move compute_file_csum to src/tools.rs

src/tools.rs

@@ -5,7 +5,7 @@ use std::any::Any;
 use std::collections::HashMap;
 use std::hash::BuildHasher;
 use std::fs::File;
-use std::io::{self, BufRead, ErrorKind, Read};
+use std::io::{self, BufRead, ErrorKind, Read, Seek, SeekFrom};
 use std::os::unix::io::RawFd;
 use std::path::Path;
 
@@ -563,3 +563,32 @@ pub fn strip_ascii_whitespace(line: &[u8]) -> &[u8] {
         None => &[],
     }
 }
+
+/// Seeks to start of file and computes the SHA256 hash
+pub fn compute_file_csum(file: &mut File) -> Result<([u8; 32], u64), Error> {
+
+    file.seek(SeekFrom::Start(0))?;
+
+    let mut hasher = openssl::sha::Sha256::new();
+    let mut buffer = proxmox::tools::vec::undefined(256*1024);
+    let mut size: u64 = 0;
+
+    loop {
+        let count = match file.read(&mut buffer) {
+            Ok(count) => count,
+            Err(ref err) if err.kind() == std::io::ErrorKind::Interrupted => {
+                continue;
+            }
+            Err(err) => return Err(err.into()),
+        };
+        if count == 0 {
+            break;
+        }
+        size += count as u64;
+        hasher.update(&buffer[..count]);
+    }
+
+    let csum = hasher.finish();
+
+    Ok((csum, size))
+}