Add option to remove v1 tags

4 files changed, 105 insertions, 10 deletions

diff --git a/src/id3v1.rs b/src/id3v1.rs
new file mode 100644
index 0000000..ccade4a
--- /dev/null
+++ b/src/id3v1.rs
@@ -0,0 +1,61 @@
+use std::fs::File;
+use std::io::{self, Read, Seek};
+
+#[derive(Copy, Clone, Debug)]
+pub enum TagType {
+    /// An ID3v1.0 tag
+    TAGv10,
+    /// An ID3v1.1 enhanced tag (TAG+) in addition to the v1.0 tag
+    TAGv11,
+    /// An ID3v1.2 extended tag (EXT) in addition to the v1.0 tag
+    TAGv12,
+}
+
+pub fn recognise(file: &mut File) -> io::Result<Option<TagType>> {
+    let length = file.seek(io::SeekFrom::End(0))?;
+    if length < 128 { return Ok(None); }
+
+    let mut buf4 = [0u8; 4];
+
+    // Check whether we have a v1.0 tag
+    file.seek(io::SeekFrom::End(-128))?;
+    file.read_exact(&mut buf4[0..3])?;
+    if &buf4[0..3] == b"TAG" {
+        // Check whether we also have a v1.1 tag
+        if length >= 128 + 227 {
+            file.seek(io::SeekFrom::End(-128 - 227))?;
+            file.read_exact(&mut buf4)?;
+            if &buf4 == b"TAG+" {
+                return Ok(Some(TagType::TAGv11));
+            }
+        }
+
+        // Otherwise, check whether we also have a v1.2 tag
+        if length >= 128 + 128 {
+            file.seek(io::SeekFrom::End(-128 - 128))?;
+            file.read_exact(&mut buf4[0..3])?;
+            if &buf4[0..3] == b"EXT" {
+                return Ok(Some(TagType::TAGv12));
+            }
+        }
+
+        // Nope, just v1.0
+        Ok(Some(TagType::TAGv10))
+    } else {
+        Ok(None)
+    }
+}
+
+pub fn remove_tag(file: &mut File, typ: TagType) -> io::Result<()> {
+    let tag_len = match typ {
+        TagType::TAGv10 => 128,
+        TagType::TAGv11 => 128 + 227,
+        TagType::TAGv12 => 128 + 128,
+    };
+
+    let length = file.seek(io::SeekFrom::End(0))?;
+    eprintln!("remove_tag: Resizing file from {} to {} bytes", length, length - tag_len);
+    file.set_len(length - tag_len)?;
+
+    Ok(())
+}
diff --git a/src/id3v2.rs b/src/id3v2.rs
index 19f5e89..b427845 100644
--- a/src/id3v2.rs
+++ b/src/id3v2.rs
@@ -246,7 +246,7 @@ impl ID3v2 {
         let mut header = [0u8; 10];
         stream.read_exact(&mut header)?;
 
-        let (id3version, flags, header_size) = parse_id3v2_header(&header).ok_or("Invalid ID3 header".ioerr())?;
+        let (id3version, flags, header_size) = parse_id3v2_header(&header).ok_or("Invalid ID3v2 header or no ID3v2 tag found".ioerr())?;
 
         let version_sub = match id3version {
             0x0300 => 3,
diff --git a/src/main.rs b/src/main.rs
index 327daa0..5af6eb1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,6 +7,7 @@ use crate::options::Options;
 
 mod encoding;
 mod error;
+mod id3v1;
 mod id3v2;
 mod options;
 
@@ -22,6 +23,10 @@ fn parse_options_into(opt: &mut Options) {
         .add_option(&["--assume-utf8"], StoreTrue,
                     "Assume that all strings specified in the MP3 as Latin-1 are really UTF-8.");
 
