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