Alexander
445 lines
15 KiB
Rust
445 lines
15 KiB
Rust
use std::{
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fs,
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io::{Cursor, Read, Seek, SeekFrom},
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path::Path,
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};
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use symphonia::core::{
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formats::FormatOptions, io::MediaSourceStream, meta::MetadataOptions, probe::Hint,
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};
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use crate::music::encoder::MusicMetadataEncoder;
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use crate::music::metadata::{MusicMetadata, extract_standard_tags};
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use crate::music::parser::MusicMetadataParser;
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const BLOCK_PADDING: u8 = 1;
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const BLOCK_VORBIS_COMMENT: u8 = 4;
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const BLOCK_PICTURE: u8 = 6;
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const BLOCK_LAST_FLAG: u8 = 0x80;
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const BLOCK_TYPE_MASK: u8 = 0x7f;
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const PADDING_SIZE: usize = 8192;
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/// FLAC parser. Owns all FLAC container parsing; returns `None` (never panics)
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/// on a file it can't read — a corrupt or mid-copy file is logged and served
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/// as plain passthrough rather than taking down the snapshot/watcher.
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pub struct FlacMusicMetadataParser;
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impl MusicMetadataParser for FlacMusicMetadataParser {
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fn parse(&self, path: &Path) -> Option<MusicMetadata> {
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match parse_flac_metadata(path) {
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Some(mm) => Some(mm),
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None => {
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eprintln!(
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"musicfs: failed to parse FLAC metadata from {}",
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path.display()
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);
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None
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}
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}
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}
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}
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/// FLAC encoder. Rebuilds the FLAC metadata header from the current tag fields,
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/// re-injecting the (possibly overridden) Vorbis comment.
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pub struct FlacMusicMetadataEncoder;
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impl MusicMetadataEncoder for FlacMusicMetadataEncoder {
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fn encode(&self, metadata: &mut MusicMetadata) {
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if metadata.header.is_empty() {
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return;
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}
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let blocks = extract_non_vorbis_blocks(&metadata.header);
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let (header, vorbis_comment_offset, vorbis_comment_length) =
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build_flac_header(blocks, metadata);
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metadata.header = header;
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metadata.vorbis_comment_offset = vorbis_comment_offset;
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metadata.vorbis_comment_length = vorbis_comment_length;
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}
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}
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fn parse_flac_metadata(path: &Path) -> Option<MusicMetadata> {
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let src = fs::File::open(path).ok()?;
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let mss = MediaSourceStream::new(Box::new(src), Default::default());
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let mut hint = Hint::new();
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hint.with_extension("flac");
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let meta_opts: MetadataOptions = Default::default();
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let fmt_opts: FormatOptions = Default::default();
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let mut format = symphonia::default::get_probe()
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.format(&hint, mss, &fmt_opts, &meta_opts)
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.ok()?;
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let metadata = format.format.metadata();
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let mut music_metadata = MusicMetadata::default();
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if let Some(revision) = metadata.current() {
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extract_standard_tags(revision, &mut music_metadata);
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}
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if let Some(parsed) = parse_flac(path) {
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music_metadata.real_audio_start = parsed.audio_start;
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music_metadata.picture_block_headers = parsed.picture_block_headers;
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music_metadata.picture_data_ranges = parsed.picture_data_ranges;
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let (header, vorbis_comment_offset, vorbis_comment_length) =
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build_flac_header(parsed.other_blocks, &music_metadata);
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music_metadata.header = header;
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music_metadata.vorbis_comment_offset = vorbis_comment_offset;
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music_metadata.vorbis_comment_length = vorbis_comment_length;
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}
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Some(music_metadata)
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}
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impl MusicMetadata {
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/// Locate the Vorbis comment block within the rebuilt FLAC header so writes
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/// to it can be intercepted. No-op for non-FLAC (e.g. ID3) headers.
