base/files/file_posix.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/files/file.h"
   6
   7 #include <errno.h>
   8 #include <fcntl.h>
   9 #include <sys/stat.h>
  10 #include <unistd.h>
  11
  12 #include "base/files/file_path.h"
  13 #include "base/files/file_posix_hooks_internal.h"
  14 #include "base/logging.h"
  15 #include "base/metrics/sparse_histogram.h"
  16 #include "base/posix/eintr_wrapper.h"
  17 #include "base/strings/utf_string_conversions.h"
  18 #include "base/threading/thread_restrictions.h"
  19
  20 #if defined(OS_ANDROID)
  21 #include "base/os_compat_android.h"
  22 #endif
  23
  24 namespace base {
  25
  26 // Make sure our Whence mappings match the system headers.
  27 COMPILE_ASSERT(File::FROM_BEGIN   == SEEK_SET &&
  28                File::FROM_CURRENT == SEEK_CUR &&
  29                File::FROM_END     == SEEK_END, whence_matches_system);
  30
  31 namespace {
  32
  33 #if defined(OS_BSD) || defined(OS_MACOSX) || defined(OS_NACL)
  34 static int CallFstat(int fd, stat_wrapper_t *sb) {
  35   base::ThreadRestrictions::AssertIOAllowed();
  36   return fstat(fd, sb);
  37 }
  38 #else
  39 static int CallFstat(int fd, stat_wrapper_t *sb) {
  40   base::ThreadRestrictions::AssertIOAllowed();
  41   return fstat64(fd, sb);
  42 }
  43 #endif
  44
  45 // NaCl doesn't provide the following system calls, so either simulate them or
  46 // wrap them in order to minimize the number of #ifdef's in this file.
  47 #if !defined(OS_NACL)
  48 static bool IsOpenAppend(PlatformFile file) {
  49   return (fcntl(file, F_GETFL) & O_APPEND) != 0;
  50 }
  51
  52 static int CallFtruncate(PlatformFile file, int64 length) {
  53   return HANDLE_EINTR(ftruncate(file, length));
  54 }
  55
  56 static int CallFsync(PlatformFile file) {
  57   return HANDLE_EINTR(fsync(file));
  58 }
  59
  60 static int CallFutimes(PlatformFile file, const struct timeval times[2]) {
  61 #ifdef __USE_XOPEN2K8
  62   // futimens should be available, but futimes might not be
  63   // http://pubs.opengroup.org/onlinepubs/9699919799/
  64
  65   timespec ts_times[2];
  66   ts_times[0].tv_sec  = times[0].tv_sec;
  67   ts_times[0].tv_nsec = times[0].tv_usec * 1000;
  68   ts_times[1].tv_sec  = times[1].tv_sec;
  69   ts_times[1].tv_nsec = times[1].tv_usec * 1000;
  70
  71   return futimens(file, ts_times);
  72 #else
  73   return futimes(file, times);
  74 #endif
  75 }
  76
  77 static File::Error CallFctnlFlock(PlatformFile file, bool do_lock) {
  78   struct flock lock;
  79   lock.l_type = F_WRLCK;
  80   lock.l_whence = SEEK_SET;
  81   lock.l_start = 0;
  82   lock.l_len = 0;  // Lock entire file.
  83   if (HANDLE_EINTR(fcntl(file, do_lock ? F_SETLK : F_UNLCK, &lock)) == -1)
  84     return File::OSErrorToFileError(errno);
  85   return File::FILE_OK;
  86 }
  87 #else  // defined(OS_NACL)
  88
  89 static bool IsOpenAppend(PlatformFile file) {
  90   // NaCl doesn't implement fcntl. Since NaCl's write conforms to the POSIX
  91   // standard and always appends if the file is opened with O_APPEND, just
  92   // return false here.
  93   return false;
  94 }
  95
  96 static int CallFtruncate(PlatformFile file, int64 length) {
  97   NOTIMPLEMENTED();  // NaCl doesn't implement ftruncate.
  98   return 0;
  99 }
 100
 101 static int CallFsync(PlatformFile file) {
 102   NOTIMPLEMENTED();  // NaCl doesn't implement fsync.
 103   return 0;
