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//
10// POSIX-like portability helper functions.
11//
12// These generally behave like the proper posix functions, with these
13// exceptions:
14// On Windows, they take paths in wchar_t* form, instead of char* form.
15// The symlink() function is split into two frontends, symlink_file()
16// and symlink_dir().
17//
18// These are provided within an anonymous namespace within the detail
19// namespace - callers need to include this header and call them as
20// detail::function(), regardless of platform.
21//
22
23#ifndef POSIX_COMPAT_H
24#define POSIX_COMPAT_H
25
26#include <__assert>
27#include <__config>
28#include <filesystem>
29
30#include "error.h"
31#include "time_utils.h"
32
33#if defined(_LIBCPP_WIN32API)
34# define WIN32_LEAN_AND_MEAN
35# define NOMINMAX
36# include <io.h>
37# include <windows.h>
38# include <winioctl.h>
39#else
40# include <fcntl.h>
41# include <sys/stat.h>
42# include <sys/statvfs.h>
43# include <sys/time.h>
44# include <unistd.h>
45#endif
46#include <stdlib.h>
47#include <time.h>
48
49#if defined(_LIBCPP_WIN32API)
50// This struct isn't defined in the normal Windows SDK, but only in the
51// Windows Driver Kit.
52struct LIBCPP_REPARSE_DATA_BUFFER {
53 unsigned long ReparseTag;
54 unsigned short ReparseDataLength;
55 unsigned short Reserved;
56 union {
57 struct {
58 unsigned short SubstituteNameOffset;
59 unsigned short SubstituteNameLength;
60 unsigned short PrintNameOffset;
61 unsigned short PrintNameLength;
62 unsigned long Flags;
63 wchar_t PathBuffer[1];
64 } SymbolicLinkReparseBuffer;
65 struct {
66 unsigned short SubstituteNameOffset;
67 unsigned short SubstituteNameLength;
68 unsigned short PrintNameOffset;
69 unsigned short PrintNameLength;
70 wchar_t PathBuffer[1];
71 } MountPointReparseBuffer;
72 struct {
73 unsigned char DataBuffer[1];
74 } GenericReparseBuffer;
75 };
76};
77#endif
78
79_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
80
81namespace detail {
82
83#if defined(_LIBCPP_WIN32API)
84
85// Various C runtime header sets provide more or less of these. As we
86// provide our own implementation, undef all potential defines from the
87// C runtime headers and provide a complete set of macros of our own.
88
89# undef _S_IFMT
90# undef _S_IFDIR
91# undef _S_IFCHR
92# undef _S_IFIFO
93# undef _S_IFREG
94# undef _S_IFBLK
95# undef _S_IFLNK
96# undef _S_IFSOCK
97
98# define _S_IFMT 0xF000
99# define _S_IFDIR 0x4000
100# define _S_IFCHR 0x2000
101# define _S_IFIFO 0x1000
102# define _S_IFREG 0x8000
103# define _S_IFBLK 0x6000
104# define _S_IFLNK 0xA000
105# define _S_IFSOCK 0xC000
106
107# undef S_ISDIR
108# undef S_ISFIFO
109# undef S_ISCHR
110# undef S_ISREG
111# undef S_ISLNK
112# undef S_ISBLK
113# undef S_ISSOCK
114
115# define S_ISDIR(m) (((m) & _S_IFMT) == _S_IFDIR)
116# define S_ISCHR(m) (((m) & _S_IFMT) == _S_IFCHR)
117# define S_ISFIFO(m) (((m) & _S_IFMT) == _S_IFIFO)
118# define S_ISREG(m) (((m) & _S_IFMT) == _S_IFREG)
119# define S_ISBLK(m) (((m) & _S_IFMT) == _S_IFBLK)
120# define S_ISLNK(m) (((m) & _S_IFMT) == _S_IFLNK)
121# define S_ISSOCK(m) (((m) & _S_IFMT) == _S_IFSOCK)
