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/__support/macros/config.h"
  14 #include "src/errno/libc_errno.h"
  15
  16 #include "hdr/types/mode_t.h"
  17 #include <stdarg.h>
  18 #include <sys/syscall.h> // For syscall numbers.
  19
  20 namespace LIBC_NAMESPACE_DECL {
  21
  22 LLVM_LIBC_FUNCTION(int, openat, (int dfd, const char *path, int flags, ...)) {
  23   mode_t mode_flags = 0;
  24   // O_TMPFILE is a multi-bit flag so we test all bits by checking for equality
  25   // with O_TMPFILE
  26   if ((flags & O_CREAT) || (flags & O_TMPFILE) == O_TMPFILE) {
  27     va_list varargs;
  28     va_start(varargs, flags);
  29     mode_flags = va_arg(varargs, mode_t);
  30     va_end(varargs);
  31   }
  32
  33   int fd = LIBC_NAMESPACE::syscall_impl<int>(SYS_openat, dfd, path, flags,
  34                                              mode_flags);
  35   if (fd > 0)
  36     return fd;
  37
  38   libc_errno = -fd;
  39   return -1;
  40 }
  41
  42 } // namespace LIBC_NAMESPACE_DECL