fmt/posix.cc

/*
 A C++ interface to POSIX functions.

 Copyright (c) 2014, Victor Zverovich
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

 1. Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "posix.h"

#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifndef _WIN32
# include <unistd.h>
#else
# include <io.h>

# define O_CREAT _O_CREAT
# define O_TRUNC _O_TRUNC
# define S_IRUSR _S_IREAD
# define S_IWUSR _S_IWRITE

# ifdef __MINGW32__
#  define _SH_DENYNO 0x40
# endif

#endif  // _WIN32

namespace {
#ifdef _WIN32
// On Windows the count argument to read and write is unsigned, so convert
// it from size_t preventing integer overflow.
inline unsigned ConvertRWCount(std::size_t count) {
  return count <= UINT_MAX ? static_cast<unsigned>(count) : UINT_MAX;
}
#else
inline std::size_t ConvertRWCount(std::size_t count) { return count; }
#endif
}

fmt::BufferedFile::~BufferedFile() FMT_NOEXCEPT(true) {
  if (file_ && FMT_SYSTEM(fclose(file_)) != 0)
    fmt::ReportSystemError(errno, "cannot close file");
}

void fmt::BufferedFile::close() {
  if (!file_)
    return;
  int result = FMT_SYSTEM(fclose(file_));
  file_ = 0;
  if (result != 0)
    throw SystemError(errno, "cannot close file");
}

int fmt::BufferedFile::fileno() const {
  int fd = FMT_POSIX_CALL(fileno(file_));
  if (fd == -1)
    throw SystemError(errno, "cannot get file descriptor");
  return fd;
}

fmt::File::File(const char *path, int oflag) {
  int mode = S_IRUSR | S_IWUSR;
#ifdef _WIN32
  fd_ = -1;
  FMT_POSIX_CALL(sopen_s(&fd_, path, oflag, _SH_DENYNO, mode));
#else
  FMT_RETRY(fd_, FMT_POSIX_CALL(open(path, oflag, mode)));
#endif
  if (fd_ == -1)
    throw SystemError(errno, "cannot open file {}", path);
}

fmt::File::~File() FMT_NOEXCEPT(true) {
  // Don't retry close in case of EINTR!
  // See http://linux.derkeiler.com/Mailing-Lists/Kernel/2005-09/3000.html
  if (fd_ != -1 && FMT_POSIX_CALL(close(fd_)) != 0)
    fmt::ReportSystemError(errno, "cannot close file");
}

void fmt::File::close() {
  if (fd_ == -1)
    return;
  // Don't retry close in case of EINTR!
  // See http://linux.derkeiler.com/Mailing-Lists/Kernel/2005-09/3000.html
  int result = FMT_POSIX_CALL(close(fd_));
  fd_ = -1;
  if (result != 0)
    throw SystemError(errno, "cannot close file");
}

std::streamsize fmt::File::read(void *buffer, std::size_t count) {
  std::streamsize result = 0;
  FMT_RETRY(result, FMT_POSIX_CALL(read(fd_, buffer, ConvertRWCount(count))));
  if (result == -1)
    throw SystemError(errno, "cannot read from file");
  return result;
}

std::streamsize fmt::File::write(const void *buffer, std::size_t count) {
  std::streamsize result = 0;
  FMT_RETRY(result, FMT_POSIX_CALL(write(fd_, buffer, ConvertRWCount(count))));
  if (result == -1)
    throw SystemError(errno, "cannot write to file");
  return result;
}

fmt::File fmt::File::dup(int fd) {
  // Don't retry as dup doesn't return EINTR.
  // http://pubs.opengroup.org/onlinepubs/009695399/functions/dup.html
  int new_fd = FMT_POSIX_CALL(dup(fd));
  if (new_fd == -1)
    throw SystemError(errno, "cannot duplicate file descriptor {}", fd);
  return File(new_fd);
}

void fmt::File::dup2(int fd) {
  int result = 0;
  FMT_RETRY(result, FMT_POSIX_CALL(dup2(fd_, fd)));
  if (result == -1) {
    throw SystemError(errno,
      "cannot duplicate file descriptor {} to {}", fd_, fd);
  }
}

void fmt::File::dup2(int fd, ErrorCode &ec) FMT_NOEXCEPT(true) {
  int result = 0;
  FMT_RETRY(result, FMT_POSIX_CALL(dup2(fd_, fd)));
  if (result == -1)
    ec = ErrorCode(errno);
}

void fmt::File::pipe(File &read_end, File &write_end) {
  // Close the descriptors first to make sure that assignments don't throw
  // and there are no leaks.
  read_end.close();
  write_end.close();
  int fds[2] = {};
#ifdef _WIN32
  // Make the default pipe capacity same as on Linux 2.6.11+.
  enum { DEFAULT_CAPACITY = 65536 };
  int result = FMT_POSIX_CALL(pipe(fds, DEFAULT_CAPACITY, _O_BINARY));
#else
  // Don't retry as the pipe function doesn't return EINTR.
  // http://pubs.opengroup.org/onlinepubs/009696799/functions/pipe.html
  int result = FMT_POSIX_CALL(pipe(fds));
#endif
  if (result != 0)
    throw SystemError(errno, "cannot create pipe");
  // The following assignments don't throw because read_fd and write_fd
  // are closed.
  read_end = File(fds[0]);
  write_end = File(fds[1]);
}

fmt::BufferedFile fmt::File::fdopen(const char *mode) {
  // Don't retry as fdopen doesn't return EINTR.
  FILE *f = FMT_POSIX_CALL(fdopen(fd_, mode));
  if (!f)
    throw SystemError(errno, "cannot associate stream with file descriptor");
  BufferedFile file(f);
  fd_ = -1;
  return file;
}