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pub fn find_vorbis_offsets(&mut self) {
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let mut cursor = Cursor::new(&self.header);
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let mut magic = [0u8; 4];
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if cursor.read_exact(&mut magic).is_err() {
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return;
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}
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if &magic != b"fLaC" {
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return;
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}
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loop {
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let mut hdr = [0u8; 4];
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if cursor.read_exact(&mut hdr).is_err() {
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break;
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}
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let (is_last, block_type, length) = read_block_header(&hdr);
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if block_type == BLOCK_VORBIS_COMMENT {
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self.vorbis_comment_offset = cursor.position();
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self.vorbis_comment_length = length;
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return;
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}
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if cursor.seek(SeekFrom::Current(length as i64)).is_err() {
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break;
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}
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if is_last {
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break;
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}
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}
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}
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/// Apply a freshly written Vorbis comment block and rebuild the header.
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pub fn update_from_vorbis_comment_data(&mut self, data: &[u8]) {
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parse_vorbis_comment_block(data, self);
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let other_blocks = extract_non_vorbis_blocks(&self.header);
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let (header, vorbis_comment_offset, vorbis_comment_length) =
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build_flac_header(other_blocks, self);
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self.header = header;
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self.vorbis_comment_offset = vorbis_comment_offset;
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self.vorbis_comment_length = vorbis_comment_length;
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}
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}
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/// Parse a 4-byte FLAC metadata block header into (is_last, block_type, data_length).
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fn read_block_header(hdr: &[u8; 4]) -> (bool, u8, u64) {
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let is_last = (hdr[0] & BLOCK_LAST_FLAG) != 0;
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let block_type = hdr[0] & BLOCK_TYPE_MASK;
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let length = u32::from_be_bytes([0, hdr[1], hdr[2], hdr[3]]) as u64;
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(is_last, block_type, length)
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}
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struct FlacParsed {
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other_blocks: Vec<(u8, Vec<u8>)>,
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picture_block_headers: Vec<Vec<u8>>,
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picture_data_ranges: Vec<(u64, u64)>,
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audio_start: u64,
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}
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fn parse_flac(path: &Path) -> Option<FlacParsed> {
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let mut f = fs::File::open(path).ok()?;
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let mut magic = [0u8; 4];
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f.read_exact(&mut magic).ok()?;
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if &magic != b"fLaC" {
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return None;
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}
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let mut other_blocks: Vec<(u8, Vec<u8>)> = vec![];
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let mut picture_block_headers: Vec<Vec<u8>> = vec![];
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let mut picture_data_ranges: Vec<(u64, u64)> = vec![];
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let mut pos = 4u64;
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loop {
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let mut hdr = [0u8; 4];
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f.read_exact(&mut hdr).ok()?;
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let (is_last, block_type, length) = read_block_header(&hdr);
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pos += 4;
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if block_type == BLOCK_PICTURE {
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// PICTURE: keep block header (we'll fix is_last later), record data range
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picture_block_headers.push(hdr.to_vec());
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picture_data_ranges.push((pos, length));
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f.seek(SeekFrom::Current(length as i64)).ok()?;
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} else {
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let mut data = vec![0u8; length as usize];
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f.read_exact(&mut data).ok()?;
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// Skip VORBIS_COMMENT — we rebuild it
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if block_type != BLOCK_VORBIS_COMMENT {
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other_blocks.push((block_type, data));
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}
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}
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pos += length;
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if is_last {
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break;
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}
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}
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// Fix is_last on the last picture block header: it must be 1 when audio follows
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if let Some(last_hdr) = picture_block_headers.last_mut() {
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last_hdr[0] = BLOCK_LAST_FLAG | (last_hdr[0] & BLOCK_TYPE_MASK);
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}
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Some(FlacParsed {
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other_blocks,
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picture_block_headers,
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picture_data_ranges,
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audio_start: pos,
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})
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}
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fn build_flac_header(blocks: Vec<(u8, Vec<u8>)>, metadata: &MusicMetadata) -> (Vec<u8>, u64, u64) {
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let vorbis = build_vorbis_comment(metadata);
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let vorbis_len = vorbis.len() as u64;
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let mut patched: Vec<(u8, Vec<u8>)> = blocks;
