folly::File Class Reference

#include <File.h>

Public Member Functions
	File () noexcept
	File (int fd, bool ownsFd=false) noexcept
	File (const char *name, int flags=O_RDONLY, mode_t mode=0666)
	File (const std::string &name, int flags=O_RDONLY, mode_t mode=0666)
	File (StringPiece name, int flags=O_RDONLY, mode_t mode=0666)
	~File ()
int	fd () const
	operator bool () const
File	dup () const
void	close ()
bool	closeNoThrow ()
int	release () noexcept
void	swap (File &other) noexcept
	File (File &&) noexcept
File &	operator= (File &&)
void	lock ()
bool	try_lock ()
void	unlock ()
void	lock_shared ()
bool	try_lock_shared ()
void	unlock_shared ()

Static Public Member Functions
template<typename... Args>
static Expected< File, exception_wrapper >	makeFile (Args &&...args) noexcept
static File	temporary ()

Private Member Functions
void	doLock (int op)
bool	doTryLock (int op)
	File (const File &)=delete
File &	operator= (const File &)=delete

Private Attributes
int	fd_
bool	ownsFd_

Detailed Description

A File represents an open file.

Definition at line 37 of file File.h.

Constructor & Destructor Documentation

folly::File::File ( )

noexcept

Creates an empty File object, for late initialization.

Definition at line 33 of file File.cpp.

Referenced by dup(), makeFile(), operator bool(), and temporary().

: fd_(-1), ownsFd_(false) {}

folly::File::File ( int  fd, bool  ownsFd = false  )

explicitnoexcept

Create a File object from an existing file descriptor. Takes ownership of the file descriptor if ownsFd is true.

Definition at line 35 of file File.cpp.

References fd().

                                       : fd_(fd), ownsFd_(ownsFd) {
  CHECK_GE(fd, -1) << "fd must be -1 or non-negative";
  CHECK(fd != -1 || !ownsFd) << "cannot own -1";
}

folly::File::File ( const char *  name, int  flags = O_RDONLY, mode_t  mode = 0666  )

explicit

Open and create a file object. Throws on error. Owns the file descriptor implicitly.

Definition at line 40 of file File.cpp.

References fd_, folly::format(), ownsFd_, and folly::throwSystemError().

    : fd_(::open(name, flags, mode)), ownsFd_(false) {
  if (fd_ == -1) {
    throwSystemError(
        folly::format("open(\"{}\", {:#o}, 0{:#o}) failed", name, flags, mode)
            .fbstr());
  }
  ownsFd_ = true;
}

folly::File::File ( const std::string &  name, int  flags = O_RDONLY, mode_t  mode = 0666  )

explicit

Definition at line 50 of file File.cpp.

    : File(name.c_str(), flags, mode) {}

folly::File::File ( StringPiece  name, int  flags = O_RDONLY, mode_t  mode = 0666  )

explicit

Definition at line 53 of file File.cpp.

    : File(name.str(), flags, mode) {}

folly::File::~File

(

)

Definition at line 66 of file File.cpp.

References closeNoThrow(), fd(), and fd_.

Referenced by makeFile().

            {
  auto fd = fd_;
  if (!closeNoThrow()) { // ignore most errors
    DCHECK_NE(errno, EBADF)
        << "closing fd " << fd << ", it may already "
        << "have been closed. Another time, this might close the wrong FD.";
  }
}

folly::File::File ( File &&  other )

noexcept

Definition at line 56 of file File.cpp.

                                : fd_(other.fd_), ownsFd_(other.ownsFd_) {
  other.release();
}

folly::File::File ( const File &  )

privatedelete

Member Function Documentation

void folly::File::close

(

)

If we own the file descriptor, close the file and throw on error. Otherwise, do nothing.

Definition at line 117 of file File.cpp.

References closeNoThrow(), and folly::throwSystemError().

Referenced by closeNoThrow(), folly::gen::detail::FileWriter::compose(), operator bool(), and TEST().

                 {
  if (!closeNoThrow()) {
    throwSystemError("close() failed");
  }
}

bool folly::File::closeNoThrow

(

)

Closes the file (if owned). Returns true on success, false (and sets errno) on error.

Definition at line 123 of file File.cpp.

References close(), fd_, ownsFd_, and release().

Referenced by close(), operator bool(), operator=(), and ~File().

                        {
  int r = ownsFd_ ? ::close(fd_) : 0;
  release();
  return r == 0;
}

void folly::File::doLock ( int  op )

private

Definition at line 142 of file File.cpp.

References folly::checkUnixError(), fd_, and folly::flockNoInt().

Referenced by lock(), lock_shared(), and operator bool().

                        {
  checkUnixError(flockNoInt(fd_, op), "flock() failed (lock)");
}

bool folly::File::doTryLock ( int  op )

private

Definition at line 146 of file File.cpp.

References folly::checkUnixError(), fd_, and folly::flockNoInt().

Referenced by operator bool(), try_lock(), and try_lock_shared().

                           {
  int r = flockNoInt(fd_, op | LOCK_NB);
  // flock returns EWOULDBLOCK if already locked
  if (r == -1 && errno == EWOULDBLOCK) {
    return false;
  }
  checkUnixError(r, "flock() failed (try_lock)");
  return true;
}

File folly::File::dup

(

)

const

Duplicate file descriptor and return File that owns it.

Definition at line 106 of file File.cpp.

References folly::checkUnixError(), fd(), fd_, and File().

Referenced by operator bool(), and temporary().

