Merge pull request #170 from ebfe/cksum

add cksum

Makefile

@@ -5,6 +5,7 @@ PROGS       := \
   base64 \
   basename \
   cat \
+  cksum \
   comm \
   dirname \
   echo \

README.md

@@ -75,7 +75,6 @@ To do
 - chown-core
 - chown
 - chroot
-- cksum
 - copy
 - cp-hash
 - cp (some work done in ```dev``` branch)

cksum/cksum.rs

@@ -0,0 +1,122 @@
+#![crate_id(name="cksum", vers="1.0.0", author="Michael Gehring")]
+#![feature(macro_rules)]
+
+/*
+ * This file is part of the uutils coreutils package.
+ *
+ * (c) Michael Gehring <mg@ebfe.org>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+extern crate getopts;
+
+use std::io::{BufferedReader, EndOfFile, File, IoError, IoResult, print};
+use std::io::stdio::stdin;
+use std::os;
+
+#[path="../common/util.rs"]
+mod util;
+
+static NAME : &'static str = "cksum";
+static VERSION : &'static str = "1.0.0";
+
+fn crc_update(mut crc: u32, input: u8) -> u32 {
+    crc ^= input as u32 << 24;
+
+    for _ in range(0, 8) {
+        if crc & 0x80000000 != 0 {
+            crc <<= 1;
+            crc ^= 0x04c11db7;
+        } else {
+            crc <<= 1;
+        }
+    }
+
+    crc
+}
+
+fn crc_final(mut crc: u32, mut length: uint) -> u32 {
+    while length != 0 {
+        crc = crc_update(crc, length as u8);
+        length >>= 8;
+    }
+
+    !crc
+}
+
+fn cksum(fname: &str) -> IoResult<(u32, uint)> {
+    let mut crc = 0u32;
+    let mut size = 0u;
+
+    let mut rd = try!(open_file(fname));
+    loop {
+        match rd.read_byte() {
+            Ok(b) => {
+                crc = crc_update(crc, b);
+                size += 1;
+            }
+            Err(err) =>  {
+                return match err {
+                    IoError{kind: k, ..} if k == EndOfFile => Ok((crc_final(crc, size), size)),
+                    _ => Err(err),
+                }
+            }
+        }
+    }
+}
+
+fn open_file(name: &str) -> IoResult<Box<Reader>> {
+    match name {
+        "-" => Ok(box stdin() as Box<Reader>),
+        _   => {
+            let f = try!(File::open(&Path::new(name)));
+            Ok(box BufferedReader::new(f) as Box<Reader>)
+        }
+    }
+}
+
+pub fn main() {
+    let opts = [
+        getopts::optflag("h", "help", "display this help and exit"),
+        getopts::optflag("V", "version", "output version information and exit"),
+    ];
+
+    let matches = match getopts::getopts(os::args().tail(), opts) {
+        Ok(m) => m,
+        Err(err) => fail!("{}", err.to_err_msg()),
+    };
+
+    if matches.opt_present("help") {
+        println!("{} {}", NAME, VERSION);
+        println!("");
+        println!("Usage:");
+        println!("  {} [OPTIONS] [FILE]...", NAME);
+        println!("");
+        print(getopts::usage("Print CRC and size for each file.", opts.as_slice()));
+        return;
+    }
+
+    if matches.opt_present("version") {
+        println!("{} {}", NAME, VERSION);
+        return;
+    }
+
+    let files = matches.free;
+
+    if files.is_empty() {
+        match cksum("-") {
+            Ok((crc, size)) => println!("{} {}", crc, size),
+            Err(err) => show_error!(2, "{}", err),
+        }
+        return
+    }
+
+    for fname in files.iter() {
+        match cksum(*fname) {
+            Ok((crc, size)) => println!("{} {} {}", crc, size, fname),
+            Err(err) => show_error!(2, "'{}' {}", fname, err),
+        }
+    }
+}