src/fsverity: split out FsVerityHashValue and impls

Split FsVerityHashValue and its two implementations out to a separate
file.  Right now it's not a lot of code, but it's going to get
substantially larger in the next commit.

Signed-off-by: Allison Karlitskaya <[email protected]>

Author: allisonkarlitskaya

src/fsverity/hashvalue.rs

@@ -0,0 +1,27 @@
+use sha2::{digest::FixedOutputReset, digest::Output, Digest, Sha256, Sha512};
+
+pub trait FsVerityHashValue
+where
+    Self: Eq + AsRef<[u8]> + Clone,
+    Self: From<Output<Self::Digest>>,
+{
+    type Digest: Digest + FixedOutputReset + std::fmt::Debug;
+    const ALGORITHM: u8;
+    const EMPTY: Self;
+}
+
+pub type Sha256HashValue = [u8; 32];
+
+impl FsVerityHashValue for Sha256HashValue {
+    type Digest = Sha256;
+    const ALGORITHM: u8 = 1;
+    const EMPTY: Self = [0; 32];
+}
+
+pub type Sha512HashValue = [u8; 64];
+
+impl FsVerityHashValue for Sha512HashValue {
+    type Digest = Sha512;
+    const ALGORITHM: u8 = 2;
+    const EMPTY: Self = [0; 64];
+}

src/fsverity/mod.rs

@@ -1,36 +1,12 @@
 mod digest;
+mod hashvalue;
 mod ioctl;
 
 use std::{io::Error, os::fd::AsFd};
 
-use sha2::{digest::FixedOutputReset, digest::Output, Digest, Sha256, Sha512};
 use thiserror::Error;
 
-pub trait FsVerityHashValue
-where
-    Self: Eq + AsRef<[u8]> + Clone,
-    Self: From<Output<Self::Digest>>,
-{
-    type Digest: Digest + FixedOutputReset + std::fmt::Debug;
-    const ALGORITHM: u8;
-    const EMPTY: Self;
-}
-
-pub type Sha256HashValue = [u8; 32];
-
-impl FsVerityHashValue for Sha256HashValue {
-    type Digest = Sha256;
-    const ALGORITHM: u8 = 1;
-    const EMPTY: Self = [0; 32];
-}
-
-pub type Sha512HashValue = [u8; 64];
-
-impl FsVerityHashValue for Sha512HashValue {
-    type Digest = Sha512;
-    const ALGORITHM: u8 = 2;
-    const EMPTY: Self = [0; 64];
-}
+pub use hashvalue::{FsVerityHashValue, Sha256HashValue, Sha512HashValue};
 
 /// Measuring fsverity failed.
 #[derive(Error, Debug)] // can't derive PartialEq because of std::io::Error