libc/src/fcntl/linux/openat.cpp

   1 //===-- Implementation of openat ------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/fcntl/openat.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13 #include "src/errno/libc_errno.h"
  14
  15 #include <fcntl.h>
  16 #include <stdarg.h>
  17 #include <sys/syscall.h> // For syscall numbers.
  18
  19 namespace LIBC_NAMESPACE {
  20
  21 LLVM_LIBC_FUNCTION(int, openat, (int dfd, const char *path, int flags, ...)) {
  22   mode_t mode_flags = 0;
  23   // O_TMPFILE is a multi-bit flag so we test all bits by checking for equality
  24   // with O_TMPFILE
  25   if ((flags & O_CREAT) || (flags & O_TMPFILE) == O_TMPFILE) {
  26     va_list varargs;
  27     va_start(varargs, flags);
  28     mode_flags = va_arg(varargs, mode_t);
  29     va_end(varargs);
  30   }
  31
  32   int fd = LIBC_NAMESPACE::syscall_impl<int>(SYS_openat, dfd, path, flags,
  33                                              mode_flags);
  34   if (fd > 0)
  35     return fd;
  36
  37   libc_errno = -fd;
  38   return -1;
  39 }
  40
  41 } // namespace LIBC_NAMESPACE