Starting implementation of a Writer

src/bin/cksummer.rs

@@ -2,19 +2,18 @@ extern crate zip;
 
 fn main()
 {
-    let stdin = std::io::stdin();
-    let mut crc_reader = zip::crc32::Crc32Reader::new(stdin);
-
+    let mut stdin = std::io::stdin();
+    let mut crc = 0u32;
     let mut buf = [0u8, ..4096];
+
     loop
     {
-        match crc_reader.read(&mut buf)
+        match stdin.read(&mut buf)
         {
             Err(_) => break,
-            _ => {},
+            Ok(n) => { crc = zip::crc32::crc32(crc, buf.slice_to(n)); },
         }
     }
-    crc_reader.read_to_end().unwrap();
 
-    println!("{:x}", crc_reader.get_checksum());
+    println!("{:x}", crc);
 }

src/crc32.rs

@@ -46,7 +46,7 @@ static CRC32_TABLE : [u32, ..256] = [
 	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
 ];
 
-fn crc32(original: u32, buf: &[u8]) -> u32
+pub fn crc32(original: u32, buf: &[u8]) -> u32
 {
     let mut crc = original ^ !0u32;
 
@@ -62,43 +62,24 @@ pub struct Crc32Reader<R>
 {
     inner: R,
     crc: u32,
-    check: Option<u32>,
+    check: u32,
 }
 
 impl<R: Reader> Crc32Reader<R>
 {
-    pub fn new(inner: R) -> Crc32Reader<R>
+    pub fn new(inner: R, checksum: u32) -> Crc32Reader<R>
     {
         Crc32Reader
         {
             inner: inner,
             crc: 0,
-            check: None,
+            check: checksum,
         }
     }
 
-    pub fn new_with_check(inner: R, checksum: u32) -> Crc32Reader<R>
-    {
-        Crc32Reader
-        {
-            inner: inner,
-            crc: 0,
-            check: Some(checksum),
-        }
-    }
-
-    pub fn get_checksum(&self) -> u32
-    {
-        self.crc
-    }
-
     fn check_matches(&self) -> bool
     {
-        match self.check
-        {
-            None => true,
-            Some(check) => check == self.crc
-        }
+        self.check == self.crc
     }
 }
 

src/lib.rs

@@ -9,3 +9,4 @@ mod spec;
 pub mod crc32;
 pub mod reader;
 pub mod types;
+pub mod writer;

src/reader.rs

@@ -78,7 +78,7 @@ impl<T: Reader+Seek> ZipReader<T>
             types::Stored =>
             {
                 box
-                    Crc32Reader::new_with_check(
+                    Crc32Reader::new(
                         limit_reader,
                         file.crc32)
                     as Box<Reader>
@@ -87,7 +87,7 @@ impl<T: Reader+Seek> ZipReader<T>
             {
                 let deflate_reader = limit_reader.deflate_decode();
                 box
-                    Crc32Reader::new_with_check(
+                    Crc32Reader::new(
                         deflate_reader,
                         file.crc32)
                     as Box<Reader>

src/spec.rs

@@ -82,6 +82,19 @@ pub fn central_header_to_zip_file<R: Reader+Seek>(reader: &mut R) -> IoResult<Zi
     Ok(result)
 }
 
+pub fn write_local_file_header<T: Writer>(writer: &mut T, file: &ZipFile) -> IoResult<()>
+{
+    try!(writer.write_le_u32(LOCAL_FILE_HEADER_SIGNATURE));
+    try!(writer.write_le_u16(20));
+    let flag = if file.encrypted { 1 } else { 0 };
+    try!(writer.write_le_u16(flag));
+    try!(writer.write_le_u16(file.compression_method as u16));
+    try!(writer.write_le_u16(util::tm_to_msdos_time(file.last_modified_time)));
+    // ...
+
+    Ok(())
+}
+
 pub struct CentralDirectoryEnd
 {
     pub number_of_disks: u16,

src/util.rs

@@ -27,6 +27,11 @@ pub fn msdos_datetime_to_tm(time: u16, date: u16) -> Tm
     }
 }
 
