std.compress.xz.Decompress: some tests passing

lib/std/compress/lzma.zig

@@ -12,11 +12,19 @@ pub const RangeDecoder = struct {
     code: u32,
 
     pub fn init(reader: *Reader) !RangeDecoder {
+        var counter: u64 = 0;
+        return initCounting(reader, &counter);
+    }
+
+    pub fn initCounting(reader: *Reader, n_read: *u64) !RangeDecoder {
         const reserved = try reader.takeByte();
+        n_read.* += 1;
         if (reserved != 0) return error.InvalidRangeCode;
+        const code = try reader.takeInt(u32, .big);
+        n_read.* += 4;
         return .{
             .range = 0xFFFF_FFFF,
-            .code = try reader.takeInt(u32, .big),
+            .code = code,
         };
     }
 
@@ -24,47 +32,47 @@ pub const RangeDecoder = struct {
         return self.code == 0;
     }
 
-    fn normalize(self: *RangeDecoder, reader: *Reader) !void {
+    fn normalize(self: *RangeDecoder, reader: *Reader, n_read: *u64) !void {
         if (self.range < 0x0100_0000) {
             self.range <<= 8;
             self.code = (self.code << 8) ^ @as(u32, try reader.takeByte());
+            n_read.* += 1;
         }
     }
 
-    fn getBit(self: *RangeDecoder, reader: *Reader) !bool {
+    fn getBit(self: *RangeDecoder, reader: *Reader, n_read: *u64) !bool {
         self.range >>= 1;
 
         const bit = self.code >= self.range;
-        if (bit)
+        if (bit) self.code -= self.range;
-            self.code -= self.range;
 
-        try self.normalize(reader);
+        try self.normalize(reader, n_read);
         return bit;
     }
 
-    pub fn get(self: *RangeDecoder, reader: *Reader, count: usize) !u32 {
+    pub fn get(self: *RangeDecoder, reader: *Reader, count: usize, n_read: *u64) !u32 {
         var result: u32 = 0;
-        var i: usize = 0;
+        for (0..count) |_| {
-        while (i < count) : (i += 1)
+            result = (result << 1) ^ @intFromBool(try self.getBit(reader, n_read));
-            result = (result << 1) ^ @intFromBool(try self.getBit(reader));
+        }
         return result;
     }
 
-    pub fn decodeBit(self: *RangeDecoder, reader: *Reader, prob: *u16) !bool {
+    pub fn decodeBit(self: *RangeDecoder, reader: *Reader, prob: *u16, n_read: *u64) !bool {
         const bound = (self.range >> 11) * prob.*;
 
         if (self.code < bound) {
             prob.* += (0x800 - prob.*) >> 5;
             self.range = bound;
 
-            try self.normalize(reader);
+            try self.normalize(reader, n_read);
             return false;
         } else {
             prob.* -= prob.* >> 5;
             self.code -= bound;
             self.range -= bound;
 
-            try self.normalize(reader);
+            try self.normalize(reader, n_read);
             return true;
         }
     }
@@ -74,11 +82,12 @@ pub const RangeDecoder = struct {
         reader: *Reader,
         num_bits: u5,
         probs: []u16,
+        n_read: *u64,
     ) !u32 {
         var tmp: u32 = 1;
         var i: @TypeOf(num_bits) = 0;
         while (i < num_bits) : (i += 1) {
-            const bit = try self.decodeBit(reader, &probs[tmp]);
+            const bit = try self.decodeBit(reader, &probs[tmp], n_read);
             tmp = (tmp << 1) ^ @intFromBool(bit);
         }
         return tmp - (@as(u32, 1) << num_bits);
@@ -90,12 +99,13 @@ pub const RangeDecoder = struct {
         num_bits: u5,
         probs: []u16,
         offset: usize,
+        n_read: *u64,
     ) !u32 {
         var result: u32 = 0;
         var tmp: usize = 1;
         var i: @TypeOf(num_bits) = 0;
         while (i < num_bits) : (i += 1) {
-            const bit = @intFromBool(try self.decodeBit(reader, &probs[offset + tmp]));
+            const bit = @intFromBool(try self.decodeBit(reader, &probs[offset + tmp], n_read));
             tmp = (tmp << 1) ^ bit;
             result ^= @as(u32, bit) << i;
         }
@@ -177,13 +187,14 @@ pub const Decode = struct {
         /// `CircularBuffer` or `std.compress.lzma2.AccumBuffer`.
         buffer: anytype,
         decoder: *RangeDecoder,
+        n_read: *u64,
     ) !ProcessingStatus {
         const gpa = allocating.allocator;
         const writer = &allocating.writer;
         const pos_state = buffer.len & ((@as(usize, 1) << self.properties.pb) - 1);
 
