tiny.choir.composition.serialization.format

1const std = @import("std");2const binary = @import("../../../serialization/root.zig").binary;34pub const magic = "CHOIRCMP";5pub const version: u32 = 6;6pub const header_size = magic.len + @sizeOf(u32) + @sizeOf(u64);7pub const checksum_size = @sizeOf(u32);8pub const max_serialized_bytes: usize = 256 * 1024 * 1024;9pub const max_string_bytes: usize = 1024 * 1024;10pub const max_blob_bytes: usize = 256 * 1024 * 1024;11pub const max_collection_entries: usize = 1 << 16;12pub const max_total_entries: usize = 1 << 18;1314/// Distinct compiler manifests one module may reference. Fragments are assembled15/// from a handful of toolchains at most, and a stream that needs more is refused16/// rather than served with a table the import store cannot hold.17pub const max_compiler_manifests: usize = 16;1819pub const limits = binary.Limits{20    .serialized_bytes = max_serialized_bytes,21    .string_bytes = max_string_bytes,22    .blob_bytes = max_blob_bytes,23    .collection_entries = max_collection_entries,24    .total_entries = max_total_entries,25};2627pub const Error = binary.Error || error{28    InvalidMagic,29    UnsupportedVersion,30    TrailingBytes,31    InvalidChecksum,32};3334pub const WriteError = binary.WriteError;35pub const Writer = binary.Writer(limits);36pub const Reader = binary.Reader(limits);3738pub fn initWriter(allocator: std.mem.Allocator) WriteError!Writer {39    var writer = Writer.init(allocator);40    errdefer writer.deinit();41    try writer.writeRaw(magic);42    try writer.writeInt(u32, version);43    try writer.writeInt(u64, 0);44    return writer;45}4647pub fn finishWriter(writer: *Writer) WriteError![]u8 {48    const payload = writer.bytes.items[header_size..];49    const payload_length = std.math.cast(u64, payload.len) orelse return error.LimitExceeded;50    const length_offset = magic.len + @sizeOf(u32);51    std.mem.writeInt(u64, writer.bytes.items[length_offset..][0..@sizeOf(u64)], payload_length, .little);52    try writer.writeInt(u32, checksum(payload));53    return try writer.finish();54}5556pub fn checksum(payload: []const u8) u32 {57    var crc = std.hash.Crc32.init();58    crc.update(payload);59    return crc.final();60}6162pub fn readPayload(bytes: []const u8) Error!Reader {63    if (bytes.len > max_serialized_bytes) return error.LimitExceeded;64    if (bytes.len < header_size + checksum_size) return error.Truncated;65    if (!std.mem.eql(u8, bytes[0..magic.len], magic)) return error.InvalidMagic;66    if (std.mem.readInt(u32, bytes[magic.len..][0..@sizeOf(u32)], .little) != version) return error.UnsupportedVersion;6768    const length_offset = magic.len + @sizeOf(u32);69    const payload_length_u64 = std.mem.readInt(u64, bytes[length_offset..][0..@sizeOf(u64)], .little);70    const payload_length = std.math.cast(usize, payload_length_u64) orelse return error.LimitExceeded;71    const expected_length = std.math.add(usize, header_size, payload_length) catch return error.LimitExceeded;72    const framed_length = std.math.add(usize, expected_length, checksum_size) catch return error.LimitExceeded;73    if (framed_length > max_serialized_bytes) return error.LimitExceeded;74    if (bytes.len < framed_length) return error.Truncated;75    if (bytes.len > framed_length) return error.TrailingBytes;7677    const payload = bytes[header_size..expected_length];78    const expected_checksum = std.mem.readInt(u32, bytes[expected_length..][0..checksum_size], .little);79    if (checksum(payload) != expected_checksum) return error.InvalidChecksum;80    return try Reader.init(payload);81}

1pub const format = @import("format.zig");