122
123# define O_NONBLOCK 0
124
125inline int set_errno(int e = GetLastError()) {
126 errno = static_cast<int>(__win_err_to_errc(e));
127 return -1;
128}
129
130class WinHandle {
131public:
132 WinHandle(const wchar_t* p, DWORD access, DWORD flags) {
133 h = CreateFileW(
134 p,
135 access,
136 FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
137 nullptr,
138 OPEN_EXISTING,
139 FILE_FLAG_BACKUP_SEMANTICS | flags,
140 nullptr);
141 }
142 ~WinHandle() {
143 if (h != INVALID_HANDLE_VALUE)
144 CloseHandle(h);
145 }
146 operator HANDLE() const { return h; }
147 operator bool() const { return h != INVALID_HANDLE_VALUE; }
148
149private:
150 HANDLE h;
151};
152
153inline int stat_handle(HANDLE h, StatT* buf) {
154 FILE_BASIC_INFO basic;
155 if (!GetFileInformationByHandleEx(h, FileBasicInfo, &basic, sizeof(basic)))
156 return set_errno();
157 memset(buf, 0, sizeof(*buf));
158 buf->st_mtim = filetime_to_timespec(basic.LastWriteTime);
159 buf->st_atim = filetime_to_timespec(basic.LastAccessTime);
160 buf->st_mode = 0555; // Read-only
161 if (!(basic.FileAttributes & FILE_ATTRIBUTE_READONLY))
162 buf->st_mode |= 0222; // Write
163 if (basic.FileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
164 buf->st_mode |= _S_IFDIR;
165 } else {
166 buf->st_mode |= _S_IFREG;
167 }
168 if (basic.FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
169 FILE_ATTRIBUTE_TAG_INFO tag;
170 if (!GetFileInformationByHandleEx(h, FileAttributeTagInfo, &tag, sizeof(tag)))
171 return set_errno();
172 if (tag.ReparseTag == IO_REPARSE_TAG_SYMLINK)
173 buf->st_mode = (buf->st_mode & ~_S_IFMT) | _S_IFLNK;
174 }
175 FILE_STANDARD_INFO standard;
176 if (!GetFileInformationByHandleEx(h, FileStandardInfo, &standard, sizeof(standard)))
177 return set_errno();
178 buf->st_nlink = standard.NumberOfLinks;
179 buf->st_size = standard.EndOfFile.QuadPart;
180 BY_HANDLE_FILE_INFORMATION info;
181 if (!GetFileInformationByHandle(h, &info))
182 return set_errno();
183 buf->st_dev = info.dwVolumeSerialNumber;
184 memcpy(&buf->st_ino.id[0], &info.nFileIndexHigh, 4);
185 memcpy(&buf->st_ino.id[4], &info.nFileIndexLow, 4);
186 return 0;
187}
188
189inline int stat_file(const wchar_t* path, StatT* buf, DWORD flags) {
190 WinHandle h(path, FILE_READ_ATTRIBUTES, flags);
191 if (!h)
192 return set_errno();
193 int ret = stat_handle(h, buf);
194 return ret;
195}
196
197inline int stat(const wchar_t* path, StatT* buf) { return stat_file(path, buf, 0); }
198
199inline int lstat(const wchar_t* path, StatT* buf) { return stat_file(path, buf, FILE_FLAG_OPEN_REPARSE_POINT); }
200
201inline int fstat(int fd, StatT* buf) {
202 HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
203 return stat_handle(h, buf);
204}
205
206inline int mkdir(const wchar_t* path, int permissions) {
207 (void)permissions;
208 if (!CreateDirectoryW(path, nullptr))
209 return set_errno();
210 return 0;
211}
212
213inline int symlink_file_dir(const wchar_t* oldname, const wchar_t* newname, bool is_dir) {
214 path dest(oldname);
215 dest.make_preferred();
216 oldname = dest.c_str();
217 DWORD flags = is_dir ? SYMBOLIC_LINK_FLAG_DIRECTORY : 0;
