Handle 2448-byte sectors

Handle images that have 2448-byte sectors, i.e. 2352 audio bytes + 96
sub-channel bytes.

src/metadata/metadata.rs

@@ -84,6 +84,21 @@ impl NrgMetadata {
         }
         self.chunk_offset
     }
+
+    /// Returns the sector size of this image.
+    ///
+    /// This information is retrieved from the first DAOX track only; it is
+    /// assumed that every track has the same sector size.
+    ///
+    /// Returns 0 if there are no DAOX tracks.
+    pub fn sector_size(&self) -> u16 {
+        if let Some(daox_chunk) = self.daox_chunk.as_ref() {
+            if let Some(first_track) = daox_chunk.tracks.first() {
+                return first_track.sector_size;
+            }
+        }
+        0
+    }
 }
 
 impl fmt::Display for NrgMetadata {

src/raw_audio.rs

@@ -29,6 +29,9 @@ use std::path::PathBuf;
 use ::error::NrgError;
 use ::metadata::metadata::NrgMetadata;
 
+const RAW_SEC_SIZE: u16 = 2352;
+const RAW96_SEC_SIZE: u16 = 2448;
+
 
 /// Extracts the raw audio data from an NRG image.
 ///
@@ -45,18 +48,19 @@ pub fn extract_nrg_raw_audio(in_fd: &mut File,
     let first_audio_byte = metadata.first_audio_byte();
     try!(in_fd.seek(SeekFrom::Start(first_audio_byte)));
 
-    // Get the last audio byte
-    let last_audio_byte = metadata.last_audio_byte();
-
     // Open output file
     let audio_name = try!(make_output_file_name(img_path));
     let mut out_fd = try!(File::create(audio_name));
 
     // Copy the audio data
-    let count = last_audio_byte - first_audio_byte;
-    let bytes_copied = try!(copy_raw_audio(in_fd, &mut out_fd, count));
-
-    assert_eq!(count, bytes_copied);
+    let count = metadata.last_audio_byte() - first_audio_byte;
+    let bytes_read = match metadata.sector_size() {
+        RAW96_SEC_SIZE => try!(copy_raw96_audio(in_fd, &mut out_fd, count)),
+        0              => return Err(NrgError::AudioReadError),
+        _              => try!(copy_raw_audio(in_fd, &mut out_fd, count)),
+    };
+
+    assert_eq!(count, bytes_read);
     Ok(())
 }
 
@@ -66,12 +70,12 @@ pub fn extract_nrg_raw_audio(in_fd: &mut File,
 /// The offsets of `in_fd` and `out_fd` are not reset prior to reading and
 /// writing.
 ///
-/// Returns the number of bytes copied.
+/// Returns the number of bytes read/written.
 fn copy_raw_audio(in_fd: &mut File, out_fd: &mut File, count: u64)
                   -> Result<u64, NrgError> {
     // The buffer size (~4,6 MiB) is a multiple of the standard audio CD sector
     // size, i.e. 2352 bytes (it doesn't have to be, though).
-    const BUF_SIZE: usize = 2352 * 1024 * 2;
+    const BUF_SIZE: usize = RAW_SEC_SIZE as usize * 1024 * 2;
 
     // Read/write audio data
     let mut bytes_read = 0;
@@ -107,6 +111,43 @@ fn copy_raw_audio(in_fd: &mut File, out_fd: &mut File, count: u64)
 }
 
 
+/// Reads `count` bytes from `in_fd` and write them to `out_fd` after stripping
+/// the sub-channel bytes.
+///
+/// `in_fd` is read by chunks of 2448 bytes, then the first 2352 bytes are
+/// written to `out_fd`, leaving out the 96 sub-channel bytes.
+///
+/// The offsets of `in_fd` and `out_fd` are not reset prior to reading and
+/// writing.
+///
+/// Returns the number of bytes read (not written).
+fn copy_raw96_audio(in_fd: &mut File, out_fd: &mut File, count: u64)
+                    -> Result<u64, NrgError> {
+    const IN_BUF_SIZE: usize = RAW96_SEC_SIZE as usize;
+    const OUT_BUF_SIZE: usize = RAW_SEC_SIZE as usize;
+
+    // Read/write audio data
+    let mut bytes_read = 0;
+    while bytes_read < count {
+        let mut audio_buf = vec![0u8; IN_BUF_SIZE];
+
+        let mut nbytes = try!(in_fd.read(&mut audio_buf));
+        if nbytes != IN_BUF_SIZE {
+            return Err(NrgError::AudioReadError);
+        }
+        bytes_read += nbytes as u64;
+
+        audio_buf.truncate(OUT_BUF_SIZE);
+        nbytes = try!(out_fd.write(&audio_buf));
+        if nbytes != OUT_BUF_SIZE {
+            return Err(NrgError::AudioWriteError);
+        }
+    }
+
+    Ok(bytes_read)
+}
+
+
 /// Generates the output file's name from the NRG image's name.
 ///
 /// The output file's name will be `img_path`'s base name stripped for its