Add compress and image to core.

2026-08-06 23:58:50 +00:00 · 2021-04-30 00:21:52 +02:00
parent 222bab501c
commit 58e023e0cf
9 changed files with 3776 additions and 0 deletions
@@ -0,0 +1,314 @@
+package gzip
+
+import "core:compress/zlib"
+import "core:compress"
+import "core:os"
+import "core:io"
+import "core:bytes"
+import "core:hash"
+
+/*
+
+	This package implements support for the GZIP file format v4.3,
+	as specified in RFC 1952.
+
+	It is implemented in such a way that it lends itself naturally
+	to be the input to a complementary TAR implementation.
+
+*/
+
+Magic :: enum u16le {
+	GZIP = 0x8b << 8 | 0x1f,
+}
+
+Header :: struct #packed {
+	magic: Magic,
+	compression_method: Compression,
+	flags: Header_Flags,
+	modification_time: u32le,
+	xfl: Compression_Flags,
+	os: OS,
+}
+#assert(size_of(Header) == 10);
+
+Header_Flag :: enum u8 {
+	// Order is important
+	text       = 0,
+	header_crc = 1,
+	extra      = 2,
+	name       = 3,
+	comment    = 4,
+	reserved_1 = 5,
+	reserved_2 = 6,
+	reserved_3 = 7,
+}
+Header_Flags :: distinct bit_set[Header_Flag; u8];
+
+OS :: enum u8 {
+	FAT = 0,
+	Amiga = 1,
+	VMS = 2,
+	Unix = 3,
+	VM_CMS = 4,
+	Atari_TOS = 5,
+	HPFS = 6,
+	Macintosh = 7,
+	Z_System = 8,
+	CP_M = 9,
+	TOPS_20 = 10,
+	NTFS = 11,
+	QDOS = 12,
+	Acorn_RISCOS = 13,
+	_Unknown = 14,
+	Unknown = 255,
+}
+OS_Name :: #partial [OS]string{
+	.FAT   = "FAT",
+	.Amiga = "Amiga",
+	.VMS   = "VMS/OpenVMS",
+	.Unix = "Unix",
+	.VM_CMS = "VM/CMS",
+	.Atari_TOS = "Atari TOS",
+	.HPFS = "HPFS",
+	.Macintosh = "Macintosh",
+	.Z_System = "Z-System",
+	.CP_M = "CP/M",
+	.TOPS_20 = "TOPS-20",
+	.NTFS = "NTFS",
+	.QDOS = "QDOS",
+	.Acorn_RISCOS = "Acorn RISCOS",
+	.Unknown = "Unknown",
+};
+
+Compression :: enum u8 {
+	DEFLATE = 8,
+}
+
+Compression_Flags :: enum u8 {
+	Maximum_Compression = 2,
+	Fastest_Compression = 4,
+}
+
+Error     :: compress.Error;
+E_General :: compress.General_Error;
+E_GZIP    :: compress.GZIP_Error;
+E_ZLIB    :: compress.ZLIB_Error;
+E_Deflate :: compress.Deflate_Error;
+is_kind   :: compress.is_kind;
+
+load_from_slice :: proc(slice: ^[]u8, buf: ^bytes.Buffer, allocator := context.allocator) -> (err: Error) {
+
+	r := bytes.Reader{};
+	bytes.reader_init(&r, slice^);
+	stream := bytes.reader_to_stream(&r);
+
+	err = load_from_stream(&stream, buf, allocator);
+
+	return err;
+}
+
+load_from_file :: proc(filename: string, buf: ^bytes.Buffer, allocator := context.allocator) -> (err: Error) {
+	data, ok := os.read_entire_file(filename, context.temp_allocator);
+	if ok {
+		err = load_from_slice(&data, buf, allocator);
+		return;
+	} else {
+		return E_General.File_Not_Found;
+	}
+}
+
+load_from_stream :: proc(stream: ^io.Stream, buf: ^bytes.Buffer, allocator := context.allocator) -> (err: Error) {
+
+	ctx := compress.Context{
+		input  = stream^,
+	};
+	buf := buf;
+	ws := bytes.buffer_to_stream(buf);
+	ctx.output = ws;
+
+	header, e := compress.read_data(&ctx, Header);
+	if e != .None {
+		return E_General.File_Too_Short;
+	}
+
+	if header.magic != .GZIP {
+		return E_GZIP.Invalid_GZIP_Signature;
+	}
+	if header.compression_method != .DEFLATE {
+		return E_General.Unknown_Compression_Method;
+	}
+
+	if header.os >= ._Unknown {
+		header.os = .Unknown;
+	}
+
+	if .reserved_1 in header.flags || .reserved_2 in header.flags || .reserved_3 in header.flags {
+		return E_GZIP.Reserved_Flag_Set;
+	}
+
+	// printf("signature: %v\n", header.magic);
+	// printf("compression: %v\n", header.compression_method);
+	// printf("flags: %v\n", header.flags);
+	// printf("modification time: %v\n", time.unix(i64(header.modification_time), 0));
+	// printf("xfl: %v (%v)\n", header.xfl, int(header.xfl));
+	// printf("os: %v\n", OS_Name[header.os]);
+
+	if .extra in header.flags {
+		xlen, e_extra := compress.read_data(&ctx, u16le);
+		if e_extra != .None {
+			return E_General.Stream_Too_Short;
+		}
+		// printf("Extra data present (%v bytes)\n", xlen);
+		if xlen < 4 {
+			// Minimum length is 2 for ID + 2 for a field length, if set to zero.