218 if (CreateSymbolicLinkW(newname, oldname, flags | SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE))
219 return 0;
220 int e = GetLastError();
221 if (e != ERROR_INVALID_PARAMETER)
222 return set_errno(e);
223 if (CreateSymbolicLinkW(newname, oldname, flags))
224 return 0;
225 return set_errno();
226}
227
228inline int symlink_file(const wchar_t* oldname, const wchar_t* newname) {
229 return symlink_file_dir(oldname, newname, false);
230}
231
232inline int symlink_dir(const wchar_t* oldname, const wchar_t* newname) {
233 return symlink_file_dir(oldname, newname, true);
234}
235
236inline int link(const wchar_t* oldname, const wchar_t* newname) {
237 if (CreateHardLinkW(newname, oldname, nullptr))
238 return 0;
239 return set_errno();
240}
241
242inline int remove(const wchar_t* path) {
243 detail::WinHandle h(path, DELETE, FILE_FLAG_OPEN_REPARSE_POINT);
244 if (!h)
245 return set_errno();
246 FILE_DISPOSITION_INFO info;
247 info.DeleteFile = TRUE;
248 if (!SetFileInformationByHandle(h, FileDispositionInfo, &info, sizeof(info)))
249 return set_errno();
250 return 0;
251}
252
253inline int truncate_handle(HANDLE h, off_t length) {
254 LARGE_INTEGER size_param;
255 size_param.QuadPart = length;
256 if (!SetFilePointerEx(h, size_param, 0, FILE_BEGIN))
257 return set_errno();
258 if (!SetEndOfFile(h))
259 return set_errno();
260 return 0;
261}
262
263inline int ftruncate(int fd, off_t length) {
264 HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
265 return truncate_handle(h, length);
266}
267
268inline int truncate(const wchar_t* path, off_t length) {
269 detail::WinHandle h(path, GENERIC_WRITE, 0);
270 if (!h)
271 return set_errno();
272 return truncate_handle(h, length);
273}
274
275inline int rename(const wchar_t* from, const wchar_t* to) {
276 if (!(MoveFileExW(from, to, MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH)))
277 return set_errno();
278 return 0;
279}
280
281inline int chdir(const wchar_t* path) {
282 if (!SetCurrentDirectoryW(path))
283 return set_errno();
284 return 0;
285}
286
287struct StatVFS {
288 uint64_t f_frsize;
289 uint64_t f_blocks;
290 uint64_t f_bfree;
291 uint64_t f_bavail;
292};
293
294inline int statvfs(const wchar_t* p, StatVFS* buf) {
295 path dir = p;
296 while (true) {
297 error_code local_ec;
298 const file_status st = status(dir, local_ec);
299 if (!exists(st) || is_directory(st))
300 break;
301 path parent = dir.parent_path();
302 if (parent == dir) {
303 errno = ENOENT;
304 return -1;
305 }
306 dir = parent;
307 }
308 ULARGE_INTEGER free_bytes_available_to_caller, total_number_of_bytes, total_number_of_free_bytes;
309 if (!GetDiskFreeSpaceExW(
310 dir.c_str(), &free_bytes_available_to_caller, &total_number_of_bytes, &total_number_of_free_bytes))
311 return set_errno();
312 buf->f_frsize = 1;
313 buf->f_blocks = total_number_of_bytes.QuadPart;
314 buf->f_bfree = total_number_of_free_bytes.QuadPart;
315 buf->f_bavail = free_bytes_available_to_caller.QuadPart;
316 return 0;
317}
318
319inline wchar_t* getcwd([[maybe_unused]] wchar_t* in_buf, [[maybe_unused]] size_t in_size) {
320 // Only expected to be used with us allocating the buffer.
