Initial

6 files changed, 285 insertions, 0 deletions

diff --git a/src/encoding.rs b/src/encoding.rs
new file mode 100644
index 0000000..a3851aa
--- /dev/null
+++ b/src/encoding.rs
@@ -0,0 +1,51 @@
+use std::convert::TryFrom;
+use crate::util::read_big_endian;
+
+macro_rules! guard {
+    ($cond:expr) => {
+        if !$cond {
+            return None;
+        }
+    }
+}
+
+pub fn from_latin_1(bytes: &[u8]) -> Option<String> {
+    guard!(bytes.len() >= 1);
+
+    Some(bytes.iter().map(|&b| char::from(b)).collect())
+}
+
+pub fn from_ucs_2_bom(bytes: &[u8]) -> Option<String> {
+    let len = bytes.len();
+
+    guard!(len % 2 == 0);
+    guard!(len >= 2);
+
+    let bom = read_big_endian(&bytes[0..2], 8);
+    guard!(bom == 0xfeff || bom == 0xfffe);
+
+    let mut res = String::with_capacity(len/2 - 1);
+
+    for i in 1 .. len/2 {
+        let val = if bom == 0xfeff {
+            256 * bytes[2*i] as u16 + bytes[2*i+1] as u16
+        } else {
+            256 * bytes[2*i+1] as u16 + bytes[2*i] as u16
+        };
+
+        match char::try_from(val as u32) {
+            Ok(c) => res.push(c),
+            Err(_) => return None,
+        };
+    }
+
+    Some(res)
+}
+
+// pub fn from_utf8_mistaken_as_latin1(latin1: &str) -> Option<String> {
+//     guard!(latin1.chars().all(|c| (c as usize) < 256));
+//     match std::str::from_utf8(latin1.as_bytes()) {
+//         Ok(res) => Some(res.to_string()),
+//         Err(_) => None,
+//     }
+// }
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..6358bfe
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,23 @@
+use std::io;
+
+pub trait IntoIOError {
+    fn ioerr(self) -> io::Error;
+}
+
+impl IntoIOError for String {
+    fn ioerr(self) -> io::Error {
+        io::Error::new(io::ErrorKind::Other, self)
+    }
+}
+
+impl IntoIOError for &str {
+    fn ioerr(self) -> io::Error {
+        io::Error::new(io::ErrorKind::Other, self)
+    }
+}
+
+impl IntoIOError for std::string::FromUtf8Error {
+    fn ioerr(self) -> io::Error {
+        io::Error::new(io::ErrorKind::Other, self)
+    }
+}
diff --git a/src/id3v2.rs b/src/id3v2.rs
new file mode 100644
index 0000000..c16c573
--- /dev/null
+++ b/src/id3v2.rs
@@ -0,0 +1,146 @@
+// http://id3.org/id3v2.3.0
+
+use std::io::{self, Read};
+use crate::encoding::{from_latin_1, from_ucs_2_bom};
+use crate::error::IntoIOError;
+use crate::options::EncodingOptions;
+use crate::util::read_big_endian;
+
+fn parse_id3v2_header(bytes: &[u8]) -> Option<(u16, u8, usize)> {
+    if bytes.len() == 10 &&
+            bytes[0] == b'I' &&
+            bytes[1] == b'D' &&
+            bytes[2] == b'3' &&
+            bytes[3] != 0xff &&
+            bytes[4] != 0xff &&
+            bytes[6..10].iter().all(|b| (b & 0x80) == 0) {
+        Some((
+            read_big_endian(&bytes[3..5], 8) as u16,
+            bytes[5],
+            read_big_endian(&bytes[6..10], 7)
+        ))
+    } else {
+        None
+    }
+}
+
+#[derive(Debug)]
+pub struct ID3v2 {
+    header_size: usize,
+    pub frames: Vec<RawFrame>,
+}
+
+#[derive(Debug)]
+pub struct RawFrame {
+    id: String,
+    flags: u16,
+    body: Vec<u8>,
+}
+
+#[derive(Debug)]
+pub enum Frame {
+    TIT2(String),
+    TYER(String),
+    TPE1(String),
+}
+
+impl RawFrame {
+    fn parse(data: &[u8]) -> Result<Option<(Self, usize)>, String> {
+        if data.len() < 10 {
+            return Err(String::from("Frame buffer too short"));
+        }
+
+        if data[0..4].iter().all(|&b| b == 0) {
+            return Ok(None)
+        }
+
+        if !data[0..4].iter().all(|&b| (b'A' <= b && b <= b'Z') || (b'0' <= b && b <= b'9')) {
+            return Err(format!("Invalid frame type {:?}", &data[0..4]));
+        }
+
+        let id = String::from_utf8(data[0..4].to_vec()).unwrap();
+        let size = read_big_endian(&data[4..8], 8);
+        let flags = read_big_endian(&data[8..10], 8) as u16;
+
+        let body = data[10..10+size].to_vec();
+
+        Ok(Some((RawFrame { id, flags, body }, 10 + size)))
+    }
+
+    fn interpret_encoded_string(&self, encopts: &EncodingOptions) -> io::Result<String> {
+        match self.body.get(0).ok_or("String field too small".ioerr())? {
+            0 => {  // Latin-1
+                let mut i = self.body.len();
+                while i > 0 && self.body[i-1] == 0 { i -= 1; }
+                if encopts.latin1_as_utf8 {
