common: add scoped_fd

Add a simple helper to automatically close a file descriptor.

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

1 files changed, 60 insertions, 0 deletions

diff --git a/gdb/common/scoped_fd.h b/gdb/common/scoped_fd.h
new file mode 100644
index 0000000..a6a8ab9
--- /dev/null
+++ b/gdb/common/scoped_fd.h
@@ -0,0 +1,60 @@
+/* scoped_fd, automatically close a file descriptor
+
+   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/>.  */
+
+#ifndef SCOPED_FD_H
+#define SCOPED_FD_H
+
+#include "config.h"
+
+#ifdef HAVE_UNISTD_H
+
+#include <unistd.h>
+
+/* A smart-pointer-like class to automatically close a file descriptor.  */
+
+class scoped_fd
+{
+public:
+  explicit scoped_fd (int fd = -1) noexcept : m_fd (fd) {}
+  ~scoped_fd ()
+  {
+    if (m_fd >= 0)
+      close (m_fd);
+  }
+
+  DISABLE_COPY_AND_ASSIGN (scoped_fd);
+
+  int release () noexcept
+  {
+    int fd = m_fd;
+    m_fd = -1;
+    return fd;
+  }
+
+  int get () const noexcept
+  {
+    return m_fd;
+  }
+
+private:
+  int m_fd;
+};
+
+#endif /* HAVE_UNISTD_H */
+#endif /* SCOPED_FD_H */