-        if (!try decoder.decodeBit(reader, &self.is_match[(self.state << 4) + pos_state])) {
+        if (!try decoder.decodeBit(reader, &self.is_match[(self.state << 4) + pos_state], n_read)) {
-            const byte: u8 = try self.decodeLiteral(reader, buffer, decoder);
+            const byte: u8 = try self.decodeLiteral(reader, buffer, decoder, n_read);
 
             try buffer.appendLiteral(gpa, byte, writer);
 
@@ -197,18 +208,18 @@ pub const Decode = struct {
         }
 
         var len: usize = undefined;
-        if (try decoder.decodeBit(reader, &self.is_rep[self.state])) {
+        if (try decoder.decodeBit(reader, &self.is_rep[self.state], n_read)) {
-            if (!try decoder.decodeBit(reader, &self.is_rep_g0[self.state])) {
+            if (!try decoder.decodeBit(reader, &self.is_rep_g0[self.state], n_read)) {
-                if (!try decoder.decodeBit(reader, &self.is_rep_0long[(self.state << 4) + pos_state])) {
+                if (!try decoder.decodeBit(reader, &self.is_rep_0long[(self.state << 4) + pos_state], n_read)) {
                     self.state = if (self.state < 7) 9 else 11;
                     const dist = self.rep[0] + 1;
                     try buffer.appendLz(gpa, 1, dist, writer);
                     return .more;
                 }
             } else {
-                const idx: usize = if (!try decoder.decodeBit(reader, &self.is_rep_g1[self.state]))
+                const idx: usize = if (!try decoder.decodeBit(reader, &self.is_rep_g1[self.state], n_read))
                     1
-                else if (!try decoder.decodeBit(reader, &self.is_rep_g2[self.state]))
+                else if (!try decoder.decodeBit(reader, &self.is_rep_g2[self.state], n_read))
                     2
                 else
                     3;
@@ -220,7 +231,7 @@ pub const Decode = struct {
                 self.rep[0] = dist;
             }
 
-            len = try self.rep_len_decoder.decode(reader, decoder, pos_state);
+            len = try self.rep_len_decoder.decode(reader, decoder, pos_state, n_read);
 
             self.state = if (self.state < 7) 8 else 11;
         } else {
@@ -228,11 +239,11 @@ pub const Decode = struct {
             self.rep[2] = self.rep[1];
             self.rep[1] = self.rep[0];
 
-            len = try self.len_decoder.decode(reader, decoder, pos_state);
+            len = try self.len_decoder.decode(reader, decoder, pos_state, n_read);
 
             self.state = if (self.state < 7) 7 else 10;
 