+                    String::from_utf8(self.body[1..i].to_vec()).map_err(|e| e.ioerr())
+                } else {
+                    from_latin_1(&self.body[1..i]).ok_or("Invalid Latin-1 string field".ioerr())
+                }
+            }
+
+            1 => {  // UCS-2
+                let mut i = self.body.len();
+                while i > 1 && self.body[i-2] == 0 && self.body[i-1] == 0 { i -= 2; }
+                from_ucs_2_bom(&self.body[1..i]).ok_or("Invalid UCS-2 string field".ioerr())
+            }
+
+            enc => {
+                Err(format!("Unknown string encoding {}", enc).ioerr())
+            }
+        }
+    }
+
+    pub fn interpret(&self, encopts: &EncodingOptions) -> io::Result<Option<Frame>> {
+        if self.id == "TIT2" {
+            self.interpret_encoded_string(encopts).map(Frame::TIT2).map(Some)
+        } else if self.id == "TYER" {
+            self.interpret_encoded_string(encopts).map(Frame::TYER).map(Some)
+        } else if self.id == "TPE1" {
+            self.interpret_encoded_string(encopts).map(Frame::TPE1).map(Some)
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+impl ID3v2 {
+    pub fn from_stream<R: Read>(stream: &mut R) -> io::Result<Self> {
+        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())?;
+        if id3version != 0x0300 {
+            return Err(format!("ID3 header version {}.{} not supported", id3version / 256, id3version % 256).ioerr())
+        }
+
+        if flags != 0 {
+            return Err(format!("No ID3 header flags supported ({:x})", flags).ioerr());
+        }
+
+        let body = {
+            let mut body = Vec::new();
+            body.resize(header_size, 0u8);
+            stream.read_exact(&mut body)?;
+            body
+        };
+
+        let mut frames = Vec::new();
+        let mut cursor = 0;
+
+        while cursor < body.len() {
+            match RawFrame::parse(&body[cursor..]).map_err(|e| e.ioerr())? {
+                Some((frame, consumed)) => {
+                    frames.push(frame);
+                    cursor += consumed;
+                }
+
+                None => {
+                    break;
+                }
+            }
+        }
+
+        Ok(ID3v2 { frames, header_size })
+    }
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..6760ee7
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,41 @@
+use std::io;
+use std::fs::File;
+use argparse::{ArgumentParser, StoreTrue, Store};
+use crate::options::{EncodingOptions, Options};
+
+mod encoding;
+mod error;
+mod id3v2;
+mod options;
+mod util;
+
+fn main() -> io::Result<()> {
+    let options = {
+        let mut options: Options = Default::default();
+
+        {
+            let mut ap = ArgumentParser::new();
+            ap.set_description("ID3v2 tag editor/fixer. Incomplete/work-in-progress.");
+            ap.refer(&mut options.latin1_as_utf8)
+                .add_option(&["--assume-utf8"], StoreTrue,
+                            "Assume that all strings specified as Latin-1 are really UTF-8.");
+            ap.refer(&mut options.file)
+                .required()
+                .add_argument("file", Store,
+                              "File to operate on (probably a .mp3)");
+            ap.parse_args_or_exit();
+        }
+
+        options
+    };
+
+    let mut f = File::open(options.file)?;
+    let tag = id3v2::ID3v2::from_stream(&mut f)?;
+    println!("{:?}", tag);
+
+    for frame in tag.frames {
+        println!("{:?}", frame.interpret(&EncodingOptions { latin1_as_utf8: options.latin1_as_utf8 }));
+    }
+
+    Ok(())
+}
diff --git a/src/options.rs b/src/options.rs
new file mode 100644
index 0000000..3b36e52
--- /dev/null
+++ b/src/options.rs
@@ -0,0 +1,17 @@
+pub struct Options {
+    pub latin1_as_utf8: bool,
+    pub file: String,
+}
+
+impl Default for Options {
+    fn default() -> Self {
+        Options {
+            latin1_as_utf8: false,
+            file: String::new(),
+        }
+    }
+}
+
+pub struct EncodingOptions {
+    pub latin1_as_utf8: bool,
+}
diff --git a/src/util.rs b/src/util.rs
new file mode 100644
index 0000000..b17e304
--- /dev/null
+++ b/src/util.rs
@@ -0,0 +1,7 @@
+pub fn read_big_endian(bytes: &[u8], bits: usize) -> usize {
+    bytes
+        .iter()
+        .enumerate()
+        .map(|(i, &b)| (b as usize) << (bits * (bytes.len() - 1 - i)))
+        .sum()
+}