1 files changed, 146 insertions, 0 deletions
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 })
+    }
+}