libc/src/__support/File/linux_dir.cpp

   1 //===--- Linux implementation of the Dir helpers --------------------------===//
   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 "dir.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/error_or.h"
  13
  14 #include <fcntl.h>       // For open flags
  15 #include <sys/syscall.h> // For syscall numbers
  16
  17 namespace __llvm_libc {
  18
  19 ErrorOr<int> platform_opendir(const char *name) {
  20   int open_flags = O_RDONLY | O_DIRECTORY | O_CLOEXEC;
  21 #ifdef SYS_open
  22   int fd = __llvm_libc::syscall_impl(SYS_open, name, open_flags);
  23 #elif defined(SYS_openat)
  24   int fd = __llvm_libc::syscall_impl(SYS_openat, AT_FDCWD, name, open_flags);
  25 #else
  26 #error                                                                         \
  27     "SYS_open and SYS_openat syscalls not available to perform an open operation."
  28 #endif
  29
  30   if (fd < 0) {
  31     return __llvm_libc::Error(-fd);
  32   }
  33   return fd;
  34 }
  35
  36 ErrorOr<size_t> platform_fetch_dirents(int fd, cpp::span<uint8_t> buffer) {
  37 #ifdef SYS_getdents64
  38   long size = __llvm_libc::syscall_impl(SYS_getdents64, fd, buffer.data(),
  39                                         buffer.size());
  40 #else
  41 #error "getdents64 syscalls not available to perform a fetch dirents operation."
  42 #endif
  43
  44   if (size < 0) {
  45     return __llvm_libc::Error(static_cast<int>(-size));
  46   }
  47   return size;
  48 }
  49
  50 int platform_closedir(int fd) {
  51   long ret = __llvm_libc::syscall_impl(SYS_close, fd);
  52   if (ret < 0) {
  53     return static_cast<int>(-ret);
  54   }
  55   return 0;
  56 }
  57
  58 } // namespace __llvm_libc