From 5a6ff0561008bf96ec90c482c2ea17d245912bba Mon Sep 17 00:00:00 2001
From: BANANASJIM <haolongjim@gmail.com>
Date: Sat, 6 Jun 2026 21:01:17 -0700
Subject: [PATCH] fix(hidraw): check ioctl errno in featureReport
 (HIDIOCSFEATURE failures were silently swallowed)
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- linux.ioctl returns usize, so the `if (rc < 0)` guard was always false;
  every HIDIOCSFEATURE failure (ENODEV/EPIPE on unplug, EINVAL, EBADF, ...)
  returned OK and the device-init handshake in init.zig never saw the error.
- Interpret the raw syscall return with linux.E.init(rc) and branch on
  errno != .SUCCESS, mapping ENODEV/EPIPE to Disconnected and the rest to Io.
- posix.errno is unsuitable here: under libc linkage it reads the C errno
  global, which a raw linux.ioctl syscall never sets, so it reported SUCCESS
  for a -EBADF return.

Test plan:
- Added Layer-0 regression "hidraw: featureReport surfaces ioctl errno as
  error": featureReport over fd=-1 (EBADF) must return WriteError.Io.
  Falsifiable: against the old `if (rc < 0)` code (libc-linked) it fails with
  "expected error.Io, found void".
- `./scripts/padctl-docker test` → EXIT=0 (1635 tests).
- `zig fmt --check src/io/hidraw.zig` clean.

refs: audit HIGH
---
 src/io/hidraw.zig | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/io/hidraw.zig b/src/io/hidraw.zig
index 918c67e5..67cd0cde 100644
--- a/src/io/hidraw.zig
+++ b/src/io/hidraw.zig
@@ -254,8 +254,8 @@ pub const HidrawDevice = struct {
         if (self.wedge) |w| w.beginWrite();
         defer if (self.wedge) |w| w.endWrite();
         const rc = linux.ioctl(self.fd, req, @intFromPtr(data.ptr));
-        if (rc < 0) {
-            const errno = posix.errno(rc);
+        const errno = linux.E.init(rc);
+        if (errno != .SUCCESS) {
             if (errno == .NODEV or errno == .PIPE) return DeviceIO.WriteError.Disconnected;
             return DeviceIO.WriteError.Io;
         }
@@ -572,3 +572,19 @@ test "hidraw: discoverWithRoot — nonexistent root returns NotFound for both nu
     const err3 = HidrawDevice.discoverWithRoot(allocator, 0x37d7, 0x2401, 0, "/nonexistent_hidraw_xyz");
     try std.testing.expectError(error.NotFound, err3);
 }
+
+// featureReport must surface HIDIOCSFEATURE failures. An invalid fd makes the
+// ioctl return EBADF → WriteError.Io.
+// Falsifiability: the old `if (rc < 0)` guard never triggered (linux.ioctl returns
+// usize, never < 0), so featureReport returned void on failure and this fails.
+test "hidraw: featureReport surfaces ioctl errno as error" {
+    var dev = HidrawDevice{
+        .fd = -1,
+        .evdev_fds = .{},
+        .allocator = std.testing.allocator,
+    };
+    const dev_io = dev.deviceIO();
+
+    const payload = [_]u8{ 0x01, 0x02, 0x03 };
+    try std.testing.expectError(DeviceIO.WriteError.Io, dev_io.featureReport(&payload));
+}