Make dynamic partition control android return a writable fd

We can return a FileDescriptor object, which encapsulates logic needed
to write to a COW. This way, filesystem verfication action can use the
turend value directly for computing verity and hash the partition.

Test: th
Change-Id: Iafe9699ef0cc15961641fc94f8ad2820230a56e1

1 files changed, 3 insertions, 1 deletions

diff --git a/common/dynamic_partition_control_interface.h b/common/dynamic_partition_control_interface.h
index da279329..d5e1d8d2 100644
--- a/common/dynamic_partition_control_interface.h
+++ b/common/dynamic_partition_control_interface.h
@@ -165,7 +165,9 @@ class DynamicPartitionControlInterface {
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
       bool is_append = false) = 0;
-  virtual FileDescriptorPtr OpenCowReader(
+  // Open a general purpose FD capable to reading and writing to COW. Note that
+  // writes must be block aligned.
+  virtual FileDescriptorPtr OpenCowFd(
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
       bool is_append = false) = 0;