vendor/sha2/examples/sha256sum.rs

   1 use sha2::{Digest, Sha256};
   2 use std::env;
   3 use std::fs;
   4 use std::io::{self, Read};
   5
   6 const BUFFER_SIZE: usize = 1024;
   7
   8 /// Print digest result as hex string and name pair
   9 fn print_result(sum: &[u8], name: &str) {
  10     for byte in sum {
  11         print!("{:02x}", byte);
  12     }
  13     println!("\t{}", name);
  14 }
  15
  16 /// Compute digest value for given `Reader` and print it
  17 /// On any error simply return without doing anything
  18 fn process<D: Digest + Default, R: Read>(reader: &mut R, name: &str) {
  19     let mut sh = D::default();
  20     let mut buffer = [0u8; BUFFER_SIZE];
  21     loop {
  22         let n = match reader.read(&mut buffer) {
  23             Ok(n) => n,
  24             Err(_) => return,
  25         };
  26         sh.update(&buffer[..n]);
  27         if n == 0 || n < BUFFER_SIZE {
  28             break;
  29         }
  30     }
  31     print_result(&sh.finalize(), name);
  32 }
  33
  34 fn main() {
  35     let args = env::args();
  36     // Process files listed in command line arguments one by one
  37     // If no files provided process input from stdin
  38     if args.len() > 1 {
  39         for path in args.skip(1) {
  40             if let Ok(mut file) = fs::File::open(&path) {
  41                 process::<Sha256, _>(&mut file, &path);
  42             }
  43         }
  44     } else {
  45         process::<Sha256, _>(&mut io::stdin(), "-");
  46     }
  47 }