commit 3c327d2996ebbfc52c9711fbb3f55de77feae316
author Jiyong Park <jiyong@google.com> Tue Jun 08 20:51:54 2021 +0900
committer Jiyong Park <jiyong@google.com> Tue Jun 08 21:29:59 2021 +0900
tree 053d0e4e6873dc2b2a1c7b0e2d0758f090b802d6
parent e8c63687760d6a0a242f22a4d0f5992cac7b0844

apkdmverity: use data_model crate for better handling of C structs

The data_model:DataInit trait provides methods for converting between
a C struct and an array of the same size, allowing us to drop the hand
crafted as_u8_slice methods.

Bug: N/A
Test: cargo test
Test: atest apkdmverity.test
Change-Id: Iaff910f0a638e91a428777b94dc6fb0b5fe53831

apkverity/src/dm/sys.rs

diff --git a/apkverity/src/dm/sys.rs b/apkverity/src/dm/sys.rs
index f623a2b..e709bf0 100644
--- a/apkverity/src/dm/sys.rs
+++ b/apkverity/src/dm/sys.rs
@@ -15,6 +15,7 @@
  */
 
 use bitflags::bitflags;
+use data_model::DataInit;
 
 // UAPI for device mapper can be found at include/uapi/linux/dm-ioctl.h
 
@@ -43,6 +44,7 @@
 }
 
 #[repr(C)]
+#[derive(Copy, Clone)]
 pub struct DmIoctl {
     pub version: [u32; 3],
     pub data_size: u32,
@@ -58,6 +60,9 @@
     pub data: [u8; 7],
 }
 
+// SAFETY: C struct is safe to be initialized from raw data
+unsafe impl DataInit for DmIoctl {}
+
 pub const DM_VERSION_MAJOR: u32 = 4;
 pub const DM_VERSION_MINOR: u32 = 0;
 pub const DM_VERSION_PATCHLEVEL: u32 = 0;

apkverity/src/dm/verity.rs

diff --git a/apkverity/src/dm/verity.rs b/apkverity/src/dm/verity.rs
index 950b26e..3a49ee2 100644
--- a/apkverity/src/dm/verity.rs
+++ b/apkverity/src/dm/verity.rs
@@ -19,6 +19,7 @@
 // which is then given to `DeviceMapper` to create a mapper device.
 
 use anyhow::{bail, Context, Result};
+use data_model::DataInit;
 use std::io::Write;
 use std::mem::size_of;
 use std::path::Path;
@@ -55,7 +56,7 @@
 pub struct DmVerityTarget(Box<[u8]>);
 
 impl DmVerityTarget {
-    pub fn as_u8_slice(&self) -> &[u8] {
+    pub fn as_slice(&self) -> &[u8] {
         self.0.as_ref()
     }
 }
@@ -188,7 +189,7 @@
         header.next = aligned_size as u32;
 
         let mut buf = Vec::with_capacity(aligned_size);
-        buf.write_all(header.as_u8_slice())?;
+        buf.write_all(header.as_slice())?;
         buf.write_all(body.as_bytes())?;
         buf.write_all(vec![0; padding].as_slice())?;
         Ok(DmVerityTarget(buf.into_boxed_slice()))