fix: don't hold onto previously decoded frames' samples to reduce mem usage

- migrate to os2
- check if the streaminfo min and max block size are within range
- use a tracking allocator for the example program

TODO.md

@@ -13,15 +13,6 @@ uncommon/11 -> We error with Invalid Signature
 
 faulty/01 -> This one works when it shouldn't (Wrong max blocksize)
 faulty/02 -> This one works when it shouldn't (Wrong max framesize)
-faulty/04 -> This one works when it shouldn't. This one has a wrong number of channels (whatever that means)
-			 Each frame has to be played by itself, otherwise plays sped up.
-faulty/05 -> This one works when it shouldn't. (Wrong number of samples)
-			 This should be fine to decode and play.
-faulty/08 -> This one works when it shouldn't. (Blocksize 65536, exceeds the allowed max of 65535)
-			 We should error here. We segfault currently.
-faulty/09 -> This one works when it shouldn't. (Blocksize 1, below the allowed min of 16 (only the last frame is allowed to have less than 16))
-			 We should error here. We play correctly currently.
-faulty/11 -> We return an error now, but we should just warn and decode the audio fine.
 
 Things:-
 [ ] Options
@@ -33,6 +24,7 @@ Things:-
 [ ] Lots of checks (look at the TODOs in flac.odin)
 [x] Memory optimizations
 [ ] Speed optimizations
+	- Does this matter? So far I haven't found a FLAC file that lags while playing or stalls the audio device even without `-o:speed`
 [ ] Seeking
 [ ] Fuzzing to test the stability of the code
 [x] Check if the use-after-free bug happens on Windows, and if so, if the address sanitizer will show us the full stacktrace

example/main_linux.odin

@@ -33,15 +33,19 @@ main :: proc() {
         fmt.eprintln("Failed to alloc memory")
         return
     }
-    allocator := virtual.arena_allocator(&arena)
+    //allocator := virtual.arena_allocator(&arena)
+
+    track: mem.Tracking_Allocator
+    mem.tracking_allocator_init(&track, context.allocator)
+    defer mem.tracking_allocator_destroy(&track)
+    context.allocator = mem.tracking_allocator(&track)
 
     start := time.now()
-    flac_data, reader, err := flac.load_from_file(os.args[1], allocator)
+    flac_data, reader, err := flac.load_from_file(os.args[1], context.allocator)
     if err != nil {
         fmt.println("Error while reading flac file:", err)
         os.exit(1)
     }
-    defer flac.destroy(flac_data, reader, allocator)
 
     fmt.println(flac_data)
 
@@ -57,7 +61,7 @@ main :: proc() {
     md5_ctx: md5.Context
     md5.init(&md5_ctx)
     for {
-        frame, err := flac.read_next_frame(reader, flac_data, allocator)
+        frame, err := flac.decode_next_frame(reader, flac_data, context.allocator)
         if err != nil {
             if err == .EOF {
                 break
@@ -123,4 +127,20 @@ main :: proc() {
 
     elapsed := time.diff(start, end)
     fmt.println("Decoding took", elapsed)
+
+    flac.destroy(flac_data, reader, context.allocator)
+
+    for _, leak in track.allocation_map {
+        fmt.printfln("%v leaked %m", leak.location, leak.size)
+    }
+    
+    for bad_free in track.bad_free_array {
+        fmt.printfln("%v allocation %p was freed badly", bad_free.location, bad_free.memory)
+    }
+    
+    fmt.printfln("Peak Mem: %m", track.peak_memory_allocated)
+    fmt.printfln("Total Mem: %m", track.total_memory_allocated)
+    fmt.printfln("Current Mem: %m", track.current_memory_allocated)
+    fmt.printfln("Total Allocs: %v, Total Frees: %v:", track.total_allocation_count, track.total_free_count)
+    fmt.printfln("Total Mem Free'd: %m", track.total_memory_freed)
 }

flac.odin

@@ -6,7 +6,7 @@ import "core:crypto/legacy/md5"
 import "core:fmt"
 import "core:io"
 import "core:mem"
-import "core:os"
+import "core:os/os2"
 import "core:time"
 
 Error :: union {
@@ -69,8 +69,7 @@ PictureType :: enum u32 {
 
 Flac :: struct {
     metadata: FlacMetadata,
-    // This holds the samples up to the currently decoded frame. If all frames have
-    // been decoded then this will hold all the decoded samples.
+    // This holds the samples of the current frame.
     samples:  [dynamic]i32,
 }
 