-            const rep_0 = try self.decodeDistance(reader, decoder, len);
+            const rep_0 = try self.decodeDistance(reader, decoder, len, n_read);
 
             self.rep[0] = rep_0;
             if (self.rep[0] == 0xFFFF_FFFF) {
@@ -257,6 +268,7 @@ pub const Decode = struct {
         /// `CircularBuffer` or `std.compress.lzma2.AccumBuffer`.
         buffer: anytype,
         decoder: *RangeDecoder,
+        n_read: *u64,
     ) !u8 {
         const def_prev_byte = 0;
         const prev_byte = @as(usize, buffer.lastOr(def_prev_byte));
@@ -275,6 +287,7 @@ pub const Decode = struct {
                 const bit = @intFromBool(try decoder.decodeBit(
                     reader,
                     &probs[((@as(usize, 1) + match_bit) << 8) + result],
+                    n_read,
                 ));
                 result = (result << 1) ^ bit;
                 if (match_bit != bit) {
@@ -284,10 +297,10 @@ pub const Decode = struct {
         }
 
         while (result < 0x100) {
-            result = (result << 1) ^ @intFromBool(try decoder.decodeBit(reader, &probs[result]));
+            result = (result << 1) ^ @intFromBool(try decoder.decodeBit(reader, &probs[result], n_read));
         }
 
-        return @as(u8, @truncate(result - 0x100));
+        return @truncate(result - 0x100);
     }
 
     fn decodeDistance(
@@ -295,12 +308,12 @@ pub const Decode = struct {
         reader: *Reader,
         decoder: *RangeDecoder,
         length: usize,
+        n_read: *u64,
     ) !usize {
         const len_state = if (length > 3) 3 else length;
 
-        const pos_slot = @as(usize, try self.pos_slot_decoder[len_state].parse(reader, decoder));
+        const pos_slot: usize = try self.pos_slot_decoder[len_state].parse(reader, decoder, n_read);
-        if (pos_slot < 4)
+        if (pos_slot < 4) return pos_slot;
-            return pos_slot;
 
         const num_direct_bits = @as(u5, @intCast((pos_slot >> 1) - 1));
         var result = (2 ^ (pos_slot & 1)) << num_direct_bits;
@@ -311,10 +324,11 @@ pub const Decode = struct {
                 num_direct_bits,
                 &self.pos_decoders,
                 result - pos_slot,
+                n_read,
             );
         } else {
-            result += @as(usize, try decoder.get(reader, num_direct_bits - 4)) << 4;
+            result += @as(usize, try decoder.get(reader, num_direct_bits - 4, n_read)) << 4;
-            result += try self.align_decoder.parseReverse(reader, decoder);
+            result += try self.align_decoder.parseReverse(reader, decoder, n_read);
         }
 
         return result;
@@ -435,16 +449,17 @@ pub const Decode = struct {
         return struct {
             probs: [1 << num_bits]u16 = @splat(0x400),
 
-            pub fn parse(self: *@This(), reader: *Reader, decoder: *RangeDecoder) !u32 {
+            pub fn parse(self: *@This(), reader: *Reader, decoder: *RangeDecoder, n_read: *u64) !u32 {
-                return decoder.parseBitTree(reader, num_bits, &self.probs);
+                return decoder.parseBitTree(reader, num_bits, &self.probs, n_read);
             }
 
             pub fn parseReverse(
                 self: *@This(),
                 reader: *Reader,
                 decoder: *RangeDecoder,
+                n_read: *u64,
             ) !u32 {
-                return decoder.parseReverseBitTree(reader, num_bits, &self.probs, 0);
+                return decoder.parseReverseBitTree(reader, num_bits, &self.probs, 0, n_read);
             }
 
             pub fn reset(self: *@This()) void {
@@ -465,13 +480,14 @@ pub const Decode = struct {
             reader: *Reader,
             decoder: *RangeDecoder,
             pos_state: usize,
+            n_read: *u64,
         ) !usize {
-            if (!try decoder.decodeBit(reader, &self.choice)) {
+            if (!try decoder.decodeBit(reader, &self.choice, n_read)) {
-                return @as(usize, try self.low_coder[pos_state].parse(reader, decoder));
+                return @as(usize, try self.low_coder[pos_state].parse(reader, decoder, n_read));
-            } else if (!try decoder.decodeBit(reader, &self.choice2)) {
+            } else if (!try decoder.decodeBit(reader, &self.choice2, n_read)) {
-                return @as(usize, try self.mid_coder[pos_state].parse(reader, decoder)) + 8;
+                return @as(usize, try self.mid_coder[pos_state].parse(reader, decoder, n_read)) + 8;
             } else {
-                return @as(usize, try self.high_coder.parse(reader, decoder)) + 16;
+                return @as(usize, try self.high_coder.parse(reader, decoder, n_read)) + 16;
             }
         }
 