 104 }
 105
 106 static int CallFutimes(PlatformFile file, const struct timeval times[2]) {
 107   NOTIMPLEMENTED();  // NaCl doesn't implement futimes.
 108   return 0;
 109 }
 110
 111 static File::Error CallFctnlFlock(PlatformFile file, bool do_lock) {
 112   NOTIMPLEMENTED();  // NaCl doesn't implement flock struct.
 113   return File::FILE_ERROR_INVALID_OPERATION;
 114 }
 115 #endif  // defined(OS_NACL)
 116
 117 }  // namespace
 118
 119 void File::Info::FromStat(const stat_wrapper_t& stat_info) {
 120   is_directory = S_ISDIR(stat_info.st_mode);
 121   is_symbolic_link = S_ISLNK(stat_info.st_mode);
 122   size = stat_info.st_size;
 123
 124 #if defined(OS_LINUX)
 125   time_t last_modified_sec = stat_info.st_mtim.tv_sec;
 126   int64 last_modified_nsec = stat_info.st_mtim.tv_nsec;
 127   time_t last_accessed_sec = stat_info.st_atim.tv_sec;
 128   int64 last_accessed_nsec = stat_info.st_atim.tv_nsec;
 129   time_t creation_time_sec = stat_info.st_ctim.tv_sec;
 130   int64 creation_time_nsec = stat_info.st_ctim.tv_nsec;
 131 #elif defined(OS_ANDROID)
 132   time_t last_modified_sec = stat_info.st_mtime;
 133   int64 last_modified_nsec = stat_info.st_mtime_nsec;
 134   time_t last_accessed_sec = stat_info.st_atime;
 135   int64 last_accessed_nsec = stat_info.st_atime_nsec;
 136   time_t creation_time_sec = stat_info.st_ctime;
 137   int64 creation_time_nsec = stat_info.st_ctime_nsec;
 138 #elif defined(OS_MACOSX) || defined(OS_IOS) || defined(OS_BSD)
 139   time_t last_modified_sec = stat_info.st_mtimespec.tv_sec;
 140   int64 last_modified_nsec = stat_info.st_mtimespec.tv_nsec;
 141   time_t last_accessed_sec = stat_info.st_atimespec.tv_sec;
 142   int64 last_accessed_nsec = stat_info.st_atimespec.tv_nsec;
 143   time_t creation_time_sec = stat_info.st_ctimespec.tv_sec;
 144   int64 creation_time_nsec = stat_info.st_ctimespec.tv_nsec;
 145 #else
 146   time_t last_modified_sec = stat_info.st_mtime;
 147   int64 last_modified_nsec = 0;
 148   time_t last_accessed_sec = stat_info.st_atime;
 149   int64 last_accessed_nsec = 0;
 150   time_t creation_time_sec = stat_info.st_ctime;
 151   int64 creation_time_nsec = 0;
 152 #endif
 153
 154   last_modified =
 155       Time::FromTimeT(last_modified_sec) +
 156       TimeDelta::FromMicroseconds(last_modified_nsec /
 157                                   Time::kNanosecondsPerMicrosecond);
 158
 159   last_accessed =
 160       Time::FromTimeT(last_accessed_sec) +
 161       TimeDelta::FromMicroseconds(last_accessed_nsec /
 162                                   Time::kNanosecondsPerMicrosecond);
 163
 164   creation_time =
 165       Time::FromTimeT(creation_time_sec) +
 166       TimeDelta::FromMicroseconds(creation_time_nsec /
 167                                   Time::kNanosecondsPerMicrosecond);
 168 }
 169
 170 // Default implementations of Protect/Unprotect hooks defined as weak symbols
 171 // where possible.
 172 void ProtectFileDescriptor(int fd) {
 173 }
 174
 175 void UnprotectFileDescriptor(int fd) {
 176 }
 177
 178 // NaCl doesn't implement system calls to open files directly.
 179 #if !defined(OS_NACL)
 180 // TODO(erikkay): does it make sense to support FLAG_EXCLUSIVE_* here?
