1//===----------------------------------------------------------------------===////
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#ifndef FILESYSTEM_FILE_DESCRIPTOR_H
10#define FILESYSTEM_FILE_DESCRIPTOR_H
11
12#include <__config>
13#include <cstdint>
14#include <filesystem>
15#include <string_view>
16#include <system_error>
17#include <utility>
18
19#include "error.h"
20#include "posix_compat.h"
21#include "time_utils.h"
22
23#if defined(_LIBCPP_WIN32API)
24# define WIN32_LEAN_AND_MEAN
25# define NOMINMAX
26# include <windows.h>
27#else
28# include <dirent.h> // for DIR & friends
29# include <fcntl.h> // values for fchmodat
30# include <sys/stat.h>
31# include <sys/statvfs.h>
32# include <unistd.h>
33#endif // defined(_LIBCPP_WIN32API)
34
35_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
36
37namespace detail {
38
39#if !defined(_LIBCPP_WIN32API)
40
41# if defined(DT_BLK)
42template <class DirEntT, class = decltype(DirEntT::d_type)>
43file_type get_file_type(DirEntT* ent, int) {
44 switch (ent->d_type) {
45 case DT_BLK:
46 return file_type::block;
47 case DT_CHR:
48 return file_type::character;
49 case DT_DIR:
50 return file_type::directory;
51 case DT_FIFO:
52 return file_type::fifo;
53 case DT_LNK:
54 return file_type::symlink;
55 case DT_REG:
56 return file_type::regular;
57 case DT_SOCK:
58 return file_type::socket;
59 // Unlike in lstat, hitting "unknown" here simply means that the underlying
60 // filesystem doesn't support d_type. Report is as 'none' so we correctly
61 // set the cache to empty.
62 case DT_UNKNOWN:
63 break;
64 }
65 return file_type::none;
66}
67# endif // defined(DT_BLK)
68
69template <class DirEntT>
70file_type get_file_type(DirEntT*, long) {
71 return file_type::none;
72}
73
74inline pair<string_view, file_type> posix_readdir(DIR* dir_stream, error_code& ec) {
75 struct dirent* dir_entry_ptr = nullptr;
76 errno = 0; // zero errno in order to detect errors
77 ec.clear();
78 if ((dir_entry_ptr = ::readdir(dirp: dir_stream)) == nullptr) {
79 if (errno)
80 ec = capture_errno();
81 return {};
82 } else {
83 return {dir_entry_ptr->d_name, get_file_type(ent: dir_entry_ptr, 0)};
84 }
85}
86
87#else // _LIBCPP_WIN32API
88
89inline file_type get_file_type(const WIN32_FIND_DATAW& data) {
90 if (data.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT && data.dwReserved0 == IO_REPARSE_TAG_SYMLINK)
91 return file_type::symlink;
92 if (data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
93 return file_type::directory;
94 return file_type::regular;
95}
96inline uintmax_t get_file_size(const WIN32_FIND_DATAW& data) {
97 return (static_cast<uint64_t>(data.nFileSizeHigh) << 32) + data.nFileSizeLow;
98}
99inline file_time_type get_write_time(const WIN32_FIND_DATAW& data) {
100 using detail::fs_time;
101 const FILETIME& time = data.ftLastWriteTime;
102 auto ts = filetime_to_timespec(time);
103 if (!fs_time::is_representable(ts))
104 return file_time_type::min();
105 return fs_time::convert_from_timespec(ts);
106}
107inline perms get_file_perm(const WIN32_FIND_DATAW& data) {
108 unsigned st_mode = 0555; // Read-only
109 if (!(data.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
110 st_mode |= 0222; // Write
111 return static_cast<perms>(st_mode) & perms::mask;
112}
113
114#endif // !_LIBCPP_WIN32API
115
116// POSIX HELPERS
117
118using value_type = path::value_type;
119using string_type = path::string_type;
120
121struct FileDescriptor {
122 const path& name;
123 int fd = -1;
124 StatT m_stat;
125 file_status m_status;
126
127 template <class... Args>
128 static FileDescriptor create(const path* p, error_code& ec, Args... args) {
129 ec.clear();
130 int fd;
131#ifdef _LIBCPP_WIN32API
132 // TODO: most of the filesystem implementation uses native Win32 calls
133 // (mostly via posix_compat.h). However, here we use the C-runtime APIs to
134 // open a file, because we subsequently pass the C-runtime fd to
135 // `std::[io]fstream::__open(int fd)` in order to implement copy_file.
136 //
137 // Because we're calling the windows C-runtime, win32 error codes are
138 // translated into C error numbers by the C runtime, and returned in errno,
139 // rather than being accessible directly via GetLastError.
140 //
141 // Ideally copy_file should be calling the Win32 CopyFile2 function, which
142 // works on paths, not open files -- at which point this FileDescriptor type
143 // will no longer be needed on windows at all.