321 _LIBCPP_ASSERT_INTERNAL(in_buf == nullptr, "Windows getcwd() assumes in_buf==nullptr");
322 _LIBCPP_ASSERT_INTERNAL(in_size == 0, "Windows getcwd() assumes in_size==0");
323
324 size_t buff_size = MAX_PATH + 10;
325 std::unique_ptr<wchar_t, decltype(&::free)> buff(static_cast<wchar_t*>(malloc(buff_size * sizeof(wchar_t))), &::free);
326 DWORD retval = GetCurrentDirectoryW(buff_size, buff.get());
327 if (retval > buff_size) {
328 buff_size = retval;
329 buff.reset(static_cast<wchar_t*>(malloc(buff_size * sizeof(wchar_t))));
330 retval = GetCurrentDirectoryW(buff_size, buff.get());
331 }
332 if (!retval) {
333 set_errno();
334 return nullptr;
335 }
336 return buff.release();
337}
338
339inline wchar_t* realpath(const wchar_t* path, [[maybe_unused]] wchar_t* resolved_name) {
340 // Only expected to be used with us allocating the buffer.
341 _LIBCPP_ASSERT_INTERNAL(resolved_name == nullptr, "Windows realpath() assumes a null resolved_name");
342
343 WinHandle h(path, FILE_READ_ATTRIBUTES, 0);
344 if (!h) {
345 set_errno();
346 return nullptr;
347 }
348 size_t buff_size = MAX_PATH + 10;
349 std::unique_ptr<wchar_t, decltype(&::free)> buff(static_cast<wchar_t*>(malloc(buff_size * sizeof(wchar_t))), &::free);
350 DWORD retval = GetFinalPathNameByHandleW(h, buff.get(), buff_size, FILE_NAME_NORMALIZED | VOLUME_NAME_DOS);
351 if (retval > buff_size) {
352 buff_size = retval;
353 buff.reset(static_cast<wchar_t*>(malloc(buff_size * sizeof(wchar_t))));
354 retval = GetFinalPathNameByHandleW(h, buff.get(), buff_size, FILE_NAME_NORMALIZED | VOLUME_NAME_DOS);
355 }
356 if (!retval) {
357 set_errno();
358 return nullptr;
359 }
360 wchar_t* ptr = buff.get();
361 if (!wcsncmp(ptr, L"\\\\?\\", 4)) {
362 if (ptr[5] == ':') { // \\?\X: -> X:
363 memmove(&ptr[0], &ptr[4], (wcslen(&ptr[4]) + 1) * sizeof(wchar_t));
364 } else if (!wcsncmp(&ptr[4], L"UNC\\", 4)) { // \\?\UNC\server -> \\server
365 wcscpy(&ptr[0], L"\\\\");
366 memmove(&ptr[2], &ptr[8], (wcslen(&ptr[8]) + 1) * sizeof(wchar_t));
367 }
368 }
369 return buff.release();
370}
371
372# define AT_FDCWD -1
373# define AT_SYMLINK_NOFOLLOW 1
374using ModeT = int;
375
376inline int fchmod_handle(HANDLE h, int perms) {
377 FILE_BASIC_INFO basic;
378 if (!GetFileInformationByHandleEx(h, FileBasicInfo, &basic, sizeof(basic)))
379 return set_errno();
380 DWORD orig_attributes = basic.FileAttributes;
381 basic.FileAttributes &= ~FILE_ATTRIBUTE_READONLY;
382 if ((perms & 0222) == 0)
383 basic.FileAttributes |= FILE_ATTRIBUTE_READONLY;
384 if (basic.FileAttributes != orig_attributes && !SetFileInformationByHandle(h, FileBasicInfo, &basic, sizeof(basic)))
385 return set_errno();
386 return 0;
387}
388
389inline int fchmodat(int /*fd*/, const wchar_t* path, int perms, int flag) {
390 DWORD attributes = GetFileAttributesW(path);
391 if (attributes == INVALID_FILE_ATTRIBUTES)
392 return set_errno();
393 if (attributes & FILE_ATTRIBUTE_REPARSE_POINT && !(flag & AT_SYMLINK_NOFOLLOW)) {
394 // If the file is a symlink, and we are supposed to operate on the target
395 // of the symlink, we need to open a handle to it, without the
396 // FILE_FLAG_OPEN_REPARSE_POINT flag, to open the destination of the
397 // symlink, and operate on it via the handle.