 181 void File::InitializeUnsafe(const FilePath& name, uint32 flags) {
 182   base::ThreadRestrictions::AssertIOAllowed();
 183   DCHECK(!IsValid());
 184
 185   int open_flags = 0;
 186   if (flags & FLAG_CREATE)
 187     open_flags = O_CREAT | O_EXCL;
 188
 189   created_ = false;
 190
 191   if (flags & FLAG_CREATE_ALWAYS) {
 192     DCHECK(!open_flags);
 193     DCHECK(flags & FLAG_WRITE);
 194     open_flags = O_CREAT | O_TRUNC;
 195   }
 196
 197   if (flags & FLAG_OPEN_TRUNCATED) {
 198     DCHECK(!open_flags);
 199     DCHECK(flags & FLAG_WRITE);
 200     open_flags = O_TRUNC;
 201   }
 202
 203   if (!open_flags && !(flags & FLAG_OPEN) && !(flags & FLAG_OPEN_ALWAYS)) {
 204     NOTREACHED();
 205     errno = EOPNOTSUPP;
 206     error_details_ = FILE_ERROR_FAILED;
 207     return;
 208   }
 209
 210   if (flags & FLAG_WRITE && flags & FLAG_READ) {
 211     open_flags |= O_RDWR;
 212   } else if (flags & FLAG_WRITE) {
 213     open_flags |= O_WRONLY;
 214   } else if (!(flags & FLAG_READ) &&
 215              !(flags & FLAG_WRITE_ATTRIBUTES) &&
 216              !(flags & FLAG_APPEND) &&
 217              !(flags & FLAG_OPEN_ALWAYS)) {
 218     NOTREACHED();
 219   }
 220
 221   if (flags & FLAG_TERMINAL_DEVICE)
 222     open_flags |= O_NOCTTY | O_NDELAY;
 223
 224   if (flags & FLAG_APPEND && flags & FLAG_READ)
 225     open_flags |= O_APPEND | O_RDWR;
 226   else if (flags & FLAG_APPEND)
 227     open_flags |= O_APPEND | O_WRONLY;
 228
 229   COMPILE_ASSERT(O_RDONLY == 0, O_RDONLY_must_equal_zero);
 230
 231   int mode = S_IRUSR | S_IWUSR;
 232 #if defined(OS_CHROMEOS)
 233   mode |= S_IRGRP | S_IROTH;
 234 #endif
 235
 236   int descriptor = HANDLE_EINTR(open(name.value().c_str(), open_flags, mode));
 237
 238   if (flags & FLAG_OPEN_ALWAYS) {
 239     if (descriptor < 0) {
 240       open_flags |= O_CREAT;
 241       if (flags & FLAG_EXCLUSIVE_READ || flags & FLAG_EXCLUSIVE_WRITE)
 242         open_flags |= O_EXCL;   // together with O_CREAT implies O_NOFOLLOW
 243
 244       descriptor = HANDLE_EINTR(open(name.value().c_str(), open_flags, mode));
 245       if (descriptor >= 0)
 246         created_ = true;
 247     }
 248   }
 249
 250   if (descriptor < 0) {
 251     error_details_ = File::OSErrorToFileError(errno);
 252     return;
 253   }
 254
 255   if (flags & (FLAG_CREATE_ALWAYS | FLAG_CREATE))
 256     created_ = true;
 257
 258   if (flags & FLAG_DELETE_ON_CLOSE)
 259     unlink(name.value().c_str());
 260
 261   async_ = ((flags & FLAG_ASYNC) == FLAG_ASYNC);
 262   error_details_ = FILE_OK;
 263   file_.reset(descriptor);
 264   ProtectFileDescriptor(descriptor);
 265 }
 266 #endif  // !defined(OS_NACL)
 267
 268 bool File::IsValid() const {
 269   return file_.is_valid();
 270 }
 271
 272 PlatformFile File::GetPlatformFile() const {
 273   return file_.get();
 274 }
 275
 276 PlatformFile File::TakePlatformFile() {
 277   if (IsValid())
 278     UnprotectFileDescriptor(GetPlatformFile());
 279   return file_.release();
 280 }
 281
 282 void File::Close() {
 283   if (!IsValid())
 284     return;
 285
 286   base::ThreadRestrictions::AssertIOAllowed();
 287   UnprotectFileDescriptor(GetPlatformFile());
 288   file_.reset();
 289 }
 290
 291 int64 File::Seek(Whence whence, int64 offset) {
 292   base::ThreadRestrictions::AssertIOAllowed();
 293   DCHECK(IsValid());
 294
 295 #if defined(OS_ANDROID)
 296   COMPILE_ASSERT(sizeof(int64) == sizeof(off64_t), off64_t_64_bit);
 297   return lseek64(file_.get(), static_cast<off64_t>(offset),
 298                  static_cast<int>(whence));
 299 #else
 300   COMPILE_ASSERT(sizeof(int64) == sizeof(off_t), off_t_64_bit);
 301   return lseek(file_.get(), static_cast<off_t>(offset),
 302                static_cast<int>(whence));
 303 #endif
 304 }
 305
 306 int File::Read(int64 offset, char* data, int size) {
 307   base::ThreadRestrictions::AssertIOAllowed();
 308   DCHECK(IsValid());
 309   if (size < 0)
 310     return -1;
 311
 312   int bytes_read = 0;
 313   int rv;
 314   do {
 315     rv = HANDLE_EINTR(pread(file_.get(), data + bytes_read,