144 fd = ::_wopen(p->c_str(), args...);
145#else
146 fd = open(p->c_str(), args...);
147#endif
148
149 if (fd == -1) {
150 ec = capture_errno();
151 return FileDescriptor{p};
152 }
153 return FileDescriptor(p, fd);
154 }
155
156 template <class... Args>
157 static FileDescriptor create_with_status(const path* p, error_code& ec, Args... args) {
158 FileDescriptor fd = create(p, ec, args...);
159 if (!ec)
160 fd.refresh_status(ec);
161
162 return fd;
163 }
164
165 file_status get_status() const { return m_status; }
166 StatT const& get_stat() const { return m_stat; }
167
168 bool status_known() const { return filesystem::status_known(s: m_status); }
169
170 file_status refresh_status(error_code& ec);
171
172 void close() noexcept {
173 if (fd != -1) {
174#ifdef _LIBCPP_WIN32API
175 ::_close(fd);
176#else
177 ::close(fd: fd);
178#endif
179 // FIXME: shouldn't this return an error_code?
180 }
181 fd = -1;
182 }
183
184 FileDescriptor(FileDescriptor&& other)
185 : name(other.name), fd(other.fd), m_stat(other.m_stat), m_status(other.m_status) {
186 other.fd = -1;
187 other.m_status = file_status{};
188 }
189
190 ~FileDescriptor() { close(); }
191
192 FileDescriptor(FileDescriptor const&) = delete;
193 FileDescriptor& operator=(FileDescriptor const&) = delete;
194
195private:
196 explicit FileDescriptor(const path* p, int descriptor = -1) : name(*p), fd(descriptor) {}
197};
198
199inline perms posix_get_perms(const StatT& st) noexcept { return static_cast<perms>(st.st_mode) & perms::mask; }
200
201inline file_status create_file_status(error_code& m_ec, path const& p, const StatT& path_stat, error_code* ec) {
202 if (ec)
203 *ec = m_ec;
204 if (m_ec && (m_ec == errc::no_such_file_or_directory || m_ec == errc::not_a_directory)) {
205 return file_status(file_type::not_found);
206 } else if (m_ec) {
207 ErrorHandler<void> err("posix_stat", ec, &p);
208 err.report(ec: m_ec, msg: "failed to determine attributes for the specified path");
209 return file_status(file_type::none);
210 }
211 // else
212
213 file_status fs_tmp;
214 auto const mode = path_stat.st_mode;
215 if (S_ISLNK(mode))
216 fs_tmp.type(ft: file_type::symlink);
217 else if (S_ISREG(mode))
218 fs_tmp.type(ft: file_type::regular);
219 else if (S_ISDIR(mode))
220 fs_tmp.type(ft: file_type::directory);
221 else if (S_ISBLK(mode))
222 fs_tmp.type(ft: file_type::block);
223 else if (S_ISCHR(mode))
224 fs_tmp.type(ft: file_type::character);
225 else if (S_ISFIFO(mode))
226 fs_tmp.type(ft: file_type::fifo);
227 else if (S_ISSOCK(mode))
228 fs_tmp.type(ft: file_type::socket);
229 else
230 fs_tmp.type(ft: file_type::unknown);
231
232 fs_tmp.permissions(p: detail::posix_get_perms(st: path_stat));
233 return fs_tmp;
234}
235
236inline file_status posix_stat(path const& p, StatT& path_stat, error_code* ec) {
237 error_code m_ec;
238 if (detail::stat(file: p.c_str(), buf: &path_stat) == -1)
239 m_ec = detail::get_last_error();
240 return create_file_status(m_ec, p, path_stat, ec);
241}
242
243inline file_status posix_stat(path const& p, error_code* ec) {
244 StatT path_stat;
245 return posix_stat(p, path_stat, ec);
246}
247
248inline file_status posix_lstat(path const& p, StatT& path_stat, error_code* ec) {
249 error_code m_ec;
250 if (detail::lstat(file: p.c_str(), buf: &path_stat) == -1)
251 m_ec = detail::get_last_error();
252 return create_file_status(m_ec, p, path_stat, ec);
253}
254
255inline file_status posix_lstat(path const& p, error_code* ec) {
256 StatT path_stat;
257 return posix_lstat(p, path_stat, ec);
258}
259
260// http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html
261inline bool posix_ftruncate(const FileDescriptor& fd, off_t to_size, error_code& ec) {
262 if (detail::ftruncate(fd: fd.fd, length: to_size) == -1) {
263 ec = get_last_error();
264 return true;
265 }
266 ec.clear();
267 return false;
268}
269
270inline bool posix_fchmod(const FileDescriptor& fd, const StatT& st, error_code& ec) {
271 if (detail::fchmod(fd: fd.fd, mode: st.st_mode) == -1) {
272 ec = get_last_error();
273 return true;
274 }
275 ec.clear();
276 return false;
277}
278
279inline bool stat_equivalent(const StatT& st1, const StatT& st2) {
280 return (st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);
281}
282
283inline file_status FileDescriptor::refresh_status(error_code& ec) {
284 // FD must be open and good.
285 m_status = file_status{};
286 m_stat = {};
287 error_code m_ec;
288 if (detail::fstat(fd: fd, buf: &m_stat) == -1)
289 m_ec = get_last_error();
290 m_status = create_file_status(m_ec, p: name, path_stat: m_stat, ec: &ec);
291 return m_status;
292}
293
294} // namespace detail
295
296_LIBCPP_END_NAMESPACE_FILESYSTEM
297
298#endif // FILESYSTEM_FILE_DESCRIPTOR_H
299