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std.compress.flate.Decompress: fix bit read at eof

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This commit is contained in:
Andrew Kelley 2025-07-28 14:36:26 -07:00
parent 9c8cb777d4
commit 73e5594c78
1 changed files with 52 additions and 3 deletions
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55
lib/std/compress/flate/Decompress.zig
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@ -372,7 +372,10 @@ fn takeBits(d: *Decompress, comptime T: type) !T {
};
}
const in = d.input;
const next_int = try in.takeInt(usize, .little);
const next_int = in.takeInt(usize, .little) catch |err| switch (err) {
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return takeBitsEnding(d, T),
};
const needed_bits = @bitSizeOf(T) - remaining_bits;
const u: U = @intCast((next_bits << needed_bits) | (next_int & ((@as(usize, 1) << needed_bits) - 1)));
d.next_bits = next_int >> needed_bits;
@ -384,6 +387,35 @@ fn takeBits(d: *Decompress, comptime T: type) !T {
};
}
fn takeBitsEnding(d: *Decompress, comptime T: type) !T {
const remaining_bits = d.remaining_bits;
const next_bits = d.next_bits;
const in = d.input;
const U = @Type(.{ .int = .{ .signedness = .unsigned, .bits = @bitSizeOf(T) } });
var u: U = 0;
var remaining_needed_bits = @bitSizeOf(U) - remaining_bits;
while (@bitSizeOf(U) >= 8 and remaining_needed_bits >= 8) {
const byte = try in.takeByte();
u = (u << 8) | byte;
remaining_needed_bits -= 8;
}
if (remaining_needed_bits == 0) {
d.next_bits = 0;
d.remaining_bits = 0;
} else {
const byte = try in.takeByte();
u = @intCast((@as(usize, u) << remaining_needed_bits) | (byte & ((@as(usize, 1) << remaining_needed_bits) - 1)));
d.next_bits = @as(usize, byte) >> remaining_needed_bits;
d.remaining_bits = @intCast(8 - remaining_needed_bits);
}
u = @intCast((@as(usize, u) << remaining_bits) | next_bits);
return switch (@typeInfo(T)) {
.int => u,
.@"enum" => @enumFromInt(u),
else => @bitCast(u),
};
}
fn peekBits(d: *Decompress, comptime T: type) !T {
const U = @Type(.{ .int = .{ .signedness = .unsigned, .bits = @bitSizeOf(T) } });
const remaining_bits = d.remaining_bits;
@ -397,7 +429,10 @@ fn peekBits(d: *Decompress, comptime T: type) !T {
};
}
const in = d.input;
const next_int = try in.peekInt(usize, .little);
const next_int = in.peekInt(usize, .little) catch |err| switch (err) {
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return peekBitsEnding(d, T),
};
const needed_bits = @bitSizeOf(T) - remaining_bits;
const u: U = @intCast((next_bits << needed_bits) | (next_int & ((@as(usize, 1) << needed_bits) - 1)));
return switch (@typeInfo(T)) {
@ -407,6 +442,11 @@ fn peekBits(d: *Decompress, comptime T: type) !T {
};
}
fn peekBitsEnding(d: *Decompress, comptime T: type) !T {
_ = d;
@panic("TODO");
}
fn tossBits(d: *Decompress, n: u6) !void {
const remaining_bits = d.remaining_bits;
const next_bits = d.next_bits;
@ -415,13 +455,22 @@ fn tossBits(d: *Decompress, n: u6) !void {
d.remaining_bits = remaining_bits - n;
} else {
const in = d.input;
const next_int = try in.takeInt(usize, .little);
const next_int = in.takeInt(usize, .little) catch |err| switch (err) {
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return tossBitsEnding(d, n),
};
const needed_bits = n - remaining_bits;
d.next_bits = next_int >> needed_bits;
d.remaining_bits = @intCast(@bitSizeOf(usize) - @as(usize, needed_bits));
}
}
fn tossBitsEnding(d: *Decompress, n: u6) !void {
_ = d;
_ = n;
@panic("TODO");
}
fn takeNBitsBuffered(d: *Decompress, n: u4) !u16 {
_ = d;
_ = n;