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. 52 struct 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 81 namespace 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 0 124 125 inline int set_errno(int e = GetLastError()) { 126 errno = static_cast<int>(__win_err_to_errc(e)); 127 return -1; 128 } 129 130 class WinHandle { 131 public: 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; } 148 149 private: 150 HANDLE h; 151 }; 152 153 inline 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 } 188 189 inline 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 } 196 197 inline int stat(const wchar_t* path, StatT* buf) { return stat_file(path, buf, 0); } 198 199 inline int lstat(const wchar_t* path, StatT* buf) { return stat_file(path, buf, FILE_FLAG_OPEN_REPARSE_POINT); } 200 201 inline int fstat(int fd, StatT* buf) { 202 HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd)); 203 return stat_handle(h, buf); 204 } 205 206 inline int mkdir(const wchar_t* path, int permissions) { 207 (void)permissions; 208 if (!CreateDirectoryW(path, nullptr)) 209 return set_errno(); 210 return 0; 211 } 212 213 inline 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 } 227 228 inline int symlink_file(const wchar_t* oldname, const wchar_t* newname) { 229 return symlink_file_dir(oldname, newname, false); 230 } 231 232 inline int symlink_dir(const wchar_t* oldname, const wchar_t* newname) { 233 return symlink_file_dir(oldname, newname, true); 234 } 235 236 inline int link(const wchar_t* oldname, const wchar_t* newname) { 237 if (CreateHardLinkW(newname, oldname, nullptr)) 238 return 0; 239 return set_errno(); 240 } 241 242 inline 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 } 252 253 inline 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 } 262 263 inline int ftruncate(int fd, off_t length) { 264 HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd)); 265 return truncate_handle(h, length); 266 } 267 268 inline 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 } 274 275 inline 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 } 280 281 inline int chdir(const wchar_t* path) { 282 if (!SetCurrentDirectoryW(path)) 283 return set_errno(); 284 return 0; 285 } 286 287 struct StatVFS { 288 uint64_t f_frsize; 289 uint64_t f_blocks; 290 uint64_t f_bfree; 291 uint64_t f_bavail; 292 }; 293 294 inline 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 } 318 319 inline 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 } 338 339 inline 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 1 374 using ModeT = int; 375 376 inline 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 } 388 389 inline 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 } 414 415 inline 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 421 using SSizeT = ::int64_t; 422 423 inline 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 464 inline int symlink_file(const char* oldname, const char* newname) { return ::symlink(oldname, newname); } 465 inline int symlink_dir(const char* oldname, const char* newname) { return ::symlink(oldname, newname); } 466 using ::chdir; 467 using ::fchmod; 468 # if defined(AT_SYMLINK_NOFOLLOW) && defined(AT_FDCWD) 469 using ::fchmodat; 470 # endif 471 using ::fstat; 472 using ::ftruncate; 473 using ::getcwd; 474 using ::link; 475 using ::lstat; 476 using ::mkdir; 477 using ::readlink; 478 using ::realpath; 479 using ::remove; 480 using ::rename; 481 using ::stat; 482 using ::statvfs; 483 using ::truncate; 484 485 # define O_BINARY 0 486 487 using StatVFS = struct statvfs; 488 using ModeT = ::mode_t; 489 using SSizeT = ::ssize_t; 490 491 #endif 492 493 } // end namespace detail 494 495 _LIBCPP_END_NAMESPACE_FILESYSTEM 496 497 #endif // POSIX_COMPAT_H 498