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patched.push((BLOCK_VORBIS_COMMENT, vorbis));
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patched.push((BLOCK_PADDING, vec![0u8; PADDING_SIZE])); // allows metaflac in-place writes
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let vorbis_idx = patched.len() - 2;
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let has_pictures = !metadata.picture_data_ranges.is_empty();
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let mut out = Vec::new();
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out.extend_from_slice(b"fLaC");
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let last = patched.len() - 1;
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let mut vorbis_offset = 0u64;
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for (i, (block_type, data)) in patched.iter().enumerate() {
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let is_last_block = i == last && !has_pictures;
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let flag: u8 = if is_last_block { BLOCK_LAST_FLAG } else { 0x00 };
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let length = data.len() as u32;
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if i == vorbis_idx {
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vorbis_offset = out.len() as u64 + 4; // data starts after 4-byte block header
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}
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out.push(flag | block_type);
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out.push((length >> 16) as u8);
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out.push((length >> 8) as u8);
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out.push(length as u8);
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out.extend_from_slice(data);
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}
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(out, vorbis_offset, vorbis_len)
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}
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fn parse_vorbis_comment_block(data: &[u8], out: &mut MusicMetadata) {
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let mut cursor = Cursor::new(data);
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let mut len_bytes = [0u8; 4];
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if cursor.read_exact(&mut len_bytes).is_err() {
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return;
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}
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let vendor_len = u32::from_le_bytes(len_bytes) as i64;
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if cursor.seek(SeekFrom::Current(vendor_len)).is_err() {
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return;
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}
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if cursor.read_exact(&mut len_bytes).is_err() {
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return;
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}
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let count = u32::from_le_bytes(len_bytes);
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out.artist.clear();
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out.other_tags.clear();
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for _ in 0..count {
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if cursor.read_exact(&mut len_bytes).is_err() {
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break;
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}
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let comment_len = u32::from_le_bytes(len_bytes) as usize;
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let mut comment_bytes = vec![0u8; comment_len];
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if cursor.read_exact(&mut comment_bytes).is_err() {
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break;
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}
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let comment = String::from_utf8_lossy(&comment_bytes).into_owned();
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if let Some((key, value)) = comment.split_once('=') {
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match key.to_ascii_uppercase().as_str() {
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"TITLE" => out.track_title = value.to_string(),
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"ALBUM" => out.album = value.to_string(),
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"TRACKNUMBER" => out.track_number = value.parse().unwrap_or(0),
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"ARTIST" => out.artist.push(value.to_string()),
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_ => out.other_tags.push(comment),
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}
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}
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}
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}
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fn extract_non_vorbis_blocks(header: &[u8]) -> Vec<(u8, Vec<u8>)> {
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let mut cursor = Cursor::new(header);
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let mut blocks = vec![];
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let mut magic = [0u8; 4];
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if cursor.read_exact(&mut magic).is_err() {
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return blocks;
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}
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loop {
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let mut hdr = [0u8; 4];
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if cursor.read_exact(&mut hdr).is_err() {
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break;
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}
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let (is_last, block_type, length) = read_block_header(&hdr);
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let mut data = vec![0u8; length as usize];
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if cursor.read_exact(&mut data).is_err() {
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break;
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}
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if block_type != BLOCK_VORBIS_COMMENT && block_type != BLOCK_PADDING {
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blocks.push((block_type, data));
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}
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if is_last {
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break;
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}
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}
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blocks
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}
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fn build_vorbis_comment(metadata: &MusicMetadata) -> Vec<u8> {
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let vendor = b"musicfs";
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let mut out = Vec::new();
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out.extend_from_slice(&(vendor.len() as u32).to_le_bytes());
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out.extend_from_slice(vendor);
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let mut comments: Vec<String> = vec![
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format!("TITLE={}", metadata.track_title),
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format!("ALBUM={}", metadata.album),
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format!("TRACKNUMBER={}", metadata.track_number),
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];
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for artist in &metadata.artist {
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comments.push(format!("ARTIST={}", artist));
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}
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comments.extend(metadata.other_tags.iter().cloned());
