From 3140ff5a081139200a39c5b1a57e29522bfb2a75 Mon Sep 17 00:00:00 2001
From: Lionel Flandrin <lionel.flandrin@gmail.com>
Date: Thu, 23 Jun 2016 01:09:48 +0200
Subject: [PATCH] Added support for track-relative MSF

---
 src/cue/mod.rs  | 11 ++++++---
 src/internal.rs | 60 ++++++++++++++++++++++++++++++++++++++++++++-----
 src/lib.rs      | 14 ++++++++++--
 3 files changed, 75 insertions(+), 10 deletions(-)

diff --git a/src/cue/mod.rs b/src/cue/mod.rs
index e407dfd..2daa7b0 100644
--- a/src/cue/mod.rs
+++ b/src/cue/mod.rs
@@ -16,6 +16,7 @@ use Image;
 use internal::IndexCache;
 use sector::{Sector, SectorBuilder, Metadata};
 use msf::Msf;
+use bcd::Bcd;
 
 use self::parser::CueParser;
 
@@ -72,11 +73,11 @@ impl Image for Cue {
                         index
                     } else {
                         match self.indices
-                            .find_index1_for_track(index.track()) {
-                                Some((_, i)) => i,
+                            .find_index01_for_track(index.track()) {
+                                Ok((_, i)) => i,
                                 // Shouldn't be reached, should be
                                 // caught by IndexCache's constructor
-                                None =>
+                                Err(_) =>
                                     panic!("Missing index 1 for track {}",
                                            index.track()),
                             }
@@ -130,6 +131,10 @@ impl Image for Cue {
 
         Ok(())
     }
+
+    fn track_msf(&self, track: Bcd, track_msf: Msf) -> Result<Msf, CdError> {
+        self.indices.track_msf(track, track_msf)
+    }
 }
 
 /// Possible types for a CUE track.
diff --git a/src/internal.rs b/src/internal.rs
index 6e8d52a..551d389 100644
--- a/src/internal.rs
+++ b/src/internal.rs
@@ -200,23 +200,73 @@ impl<T> IndexCache<T> {
     /// a reference to the `Index` struct.
     pub fn find_index_for_track(&self,
                                 track: Bcd,
-                                index: Bcd) -> Option<(usize, &Index<T>)> {
+                                index: Bcd) -> Result<(usize, &Index<T>),
+                                                      CdError> {
         match self.indices.binary_search_by(
             |idx| match idx.track().cmp(&track) {
                 cmp::Ordering::Equal => idx.index().cmp(&index),
                 o => o,
             }) {
-            Ok(i) => Some((i, &self.indices[i])),
-            Err(_) => None,
+            Ok(i) => Ok((i, &self.indices[i])),
+            Err(_) => Err(CdError::BadTrack),
         }
     }
 
     /// Locate index1 for `track` and return its position along with a
     /// reference to the `Index` struct.
-    pub fn find_index1_for_track(&self,
-                                 track: Bcd) -> Option<(usize, &Index<T>)> {
+    pub fn find_index01_for_track(&self,
+                                  track: Bcd) -> Result<(usize, &Index<T>),
+                                                        CdError> {
         self.find_index_for_track(track, Bcd::one())
     }
+
+    /// Return the length of the given track starting at INDEX 01, not
+    /// counting the pregap. Also returns the position and a reference
+    /// to the INDEX 01 for this track.
+    pub fn track_length(&self, track: Bcd) -> Result<(Msf, usize, &Index<T>),
+                                                     CdError> {
+        let (pos01, index01) =
+            try!(self.find_index01_for_track(track));
+
+        // Iterate over the remaining indices to find the beginning of
+        // the next track
+
+        let next_track =
+            self.indices[pos01 + 1..].iter().find(|i| i.track() != track);
+
+        let end =
+            match next_track {
+                // We found the next track, the previous sector is the
+                // last one in our track.
+                Some(next) => next.sector_index(),
+                // Seems like we got the last track
+                None => self.lead_out,
+            };
+
+        let len =
+            Msf::from_sector_index(end - index01.sector_index()).unwrap();
+
+        Ok((len, pos01, index01))
+    }
+
+    /// Return the absolute Msf for the position `track_msf` in
+    /// `track`. Will return an error if the `track_msf` is outside of
+    /// the track or if `track` doesn't exist.
+    pub fn track_msf(&self,
+                     track: Bcd,
+                     track_msf: Msf) -> Result<Msf, CdError> {
+
+        // We need to make sure that `track_msf` is not bigger than
+        // this tracks' length.
+        let (len, _, index01) =
+            try!(self.track_length(track));
+
+        if track_msf < len {
+            Ok(index01.msf() + track_msf)
+        } else {
+            Err(CdError::EndOfTrack)
+        }
+    }
 }
 
 impl<T> fmt::Debug for IndexCache<T> {
diff --git a/src/lib.rs b/src/lib.rs
index 0355af4..58187b2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,6 +16,7 @@ use std::io;
 use std::fmt;
 use sector::Sector;
 use msf::Msf;
+use bcd::Bcd;
 
 pub mod bcd;
 pub mod msf;
@@ -34,6 +35,11 @@ pub trait Image {
 
     /// Read a single sector at the given MSF
     fn read_sector(&mut self, &mut Sector, Msf) -> Result<(), CdError>;
+
+    /// Return the absolute Msf for the position `track_msf` in
+    /// `track`. Will return an error if the `track_msf` is outside of
+    /// the track or if `track` doesn't exist.
+    fn track_msf(&self, track: Bcd, track_msf: Msf) -> Result<Msf, CdError>;
 }
 
 /// Possible session formats.
@@ -68,6 +74,8 @@ pub enum TrackFormat {
 /// Error type for disc operations.
 #[derive(Debug)]
 pub enum CdError {
+    /// Generic I/O error
+    IoError(io::Error),
     /// Format missmatch. For instance when one attempts to retrieve
     /// CD-ROM payloads on an audio track.
     BadFormat,
@@ -81,8 +89,10 @@ pub enum CdError {
     /// track, absurd index etc...). Contains the path of the file and
     /// a `String` describing the problem.
     BadImage(PathBuf, String),
-    /// Generic I/O error
-    IoError(io::Error),
+    /// Attempted to access an invalid track number
+    BadTrack,
+    /// Attempted to access a track past its end
+    EndOfTrack,
 }
 
 impl fmt::Display for CdError {