+pub fn tm_to_msdos_time(time: Tm) -> u16
+{
+    ((time.tm_sec >> 2) | (time.tm_min << 5) | (time.tm_hour << 11)) as u16
+}
+
 pub struct RefMutReader<'a, R:'a>
 {
     inner: RefMut<'a, R>,

src/writer.rs

@@ -0,0 +1,144 @@
+use types;
+use types::ZipFile;
+use spec;
+use std::default::Default;
+use std::io;
+use std::io::{IoResult, IoError};
+use std::mem;
+use time;
+use flate2;
+use flate2::FlateWriter;
+use flate2::writer::DeflateEncoder;
+
+enum GenericZipWriter<W>
+{
+    Invalid,
+    Storer(W),
+    Deflater(DeflateEncoder<W>),
+}
+
+pub struct ZipWriter<W>
+{
+    inner: GenericZipWriter<W>,
+    files: Vec<ZipFile>,
+    stats: ZipWriterStats,
+}
+
+#[deriving(Default)]
+struct ZipWriterStats
+{
+    crc32: u32,
+    start: u64,
+    bytes_written: u64,
+}
+
+impl<W: Writer+Seek> Writer for ZipWriter<W>
+{
+    fn write(&mut self, buf: &[u8]) -> IoResult<()>
+    {
+        if self.files.len() == 0 { return Err(IoError { kind: io::OtherIoError, desc: "No file has been started", detail: None, }) }
+        self.stats.update(buf);
+        match self.inner
+        {
+            Storer(ref mut w) => w.write(buf),
+            Deflater(ref mut w) => w.write(buf),
+            Invalid => Err(IoError { kind: io::OtherIoError, desc: "The writer has previously failed", detail: None }),
+        }
+    }
+}
+
+impl ZipWriterStats
+{
+    fn update(&mut self, buf: &[u8])
+    {
+        self.crc32 = ::crc32::crc32(self.crc32, buf);
+        self.bytes_written += buf.len() as u64;
+    }
+}
+
+impl<W: Writer+Seek> ZipWriter<W>
+{
+    pub fn new(inner: W) -> ZipWriter<W>
+    {
+        ZipWriter
+        {
+            inner: Storer(inner),
+            files: Vec::new(),
+            stats: Default::default(),
+        }
+    }
+
+    pub fn start_new_file(&mut self, name: &[u8], compression: types::CompressionMethod) -> IoResult<()>
+    {
+        try!(self.finish_file());
+
+        let writer = match self.inner
+        {
+            Storer(ref mut r) => r,
+            _ => fail!("Should have switched to stored first"),
+        };
+        let header_start = try!(writer.tell());
+        try!(writer.seek(30 + name.len() as i64, io::SeekCur));
+        self.stats.start = header_start + 30 + name.len() as u64;
+
+        self.files.push(ZipFile
+        {
+            encrypted: false,
+            compression_method: compression,
+            last_modified_time: time::now(),
+            crc32: 0,
+            compressed_size: 0,
+            uncompressed_size: 0,
+            file_name: Vec::from_slice(name),
+            file_comment: Vec::new(),
+            data_start: self.stats.start,
+        });
+
+        Ok(())
+    }
+
+    fn finish_file(&mut self) -> IoResult<()>
+    {
+        try!(self.inner.switch_to(types::Stored));
+        let writer = match self.inner
+        {
+            Storer(ref mut r) => r,
+            _ => fail!("Should have switched to stored first"),
+        };
+
+        let file = match self.files.mut_last()
+        {
+            None => return Ok(()),
+            Some(f) => f,
+        };
+        file.crc32 = self.stats.crc32;
+        file.uncompressed_size = self.stats.bytes_written;
+        file.compressed_size = try!(writer.tell()) - self.stats.start;
+
+        // write header
+        try!(spec::write_local_file_header(writer, file));
+        Ok(())
+    }
+}
+
+impl<W: Writer+Seek> GenericZipWriter<W>
+{
+    fn switch_to(&mut self, compression: types::CompressionMethod) -> IoResult<()>
+    {
+        let bare = match mem::replace(self, Invalid)
+        {
+            Storer(w) => w,
+            Deflater(w) => try!(w.finish()),
+            Invalid => return Err(IoError { kind: io::OtherIoError, desc: "The writer has previously failed", detail: None }),
+        };
+
+        *self = match compression
+        {
+            types::Stored => Storer(bare),
+            types::Deflated => Deflater(bare.deflate_encode(flate2::Default)),
+            _ => return Err(IoError { kind: io::OtherIoError, desc: "Unsupported compression requested", detail: None }),
+        };
+
+        Ok(())
+    }
+}