Initial project import

tools/v/vlib/compress/deflate/deflate.v

@@ -0,0 +1,291 @@
+module deflate
+
+import encoding.binary
+import hash.adler32
+import hash.crc32
+
+pub type ChunkCallback = fn (chunk []u8, userdata voidptr) int
+
+// CompressFormat selects the output container around the RFC 1951 payload.
+pub enum CompressFormat {
+	zlib
+	gzip
+	raw_deflate
+}
+
+@[params]
+pub struct CompressParams {
+pub:
+	format CompressFormat = .zlib
+}
+
+pub struct RawInflateResult {
+pub:
+	decoded  []u8
+	consumed int
+}
+
+pub struct ZlibHeader {
+pub:
+	payload_start int = 2
+}
+
+pub struct GzipHeader {
+pub mut:
+	flags             u8
+	payload_start     int
+	extra             []u8
+	filename          []u8
+	comment           []u8
+	modification_time u32
+	operating_system  u8
+}
+
+// validate_zlib_header validates a RFC 1950 zlib header.
+@[direct_array_access]
+pub fn validate_zlib_header(data []u8) !ZlibHeader {
+	if data.len < 6 {
+		return error('invalid zlib stream: too short')
+	}
+	if data[0] & 0x0f != 8 {
+		return error('invalid zlib stream: unsupported compression method')
+	}
+	if (u32(data[0]) * 256 + u32(data[1])) % 31 != 0 {
+		return error('invalid zlib stream: bad header checksum')
+	}
+	if data[1] & 0x20 != 0 {
+		return error('invalid zlib stream: preset dictionary not supported')
+	}
+	return ZlibHeader{}
+}
+
+// validate_gzip_header validates a RFC 1952 gzip header and returns parsed fields.
+@[direct_array_access]
+pub fn validate_gzip_header(data []u8) !GzipHeader {
+	if data.len < 18 {
+		return error('invalid gzip stream: too short')
+	}
+	if data[0] != 0x1f || data[1] != 0x8b {
+		return error('invalid gzip stream: bad magic')
+	}
+	if data[2] != 8 {
+		return error('invalid gzip stream: unsupported compression method')
+	}
+	flg := data[3]
+	if flg & 0xe0 != 0 {
+		return error('invalid gzip stream: reserved flags set')
+	}
+	mut header := GzipHeader{
+		flags:             flg
+		payload_start:     10
+		modification_time: binary.little_endian_u32_at(data, 4)
+		operating_system:  data[9]
+	}
+	if flg & 0x04 != 0 {
+		if header.payload_start + 2 > data.len {
+			return error('invalid gzip stream: truncated extra')
+		}
+		xlen := int(u32(data[header.payload_start]) | u32(data[header.payload_start + 1]) << 8)
+		header.payload_start += 2
+		if header.payload_start + xlen > data.len {
+			return error('invalid gzip stream: truncated extra')
+		}
+		header.extra = data[header.payload_start..header.payload_start + xlen]
+		header.payload_start += xlen
+	}
+	if flg & 0x08 != 0 {
+		for header.payload_start < data.len && data[header.payload_start] != 0 {
+			header.filename << data[header.payload_start]
+			header.payload_start++
+		}
+		header.payload_start++
+	}
+	if flg & 0x10 != 0 {
+		for header.payload_start < data.len && data[header.payload_start] != 0 {
+			header.comment << data[header.payload_start]
+			header.payload_start++
+		}
+		header.payload_start++
+	}
+	if flg & 0x02 != 0 {
+		if header.payload_start + 2 > data.len {
+			return error('invalid gzip stream: truncated fhcrc')
+		}
+		expected_crc16 := u16(data[header.payload_start]) | (u16(data[header.payload_start + 1]) << 8)
+		actual_crc16 := u16(crc32.sum(data[..header.payload_start]) & 0xffff)
+		if actual_crc16 != expected_crc16 {
+			return error('invalid gzip stream: header crc16 mismatch')
+		}
+		header.payload_start += 2
+	}
+	if header.payload_start + 8 > data.len {
+		return error('invalid gzip stream: truncated payload')
+	}
+	return header
+}
+
+// compress compresses data as zlib, gzip, or raw DEFLATE.
+pub fn compress(data []u8, format CompressParams) ![]u8 {
+	return match format.format {
+		.zlib { compress_zlib(data) }
+		.gzip { compress_gzip(data) }
+		.raw_deflate { deflate_compress_fixed(data)! }
+	}
+}
+
+pub fn compress_zlib(data []u8) ![]u8 {
+	payload := deflate_compress_fixed(data)!
+	cksum := adler32.sum(data)
+	mut out := []u8{cap: 2 + payload.len + 4}
+	out << u8(0x78) // CMF: CM=8 deflate, CINFO=7 (32K window)
+	out << u8(0x9c) // FLG: default compression, FCHECK satisfies (CMF*256+FLG)%31==0
+	out << payload
+	out << binary.big_endian_get_u32(cksum)
+	return out
+}
+
+// compress_gzip compresses data into a gzip stream (RFC 1952).
+pub fn compress_gzip(data []u8) ![]u8 {
+	payload := deflate_compress_fixed(data)!
+	mut out := []u8{cap: 10 + payload.len + 8}
+	// 10-byte gzip header: ID1 ID2 CM FLG MTIME(4) XFL OS
+	out << [u8(0x1f), 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff]
+	out << payload
+	out << binary.little_endian_get_u32(crc32.sum(data))
+	out << binary.little_endian_get_u32(u32(data.len))
+	return out
+}
+
+// compress_raw compresses data to a raw RFC 1951 DEFLATE stream.