@@ -701,7 +717,8 @@ pub const Decompress = struct {
             } else if (d.range_decoder.isFinished()) {
                 break :process_next;
             }
-            switch (d.decode.process(d.input, &allocating, &d.buffer, &d.range_decoder) catch |err| switch (err) {
+            var n_read: u64 = 0;
+            switch (d.decode.process(d.input, &allocating, &d.buffer, &d.range_decoder, &n_read) catch |err| switch (err) {
                 error.WriteFailed => {
                     d.err = error.OutOfMemory;
                     return error.ReadFailed;

lib/std/compress/lzma2.zig

@@ -116,24 +116,29 @@ pub const Decode = struct {
         self.* = undefined;
     }
 
-    pub fn decompress(d: *Decode, reader: *Reader, allocating: *Writer.Allocating) !void {
+    /// Returns how many compressed bytes were consumed.
+    pub fn decompress(d: *Decode, reader: *Reader, allocating: *Writer.Allocating) !u64 {
         const gpa = allocating.allocator;
 
         var accum = AccumBuffer.init(std.math.maxInt(usize));
         defer accum.deinit(gpa);
 
+        var n_read: u64 = 0;
+
         while (true) {
             const status = try reader.takeByte();
+            n_read += 1;
 
             switch (status) {
                 0 => break,
-                1 => try parseUncompressed(reader, allocating, &accum, true),
+                1 => n_read += try parseUncompressed(reader, allocating, &accum, true),
-                2 => try parseUncompressed(reader, allocating, &accum, false),
+                2 => n_read += try parseUncompressed(reader, allocating, &accum, false),
-                else => try d.parseLzma(reader, allocating, &accum, status),
+                else => n_read += try d.parseLzma(reader, allocating, &accum, status),
             }
         }
 
         try accum.finish(&allocating.writer);
+        return n_read;
     }
 
     fn parseLzma(
@@ -142,7 +147,7 @@ pub const Decode = struct {
         allocating: *Writer.Allocating,
         accum: *AccumBuffer,
         status: u8,
-    ) !void {
+    ) !u64 {
         if (status & 0x80 == 0) return error.CorruptInput;
 
         const Reset = struct {
@@ -175,15 +180,19 @@ pub const Decode = struct {
             else => unreachable,
         };
 
+        var n_read: u64 = 0;
+
         const unpacked_size = blk: {
             var tmp: u64 = status & 0x1F;
             tmp <<= 16;
             tmp |= try reader.takeInt(u16, .big);
+            n_read += 2;
             break :blk tmp + 1;
         };
 
         const packed_size = blk: {
             const tmp: u17 = try reader.takeInt(u16, .big);
+            n_read += 2;
             break :blk tmp + 1;
         };
 
@@ -196,6 +205,7 @@ pub const Decode = struct {
 
             if (reset.props) {
                 var props = try reader.takeByte();
+                n_read += 1;
                 if (props >= 225) {
                     return error.CorruptInput;
                 }
@@ -216,23 +226,21 @@ pub const Decode = struct {
             try ld.resetState(allocating.allocator, new_props);
         }
 
-        var range_decoder = try lzma.RangeDecoder.init(reader);
+        const start_count = n_read;
+        var range_decoder = try lzma.RangeDecoder.initCounting(reader, &n_read);
 
         while (true) {
             if (accum.len >= unpacked_size) break;
             if (range_decoder.isFinished()) break;
-            switch (try ld.process(reader, allocating, accum, &range_decoder)) {
+            switch (try ld.process(reader, allocating, accum, &range_decoder, &n_read)) {
                 .more => continue,
                 .finished => break,
             }
         }
         if (accum.len != unpacked_size) return error.DecompressedSizeMismatch;
+        if (n_read - start_count != packed_size) return error.CompressedSizeMismatch;
 
