Zig deflate compression/decompression implementation. It supports compression and decompression of gzip, zlib and raw deflate format.
Fixes#18062.
This PR replaces current compress/gzip and compress/zlib packages. Deflate package is renamed to flate. Flate is common name for deflate/inflate where deflate is compression and inflate decompression.
There are breaking change. Methods signatures are changed because of removal of the allocator, and I also unified API for all three namespaces (flate, gzip, zlib).
Currently I put old packages under v1 namespace they are still available as compress/v1/gzip, compress/v1/zlib, compress/v1/deflate. Idea is to give users of the current API little time to postpone analyzing what they had to change. Although that rises question when it is safe to remove that v1 namespace.
Here is current API in the compress package:
```Zig
// deflate
fn compressor(allocator, writer, options) !Compressor(@TypeOf(writer))
fn Compressor(comptime WriterType) type
fn decompressor(allocator, reader, null) !Decompressor(@TypeOf(reader))
fn Decompressor(comptime ReaderType: type) type
// gzip
fn compress(allocator, writer, options) !Compress(@TypeOf(writer))
fn Compress(comptime WriterType: type) type
fn decompress(allocator, reader) !Decompress(@TypeOf(reader))
fn Decompress(comptime ReaderType: type) type
// zlib
fn compressStream(allocator, writer, options) !CompressStream(@TypeOf(writer))
fn CompressStream(comptime WriterType: type) type
fn decompressStream(allocator, reader) !DecompressStream(@TypeOf(reader))
fn DecompressStream(comptime ReaderType: type) type
// xz
fn decompress(allocator: Allocator, reader: anytype) !Decompress(@TypeOf(reader))
fn Decompress(comptime ReaderType: type) type
// lzma
fn decompress(allocator, reader) !Decompress(@TypeOf(reader))
fn Decompress(comptime ReaderType: type) type
// lzma2
fn decompress(allocator, reader, writer !void
// zstandard:
fn DecompressStream(ReaderType, options) type
fn decompressStream(allocator, reader) DecompressStream(@TypeOf(reader), .{})
struct decompress
```
The proposed naming convention:
- Compressor/Decompressor for functions which return type, like Reader/Writer/GeneralPurposeAllocator
- compressor/compressor for functions which are initializers for that type, like reader/writer/allocator
- compress/decompress for one shot operations, accepts reader/writer pair, like read/write/alloc
```Zig
/// Compress from reader and write compressed data to the writer.
fn compress(reader: anytype, writer: anytype, options: Options) !void
/// Create Compressor which outputs the writer.
fn compressor(writer: anytype, options: Options) !Compressor(@TypeOf(writer))
/// Compressor type
fn Compressor(comptime WriterType: type) type
/// Decompress from reader and write plain data to the writer.
fn decompress(reader: anytype, writer: anytype) !void
/// Create Decompressor which reads from reader.
fn decompressor(reader: anytype) Decompressor(@TypeOf(reader)
/// Decompressor type
fn Decompressor(comptime ReaderType: type) type
```
Comparing this implementation with the one we currently have in Zig's standard library (std).
Std is roughly 1.2-1.4 times slower in decompression, and 1.1-1.2 times slower in compression. Compressed sizes are pretty much same in both cases.
More resutls in [this](https://github.com/ianic/flate) repo.
This library uses static allocations for all structures, doesn't require allocator. That makes sense especially for deflate where all structures, internal buffers are allocated to the full size. Little less for inflate where we std version uses less memory by not preallocating to theoretical max size array which are usually not fully used.
For deflate this library allocates 395K while std 779K.
For inflate this library allocates 74.5K while std around 36K.
Inflate difference is because we here use 64K history instead of 32K in std.
