Initial import

libc/calls/chmod.c

@@ -0,0 +1,49 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ 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; version 2 of the License.                      │
+│                                                                              │
+│ 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, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
+#include "libc/calls/internal.h"
+#include "libc/dce.h"
+#include "libc/sysv/consts/at.h"
+#include "libc/sysv/errfuns.h"
+
+/**
+ * Changes permissions on file, e.g.:
+ *
+ *   CHECK_NE(-1, chmod("foo/bar.txt", 0644));
+ *   CHECK_NE(-1, chmod("o/default/program.com", 0755));
+ *   CHECK_NE(-1, chmod("privatefolder/", 0700));
+ *
+ * The esoteric bits generally available on System Five are:
+ *
+ *   CHECK_NE(-1, chmod("/opt/", 01000));          // sticky bit
+ *   CHECK_NE(-1, chmod("/usr/bin/sudo", 04755));  // setuid bit
+ *   CHECK_NE(-1, chmod("/usr/bin/wall", 02755));  // setgid bit
+ *
+ * This works on Windows NT if you ignore the error ;-)
+ *
+ * @param pathname must exist
+ * @param mode contains octal flags (base 8)
+ * @errors ENOENT, ENOTDIR, ENOSYS
+ * @asyncsignalsafe
+ * @see fchmod()
+ */
+int chmod(const char *pathname, uint32_t mode) {
+  return fchmodat$sysv(AT_FDCWD, pathname, mode, 0);
+}