398 detail::WinHandle h(path, FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES, 0);
399 if (!h)
400 return set_errno();
401 return fchmod_handle(h, perms);
402 } else {
403 // For a non-symlink, or if operating on the symlink itself instead of
404 // its target, we can use SetFileAttributesW, saving a few calls.
405 DWORD orig_attributes = attributes;
406 attributes &= ~FILE_ATTRIBUTE_READONLY;
407 if ((perms & 0222) == 0)
408 attributes |= FILE_ATTRIBUTE_READONLY;
409 if (attributes != orig_attributes && !SetFileAttributesW(path, attributes))
410 return set_errno();
411 }
412 return 0;
413}
414
415inline int fchmod(int fd, int perms) {
416 HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
417 return fchmod_handle(h, perms);
418}
419
420# define MAX_SYMLINK_SIZE MAXIMUM_REPARSE_DATA_BUFFER_SIZE
421using SSizeT = ::int64_t;
422
423inline SSizeT readlink(const wchar_t* path, wchar_t* ret_buf, size_t bufsize) {
424 uint8_t buf[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
425 detail::WinHandle h(path, FILE_READ_ATTRIBUTES, FILE_FLAG_OPEN_REPARSE_POINT);
426 if (!h)
427 return set_errno();
428 DWORD out;
429 if (!DeviceIoControl(h, FSCTL_GET_REPARSE_POINT, nullptr, 0, buf, sizeof(buf), &out, 0))
430 return set_errno();
431 const auto* reparse = reinterpret_cast<LIBCPP_REPARSE_DATA_BUFFER*>(buf);
432 size_t path_buf_offset = offsetof(LIBCPP_REPARSE_DATA_BUFFER, SymbolicLinkReparseBuffer.PathBuffer[0]);
433 if (out < path_buf_offset) {
434 errno = EINVAL;
435 return -1;
436 }
437 if (reparse->ReparseTag != IO_REPARSE_TAG_SYMLINK) {
438 errno = EINVAL;
439 return -1;
440 }
441 const auto& symlink = reparse->SymbolicLinkReparseBuffer;
442 unsigned short name_offset, name_length;
443 if (symlink.PrintNameLength == 0) {
444 name_offset = symlink.SubstituteNameOffset;
445 name_length = symlink.SubstituteNameLength;
446 } else {
447 name_offset = symlink.PrintNameOffset;
448 name_length = symlink.PrintNameLength;
449 }
450 // name_offset/length are expressed in bytes, not in wchar_t
451 if (path_buf_offset + name_offset + name_length > out) {
452 errno = EINVAL;
453 return -1;
454 }
455 if (name_length / sizeof(wchar_t) > bufsize) {
456 errno = ENOMEM;
457 return -1;
458 }
459 memcpy(ret_buf, &symlink.PathBuffer[name_offset / sizeof(wchar_t)], name_length);
460 return name_length / sizeof(wchar_t);
461}
462
463#else
464inline int symlink_file(const char* oldname, const char* newname) { return ::symlink(from: oldname, to: newname); }
465inline int symlink_dir(const char* oldname, const char* newname) { return ::symlink(from: oldname, to: newname); }
466using ::chdir;
467using ::fchmod;
468# if defined(AT_SYMLINK_NOFOLLOW) && defined(AT_FDCWD)
469using ::fchmodat;
470# endif
471using ::fstat;
472using ::ftruncate;
473using ::getcwd;
474using ::link;
475using ::lstat;
476using ::mkdir;
477using ::readlink;
478using ::realpath;
479using ::remove;
480using ::rename;
481using ::stat;
482using ::statvfs;
483using ::truncate;
484
485# define O_BINARY 0
486
487using StatVFS = struct statvfs;
488using ModeT = ::mode_t;
489using SSizeT = ::ssize_t;
490
491#endif
492
493} // end namespace detail
494
495_LIBCPP_END_NAMESPACE_FILESYSTEM
496
497#endif // POSIX_COMPAT_H
498

source code of libcxx/src/filesystem/posix_compat.h