-        // TODO restore this error
+        return n_read;
-        //if (counter.bytes_read != packed_size) {
-        //    return error.CorruptInput;
-        //}
-        _ = packed_size;
     }
 
     fn parseUncompressed(
@@ -240,18 +248,17 @@ pub const Decode = struct {
         allocating: *Writer.Allocating,
         accum: *AccumBuffer,
         reset_dict: bool,
-    ) !void {
+    ) !usize {
         const unpacked_size = @as(u17, try reader.takeInt(u16, .big)) + 1;
 
         if (reset_dict) try accum.reset(&allocating.writer);
 
         const gpa = allocating.allocator;
 
-        var i = unpacked_size;
+        for (0..unpacked_size) |_| {
-        while (i != 0) {
             try accum.appendByte(gpa, try reader.takeByte());
-            i -= 1;
         }
+        return 2 + unpacked_size;
     }
 };
 
@@ -268,6 +275,7 @@ test "decompress hello world stream" {
     var result: std.Io.Writer.Allocating = .init(gpa);
     defer result.deinit();
 
-    try decode.decompress(&stream, &result);
+    const n_read = try decode.decompress(&stream, &result);
+    try std.testing.expectEqual(compressed.len, n_read);
     try std.testing.expectEqualStrings(expected, result.written());
 }

lib/std/compress/xz/Decompress.zig

@@ -8,6 +8,7 @@ const Sha256 = std.crypto.hash.sha2.Sha256;
 const lzma2 = std.compress.lzma2;
 const Writer = std.Io.Writer;
 const Reader = std.Io.Reader;
+const assert = std.debug.assert;
 
 /// Underlying compressed data stream to pull bytes from.
 input: *Reader,
@@ -28,6 +29,7 @@ pub const Error = error{
     Overflow,
     InvalidRangeCode,
     DecompressedSizeMismatch,
+    CompressedSizeMismatch,
 };
 
 pub const Check = enum(u4) {
@@ -62,10 +64,10 @@ pub fn init(
     if (!std.mem.eql(u8, magic, &.{ 0xFD, '7', 'z', 'X', 'Z', 0x00 }))
         return error.NotXzStream;
 
-    const actual_hash = Crc32.hash(try input.peek(@sizeOf(StreamFlags)));
+    const computed_checksum = Crc32.hash(try input.peek(@sizeOf(StreamFlags)));
     const stream_flags = input.takeStruct(StreamFlags, .little) catch unreachable;
     const stored_hash = try input.takeInt(u32, .little);
-    if (actual_hash != stored_hash) return error.WrongChecksum;
+    if (computed_checksum != stored_hash) return error.WrongChecksum;
 
     return .{
         .input = input,
@@ -129,6 +131,7 @@ fn readIndirect(r: *Reader) Reader.Error!usize {
         r.end = allocating.writer.end;
     }
 
+    if (d.err != null) return error.ReadFailed;
     if (d.block_count == std.math.maxInt(usize)) return error.EndOfStream;
 
     readBlock(input, &allocating) catch |err| switch (err) {
@@ -137,7 +140,10 @@ fn readIndirect(r: *Reader) Reader.Error!usize {
             return error.ReadFailed;
         },
         error.SuccessfulEndOfStream => {
-            finish(d);
+            finish(d) catch |finish_err| {
+                d.err = finish_err;
+                return error.ReadFailed;
+            };
             d.block_count = std.math.maxInt(usize);
             return error.EndOfStream;
         },
@@ -184,7 +190,7 @@ fn readBlock(input: *Reader, allocating: *Writer.Allocating) !void {
     var packed_size: ?u64 = null;
     var unpacked_size: ?u64 = null;
 