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out.extend_from_slice(&(comments.len() as u32).to_le_bytes());
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for comment in &comments {
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let bytes = comment.as_bytes();
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out.extend_from_slice(&(bytes.len() as u32).to_le_bytes());
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out.extend_from_slice(bytes);
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}
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out
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn read_block_header_normal() {
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let hdr = [0x04, 0x00, 0x01, 0x00];
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let (is_last, block_type, length) = read_block_header(&hdr);
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assert!(!is_last);
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assert_eq!(block_type, 4);
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assert_eq!(length, 256);
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}
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#[test]
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fn read_block_header_last() {
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let hdr = [0x84, 0x00, 0x00, 0x10];
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let (is_last, block_type, length) = read_block_header(&hdr);
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assert!(is_last);
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assert_eq!(block_type, 4);
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assert_eq!(length, 16);
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}
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#[test]
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fn build_vorbis_comment_roundtrip() {
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let mut metadata = MusicMetadata::default();
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metadata.artist = vec!["Artist1".to_string(), "Artist2".to_string()];
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metadata.album = "Album".to_string();
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metadata.track_number = 3;
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metadata.track_title = "Title".to_string();
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metadata.other_tags = vec!["GENRE=Rock".to_string()];
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let vorbis_bytes = build_vorbis_comment(&metadata);
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let mut parsed = MusicMetadata::default();
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parse_vorbis_comment_block(&vorbis_bytes, &mut parsed);
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assert_eq!(parsed.artist, vec!["Artist1", "Artist2"]);
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assert_eq!(parsed.album, "Album");
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assert_eq!(parsed.track_number, 3);
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assert_eq!(parsed.track_title, "Title");
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assert_eq!(parsed.other_tags, vec!["GENRE=Rock"]);
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}
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#[test]
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fn parse_vorbis_comment_multi_artist() {
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let mut vorbis_bytes = Vec::new();
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let vendor = b"test";
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vorbis_bytes.extend_from_slice(&(vendor.len() as u32).to_le_bytes());
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vorbis_bytes.extend_from_slice(vendor);
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let comments = vec!["ARTIST=Artist1", "ARTIST=Artist2"];
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vorbis_bytes.extend_from_slice(&(comments.len() as u32).to_le_bytes());
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for comment in &comments {
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let bytes = comment.as_bytes();
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vorbis_bytes.extend_from_slice(&(bytes.len() as u32).to_le_bytes());
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vorbis_bytes.extend_from_slice(bytes);
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}
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let mut metadata = MusicMetadata::default();
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parse_vorbis_comment_block(&vorbis_bytes, &mut metadata);
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assert_eq!(metadata.artist.len(), 2);
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assert_eq!(metadata.artist[0], "Artist1");
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assert_eq!(metadata.artist[1], "Artist2");
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}
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#[test]
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fn extract_non_vorbis_blocks_strips_vc_and_padding() {
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let mut header = Vec::new();
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header.extend_from_slice(b"fLaC");
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let streaminfo_data = vec![0u8; 34];
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header.push(0x00);
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header.extend_from_slice(&[0x00, 0x00, 0x22]);
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header.extend_from_slice(&streaminfo_data);
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let vorbis_data = vec![0u8; 50];
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header.push(0x04);
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header.extend_from_slice(&[0x00, 0x00, 0x32]);
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header.extend_from_slice(&vorbis_data);
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let padding_data = vec![0u8; 100];
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header.push(0x81);
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header.extend_from_slice(&[0x00, 0x00, 0x64]);
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header.extend_from_slice(&padding_data);
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let blocks = extract_non_vorbis_blocks(&header);
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assert_eq!(blocks.len(), 1);
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assert_eq!(blocks[0].0, 0);
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assert_eq!(blocks[0].1.len(), 34);
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}
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#[test]
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fn find_vorbis_offsets_correct() {
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let mut metadata = MusicMetadata::default();
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metadata.artist = vec!["TestArtist".to_string()];
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metadata.album = "TestAlbum".to_string();
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metadata.track_number = 1;
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metadata.track_title = "TestTitle".to_string();
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let other_blocks = vec![(0, vec![0u8; 34])];
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let (header, expected_offset, expected_length) = build_flac_header(other_blocks, &metadata);
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metadata.header = header;
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metadata.find_vorbis_offsets();
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assert_eq!(metadata.vorbis_comment_offset, expected_offset);
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assert_eq!(metadata.vorbis_comment_length, expected_length);
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}
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}
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