+			return E_GZIP.Invalid_Extra_Data;
+		}
+
+		field_id:     [2]u8;
+		field_length: u16le;
+		field_error: io.Error;
+
+		for xlen >= 4 {
+			// println("Parsing Extra field(s).");
+			field_id, field_error = compress.read_data(&ctx, [2]u8);
+			if field_error != .None {
+				// printf("Parsing Extra returned: %v\n", field_error);
+				return E_General.Stream_Too_Short;
+			}
+			xlen -= 2;
+
+			field_length, field_error = compress.read_data(&ctx, u16le);
+			if field_error != .None {
+				// printf("Parsing Extra returned: %v\n", field_error);
+				return E_General.Stream_Too_Short;
+			}
+			xlen -= 2;
+
+			if xlen <= 0 {
+				// We're not going to try and recover by scanning for a ZLIB header.
+				// Who knows what else is wrong with this file.
+				return E_GZIP.Invalid_Extra_Data;
+			}
+
+			// printf("    Field \"%v\" of length %v found: ", string(field_id[:]), field_length);
+			if field_length > 0 {
+				field_data := make([]u8, field_length, context.temp_allocator);
+				_, field_error = ctx.input->impl_read(field_data);
+				if field_error != .None {
+					// printf("Parsing Extra returned: %v\n", field_error);
+					return E_General.Stream_Too_Short;
+				}
+				xlen -= field_length;
+
+				// printf("%v\n", string(field_data));
+	 		}
+
+			if xlen != 0 {
+				return E_GZIP.Invalid_Extra_Data;
+			}
+		}
+	}
+
+	if .name in header.flags {
+		// Should be enough.
+		name: [1024]u8;
+		b: [1]u8;
+		i := 0;
+		name_error: io.Error;
+
+		for i < len(name) {
+			_, name_error = ctx.input->impl_read(b[:]);
+			if name_error != .None {
+				return E_General.Stream_Too_Short;
+			}
+			if b == 0 {
+				break;
+			}
+			name[i] = b[0];
+			i += 1;
+			if i >= len(name) {
+				return E_GZIP.Original_Name_Too_Long;
+			}
+		}
+		// printf("Original filename: %v\n", string(name[:i]));
+	}
+
+	if .comment in header.flags {
+		// Should be enough.
+		comment: [1024]u8;
+		b: [1]u8;
+		i := 0;
+		comment_error: io.Error;
+
+		for i < len(comment) {
+			_, comment_error = ctx.input->impl_read(b[:]);
+			if comment_error != .None {
+				return E_General.Stream_Too_Short;
+			}
+			if b == 0 {
+				break;
+			}
+			comment[i] = b[0];
+			i += 1;
+			if i >= len(comment) {
+				return E_GZIP.Comment_Too_Long;
+			}
+		}
+		// printf("Comment: %v\n", string(comment[:i]));
+	}
+
+	if .header_crc in header.flags {
+		crc16: [2]u8;
+		crc_error: io.Error;
+		_, crc_error = ctx.input->impl_read(crc16[:]);
+		if crc_error != .None {
+			return E_General.Stream_Too_Short;
+		}
+		/*
+			We don't actually check the CRC16 (lower 2 bytes of CRC32 of header data until the CRC field).
+			If we find a gzip file in the wild that sets this field, we can add proper support for it.
+		*/
+	}
+
+	/*
+		We should have arrived at the ZLIB payload.
+	*/
+
+	zlib_error := zlib.inflate_raw(&ctx);
+
+	// fmt.printf("ZLIB returned: %v\n", zlib_error);
+
+	if !is_kind(zlib_error, E_General.OK) || zlib_error == nil {
+		return zlib_error;
+	}
+
+	/*
+		Read CRC32 using the ctx bit reader because zlib may leave bytes in there.
+	*/
+	compress.discard_to_next_byte_lsb(&ctx);
+
+	payload_crc_b: [4]u8;
+	payload_len_b: [4]u8;
+	for i in 0..3 {
+		payload_crc_b[i] = u8(compress.read_bits_lsb(&ctx, 8));
+	}
+	payload_crc := transmute(u32le)payload_crc_b;
+	for i in 0..3 {
+		payload_len_b[i] = u8(compress.read_bits_lsb(&ctx, 8));
+	}
+	payload_len := int(transmute(u32le)payload_len_b);
+
+	payload := bytes.buffer_to_bytes(buf);
+	crc32 := u32le(hash.crc32(payload));
+
+	if crc32 != payload_crc {
+		return E_GZIP.Payload_CRC_Invalid;
+	}
+
+	if len(payload) != payload_len {
+		return E_GZIP.Payload_Length_Invalid;
+	}
+	return E_General.OK;
+}
+
+load :: proc{load_from_file, load_from_slice, load_from_stream};