getrandom: Add tests.

* tests/test-getrandom.c: New file.
* modules/getrandom-tests: New file.

1 files changed, 83 insertions, 0 deletions

diff --git a/tests/test-getrandom.c b/tests/test-getrandom.c
new file mode 100644
index 0000000000..3c84f871ef
--- /dev/null
+++ b/tests/test-getrandom.c
@@ -0,0 +1,83 @@
+/* Test of getting random bytes.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible.  */
+
+#include <config.h>
+
+#include <sys/random.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (getrandom, ssize_t, (void *, size_t, unsigned int));
+
+#include <errno.h>
+#include <string.h>
+
+#include "macros.h"
+
+int
+main (void)
+{
+  char buf1[8];
+  char buf2[8];
+  char large_buf[100000];
+  ssize_t ret;
+
+  /* Check that different calls produce different results (with a high
+     probability).  */
+  ret = getrandom (buf1, sizeof (buf1), 0);
+  if (ret < 0)
+    ASSERT (errno == ENOSYS);
+  else
+    {
+      ret = getrandom (buf2, sizeof (buf2), 0);
+      if (ret < 0)
+        ASSERT (errno == ENOSYS);
+      else
+        {
+          /* It is very unlikely that two calls to getrandom produce the
+             same results.  */
+          ASSERT (memcmp (buf1, buf2, sizeof (buf1)) != 0);
+        }
+    }
+
+  /* Likewise with the "truly random" number generator.  */
+  ret = getrandom (buf1, sizeof (buf1), GRND_RANDOM);
+  if (ret < 0)
+    ASSERT (errno == ENOSYS);
+  else
+    {
+      ret = getrandom (buf2, sizeof (buf2), GRND_RANDOM);
+      if (ret < 0)
+        ASSERT (errno == ENOSYS);
+      else
+        {
+          /* It is very unlikely that two calls to getrandom produce the
+             same results.  */
+          ASSERT (memcmp (buf1, buf2, sizeof (buf1)) != 0);
+        }
+    }
+
+  /* Check that GRND_NONBLOCK works.  */
+  ret = getrandom (large_buf, sizeof (large_buf), GRND_RANDOM | GRND_NONBLOCK);
+  /* It is very unlikely that so many truly random bytes were ready.  */
+  if (ret < 0)
+    ASSERT (errno == ENOSYS || errno == EAGAIN);
+  else
+    ASSERT (ret > 0 && ret < sizeof (large_buf));
+
+  return 0;
+}