Implement PR_SET_CHILD_SUBREAPER when the calling task is PID 1.

In this case, the task is already a subreaper, so setting this bit is a noop.

Updates #2323

PiperOrigin-RevId: 388828034

1 files changed, 6 insertions, 0 deletions

diff --git a/test/syscalls/linux/prctl.cc b/test/syscalls/linux/prctl.cc
index 25b0e63d4..286b3d168 100644
--- a/test/syscalls/linux/prctl.cc
+++ b/test/syscalls/linux/prctl.cc
@@ -214,6 +214,12 @@ TEST(PrctlTest, RootDumpability) {
               SyscallFailsWithErrno(EINVAL));
 }
 
+TEST(PrctlTest, SetGetSubreaper) {
+  // Setting subreaper on PID 1 works vacuously because PID 1 is always a
+  // subreaper.
+  EXPECT_THAT(prctl(PR_SET_CHILD_SUBREAPER, 1), SyscallSucceeds());
+}
+
 }  // namespace
 
 }  // namespace testing