                     {
  if (fd_ != -1) {
    int fd = ::dup(fd_);
    checkUnixError(fd, "dup() failed");

    return File(fd, true);
  }

  return File();
}

int folly::File::fd ( ) const

inline

Return the file descriptor, or -1 if the file was closed.

Definition at line 85 of file File.h.

References fd_.

Referenced by folly::gen::detail::FileReader::apply(), folly::ShutdownSocketSet::doShutdown(), dup(), folly::MemoryMapping::fd(), File(), folly::MemoryMapping::init(), folly::AsyncFileWriter::onIoError(), folly::AsyncFileWriter::performIO(), folly::test::CaptureFD::readIncremental(), folly::RecordIOWriter::RecordIOWriter(), temporary(), folly::TEST(), TEST(), folly::test::TEST(), folly::ImmediateFileWriter::ttyOutput(), folly::AsyncFileWriter::ttyOutput(), folly::RecordIOWriter::write(), folly::gen::detail::FileWriter::write(), folly::ImmediateFileWriter::writeMessage(), and ~File().

                 {
    return fd_;
  }

void folly::File::lock

(

)

Definition at line 129 of file File.cpp.

References doLock().

Referenced by operator bool().

                {
  doLock(LOCK_EX);
}

void folly::File::lock_shared

(

)

Definition at line 135 of file File.cpp.

References doLock().

Referenced by operator bool().

                       {
  doLock(LOCK_SH);
}

template<typename... Args>

static Expected<File, exception_wrapper> folly::File::makeFile ( Args &&...  args )

inlinestaticnoexcept

All the constructors that are not noexcept can throw std::system_error. This is a helper method to use folly::Expected to chain a file open event to something else you want to do with the open fd.

Definition at line 67 of file File.h.

References File(), folly::makeUnexpected(), temporary(), and ~File().

Referenced by TEST().

                                                                             {
    try {
      return File(std::forward<Args>(args)...);
    } catch (const std::system_error& se) {
      return makeUnexpected(exception_wrapper(std::current_exception(), se));
    }
  }

folly::File::operator bool ( ) const

inlineexplicit

Returns 'true' iff the file was successfully opened.

Definition at line 92 of file File.h.

References close(), closeNoThrow(), doLock(), doTryLock(), dup(), fd_, File(), lock(), lock_shared(), folly::pushmi::__adl::noexcept(), operator=(), release(), swap(), try_lock(), try_lock_shared(), unlock(), and unlock_shared().

                                 {
    return fd_ != -1;
  }

File & folly::File::operator=

(

File &&

other

)

Definition at line 60 of file File.cpp.

References closeNoThrow(), and swap().

Referenced by operator bool().

                                  {
  closeNoThrow();
  swap(other);
  return *this;
}

File& folly::File::operator= ( const File &  )

privatedelete

int folly::File::release ( )

noexcept

Returns and releases the file descriptor; no longer owned by this File. Returns -1 if the File object didn't wrap a file.

Definition at line 89 of file File.cpp.

References fd_, and ownsFd_.

Referenced by closeNoThrow(), operator bool(), and TEST().

                           {
  int released = fd_;
  fd_ = -1;
  ownsFd_ = false;
  return released;
}

void folly::File::swap ( File &  other )

noexcept

Swap this File with another.

Definition at line 96 of file File.cpp.

References fd_, ownsFd_, and folly::swap().

Referenced by operator bool(), and operator=().

                                    {
  using std::swap;
  swap(fd_, other.fd_);
  swap(ownsFd_, other.ownsFd_);
}

File folly::File::temporary ( )

static

Create and return a temporary, owned file (uses tmpfile()).

Definition at line 75 of file File.cpp.

References folly::checkFopenError(), folly::checkUnixError(), dup(), fd(), FILE, File(), and SCOPE_EXIT.

Referenced by makeFile(), folly::TEST(), and TEST().

                       {
  // make a temp file with tmpfile(), dup the fd, then return it in a File.
  FILE* tmpFile = tmpfile();
  checkFopenError(tmpFile, "tmpfile() failed");
  SCOPE_EXIT {
    fclose(tmpFile);
  };

  int fd = ::dup(fileno(tmpFile));
  checkUnixError(fd, "dup() failed");

  return File(fd, true);
}

bool folly::File::try_lock

(

)

Definition at line 132 of file File.cpp.

References doTryLock().

Referenced by main(), and operator bool().

                    {
  return doTryLock(LOCK_EX);
}

bool folly::File::try_lock_shared

(

)

Definition at line 138 of file File.cpp.

References doTryLock().

Referenced by main(), and operator bool().

                           {
  return doTryLock(LOCK_SH);
}

void folly::File::unlock

(

)

Definition at line 156 of file File.cpp.

References folly::checkUnixError(), fd_, and folly::flockNoInt().

Referenced by operator bool(), and unlock_shared().

                  {
  checkUnixError(flockNoInt(fd_, LOCK_UN), "flock() failed (unlock)");
}

void folly::File::unlock_shared

(

)

Definition at line 159 of file File.cpp.

References unlock().

Referenced by operator bool().

                         {
  unlock();
}

Member Data Documentation

int folly::File::fd_

private

Definition at line 152 of file File.h.

Referenced by closeNoThrow(), doLock(), doTryLock(), dup(), fd(), File(), operator bool(), release(), swap(), unlock(), and ~File().

bool folly::File::ownsFd_

private

Definition at line 153 of file File.h.

Referenced by closeNoThrow(), File(), release(), and swap().

---

The documentation for this class was generated from the following files:

• proxygen/folly/folly/File.h
• proxygen/folly/folly/File.cpp