From ecd3ea9bd2f543f44813da21fd6b77d53dd72d7c Mon Sep 17 00:00:00 2001
From: Kendall Condon <goon.pri.low@gmail.com>
Date: Mon, 28 Jul 2025 19:13:22 -0400
Subject: [PATCH] DeprecatedReader.Adapted: fix EndOfStream handling

---
 lib/std/Io.zig                  | 1 +
 lib/std/Io/DeprecatedReader.zig | 1 +
 lib/std/Io/test.zig             | 8 ++++++++
 3 files changed, 10 insertions(+)

diff --git a/lib/std/Io.zig b/lib/std/Io.zig
index 1511f0dcadd06f9748f06151f36954a2ed0dadba..b90276cfabe76017d27e643aaa00b9515f35b963 100644
--- a/lib/std/Io.zig
+++ b/lib/std/Io.zig
@@ -333,6 +333,7 @@ pub fn GenericReader(
                     a.err = err;
                     return error.ReadFailed;
                 };
+                if (n == 0) return error.EndOfStream;
                 w.advance(n);
                 return n;
             }
diff --git a/lib/std/Io/DeprecatedReader.zig b/lib/std/Io/DeprecatedReader.zig
index af1eda84153e9a5a5131e61bab8a98e2b504d7cf..59f163b39ca9d7cfccf608119f58d2458e689c44 100644
--- a/lib/std/Io/DeprecatedReader.zig
+++ b/lib/std/Io/DeprecatedReader.zig
@@ -397,6 +397,7 @@ pub const Adapter = struct {
             a.err = err;
             return error.ReadFailed;
         };
+        if (n == 0) return error.EndOfStream;
         w.advance(n);
         return n;
     }
diff --git a/lib/std/Io/test.zig b/lib/std/Io/test.zig
index bf14f0c24ca15447283e531db5f125680a9767d0..c08879316e4bd600e8e2f4706908c7839132bc6d 100644
--- a/lib/std/Io/test.zig
+++ b/lib/std/Io/test.zig
@@ -180,3 +180,11 @@ test "GenericReader methods can return error.EndOfStream" {
         fbs.reader().isBytes("foo"),
     );
 }
+
+test "Adapted DeprecatedReader EndOfStream" {
+    var fbs: io.FixedBufferStream([]const u8) = .{ .buffer = &.{}, .pos = 0 };
+    const reader = fbs.reader();
+    var buf: [1]u8 = undefined;
+    var adapted = reader.adaptToNewApi(&buf);
+    try std.testing.expectError(error.EndOfStream, adapted.new_interface.takeByte());
+}
-- 
2.54.0