From 6bcdcf85c7a26f03926bdb35120901545dc19206 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 13 Aug 2025 22:16:08 -0700
Subject: [PATCH] std.fs.File.Writer.sendFile: handle sendfile errors

fixes #24842
---
 lib/std/fs/File.zig | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/std/fs/File.zig b/lib/std/fs/File.zig
index c698840f24..08dc00de8f 100644
--- a/lib/std/fs/File.zig
+++ b/lib/std/fs/File.zig
@@ -1823,6 +1823,11 @@ pub const Writer = struct {
                 .NOBUFS => w.sendfile_err = error.SystemResources,
                 else => |err| w.sendfile_err = posix.unexpectedErrno(err),
             }
+            if (w.sendfile_err != null) {
+                // Give calling code chance to observe the error before trying
+                // something else.
+                return 0;
+            }
             if (sbytes == 0) {
                 file_reader.size = file_reader.pos;
                 return error.EndOfStream;
@@ -1879,6 +1884,11 @@ pub const Writer = struct {
                 .PIPE => w.sendfile_err = error.BrokenPipe,
                 else => |err| w.sendfile_err = posix.unexpectedErrno(err),
             }
+            if (w.sendfile_err != null) {
+                // Give calling code chance to observe the error before trying
+                // something else.
+                return 0;
+            }
             if (len == 0) {
                 file_reader.size = file_reader.pos;
                 return error.EndOfStream;