Merge pull request rust-lang#135 from est31/master

Two little improvements

src/gz/bufread.rs

@@ -53,7 +53,7 @@ fn read_gz_header<R: Read>(r: &mut R) -> io::Result<GzHeader> {
     let mtime = ((header[4] as u32) << 0) | ((header[5] as u32) << 8) | ((header[6] as u32) << 16) |
         ((header[7] as u32) << 24);
     let _xfl = header[8];
-    let _os = header[9];
+    let os = header[9];
 
     let extra = if flg & FEXTRA != 0 {
         let xlen = try!(read_le_u16(&mut crc_reader));
@@ -104,6 +104,7 @@ fn read_gz_header<R: Read>(r: &mut R) -> io::Result<GzHeader> {
         extra: extra,
         filename: filename,
         comment: comment,
+        operating_system: os,
         mtime: mtime,
     })
 }

src/gz/mod.rs

@@ -19,11 +19,12 @@ pub mod write;
 ///
 /// The header can contain metadata about the file that was compressed, if
 /// present.
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Clone, Debug)]
 pub struct GzHeader {
     extra: Option<Vec<u8>>,
     filename: Option<Vec<u8>>,
     comment: Option<Vec<u8>>,
+    operating_system: u8,
     mtime: u32,
 }
 
@@ -43,6 +44,14 @@ impl GzHeader {
         self.comment.as_ref().map(|s| &s[..])
     }
 
+    /// Returns the `operating_system` field of this gzip stream's header.
+    ///
+    /// There are predefined values for various operating systems.
+    /// 255 means that the value is unknown.
+    pub fn operating_system(&self) -> u8 {
+        self.operating_system
+    }
+
     /// This gives the most recent modification time of the original file being compressed.
     ///
     /// The time is in Unix format, i.e., seconds since 00:00:00 GMT, Jan. 1, 1970.
@@ -105,6 +114,7 @@ pub struct GzBuilder {
     extra: Option<Vec<u8>>,
     filename: Option<CString>,
     comment: Option<CString>,
+    operating_system: Option<u8>,
     mtime: u32,
 }
 
@@ -115,6 +125,7 @@ impl GzBuilder {
             extra: None,
             filename: None,
             comment: None,
+            operating_system: None,
             mtime: 0,
         }
     }
@@ -125,6 +136,12 @@ impl GzBuilder {
         self
     }
 
+    /// Configure the `operating_system` field in the gzip header.
+    pub fn operating_system(mut self, os: u8) -> GzBuilder {
+        self.operating_system = Some(os);
+        self
+    }
+
     /// Configure the `extra` field in the gzip header.
     pub fn extra<T: Into<Vec<u8>>>(mut self, extra: T) -> GzBuilder {
         self.extra = Some(extra.into());
@@ -183,6 +200,7 @@ impl GzBuilder {
             extra,
             filename,
             comment,
+            operating_system,
             mtime,
         } = self;
         let mut flg = 0;
@@ -222,9 +240,9 @@ impl GzBuilder {
 
         // Typically this byte indicates what OS the gz stream was created on,
         // but in an effort to have cross-platform reproducible streams just
-        // always set this to 255. I'm not sure that if we "correctly" set this
-        // it'd do anything anyway...
-        header[9] = 255;
+        // default this value to 255. I'm not sure that if we "correctly" set
+        // this it'd do anything anyway...
+        header[9] = operating_system.unwrap_or(255);
         return header;
     }
 }