-    {
+    const header_size = h: {
         // Read the block header via peeking so that we can hash the whole thing too.
         const first_byte: usize = try input.peekByte();
         if (first_byte == 0) return error.SuccessfulEndOfStream;
@@ -223,95 +229,92 @@ fn readBlock(input: *Reader, allocating: *Writer.Allocating) !void {
 
         const actual_header_size = input.seek - header_seek_start;
         if (actual_header_size > declared_header_size) return error.CorruptInput;
-        var remaining_bytes = declared_header_size - actual_header_size;
+        const remaining_bytes = declared_header_size - actual_header_size;
-        while (remaining_bytes != 0) {
+        for (0..remaining_bytes) |_| {
             if (try input.takeByte() != 0) return error.CorruptInput;
-            remaining_bytes -= 1;
         }
 
         const header_slice = input.buffer[header_seek_start..][0..declared_header_size];
-        const actual_hash = Crc32.hash(header_slice);
+        const computed_checksum = Crc32.hash(header_slice);
-        const declared_hash = try input.takeInt(u32, .little);
+        const declared_checksum = try input.takeInt(u32, .little);
-        if (actual_hash != declared_hash) return error.WrongChecksum;
+        if (computed_checksum != declared_checksum) return error.WrongChecksum;
-    }
+        break :h declared_header_size;
+    };
 
     // Compressed Data
 
     var lzma2_decode = try lzma2.Decode.init(allocating.allocator);
+    defer lzma2_decode.deinit(allocating.allocator);
     const before_size = allocating.writer.end;
-    try lzma2_decode.decompress(input, allocating);
+    const packed_bytes_read = try lzma2_decode.decompress(input, allocating);
     const unpacked_bytes = allocating.writer.end - before_size;
 
-    // TODO restore this check
+    if (packed_size) |s| {
-    //if (packed_size) |s| {
+        if (s != packed_bytes_read) return error.CorruptInput;
-    //    if (s != packed_counter.bytes_read)
+    }
-    //        return error.CorruptInput;
-    //}
 
     if (unpacked_size) |s| {
         if (s != unpacked_bytes) return error.CorruptInput;
     }
 
     // Block Padding
-    if (true) @panic("TODO account for block padding");
+    const block_counter = header_size + packed_bytes_read;
-    //while (block_counter.bytes_read % 4 != 0) {
+    const padding = (4 - (block_counter % 4)) % 4;
-    //    if (try block_reader.takeByte() != 0)
+    for (0..padding) |_| {
-    //        return error.CorruptInput;
+        if (try input.takeByte() != 0) return error.CorruptInput;
-    //}
+    }
-
 }
 
-fn finish(d: *Decompress) void {
+fn finish(d: *Decompress) !void {
-    _ = d;
+    const input = d.input;
-    @panic("TODO");
+    const index_size = blk: {
-    //const input = d.input;
+        // Assume that we already peeked a zero in readBlock().
-    //const index_size = blk: {
+        assert(input.buffered()[0] == 0);
-    //    const record_count = try input.takeLeb128(u64);
+        var input_counter: u64 = 1;
-    //    if (record_count != d.block_decode.block_count)
+        var checksum: Crc32 = .init();
-    //        return error.CorruptInput;
+        checksum.update(&.{0});
+        input.toss(1);
 
-    //    var i: usize = 0;
+        const record_count = try countLeb128(input, u64, &input_counter, &checksum);
-    //    while (i < record_count) : (i += 1) {
+        if (record_count != d.block_count)
-    //        // TODO: validate records
+            return error.CorruptInput;
-    //        _ = try std.leb.readUleb128(u64, counting_reader);
-    //        _ = try std.leb.readUleb128(u64, counting_reader);
-    //    }
 
