1 files changed, 107 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/tst-sched_setattr.c b/sysdeps/unix/sysv/linux/tst-sched_setattr.c
new file mode 100644
index 0000000000..fbb73c31a7
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-sched_setattr.c
@@ -0,0 +1,107 @@
+/* Tests for sched_setattr and sched_getattr.
+   Copyright (C) 2024 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 <sched.h>
+
+#include <errno.h>
+#include <stddef.h>
+#include <string.h>
+#include <support/check.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+/* Padding struct to detect unexpected writes.   */
+union
+{
+  struct sched_attr attr;
+  /* Hopefully the kernel will never need as much.  */
+  unsigned char padding[4096];
+} u;
+
+static void
+check_unused (void)
+{
+  TEST_VERIFY (u.attr.size < sizeof (u));
+  for (unsigned int i = u.attr.size; i < sizeof (u); ++i)
+    TEST_COMPARE (u.padding[i], 0xcc);
+}
+
+static int
+do_test (void)
+{
+  _Static_assert (SCHED_OTHER == SCHED_NORMAL,
+                  "SCHED_OTHER, SCHED_NORMAL values");
+  TEST_VERIFY (sizeof (struct sched_attr) < sizeof (u));
+
+  /* Check that reading and re-applying the current policy works.  */
+  memset (&u, 0xcc, sizeof (u));
+  /* Compiler barrier to bypass write access attribute.  */
+  volatile unsigned int size = sizeof (u);
+  TEST_COMPARE (sched_getattr (0, (struct sched_attr *) &u, size, 0), 0);
+  check_unused ();
+  TEST_COMPARE (sched_setattr (0, &u.attr, 0), 0); /* Apply unchanged.  */
+
+  /* Try to switch to the SCHED_OTHER policy.   */
+  memset (&u, 0, sizeof (u));
+  u.attr.size = sizeof (u); /* With padding, kernel should accept zeroes.  */
+  u.attr.sched_policy = SCHED_OTHER; /* Should be the default.  */
+  {
+    errno = 0;
+    int prio = getpriority (PRIO_PROCESS, 0);
+    if (errno != 0)
+      prio = 0;
+    u.attr.sched_nice = prio;
+  }
+  TEST_COMPARE (sched_setattr (0, &u.attr, 0), 0);
+
+  /* Non-zero values not known to the kernel result in an E2BIG error.  */
+  memset (&u, 0, sizeof (u));
+  TEST_COMPARE (sched_getattr (0, (struct sched_attr *) &u, size, 0), 0);
+  u.padding[u.attr.size] = 0xcc;
+  u.attr.size = sizeof (u);
+  errno = 0;
+  TEST_COMPARE (sched_setattr (0, &u.attr, 0), -1);
+  TEST_COMPARE (errno, E2BIG);
+
+  memset (&u, 0xcc, sizeof (u));
+  TEST_COMPARE (sched_getattr (0, (struct sched_attr *) &u, size, 0), 0);
+  TEST_COMPARE (u.attr.sched_policy, SCHED_OTHER);
+  check_unused ();
+
+  /* Raise the niceless level to 19 and observe its effect.  */
+  TEST_COMPARE (nice (19), 19);
+  TEST_COMPARE (sched_getattr (0, &u.attr, sizeof (u.attr), 0), 0);
+  TEST_COMPARE (u.attr.sched_policy, SCHED_OTHER);
+  TEST_COMPARE (u.attr.sched_nice, 19);
+  check_unused ();
+
+  /* Invalid buffer arguments result in EINVAL (not EFAULT).  */
+  {
+    errno = 0;
+    void *volatile null_pointer = NULL; /* compiler barrier.  */
+    TEST_COMPARE (sched_setattr (0, null_pointer, 0), -1);
+    TEST_COMPARE (errno, EINVAL);
+    errno = 0;
+    TEST_COMPARE (sched_getattr (0, null_pointer, size, 0), -1);
+    TEST_COMPARE (errno, EINVAL);
+  }
+
+  return 0;
+}
+
+#include <support/test-driver.c>