linux: Add process_mrelease

Added in Linux 5.15 (884a7e5964e06ed93c7771c0d7cf19c09a8946f1), the new
syscalls allows a caller to free the memory of a dying target process.

Checked on x86_64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/tst-process_mrelease.c b/sysdeps/unix/sysv/linux/tst-process_mrelease.c
new file mode 100644
index 0000000000..958db3cbb8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-process_mrelease.c
@@ -0,0 +1,86 @@
+/* Basic tests for Linux process_mrelease.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xsocket.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+#include <sys/pidfd.h>
+#include <sys/wait.h>
+
+static void
+exit_subprocess (int dummy)
+{
+  exit (EXIT_FAILURE);
+}
+
+static void
+subprocess (void)
+{
+  /* In case something goes wrong with parent before pidfd_send_signal.  */
+  support_create_timer (5, 0, false, exit_subprocess);
+
+  pause ();
+  _exit (0);
+}
+
+static int
+do_test (void)
+{
+  {
+    int r = process_mrelease (-1, 0);
+    TEST_COMPARE (r, -1);
+    if (errno == ENOSYS)
+      FAIL_UNSUPPORTED ("kernel does not support process_mrelease, "
+		        "skipping test");
+    TEST_COMPARE (errno, EBADF);
+  }
+
+  pid_t pid = xfork ();
+  if (pid == 0)
+    subprocess ();
+
+  int pidfd = pidfd_open (pid, 0);
+  TEST_VERIFY (pidfd != -1);
+
+  /* The syscall only succeedes if the target process is exiting and there
+     is no guarantee that calling if after pidfd_send_signal will not error
+     (ince the process might have already been reaped by the OS).  So just
+     check if it does fail when the process is stll running.  */
+  TEST_COMPARE (process_mrelease (pidfd, 0), -1);
+  TEST_COMPARE (errno, EINVAL);
+
+  TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), 0);
+  {
+    siginfo_t info;
+    int r = waitid (P_PIDFD, pidfd, &info, WEXITED);
+    TEST_COMPARE (r, 0);
+    TEST_COMPARE (info.si_status, SIGKILL);
+    TEST_COMPARE (info.si_code, CLD_KILLED);
+  }
+
+  TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), -1);
+  TEST_COMPARE (errno, ESRCH);
+
+  return 0;
+}
+
+#include <support/test-driver.c>