-    //    while (counter.bytes_read % 4 != 0) {
+        for (0..record_count) |_| {
-    //        if (try counting_reader.takeByte() != 0)
+            // TODO: validate records
-    //            return error.CorruptInput;
+            _ = try countLeb128(input, u64, &input_counter, &checksum);
-    //    }
+            _ = try countLeb128(input, u64, &input_counter, &checksum);
+        }
 
-    //    const hash_a = hasher.hasher.final();
+        const padding_len = (4 - (input_counter % 4)) % 4;
-    //    const hash_b = try counting_reader.takeInt(u32, .little);
+        const padding = try input.take(padding_len);
-    //    if (hash_a != hash_b)
+        for (padding) |byte| {
-    //        return error.WrongChecksum;
+            if (byte != 0) return error.CorruptInput;
+        }
+        checksum.update(padding);
 
-    //    break :blk counter.bytes_read;
+        const declared_checksum = try input.takeInt(u32, .little);
-    //};
+        const computed_checksum = checksum.final();
+        if (computed_checksum != declared_checksum) return error.WrongChecksum;
 
-    //const hash_a = try d.in_reader.takeInt(u32, .little);
+        break :blk input_counter + padding.len + 4;
+    };
 
-    //const hash_b = blk: {
+    const declared_checksum = try input.takeInt(u32, .little);
-    //    var hasher = hashedReader(d.in_reader, Crc32.init());
+    const computed_checksum = Crc32.hash(try input.peek(4 + @sizeOf(StreamFlags)));
-    //    const hashed_reader = hasher.reader();
+    if (declared_checksum != computed_checksum) return error.WrongChecksum;
-
+    const backward_size = (@as(u64, try input.takeInt(u32, .little)) + 1) * 4;
-    //    const backward_size = (@as(u64, try hashed_reader.takeInt(u32, .little)) + 1) * 4;
+    if (backward_size != index_size) return error.CorruptInput;
-    //    if (backward_size != index_size)
+    input.toss(@sizeOf(StreamFlags));
-    //        return error.CorruptInput;
+    if (!std.mem.eql(u8, try input.takeArray(2), &.{ 'Y', 'Z' }))
-
+        return error.CorruptInput;
-    //    var check: Check = undefined;
+}
-    //    try readStreamFlags(hashed_reader, &check);
+
-
+fn countLeb128(reader: *Reader, comptime T: type, counter: *u64, hasher: *Crc32) !T {
-    //    break :blk hasher.hasher.final();
+    try reader.fill(8);
-    //};
+    const start = reader.seek;
-
+    const result = try reader.takeLeb128(T);
-    //if (hash_a != hash_b)
+    const read_slice = reader.buffer[start..reader.seek];
-    //    return error.WrongChecksum;
+    hasher.update(read_slice);
-
+    counter.* += read_slice.len;
-    //const magic = try d.in_reader.takeBytesNoEof(2);
+    return result;
-    //if (!std.mem.eql(u8, &magic, &.{ 'Y', 'Z' }))
-    //    return error.CorruptInput;
-
-    //return 0;
 }

lib/std/compress/xz/test.zig

@@ -22,47 +22,79 @@ fn testReader(data: []const u8, comptime expected: []const u8) !void {
     try testing.expectEqualSlices(u8, expected, result);
 }
 
-test "compressed data" {
+test "fixture good-0-empty.xz" {
     try testReader(@embedFile("testdata/good-0-empty.xz"), "");
+}
 
-    inline for ([_][]const u8{
+const hello_world_text =
-        "good-1-check-none.xz",
+    \\Hello
-        "good-1-check-crc32.xz",
+    \\World!
-        "good-1-check-crc64.xz",
+    \\
-        "good-1-check-sha256.xz",
+;
-        "good-2-lzma2.xz",
-        "good-1-block_header-1.xz",
-        "good-1-block_header-2.xz",
-        "good-1-block_header-3.xz",
-    }) |filename| {
-        try testReader(@embedFile("testdata/" ++ filename),
-            \\Hello
-            \\World!
-            \\
-        );
-    }
 