If merged existing usage of compress gzip/zlib/deflate need some changes. Here is example with necessary changes in comments:
```Zig
const std = @import("std");
// To get this file:
// wget -nc -O war_and_peace.txt https://www.gutenberg.org/ebooks/2600.txt.utf-8
const data = @embedFile("war_and_peace.txt");
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer std.debug.assert(gpa.deinit() == .ok);
const allocator = gpa.allocator();
try oldDeflate(allocator);
try new(std.compress.flate, allocator);
try oldZlib(allocator);
try new(std.compress.zlib, allocator);
try oldGzip(allocator);
try new(std.compress.gzip, allocator);
}
pub fn new(comptime pkg: type, allocator: std.mem.Allocator) !void {
var buf = std.ArrayList(u8).init(allocator);
defer buf.deinit();
// Compressor
var cmp = try pkg.compressor(buf.writer(), .{});
_ = try cmp.write(data);
try cmp.finish();
var fbs = std.io.fixedBufferStream(buf.items);
// Decompressor
var dcp = pkg.decompressor(fbs.reader());
const plain = try dcp.reader().readAllAlloc(allocator, std.math.maxInt(usize));
defer allocator.free(plain);
try std.testing.expectEqualSlices(u8, data, plain);
}
pub fn oldDeflate(allocator: std.mem.Allocator) !void {
const deflate = std.compress.v1.deflate;
// Compressor
var buf = std.ArrayList(u8).init(allocator);
defer buf.deinit();
// Remove allocator
// Rename deflate -> flate
var cmp = try deflate.compressor(allocator, buf.writer(), .{});
_ = try cmp.write(data);
try cmp.close(); // Rename to finish
cmp.deinit(); // Remove
// Decompressor
var fbs = std.io.fixedBufferStream(buf.items);
// Remove allocator and last param
// Rename deflate -> flate
// Remove try
var dcp = try deflate.decompressor(allocator, fbs.reader(), null);
defer dcp.deinit(); // Remove
const plain = try dcp.reader().readAllAlloc(allocator, std.math.maxInt(usize));
defer allocator.free(plain);
try std.testing.expectEqualSlices(u8, data, plain);
}
pub fn oldZlib(allocator: std.mem.Allocator) !void {
const zlib = std.compress.v1.zlib;
var buf = std.ArrayList(u8).init(allocator);
defer buf.deinit();
// Compressor
// Rename compressStream => compressor
// Remove allocator
var cmp = try zlib.compressStream(allocator, buf.writer(), .{});
_ = try cmp.write(data);
try cmp.finish();
cmp.deinit(); // Remove
var fbs = std.io.fixedBufferStream(buf.items);
// Decompressor
// decompressStream => decompressor
// Remove allocator
// Remove try
var dcp = try zlib.decompressStream(allocator, fbs.reader());
defer dcp.deinit(); // Remove
const plain = try dcp.reader().readAllAlloc(allocator, std.math.maxInt(usize));
defer allocator.free(plain);
try std.testing.expectEqualSlices(u8, data, plain);
}
pub fn oldGzip(allocator: std.mem.Allocator) !void {
const gzip = std.compress.v1.gzip;
var buf = std.ArrayList(u8).init(allocator);
defer buf.deinit();
// Compressor
// Rename compress => compressor
// Remove allocator
var cmp = try gzip.compress(allocator, buf.writer(), .{});
_ = try cmp.write(data);
try cmp.close(); // Rename to finisho
cmp.deinit(); // Remove
var fbs = std.io.fixedBufferStream(buf.items);
// Decompressor
// Rename decompress => decompressor
// Remove allocator
// Remove try
var dcp = try gzip.decompress(allocator, fbs.reader());
defer dcp.deinit(); // Remove
const plain = try dcp.reader().readAllAlloc(allocator, std.math.maxInt(usize));
defer allocator.free(plain);
try std.testing.expectEqualSlices(u8, data, plain);
}
```
Use inline to vastly simplify the exposed API. This allows a
comptime-known endian parameter to be propogated, making extra functions
for a specific endianness completely unnecessary.
This reverts commit 0c99ba1eab, reversing
changes made to 5f92b070bf.
This caused a CI failure when it landed in master branch due to a
128-bit `@byteSwap` in std.mem.
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
This includes a breaking change:
std.compress.gzip.GzipStream renamed to
std.compress.gzip.Decompress
This follows the same naming convention as std.compress.xz so that the
stream type can be passed as a comptime parameter.
From RFC 1952:
> If FHCRC is set, a CRC16 for the gzip header is present,
> immediately before the compressed data. The CRC16 consists
> of the two least significant bytes of the CRC32 for all
> bytes of the gzip header up to and not including the CRC16.
- Previously, some of the compress tests used `@src()` in combination with `dirname` and `openDirAbsolute` to read test files at runtime, which both excludes platforms that `openDirAbsolute` is not implemented for (WASI) and platforms that `SourceLocation.file` is not absolute (this was true for me locally on Windows). Instead of converting the tests to use `fs.cwd().openDir`, they have been converted to use `@embedFile` to avoid any potential problems with the runtime cwd.
- In order to use `@embedFile`, some of the `[]u8` parameters needed to be changed to `[]const u8`; none of them needed to be non-const anyway
- The tests now use `expectEqual` and `expectEqualSlices` where appropriate for better diagnostics
Replaces the inflate API from `inflateStream(reader: anytype, window_slice: []u8)` to
`decompressor(allocator: mem.Allocator, reader: anytype, dictionary: ?[]const u8)` and
`compressor(allocator: mem.Allocator, writer: anytype, options: CompressorOptions)`
Read bytes to check expected values instead of reading and hashing them.
Hashing is a waste of time when we can just read and compare.
This also removes a dependency on std.crypto.hash.sha2.Sha256 for tests.
We already have a LICENSE file that covers the Zig Standard Library. We
no longer need to remind everyone that the license is MIT in every single
file.
Previously this was introduced to clarify the situation for a fork of
Zig that made Zig's LICENSE file harder to find, and replaced it with
their own license that required annual payments to their company.
However that fork now appears to be dead. So there is no need to
reinforce the copyright notice in every single file.
