From 46b5eb6ec3fed3c97512c05c13aa6f3dd9b71b87 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Tue, 27 Jan 2026 13:34:36 -0800
Subject: [PATCH] std.Io.Threaded: detect 0 byte successful reads

according to ms docs this can happen with 0 byte writes to pipes.
---
 lib/std/Io/Threaded.zig | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/std/Io/Threaded.zig b/lib/std/Io/Threaded.zig
index bd6e4db4c2..3e67ade835 100644
--- a/lib/std/Io/Threaded.zig
+++ b/lib/std/Io/Threaded.zig
@@ -8249,7 +8249,18 @@ fn fileReadStreamingWindows(file: File, data: []const []u8) File.Reader.Error!us
             null, // byte offset
             null, // key
         )) {
-            .SUCCESS, .END_OF_FILE, .PIPE_BROKEN => {
+            .SUCCESS => {
+                // Only END_OF_FILE is the true end.
+                if (io_status_block.Information == 0) {
+                    try syscall.checkCancel();
+                    continue;
+                } else {
+                    syscall.finish();
+                    io_status_block.u.Status = .SUCCESS;
+                    return io_status_block.Information;
+                }
+            },
+            .END_OF_FILE, .PIPE_BROKEN => {
                 syscall.finish();
                 return io_status_block.Information;
             },