support: Add xdup

Add xdup as the error-checking version of dup for test cases.

Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

support/Makefile

@@ -128,6 +128,7 @@ libsupport-routines = \
   xcopy_file_range \
   xdlfcn \
   xdlmopen \
+  xdup \
   xdup2 \
   xfchmod \
   xfclose \

support/xdup.c

@@ -0,0 +1,30 @@
+/* dup with error checking.
+   Copyright The GNU Toolchain Authors.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+#include <support/check.h>
+
+int
+xdup (int from)
+{
+  int ret = dup (from);
+  if (ret < 0)
+    FAIL_EXIT1 ("dup (%d): %m", from);
+
+  return ret;
+}

support/xunistd.h

@@ -35,6 +35,7 @@ pid_t xfork (void);
 pid_t xwaitpid (pid_t, int *status, int flags);
 void xpipe (int[2]);
 void xdup2 (int, int);
+int xdup (int);
 int xopen (const char *path, int flags, mode_t);
 void support_check_stat_fd (const char *name, int fd, int result);
 void support_check_stat_path (const char *name, const char *path, int result);