tool: move file_hash() to utils module

rust/tool/src/pe.rs

@@ -6,13 +6,10 @@ use std::process::Command;
 
 use anyhow::{Context, Result};
 use goblin::pe::PE;
-use sha2::{Digest, Sha256};
 use tempfile::TempDir;
 
 use crate::esp::EspGenerationPaths;
-use crate::utils::{tmpname, SecureTempDirExt};
-
-type Hash = sha2::digest::Output<Sha256>;
+use crate::utils::{file_hash, tmpname, SecureTempDirExt};
 
 /// Assemble a lanzaboote image.
 #[allow(clippy::too_many_arguments)]
@@ -61,11 +58,6 @@ pub fn lanzaboote_image(
     Ok(image_path)
 }
 
-/// Compute the SHA 256 hash of a file.
-fn file_hash(file: &Path) -> Result<Hash> {
-    Ok(Sha256::digest(fs::read(file)?))
-}
-
 /// Take a PE binary stub and attach sections to it.
 ///
 /// The resulting binary is then written to a newly created file at the provided output path.

rust/tool/src/utils.rs

@@ -6,6 +6,7 @@ use std::os::unix::fs::OpenOptionsExt;
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context, Result};
+use sha2::{Digest, Sha256};
 use tempfile::TempDir;
 
 /// The number of random alphanumeric characters in the tempfiles.
@@ -64,3 +65,12 @@ pub fn tmpname() -> OsString {
     }
     buf
 }
+
+type Hash = sha2::digest::Output<Sha256>;
+
+/// Compute the SHA 256 hash of a file.
+pub fn file_hash(file: &Path) -> Result<Hash> {
+    Ok(Sha256::digest(fs::read(file).with_context(|| {
+        format!("Failed to read file to hash: {file:?}")
+    })?))
+}