authfs: refine/rename trait ReadOnlyDataByChunk
- ReadOnlyDataByChunk is renamed to ReadByChunk
- `fn read_chunk` now takes a fixed-size array of chunk size
- Behavior change:
1. Reading beyond file size now should not crash, and should return 0.
2. `read_chunk` should return a full chunk unless it's the last
(wasn't clearly defined previously).
Bug: 181674212
Bug: 182173887
Test: atest
Change-Id: I7017b5ed986d0bfc594da58a1ed9f59ac555643e
diff --git a/authfs/src/file.rs b/authfs/src/file.rs
index 89fbd9d..9ff8ea5 100644
--- a/authfs/src/file.rs
+++ b/authfs/src/file.rs
@@ -6,6 +6,8 @@
use std::io;
+use crate::common::CHUNK_SIZE;
+
use authfs_aidl_interface::aidl::com::android::virt::fs::IVirtFdService;
use authfs_aidl_interface::binder::{get_interface, Strong};
@@ -15,14 +17,15 @@
get_interface(&service_name).expect("Cannot reach authfs_fd_server binder service")
}
-/// A trait for reading data by chunks. The data is assumed readonly and has fixed length. Chunks
-/// can be read by specifying the chunk index. Only the last chunk may have incomplete chunk size.
-pub trait ReadOnlyDataByChunk {
- /// Read the `chunk_index`-th chunk to `buf`. Each slice/chunk has size `CHUNK_SIZE` except for
- /// the last one, which can be an incomplete chunk. `buf` is currently required to be large
- /// enough to hold a full chunk of data. Reading beyond the file size (including empty file)
- /// will crash.
- fn read_chunk(&self, chunk_index: u64, buf: &mut [u8]) -> io::Result<usize>;
+pub type ChunkBuffer = [u8; CHUNK_SIZE as usize];
+
+/// A trait for reading data by chunks. Chunks can be read by specifying the chunk index. Only the
+/// last chunk may have incomplete chunk size.
+pub trait ReadByChunk {
+ /// Reads the `chunk_index`-th chunk to a `ChunkBuffer`. Returns the size read, which has to be
+ /// `CHUNK_SIZE` except for the last incomplete chunk. Reading beyond the file size (including
+ /// empty file) should return 0.
+ fn read_chunk(&self, chunk_index: u64, buf: &mut ChunkBuffer) -> io::Result<usize>;
}
/// A trait to write a buffer to the destination at a given offset. The implementation does not