@@ -94,14 +93,15 @@ Picture :: struct {
     height: u32,
     depth: u32,
     num_colors: u32,
-    data: []byte,
+    data: []byte `fmt:"-"`,
 }
 
 Frame :: struct {
     channels: u8,
     sample_rate: u32,
-    // A slice of `Flac`'s `samples` field.
+    // A slice view of `Flac`'s `samples` field.
     // Contains the frame's decoded samples.
+    // DO NOT FREE.
     samples: []i32,
 }
 
@@ -436,6 +436,12 @@ read_metadata :: proc(r: ^Reader, allocator := context.allocator) -> (flac: ^Fla
         return nil, .Invalid_Signature
     }
 
+	if (header.streaminfo.min_block_size < 16 || header.streaminfo.min_block_size > 65535)  ||
+		(header.streaminfo.max_block_size < 16 || header.streaminfo.max_block_size > 65535) ||
+		(header.streaminfo.min_block_size > header.streaminfo.max_block_size) {
+		return nil, .Invalid_Block_Size
+	}
+
     sample_rate := header.streaminfo.sr_chan_bps_ts >> 44
     num_channel_minus_one := (header.streaminfo.sr_chan_bps_ts >> 41) & 7
     bits_per_sample_minus_one := (header.streaminfo.sr_chan_bps_ts >> 36) & 0x1F
@@ -583,7 +589,7 @@ read_metadata :: proc(r: ^Reader, allocator := context.allocator) -> (flac: ^Fla
     return flac, nil
 }
 
-read_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator) -> (frame: Frame, err: Error) {
+decode_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator) -> (frame: Frame, err: Error) {
     //
     // Frame Header
     //
@@ -652,6 +658,14 @@ read_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator)
             return {}, .Invalid_Block_Size
     }
 
+    // TODO: Any frame but the last one MUST have a block size equal to or greater
+    // than the minimum block size and MUST have a block size equal to or
+    // less than the maximum block size.  The last frame MUST have a block
+    // size equal to or less than the maximum block size; it does not have
+    // to comply to the minimum block size because the block size of that
+    // frame must be able to accommodate the length of the audio data the
+    // stream contains
+    //
     //if actual_block_size < 15 && !last_frame {
         // TODO: block sizes less than 16 are only valid for the last frame and MUST NOT be used for any other frame.
     //}
@@ -780,7 +794,7 @@ read_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator)
 
     correlate(subframes, channel_assignment)
 
-    start := len(flac.samples)
+    clear(&flac.samples)
 
     // Write the samples interleaved.
     for i in 0..<len(subframes[0]) {
@@ -794,7 +808,7 @@ read_next_frame :: proc(r: ^Reader, flac: ^Flac, allocator := context.allocator)
         delete(subframe)
     }
 
-    frame.samples = flac.samples[start:]
+    frame.samples = flac.samples[:]
     frame.channels = frame_channels
     frame.sample_rate = actual_sample_rate_in_Hz
 
@@ -861,14 +875,14 @@ md5sum :: proc(md5_ctx: ^md5.Context, flac: ^Flac) -> Error {
 load_from_file :: proc(filename: string, allocator := context.allocator) -> (flac: ^Flac, r: ^Reader, err: Error) {
     context.allocator = allocator
 
-    file, open_err := os.open(filename)
-    if open_err != os.ERROR_NONE {
+    file, open_err := os2.open(filename)
+    if open_err != nil {
         fmt.eprintln(open_err)
         return nil, {}, .Unable_To_Read_File
     }
 
     br := new(bufio.Reader)
-    bufio.reader_init(br, os.stream_from_handle(file))
+    bufio.reader_init(br, os2.to_stream(file))
 
     r = new(Reader)
     r.r = bufio.reader_to_stream(br)

internal.odin

@@ -240,6 +240,7 @@ CueSheetTrackIndex :: struct #packed {
     reserved:           [3]byte,
 }
 
+@(optimization_mode="favor_size")
 decode_extended_utf8 :: proc(r: ^Reader) -> (decoded_num: u64, err: Error) {
     MASKX :: 0b0011_1111
     MASK2 :: 0b0001_1111