+    ap.refer(&mut opt.remove_v1)
+        .add_option(&["--remove-v1"], StoreTrue,
+                    "Remove any existing ID3v1.* tags.");
+
     ap.refer(&mut opt.set_tags.album) .add_option(&["-A", "--album"],  StoreOption, "Set/replace album");
     ap.refer(&mut opt.set_tags.artist).add_option(&["-a", "--artist"], StoreOption, "Set/replace artist");
     ap.refer(&mut opt.set_tags.title) .add_option(&["-t", "--title"],  StoreOption, "Set/replace title");
@@ -86,8 +91,36 @@ fn modify_tag(tag: &mut ID3v2, new_frame: Frame) -> io::Result<()> {
 fn main() -> io::Result<()> {
     let options = parse_options();
 
-    let mut tag = ID3v2::from_stream(&mut File::open(&options.file)?)?;
-    // println!("{:?}", tag);
+    let open_read = || File::open(&options.file);
+    let open_write = || OpenOptions::new().write(true).open(&options.file);
+
+    let mut tag = {
+        let (tag, tag_v1) = {
+            let mut file = open_read()?;
+            let tag = ID3v2::from_stream(&mut file)?;
+            let tag_v1 = id3v1::recognise(&mut file)?;
+            (tag, tag_v1)
+        };
+
+        if options.remove_v1 {
+            if let Some(tag_type) = tag_v1 {
+                id3v1::remove_tag(&mut open_write()?, tag_type)?;
+            } else {
+                eprintln!("WARNING: Told to remove ID3v1 tag while none is present.");
+            }
+        } else {
+            if let Some(tag_type) = tag_v1 {
+                let descr = match tag_type {
+                    id3v1::TagType::TAGv10 => "ID3v1.0",
+                    id3v1::TagType::TAGv11 => "ID3v1.1",
+                    id3v1::TagType::TAGv12 => "ID3v1.2",
+                };
+                eprintln!("WARNING: {} tag found at end of file; use --remove-v1 to remove it.", descr);
+            }
+        }
+
+        tag
+    };
 
     if options.latin1_as_utf8 {
         for frame in &mut tag.frames {
@@ -99,19 +132,18 @@ fn main() -> io::Result<()> {
         }
     }
 
-    if let Some(s) = options.set_tags.album  { modify_tag(&mut tag, Frame::TALB(s))?; }
-    if let Some(s) = options.set_tags.artist { modify_tag(&mut tag, Frame::TPE1(s))?; }
-    if let Some(s) = options.set_tags.title  { modify_tag(&mut tag, Frame::TIT2(s))?; }
-    if let Some(s) = options.set_tags.track  { modify_tag(&mut tag, Frame::TRCK(s))?; }
-    if let Some(s) = options.set_tags.year   { modify_tag(&mut tag, Frame::TYER(s))?; }
+    if let Some(s) = &options.set_tags.album  { modify_tag(&mut tag, Frame::TALB(s.clone()))?; }
+    if let Some(s) = &options.set_tags.artist { modify_tag(&mut tag, Frame::TPE1(s.clone()))?; }
+    if let Some(s) = &options.set_tags.title  { modify_tag(&mut tag, Frame::TIT2(s.clone()))?; }
+    if let Some(s) = &options.set_tags.track  { modify_tag(&mut tag, Frame::TRCK(s.clone()))?; }
+    if let Some(s) = &options.set_tags.year   { modify_tag(&mut tag, Frame::TYER(s.clone()))?; }
 
     print_tag(&tag)?;
 
     // TODO: if -w, then write tags to file (if it fits)
     if options.write {
         let encoded = tag.encode()?;
-        let mut f = OpenOptions::new().write(true).open(&options.file)?;
-        f.write_all(&encoded)?;
+        open_write()?.write_all(&encoded)?;
         println!("Tag written!");
     }
 
diff --git a/src/options.rs b/src/options.rs
index 5f1dec9..b2223de 100644
--- a/src/options.rs
+++ b/src/options.rs
@@ -1,5 +1,6 @@
 pub struct Options {
     pub latin1_as_utf8: bool,
+    pub remove_v1: bool,
     pub file: String,
     pub write: bool,
     pub set_tags: TagOptions,
@@ -18,6 +19,7 @@ impl Default for Options {
     fn default() -> Self {
         Options {
             latin1_as_utf8: false,
+            remove_v1: false,
             file: String::new(),
             write: false,
             set_tags: Default::default(),