 316                             size - bytes_read, offset + bytes_read));
 317     if (rv <= 0)
 318       break;
 319
 320     bytes_read += rv;
 321   } while (bytes_read < size);
 322
 323   return bytes_read ? bytes_read : rv;
 324 }
 325
 326 int File::ReadAtCurrentPos(char* data, int size) {
 327   base::ThreadRestrictions::AssertIOAllowed();
 328   DCHECK(IsValid());
 329   if (size < 0)
 330     return -1;
 331
 332   int bytes_read = 0;
 333   int rv;
 334   do {
 335     rv = HANDLE_EINTR(read(file_.get(), data + bytes_read, size - bytes_read));
 336     if (rv <= 0)
 337       break;
 338
 339     bytes_read += rv;
 340   } while (bytes_read < size);
 341
 342   return bytes_read ? bytes_read : rv;
 343 }
 344
 345 int File::ReadNoBestEffort(int64 offset, char* data, int size) {
 346   base::ThreadRestrictions::AssertIOAllowed();
 347   DCHECK(IsValid());
 348
 349   return HANDLE_EINTR(pread(file_.get(), data, size, offset));
 350 }
 351
 352 int File::ReadAtCurrentPosNoBestEffort(char* data, int size) {
 353   base::ThreadRestrictions::AssertIOAllowed();
 354   DCHECK(IsValid());
 355   if (size < 0)
 356     return -1;
 357
 358   return HANDLE_EINTR(read(file_.get(), data, size));
 359 }
 360
 361 int File::Write(int64 offset, const char* data, int size) {
 362   base::ThreadRestrictions::AssertIOAllowed();
 363
 364   if (IsOpenAppend(file_.get()))
 365     return WriteAtCurrentPos(data, size);
 366
 367   DCHECK(IsValid());
 368   if (size < 0)
 369     return -1;
 370
 371   int bytes_written = 0;
 372   int rv;
 373   do {
 374     rv = HANDLE_EINTR(pwrite(file_.get(), data + bytes_written,
 375                              size - bytes_written, offset + bytes_written));
 376     if (rv <= 0)
 377       break;
 378
 379     bytes_written += rv;
 380   } while (bytes_written < size);
 381
 382   return bytes_written ? bytes_written : rv;
 383 }
 384
 385 int File::WriteAtCurrentPos(const char* data, int size) {
 386   base::ThreadRestrictions::AssertIOAllowed();
 387   DCHECK(IsValid());
 388   if (size < 0)
 389     return -1;
 390
 391   int bytes_written = 0;
 392   int rv;
 393   do {
 394     rv = HANDLE_EINTR(write(file_.get(), data + bytes_written,
 395                             size - bytes_written));
 396     if (rv <= 0)
 397       break;
 398
 399     bytes_written += rv;
 400   } while (bytes_written < size);
 401
 402   return bytes_written ? bytes_written : rv;
 403 }
 404
 405 int File::WriteAtCurrentPosNoBestEffort(const char* data, int size) {
 406   base::ThreadRestrictions::AssertIOAllowed();
 407   DCHECK(IsValid());
 408   if (size < 0)
 409     return -1;
 410
 411   return HANDLE_EINTR(write(file_.get(), data, size));
 412 }
 413
 414 int64 File::GetLength() {
 415   DCHECK(IsValid());
 416
 417   stat_wrapper_t file_info;
 418   if (CallFstat(file_.get(), &file_info))
 419     return false;
 420
 421   return file_info.st_size;
 422 }
 423
 424 bool File::SetLength(int64 length) {
 425   base::ThreadRestrictions::AssertIOAllowed();
 426   DCHECK(IsValid());
 427   return !CallFtruncate(file_.get(), length);
 428 }
 429
 430 bool File::Flush() {
 431   base::ThreadRestrictions::AssertIOAllowed();
 432   DCHECK(IsValid());
 433   return !CallFsync(file_.get());
 434 }
 435
 436 bool File::SetTimes(Time last_access_time, Time last_modified_time) {
 437   base::ThreadRestrictions::AssertIOAllowed();
 438   DCHECK(IsValid());
 439
 440   timeval times[2];
 441   times[0] = last_access_time.ToTimeVal();
 442   times[1] = last_modified_time.ToTimeVal();
 443
 444   return !CallFutimes(file_.get(), times);
 445 }
 446
 447 bool File::GetInfo(Info* info) {
 448   DCHECK(IsValid());
 449
 450   stat_wrapper_t file_info;
 451   if (CallFstat(file_.get(), &file_info))
 452     return false;
 453
 454   info->FromStat(file_info);
 455   return true;
 456 }
 457
 458 File::Error File::Lock() {
 459   return CallFctnlFlock(file_.get(), true);
 460 }
 461
 462 File::Error File::Unlock() {
 463   return CallFctnlFlock(file_.get(), false);
 464 }
 465
 466 // Static.
