[PATCH v2 1/7] common: add scoped_fd

Markus Metzger
2018-01-26T14:14:40Z

Add a simple helper to automatically close a file descriptor.

2018-01-26 Markus Metzger <markus.t.metzger@intel.com>

gdb/
* common/scoped_fd.h: New.
* unittests/scoped_fd-selftest.c: New.
* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
unittests/scoped_fd-selftest.c.
---
gdb/Makefile.in | 1 +
gdb/common/scoped_fd.h | 60 +++++++++++++++++++++++++
gdb/unittests/scoped_fd-selftests.c | 90 +++++++++++++++++++++++++++++++++++++
3 files changed, 151 insertions(+)
create mode 100644 gdb/common/scoped_fd.h
create mode 100644 gdb/unittests/scoped_fd-selftests.c

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 0f87398..a982cdf5 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -424,6 +424,7 @@ SUBDIR_UNITTESTS_SRCS = \
unittests/optional-selftests.c \
unittests/ptid-selftests.c \
unittests/rsp-low-selftests.c \
+ unittests/scoped_fd-selftests.c \
unittests/scoped_restore-selftests.c \
unittests/xml-utils-selftests.c

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 */
diff --git a/gdb/unittests/scoped_fd-selftests.c b/gdb/unittests/scoped_fd-selftests.c
new file mode 100644
index 0000000..4d74541
--- /dev/null
+++ b/gdb/unittests/scoped_fd-selftests.c
@@ -0,0 +1,90 @@
+/* Self tests for scoped_fd 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_fd.h"
+#include "config.h"
+
+#ifdef HAVE_UNISTD_H
+
+#include "selftest.h"
+
+namespace selftests {
+namespace scoped_fd {
+
+/* Test that the file descriptor is closed. */
+static void
+test_destroy ()
+{
+ char filename[] = "scoped_fd-selftest-XXXXXX";
+ int fd = mkstemp (filename);
+ SELF_CHECK (fd >= 0);
+
+ unlink (filename);
+ errno = 0;
+ {
+ ::scoped_fd sfd (fd);
+
+ SELF_CHECK (sfd.get () == fd);
+ }
+
+ SELF_CHECK (close (fd) == -1 && errno == EBADF);
+}
+
+/* Test that the file descriptor can be released. */
+static void
+test_release ()
+{
+ char filename[] = "scoped_fd-selftest-XXXXXX";
+ int fd = mkstemp (filename);
+ SELF_CHECK (fd >= 0);
+
+ unlink (filename);
+ errno = 0;
+ {
+ ::scoped_fd sfd (fd);
+
+ SELF_CHECK (sfd.release () == fd);
+ }
+
+ SELF_CHECK (close (fd) == 0 || errno != EBADF);
+}
+
+/* Run selftests. */
+static void
+run_tests ()
+{
+ test_destroy ();
+ test_release ();
+}
+
+} /* namespace scoped_fd */
+} /* namespace selftests */
+
+#endif /* HAVE_UNISTD_H */
+
+void
+_initialize_scoped_fd_selftests ()
+{
+#ifdef HAVE_UNISTD_H
+ selftests::register_test ("scoped_fd",
+ selftests::scoped_fd::run_tests);
+#endif
+}
--
1.8.3.1