Add support for `getrandom`.

And a simple test.

Bug: linux-syscall-support:31
Change-Id: Ifea152cdea89183f69d881807f3bd60da56a4513
Reviewed-on: https://chromium-review.googlesource.com/c/linux-syscall-support/+/2351965
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/linux_syscall_support.h b/linux_syscall_support.h
index a087903..e4ac226 100644
--- a/linux_syscall_support.h
+++ b/linux_syscall_support.h
@@ -954,6 +954,9 @@
 #ifndef __NR_fallocate
 #define __NR_fallocate          324
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          355
+#endif
 /* End of i386 definitions                                                   */
 #elif defined(__ARM_ARCH_3__) || defined(__ARM_EABI__)
 #ifndef __NR_setresuid
@@ -1058,6 +1061,9 @@
 #ifndef __NR_getcpu
 #define __NR_getcpu             (__NR_SYSCALL_BASE + 345)
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          (__NR_SYSCALL_BASE + 384)
+#endif
 /* End of ARM 3/EABI definitions                                             */
 #elif defined(__aarch64__)
 #ifndef __NR_setxattr
@@ -1155,6 +1161,9 @@
 #ifndef __NR_move_pages
 #define __NR_move_pages         239
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          278
+#endif
 /* End of aarch64 definitions                                                */
 #elif defined(__x86_64__)
 #ifndef __NR_pread64
@@ -1246,6 +1255,9 @@
 #ifndef __NR_fallocate
 #define __NR_fallocate          285
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          318
+#endif
 /* End of x86-64 definitions                                                 */
 #elif defined(__mips__)
 #if _MIPS_SIM == _MIPS_SIM_ABI32
@@ -1347,6 +1359,9 @@
 #ifndef __NR_ioprio_get
 #define __NR_ioprio_get         (__NR_Linux + 315)
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          (__NR_Linux + 353)
+#endif
 /* End of MIPS (old 32bit API) definitions */
 #elif  _MIPS_SIM == _MIPS_SIM_ABI64
 #ifndef __NR_pread64
@@ -1425,6 +1440,9 @@
 #ifndef __NR_ioprio_get
 #define __NR_ioprio_get         (__NR_Linux + 274)
 #endif
+#ifndef __NT_getrandom
+#define                         (__NR_Linux + 313)
+#endif
 /* End of MIPS (64bit API) definitions */
 #else
 #ifndef __NR_setresuid
@@ -3658,6 +3676,10 @@
                          int, f, int, mode, loff_t, offset, loff_t, len)
     #endif
   #endif
+  #if defined(__NR_getrandom)
+    LSS_INLINE _syscall3(ssize_t, getrandom, void*, buffer, size_t, length,
+                         unsigned int, flags)
+  #endif
   #if defined(__NR_newfstatat)
     LSS_INLINE _syscall4(int, newfstatat,         int,   d,
                          const char *,            p,
diff --git a/tests/Makefile b/tests/Makefile
index bcf7e1f..60ec06e 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -42,6 +42,7 @@
 TESTS = \
 	fallocate \
 	sigaction \
+	getrandom \
 	sigtimedwait \
 	unlink \
 
diff --git a/tests/getrandom.c b/tests/getrandom.c
new file mode 100644
index 0000000..eb1f162
--- /dev/null
+++ b/tests/getrandom.c
@@ -0,0 +1,59 @@
+/* Copyright 2020, Google Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "test_skel.h"
+
+#define BUFFER_SIZE 256
+
+int main(int argc, char *argv[]) {
+  char buffer[BUFFER_SIZE];
+  // Zero it out so we can check later that it's at least not all 0s.
+  memset(buffer, 0, BUFFER_SIZE);
+  bool buffer_contains_all_zeros = true;
+
+  // Don't bother passing any flags. (If we're using lss, we might not have the
+  // right header files with the flags defined anyway, and we'd have to copy
+  // this in here too, and risk getting out of sync in yet another way.)
+  const ssize_t r = sys_getrandom(buffer, BUFFER_SIZE, 0);
+
+  // Make sure it either worked, or that it's just not supported.
+  assert(r == BUFFER_SIZE || errno == ENOSYS);
+
+  if (r == BUFFER_SIZE) {
+    // If all the bytes are 0, it didn't really work.
+    for (size_t i = 0; i < BUFFER_SIZE; ++i) {
+      if (buffer[i] != 0) {
+        buffer_contains_all_zeros = false;
+      }
+    }
+    assert(!buffer_contains_all_zeros);
+  }
+
+  return 0;
+}
diff --git a/tests/test_skel.h b/tests/test_skel.h
index 9ff0eb3..13d8bea 100644
--- a/tests/test_skel.h
+++ b/tests/test_skel.h
@@ -44,9 +44,11 @@
 #include <assert.h>
 #include <fcntl.h>
 #include <sched.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/mman.h>
 #include <sys/prctl.h>
 #include <sys/stat.h>