From 730884ef9129b594fbcb1cd81a0aa215c034901a Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Mon, 1 May 2023 19:48:12 +0000
Subject: [PATCH] Fix the WIFSTOPPED definition.

Although this breaks job control in several shells (including mksh),
this has been broken since the initial commit and no-one's noticed until
now.

Bug: https://github.com/android/ndk/issues/1878
Test: treehugger
Change-Id: Id7c4805965c5e5847db99b57df1af13355adcc22
---
 libc/include/bits/wait.h |  2 +-
 tests/sys_wait_test.cpp  | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/libc/include/bits/wait.h b/libc/include/bits/wait.h
index a6a212904a..c7f1fb0978 100644
--- a/libc/include/bits/wait.h
+++ b/libc/include/bits/wait.h
@@ -53,7 +53,7 @@
 #define WIFEXITED(__status) (WTERMSIG(__status) == 0)
 
 /** Returns true if the process was stopped by a signal. */
-#define WIFSTOPPED(__status) (WTERMSIG(__status) == 0x7f)
+#define WIFSTOPPED(__status) (((__status) & 0xff) == 0x7f)
 
 /** Returns true if the process was terminated by a signal. */
 #define WIFSIGNALED(__status) (WTERMSIG((__status)+1) >= 2)
diff --git a/tests/sys_wait_test.cpp b/tests/sys_wait_test.cpp
index c0069721d0..200fabe8a0 100644
--- a/tests/sys_wait_test.cpp
+++ b/tests/sys_wait_test.cpp
@@ -42,3 +42,22 @@ TEST(sys_wait, waitid) {
   ASSERT_EQ(66, si.si_status);
   ASSERT_EQ(CLD_EXITED, si.si_code);
 }
+
+// https://github.com/android/ndk/issues/1878
+TEST(sys_wait, macros) {
+#if defined(__GLIBC__)
+  // glibc before 2016 requires an lvalue.
+#else
+  ASSERT_FALSE(WIFEXITED(0x7f));
+  ASSERT_TRUE(WIFSTOPPED(0x7f));
+  ASSERT_FALSE(WIFCONTINUED(0x7f));
+
+  ASSERT_TRUE(WIFEXITED(0x80));
+  ASSERT_FALSE(WIFSTOPPED(0x80));
+  ASSERT_FALSE(WIFCONTINUED(0x80));
+
+  ASSERT_FALSE(WIFEXITED(0xffff));
+  ASSERT_FALSE(WIFSTOPPED(0xffff));
+  ASSERT_TRUE(WIFCONTINUED(0xffff));
+#endif
+}