Add: compute SHA256

1 files changed, 37 insertions, 1 deletions

diff --git a/src/main.rs b/src/main.rs
index 20499d8..cac0646 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,7 @@ use std::io;
 use std::fs;
 use std::os::unix::fs::PermissionsExt;
 use std::os::linux::fs::MetadataExt;
+use std::io::prelude::*;
 
 extern crate users;
 
@@ -10,6 +11,11 @@ extern crate chrono;
 use chrono::prelude::DateTime;
 use chrono::{Utc};
 
+extern crate crypto_hash;
+use crypto_hash::{Algorithm, Hasher};
+
+extern crate hex;
+
 mod fswalk;
 use fswalk::DirTree;
 
@@ -38,7 +44,7 @@ fn write_info(path: &str, meta: &fs::Metadata) {
     println!("Username: {}", format_username(meta));
     println!("Gid: {}", format_gid(meta));
     println!("Group: {}", format_group(meta));
-    println!("SHA256: xxx");
+    println!("SHA256: {}", format_sha256(path));
     println!("");
 }
 
@@ -102,3 +108,33 @@ fn format_group(meta: &fs::Metadata) -> String {
         format!("unknown group")
     }
 }
+
+
+fn format_sha256(filename: &str) -> String {
+    let mut ok = true;
+    let mut hasher = Hasher::new(Algorithm::SHA256);
+    if let Ok(file) = fs::File::open(filename) {
+        let mut reader = io::BufReader::new(file);
+        let mut buf = [0; 1024 * 1024];
+        let mut done = false;
+        while ok && !done{
+            if let Ok(n) = reader.read(&mut buf) {
+                if n == 0 {
+                    done = true;
+                } else if let Err(_) = hasher.write(&buf[0..n]) {
+                    ok = false;
+                }
+            } else {
+                ok = false;
+            }
+        }
+    } else {
+        ok = false;
+    }
+    if ok {
+        let digest = hasher.finish();
+        hex::encode(digest)
+    } else {
+        format!("can't read file")
+    }
+}