Refactor extent writer to take filedescriptor in constructor

Functions which receive an instance of extent writer need to manually
pass fd to ExtentWriter via Init() call, which breaks separation of
concerns. It makes it hard for us to decouple InstallOp execution from
writing of data, as the execution unit must be aware of which fd to pass
to extent writer. In addition, many extents writer, such as snapshot
extent writer, simply ignores the fd parameter, which is a indication of
poor code structure.

To address the above issue, we pass FileDescriptorPtr via constructor if
needed. This way, whoever is "executing" InstallOps don't need to care
about where the output data is going, and whoever's writing the data
would be responsible for initializing an ExtentWriter.

Test: th
Change-Id: I6d1eabde085eefd55da9ecc0352d4a16ae458698

1 files changed, 2 insertions, 4 deletions

diff --git a/payload_generator/zip_unittest.cc b/payload_generator/zip_unittest.cc
index e357b156..10e899b0 100644
--- a/payload_generator/zip_unittest.cc
+++ b/payload_generator/zip_unittest.cc
@@ -33,7 +33,6 @@
 using chromeos_update_engine::test_utils::kRandomString;
 using google::protobuf::RepeatedPtrField;
 using std::string;
-using std::vector;
 
 namespace chromeos_update_engine {
 
@@ -50,8 +49,7 @@ class MemoryExtentWriter : public ExtentWriter {
   }
   ~MemoryExtentWriter() override = default;
 
-  bool Init(FileDescriptorPtr fd,
-            const RepeatedPtrField<Extent>& extents,
+  bool Init(const RepeatedPtrField<Extent>& extents,
             uint32_t block_size) override {
     return true;
   }
@@ -72,7 +70,7 @@ bool DecompressWithWriter(const brillo::Blob& in, brillo::Blob* out) {
   std::unique_ptr<ExtentWriter> writer(
       new W(std::make_unique<MemoryExtentWriter>(out)));
   // Init() parameters are ignored by the testing MemoryExtentWriter.
-  bool ok = writer->Init(nullptr, {}, 1);
+  bool ok = writer->Init({}, 1);
   ok = writer->Write(in.data(), in.size()) && ok;
   return ok;
 }