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std.compress.xz: fix for big-endian targets

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fn ⌃ ⌥ 2023-01-25 08:43:13 -08:00
parent 92ea7bce5d
commit d0dedefde9
2 changed files with 43 additions and 40 deletions
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77
lib/std/compress/xz.zig
View file

@ -3,25 +3,6 @@ const block = @import("xz/block.zig");
const Allocator = std.mem.Allocator;
const Crc32 = std.hash.Crc32;
pub const Flags = packed struct(u16) {
reserved1: u8,
check_kind: Check,
reserved2: u4,
};
pub const Header = extern struct {
magic: [6]u8,
flags: Flags,
crc32: u32,
};
pub const Footer = extern struct {
crc32: u32,
backward_size: u32,
flags: Flags,
magic: [2]u8,
};
pub const Check = enum(u4) {
none = 0x00,
crc32 = 0x01,
@ -30,6 +11,20 @@ pub const Check = enum(u4) {
_,
};
fn readStreamFlags(reader: anytype, check: *Check) !void {
var bit_reader = std.io.bitReader(.Little, reader);
const reserved1 = try bit_reader.readBitsNoEof(u8, 8);
if (reserved1 != 0)
return error.CorruptInput;
check.* = @intToEnum(Check, try bit_reader.readBitsNoEof(u4, 4));
const reserved2 = try bit_reader.readBitsNoEof(u4, 4);
if (reserved2 != 0)
return error.CorruptInput;
}
pub fn decompress(allocator: Allocator, reader: anytype) !Decompress(@TypeOf(reader)) {
return Decompress(@TypeOf(reader)).init(allocator, reader);
}
@ -46,21 +41,24 @@ pub fn Decompress(comptime ReaderType: type) type {
in_reader: ReaderType,
fn init(allocator: Allocator, source: ReaderType) !Self {
const header = try source.readStruct(Header);
if (!std.mem.eql(u8, &header.magic, &.{ 0xFD, '7', 'z', 'X', 'Z', 0x00 }))
const magic = try source.readBytesNoEof(6);
if (!std.mem.eql(u8, &magic, &.{ 0xFD, '7', 'z', 'X', 'Z', 0x00 }))
return error.BadHeader;
if (header.flags.reserved1 != 0 or header.flags.reserved2 != 0)
return error.BadHeader;
var check: Check = undefined;
const hash_a = blk: {
var hasher = std.compress.hashedReader(source, Crc32.init());
try readStreamFlags(hasher.reader(), &check);
break :blk hasher.hasher.final();
};
const hash = Crc32.hash(std.mem.asBytes(&header.flags));
if (hash != header.crc32)
const hash_b = try source.readIntLittle(u32);
if (hash_a != hash_b)
return error.WrongChecksum;
return Self{
.allocator = allocator,
.block_decoder = try block.decoder(allocator, source, header.flags.check_kind),
.block_decoder = try block.decoder(allocator, source, check),
.in_reader = source,
};
}
@ -114,22 +112,27 @@ pub fn Decompress(comptime ReaderType: type) type {
break :blk counter.bytes_read;
};
const footer = try self.in_reader.readStruct(Footer);
const backward_size = (footer.backward_size + 1) * 4;
const hash_a = try self.in_reader.readIntLittle(u32);
const hash_b = blk: {
var hasher = std.compress.hashedReader(self.in_reader, Crc32.init());
const hashed_reader = hasher.reader();
const backward_size = (try hashed_reader.readIntLittle(u32) + 1) * 4;
if (backward_size != index_size)
return error.CorruptInput;
if (footer.flags.reserved1 != 0 or footer.flags.reserved2 != 0)
return error.CorruptInput;
var check: Check = undefined;
try readStreamFlags(hashed_reader, &check);
var hasher = Crc32.init();
hasher.update(std.mem.asBytes(&footer.backward_size));
hasher.update(std.mem.asBytes(&footer.flags));
const hash = hasher.final();
if (hash != footer.crc32)
break :blk hasher.hasher.final();
};
if (hash_a != hash_b)
return error.WrongChecksum;
if (!std.mem.eql(u8, &footer.magic, &.{ 'Y', 'Z' }))
const magic = try self.in_reader.readBytesNoEof(2);
if (!std.mem.eql(u8, &magic, &.{ 'Y', 'Z' }))
return error.CorruptInput;
return 0;

2
lib/std/compress/xz/block.zig
View file

@ -109,7 +109,7 @@ pub fn Decoder(comptime ReaderType: type) type {
has_unpacked_size: bool,
};
const flags = try header_reader.readStruct(Flags);
const flags = @bitCast(Flags, try header_reader.readByte());
const filter_count = @as(u3, flags.last_filter_index) + 1;
if (filter_count > 1)
return error.Unsupported;