Commit fd2718f82ab70d99186f43845e4291515efb66a5 | zig

author	glowsquid <sachabarsayuracko@gmail.com> 2026-04-06 02:03:11+02:00
committer	Ryan Liptak <squeek502@hotmail.com> 2026-04-06 02:03:11+02:00
log	fd2718f82ab70d99186f43845e4291515efb66a5
tree	eb8774b79fb27efaf4fe409359d96597e6bdaa52
parent	8bd0af5eb97c8b76e519f4d61d391b04d99658eb

fix positional reader discarding (#31593)

closes #30151
closes #30126

Reviewed-on: https://codeberg.org/ziglang/zig/pulls/31593
Reviewed-by: Ryan Liptak <squeek502@noreply.codeberg.org>
Co-authored-by: glowsquid <sachabarsayuracko@gmail.com>
Co-committed-by: glowsquid <sachabarsayuracko@gmail.com>

2 files changed, 25 insertions(+), 1 deletions(-)

lib
- std
  - Io
    File
    Reader.zig
    test.zig

lib/std/Io/File/Reader.zig+3-1

 @@ -309,7 +309,9 @@ fn discard(io_reader: *Io.Reader, limit: Io.Limit) Io.Reader.Error!usize {
                 return 0;
             };
             const logical_pos = logicalPos(r);
-            const delta = @min(@intFromEnum(limit), size - logical_pos);
+            const bytes_remaining = size - logical_pos;
+            if (bytes_remaining == 0) return error.EndOfStream;
+            const delta = @min(@intFromEnum(limit), bytes_remaining);
             setLogicalPos(r, logical_pos + delta);
             return delta;
         },

lib/std/Io/test.zig+22

...	@@ -85,6 +85,28 @@ test "File.Writer.seekTo" {	...	@@ -85,6 +85,28 @@ test "File.Writer.seekTo" {
85	try expect(fw.logicalPos() == 1234);	85	try expect(fw.logicalPos() == 1234);
86	}	86	}
87		87
		88	test "file discard" {
		89	var tmp = tmpDir(.{});
		90	defer tmp.cleanup();
		91
		92	const io = testing.io;
		93
		94	const tmp_file_name = "temp_test_file.txt";
		95	var file = try tmp.dir.createFile(io, tmp_file_name, .{ .read = true });
		96	defer file.close(io);
		97
		98	var fw = file.writerStreaming(io, &.{});
		99
		100	try fw.interface.writeAll("test");
		101
		102	var fr = file.reader(io, &.{});
		103	const r = &fr.interface;
		104
		105	try std.testing.expectEqual(error.EndOfStream, r.discardAll(1024));
		106	try fr.seekTo(0);
		107	try std.testing.expectEqual(4, fr.interface.discardRemaining());
		108	}
		109
88	test "File.setLength" {	110	test "File.setLength" {
89	const io = testing.io;	111	const io = testing.io;
90		112