+pub fn compress_raw(data []u8) ![]u8 {
+	return deflate_compress_fixed(data)!
+}
+
+// decompress decompresses a zlib (RFC 1950), gzip (RFC 1952), or raw DEFLATE (RFC 1951) stream.
+// The format is auto-detected.
+pub fn decompress(data []u8) ![]u8 {
+	if data.len >= 2 {
+		// gzip magic: 0x1f 0x8b
+		if data[0] == 0x1f && data[1] == 0x8b {
+			return decompress_gzip(data)
+		}
+		// zlib: CM=8 and header checksum passes
+		if data[0] & 0x0f == 8 && (u32(data[0]) * 256 + u32(data[1])) % 31 == 0 {
+			return decompress_zlib(data)
+		}
+	}
+	// raw DEFLATE
+	return inflate(data)
+}
+
+// decompress_zlib decompresses a zlib stream (RFC 1950).
+// It returns the decompressed bytes in a new array.
+pub fn decompress_zlib(data []u8) ![]u8 {
+	header := validate_zlib_header(data)!
+	payload := data[header.payload_start..data.len - 4]
+	expected := binary.big_endian_u32_at(data, data.len - 4)
+	res := inflate_with_consumed(payload)!
+	if res.consumed != payload.len {
+		return error('invalid zlib stream: trailing data before adler32')
+	}
+	decoded := res.decoded
+	if adler32.sum(decoded) != expected { return error('invalid zlib stream: adler32 mismatch') }
+	return decoded
+}
+
+// decompress_gzip decompresses a gzip stream (RFC 1952).
+// It returns the decompressed bytes in a new array.
+pub fn decompress_gzip(data []u8) ![]u8 {
+	header := validate_gzip_header(data)!
+	payload := data[header.payload_start..data.len - 8]
+	expected_crc := binary.little_endian_u32_at(data, data.len - 8)
+	expected_size := binary.little_endian_u32_at(data, data.len - 4)
+	res := inflate_with_consumed(payload)!
+	if res.consumed != payload.len {
+		return error('invalid gzip stream: trailing data before trailer')
+	}
+	decoded := res.decoded
+	if crc32.sum(decoded) != expected_crc {
+		return error('invalid gzip stream: crc32 mismatch')
+	}
+	if u32(decoded.len) != expected_size {
+		return error('invalid gzip stream: size mismatch')
+	}
+	return decoded
+}
+
+// decompress_raw_with_consumed decompresses raw RFC 1951 DEFLATE data and tracks consumed bytes.
+pub fn decompress_raw_with_consumed(data []u8) !RawInflateResult {
+	res := inflate_with_consumed(data)!
+	return RawInflateResult{
+		decoded:  res.decoded
+		consumed: res.consumed
+	}
+}
+
+// decompress_with_callback decompresses a zlib/gzip/raw stream (RFC 1950, RFC 1952) using a callback for chunked delivery.
+// The callback receives chunks of decompressed data and should return the chunk length to continue, or 0 to abort.
+// Returns the total decompressed length.
+pub fn decompress_with_callback(data []u8, cb ChunkCallback, userdata voidptr) !int {
+	if data.len >= 2 {
+		// gzip magic: 0x1f 0x8b
+		if data[0] == 0x1f && data[1] == 0x8b {
+			return decompress_gzip_with_callback(data, cb, userdata)
+		}
+		// zlib: CM=8 and header checksum passes
+		if data[0] & 0x0f == 8 && (u32(data[0]) * 256 + u32(data[1])) % 31 == 0 {
+			return decompress_zlib_with_callback(data, cb, userdata)
+		}
+	}
+	// raw DEFLATE
+	res := inflate_with_callback(data, cb, userdata)!
+	return res.delivered
+}
+
+fn decompress_zlib_with_callback(data []u8, cb ChunkCallback, userdata voidptr) !int {
+	header := validate_zlib_header(data)!
+	payload := data[header.payload_start..data.len - 4]
+	expected := binary.big_endian_u32_at(data, data.len - 4)
+	res := inflate_with_callback(payload, cb, userdata)!
+	if res.aborted {
+		return res.delivered
+	}
+	if res.consumed != payload.len {
+		return error('invalid zlib stream: trailing data before adler32')
+	}
+	if adler32.sum(res.decoded) != expected {
+		return error('invalid zlib stream: adler32 mismatch')
+	}
+	return res.delivered
+}
+
+fn decompress_gzip_with_callback(data []u8, cb ChunkCallback, userdata voidptr) !int {
+	header := validate_gzip_header(data)!
+	payload := data[header.payload_start..data.len - 8]
+	expected_crc := binary.little_endian_u32_at(data, data.len - 8)
+	expected_size := binary.little_endian_u32_at(data, data.len - 4)
+	res := inflate_with_callback(payload, cb, userdata)!
+	if res.aborted {
+		return res.delivered
+	}
+	if res.consumed != payload.len {
+		return error('invalid gzip stream: trailing data before trailer')
+	}
+	if crc32.sum(res.decoded) != expected_crc {
+		return error('invalid gzip stream: crc32 mismatch')
+	}
+	if u32(res.decoded.len) != expected_size {
+		return error('invalid gzip stream: size mismatch')
+	}
+	return res.delivered
+}
+
+fn bit_reverse(v u32, n int) u32 {
+	mut r := u32(0)
+	mut val := v
+	for _ in 0 .. n {
+		r = (r << 1) | (val & 1)
+		val >>= 1
+	}
+	return r
+}