 467 File::Error File::OSErrorToFileError(int saved_errno) {
 468   switch (saved_errno) {
 469     case EACCES:
 470     case EISDIR:
 471     case EROFS:
 472     case EPERM:
 473       return FILE_ERROR_ACCESS_DENIED;
 474 #if !defined(OS_NACL)  // ETXTBSY not defined by NaCl.
 475     case ETXTBSY:
 476       return FILE_ERROR_IN_USE;
 477 #endif
 478     case EEXIST:
 479       return FILE_ERROR_EXISTS;
 480     case ENOENT:
 481       return FILE_ERROR_NOT_FOUND;
 482     case EMFILE:
 483       return FILE_ERROR_TOO_MANY_OPENED;
 484     case ENOMEM:
 485       return FILE_ERROR_NO_MEMORY;
 486     case ENOSPC:
 487       return FILE_ERROR_NO_SPACE;
 488     case ENOTDIR:
 489       return FILE_ERROR_NOT_A_DIRECTORY;
 490     default:
 491 #if !defined(OS_NACL)  // NaCl build has no metrics code.
 492       UMA_HISTOGRAM_SPARSE_SLOWLY("PlatformFile.UnknownErrors.Posix",
 493                                   saved_errno);
 494 #endif
 495       return FILE_ERROR_FAILED;
 496   }
 497 }
 498
 499 File::MemoryCheckingScopedFD::MemoryCheckingScopedFD() {
 500   UpdateChecksum();
 501 }
 502
 503 File::MemoryCheckingScopedFD::MemoryCheckingScopedFD(int fd) : file_(fd) {
 504   UpdateChecksum();
 505 }
 506
 507 File::MemoryCheckingScopedFD::~MemoryCheckingScopedFD() {}
 508
 509 // static
 510 void File::MemoryCheckingScopedFD::ComputeMemoryChecksum(
 511     unsigned int* out_checksum) const {
 512   // Use a single iteration of a linear congruentional generator (lcg) to
 513   // provide a cheap checksum unlikely to be accidentally matched by a random
 514   // memory corruption.
 515
 516   // By choosing constants that satisfy the Hull-Duebell Theorem on lcg cycle
 517   // length, we insure that each distinct fd value maps to a distinct checksum,
 518   // which maximises the utility of our checksum.
 519
 520   // This code uses "unsigned int" throughout for its defined modular semantics,
 521   // which implicitly gives us a divisor that is a power of two.
 522
 523   const unsigned int kMultiplier = 13035 * 4 + 1;
 524   COMPILE_ASSERT(((kMultiplier - 1) & 3) == 0, pred_must_be_multiple_of_four);
 525   const unsigned int kIncrement = 1595649551;
 526   COMPILE_ASSERT(kIncrement & 1, must_be_coprime_to_powers_of_two);
 527
 528   *out_checksum =
 529       static_cast<unsigned int>(file_.get()) * kMultiplier + kIncrement;
 530 }
 531
 532 void File::MemoryCheckingScopedFD::Check() const {
 533   unsigned int computed_checksum;
 534   ComputeMemoryChecksum(&computed_checksum);
 535   CHECK_EQ(file_memory_checksum_, computed_checksum) << "corrupted fd memory";
 536 }
 537
 538 void File::MemoryCheckingScopedFD::UpdateChecksum() {
 539   ComputeMemoryChecksum(&file_memory_checksum_);
 540 }
 541
 542 void File::SetPlatformFile(PlatformFile file) {
 543   CHECK(!file_.is_valid());
 544   file_.reset(file);
 545   if (file_.is_valid())
 546     ProtectFileDescriptor(GetPlatformFile());
 547 }
 548
 549 }  // namespace base