

@@ -47,7 +47,8 @@ TEST(generate_image, encode_decode_compare_one_step) {
   SapiLodepngSandbox sandbox(images_path);
   ASSERT_TRUE(sandbox.Init().ok());
   LodepngApi api(&sandbox);
-  // std::cout << "path = " << images_path << std::endl;
+
+  // generate the values
   unsigned int width = 512, height = 512;
   unsigned char *image = (unsigned char *)malloc(width * height * 4);
 
@@ -60,14 +61,12 @@ TEST(generate_image, encode_decode_compare_one_step) {
     }
   }
 
+  // encode the image
   sapi::v::Array<unsigned char> sapi_image(image, width * height * 4);
   sapi::v::UInt sapi_width(width), sapi_height(height);
   std::string filename = images_path + "/out_generated1.png";
   sapi::v::ConstCStr sapi_filename(filename.c_str());
 
-  //   ASSERT_TRUE(sandbox.Allocate(&image_).ok());
-  //   ASSERT_TRUE(sandbox.TransferToSandboxee(&image_).ok());
-
   sapi::StatusOr<unsigned int> result = api.lodepng_encode32_file(
       sapi_filename.PtrBefore(), sapi_image.PtrBefore(), sapi_width.GetValue(),
       sapi_height.GetValue());
@@ -75,6 +74,9 @@ TEST(generate_image, encode_decode_compare_one_step) {
   ASSERT_TRUE(result.ok());
   ASSERT_EQ(result.value(), 0);
 
+  // after the image has been encoded, decode it to check that the
+  // pixel values are the same
+
   sapi::v::UInt sapi_width2, sapi_height2;
   sapi::v::IntBase<unsigned char *> sapi_image_ptr(0);
 
@@ -88,6 +90,10 @@ TEST(generate_image, encode_decode_compare_one_step) {
   ASSERT_EQ(sapi_width2.GetValue(), width);
   ASSERT_EQ(sapi_height2.GetValue(), height);
 
+  // the pixels have been allocated inside the sandboxed process
+  // memory, so we need to transfer them to this process.
+  // Transferring the memory has the following steps:
+  // 1) define a RemotePtr variable
   sapi::v::RemotePtr sapi_remote_out_ptr(
       reinterpret_cast<void *>(sapi_image_ptr.GetValue()));
   sapi::v::Array<unsigned char> sapi_pixels(sapi_width2.GetValue() *
@@ -96,8 +102,11 @@ TEST(generate_image, encode_decode_compare_one_step) {
 
   ASSERT_TRUE(sandbox.TransferFromSandboxee(&sapi_pixels).ok());
 
+  // after the memory has been transferred, we can access it
+  // using the GetData function
   unsigned char *pixels_ptr = sapi_pixels.GetData();
 
+  // now, we can compare the values
   for (size_t i = 0; i < width * height * 4; ++i) {
     ASSERT_EQ(pixels_ptr[i], image[i]);
   }
@@ -107,13 +116,13 @@ TEST(generate_image, encode_decode_compare_one_step) {
 
 // similar to the previous test, only that we use encoding by saving the data in
 // memory and then writing it to the file and decoding by first decoding in
-// memory and then getting the pixels.
+// memory and then getting the actual pixel values.
 TEST(generate_image, encode_decode_compare_two_step) {
   SapiLodepngSandbox sandbox(images_path);
   ASSERT_TRUE(sandbox.Init().ok());
   LodepngApi api(&sandbox);
 
-  // generate the image
+  // generate the values
   unsigned int width = 512, height = 512;
   unsigned char *image = (unsigned char *)malloc(width * height * 4);
 
@@ -126,6 +135,7 @@ TEST(generate_image, encode_decode_compare_two_step) {
     }
   }
 
+  // encode the image into memory first
   sapi::v::Array<unsigned char> sapi_image(image, width * height * 4);
   sapi::v::UInt sapi_width(width), sapi_height(height);
   std::string filename = images_path + "/out_generated2.png";
@@ -145,7 +155,9 @@ TEST(generate_image, encode_decode_compare_two_step) {
 
   std::cout << "sapi_pngsize = " << sapi_pngsize.GetValue() << std::endl;
 
-  // transfer the array from the sandboxed process
+  // the new array (pointed to by sapi_png_ptr) is allocated
+  // inside the sandboxed process so we need to transfer it to this
+  // process
 
   sapi::v::RemotePtr sapi_remote_out_ptr(
       reinterpret_cast<void *>(sapi_png_ptr.GetValue()));
@@ -163,12 +175,13 @@ TEST(generate_image, encode_decode_compare_two_step) {
   ASSERT_TRUE(result.ok());
   ASSERT_EQ(result.value(), 0);
 
-  // now, decode the image using the 2 steps
+  // now, decode the image using the 2 steps in order to compare the values
 
   sapi::v::UInt sapi_width2, sapi_height2;
   sapi::v::IntBase<unsigned char *> sapi_png_ptr2(0);
   sapi::v::ULLong sapi_pngsize2;
 
+  // load the file in memory
   result =
       api.lodepng_load_file(sapi_png_ptr2.PtrBoth(), sapi_pngsize2.PtrBoth(),
                             sapi_filename.PtrBefore());
@@ -178,6 +191,7 @@ TEST(generate_image, encode_decode_compare_two_step) {
 
   ASSERT_EQ(sapi_pngsize.GetValue(), sapi_pngsize2.GetValue());
 
+  // transfer the png array
   sapi::v::RemotePtr sapi_remote_out_ptr2(
       reinterpret_cast<void *>(sapi_png_ptr2.GetValue()));
   sapi::v::Array<unsigned char> sapi_png_array2(sapi_pngsize2.GetValue());
@@ -186,9 +200,9 @@ TEST(generate_image, encode_decode_compare_two_step) {
 
   ASSERT_TRUE(sandbox.TransferFromSandboxee(&sapi_png_array2).ok());
 
-  // after the file is loaded, decode it
+  // after the file is loaded, decode it so we have access to the values
+  // directly
   sapi::v::IntBase<unsigned char *> sapi_png_ptr3(0);
-  //   sapi::v::UInt sapi_width2, sapi_height2;
   result = api.lodepng_decode32(
       sapi_png_ptr3.PtrBoth(), sapi_width2.PtrBoth(), sapi_height2.PtrBoth(),
       sapi_png_array2.PtrBefore(), sapi_pngsize2.GetValue());
@@ -196,9 +210,6 @@ TEST(generate_image, encode_decode_compare_two_step) {
   ASSERT_TRUE(result.ok());
   ASSERT_EQ(result.value(), 0);
 
-  std::cout << "w2 = " << sapi_width2.GetValue()
-            << " h2 = " << sapi_height2.GetValue() << std::endl;
-
   ASSERT_EQ(sapi_width2.GetValue(), width);
   ASSERT_EQ(sapi_height2.GetValue(), height);