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 "src/__support/File/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 LIBC_NAMESPACE {
  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 = LIBC_NAMESPACE::syscall_impl<int>(SYS_open, name, open_flags);
  23 #elif defined(SYS_openat)
  24   int fd =
  25       LIBC_NAMESPACE::syscall_impl<int>(SYS_openat, AT_FDCWD, name, open_flags);
  26 #else
  27 #error                                                                         \
  28     "SYS_open and SYS_openat syscalls not available to perform an open operation."
  29 #endif
  30
  31   if (fd < 0) {
  32     return LIBC_NAMESPACE::Error(-fd);
  33   }
  34   return fd;
  35 }
  36
  37 ErrorOr<size_t> platform_fetch_dirents(int fd, cpp::span<uint8_t> buffer) {
  38 #ifdef SYS_getdents64
  39   long size = LIBC_NAMESPACE::syscall_impl<long>(SYS_getdents64, fd,
  40                                                  buffer.data(), buffer.size());
  41 #else
  42 #error "getdents64 syscalls not available to perform a fetch dirents operation."
  43 #endif
  44
  45   if (size < 0) {
  46     return LIBC_NAMESPACE::Error(static_cast<int>(-size));
  47   }
  48   return size;
  49 }
  50
  51 int platform_closedir(int fd) {
  52   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_close, fd);
  53   if (ret < 0) {
  54     return static_cast<int>(-ret);
  55   }
  56   return 0;
  57 }
  58
  59 } // namespace LIBC_NAMESPACE