support: Add xchmod wrapper

Checked on x86_64-linux-gnu.

support/xchmod.c

@@ -0,0 +1,30 @@
+/* chmod with error checking.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   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>
+
+#include <sys/stat.h>
+
+void
+xchmod (const char *pathname, mode_t mode)
+{
+  int r = chmod (pathname, mode);
+  if (r < 0)
+    FAIL_EXIT1 ("chmod (%s, %d): %m", pathname, mode);
+}

support/xunistd.h

@@ -47,6 +47,7 @@ void xftruncate (int fd, long long length);
 void xsymlink (const char *target, const char *linkpath);
 void xchdir (const char *path);
 void xfchmod (int fd, mode_t mode);
+void xchmod (const char *pathname, mode_t mode);
 
 /* Equivalent of "mkdir -p".  */
 void xmkdirp (const char *, mode_t);