-    inline for ([_][]const u8{
+test "fixture good-1-check-none.xz" {
-        "good-1-lzma2-1.xz",
+    try testReader(@embedFile("testdata/good-1-check-none.xz"), hello_world_text);
-        "good-1-lzma2-2.xz",
+}
-        "good-1-lzma2-3.xz",
-        "good-1-lzma2-4.xz",
-    }) |filename| {
-        try testReader(@embedFile("testdata/" ++ filename),
-            \\Lorem ipsum dolor sit amet, consectetur adipisicing 
-            \\elit, sed do eiusmod tempor incididunt ut 
-            \\labore et dolore magna aliqua. Ut enim 
-            \\ad minim veniam, quis nostrud exercitation ullamco 
-            \\laboris nisi ut aliquip ex ea commodo 
-            \\consequat. Duis aute irure dolor in reprehenderit 
-            \\in voluptate velit esse cillum dolore eu 
-            \\fugiat nulla pariatur. Excepteur sint occaecat cupidatat 
-            \\non proident, sunt in culpa qui officia 
-            \\deserunt mollit anim id est laborum. 
-            \\
-        );
-    }
 
+test "fixture good-1-check-crc32.xz" {
+    try testReader(@embedFile("testdata/good-1-check-crc32.xz"), hello_world_text);
+}
+
+test "fixture good-1-check-crc64.xz" {
+    try testReader(@embedFile("testdata/good-1-check-crc64.xz"), hello_world_text);
+}
+
+test "fixture good-1-check-sha256.xz" {
+    try testReader(@embedFile("testdata/good-1-check-sha256.xz"), hello_world_text);
+}
+
+test "fixture good-2-lzma2.xz" {
+    try testReader(@embedFile("testdata/good-2-lzma2.xz"), hello_world_text);
+}
+
+test "fixture good-1-block_header-1.xz" {
+    try testReader(@embedFile("testdata/good-1-block_header-1.xz"), hello_world_text);
+}
+
+test "fixture good-1-block_header-2.xz" {
+    try testReader(@embedFile("testdata/good-1-block_header-2.xz"), hello_world_text);
+}
+
+test "fixture good-1-block_header-3.xz" {
+    try testReader(@embedFile("testdata/good-1-block_header-3.xz"), hello_world_text);
+}
+
+const lorem_ipsum_text =
+    \\Lorem ipsum dolor sit amet, consectetur adipisicing 
+    \\elit, sed do eiusmod tempor incididunt ut 
+    \\labore et dolore magna aliqua. Ut enim 
+    \\ad minim veniam, quis nostrud exercitation ullamco 
+    \\laboris nisi ut aliquip ex ea commodo 
+    \\consequat. Duis aute irure dolor in reprehenderit 
+    \\in voluptate velit esse cillum dolore eu 
+    \\fugiat nulla pariatur. Excepteur sint occaecat cupidatat 
+    \\non proident, sunt in culpa qui officia 
+    \\deserunt mollit anim id est laborum. 
+    \\
+;
+
+test "fixture good-1-lzma2-1.xz" {
+    try testReader(@embedFile("testdata/good-1-lzma2-1.xz"), lorem_ipsum_text);
+}
+
+test "fixture good-1-lzma2-2.xz" {
+    try testReader(@embedFile("testdata/good-1-lzma2-2.xz"), lorem_ipsum_text);
+}
+
+test "fixture good-1-lzma2-3.xz" {
+    try testReader(@embedFile("testdata/good-1-lzma2-3.xz"), lorem_ipsum_text);
+}
+
+test "fixture good-1-lzma2-4.xz" {
+    try testReader(@embedFile("testdata/good-1-lzma2-4.xz"), lorem_ipsum_text);
+}
+
+test "fixture good-1-lzma2-5.xz" {
     try testReader(@embedFile("testdata/good-1-lzma2-5.xz"), "");
 }