common: add scoped_mmap

Add a simple helper to automatically unmap a memory mapping.

gdb/
	* common/scoped_mmap.h: New.
	* unittests/scoped_mmap-selftest.c: New.
	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	unittests/scoped_mmap-selftest.c.

1 files changed, 92 insertions, 0 deletions

diff --git a/gdb/unittests/scoped_mmap-selftests.c b/gdb/unittests/scoped_mmap-selftests.c
new file mode 100644
index 0000000..ece3d7a
--- /dev/null
+++ b/gdb/unittests/scoped_mmap-selftests.c
@@ -0,0 +1,92 @@
+/* Self tests for scoped_mmap for GDB, the GNU debugger.
+
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+
+#include "common/scoped_mmap.h"
+#include "config.h"
+
+#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_UNISTD_H)
+
+#include "selftest.h"
+
+#include <unistd.h>
+
+namespace selftests {
+namespace scoped_mmap {
+
+/* Test that the file is unmapped.  */
+static void
+test_destroy ()
+{
+  void *mem;
+
+  errno = 0;
+  {
+    ::scoped_mmap smmap (nullptr, sysconf (_SC_PAGESIZE), PROT_WRITE,
+			 MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+
+    mem = smmap.get ();
+    SELF_CHECK (mem != nullptr);
+  }
+
+  SELF_CHECK (msync (mem, sysconf (_SC_PAGESIZE), 0) == -1 && errno == ENOMEM);
+}
+
+/* Test that the memory can be released.  */
+static void
+test_release ()
+{
+  void *mem;
+
+  errno = 0;
+  {
+    ::scoped_mmap smmap (nullptr, sysconf (_SC_PAGESIZE), PROT_WRITE,
+			 MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+
+    mem = smmap.release ();
+    SELF_CHECK (mem != nullptr);
+  }
+
+  SELF_CHECK (msync (mem, sysconf (_SC_PAGESIZE), 0) == 0 || errno != ENOMEM);
+
+  munmap (mem, sysconf (_SC_PAGESIZE));
+}
+
+/* Run selftests.  */
+static void
+run_tests ()
+{
+  test_destroy ();
+  test_release ();
+}
+
+} /* namespace scoped_mmap */
+} /* namespace selftests */
+
+#endif /* !defined(HAVE_SYS_MMAN_H) || !defined(HAVE_UNISTD_H) */
+
+void
+_initialize_scoped_mmap_selftests ()
+{
+#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_UNISTD_H)
+  selftests::register_test ("scoped_mmap",
+			    selftests::scoped_mmap::run_tests);
+#endif
+}