/*
 A C++ interface to POSIX functions.

 Copyright (c) 2012 - 2016, Victor Zverovich
 All rights reserved.

 For the license information refer to format.h.
 */

// Disable bogus MSVC warnings.
#ifndef _CRT_SECURE_NO_WARNINGS
# define _CRT_SECURE_NO_WARNINGS
#endif

#include "mp/posix.h"

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

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

# define O_CREAT _O_CREAT
# define O_TRUNC _O_TRUNC

# ifndef S_IRUSR
#  define S_IRUSR _S_IREAD
# endif

# ifndef S_IWUSR
#  define S_IWUSR _S_IWRITE
# endif

# ifdef __MINGW32__
#  define _SH_DENYNO 0x40
# endif

#endif  // _WIN32

#ifdef fileno
# undef fileno
#endif

namespace {
#ifdef _WIN32
// Return type of read and write functions.
typedef int RWResult;

// On Windows the count argument to read and write is unsigned, so convert
// it from size_t preventing integer overflow.
inline unsigned convert_rwcount(std::size_t count) {
  return count <= UINT_MAX ? static_cast<unsigned>(count) : UINT_MAX;
}
#else
// Return type of read and write functions.
typedef ssize_t RWResult;

inline std::size_t convert_rwcount(std::size_t count) { return count; }
#endif
}

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

fmt::BufferedFile::BufferedFile(
    fmt::CStringRef filename, fmt::CStringRef mode) {
  FMT_RETRY_VAL(file_, FMT_SYSTEM(fopen(filename.c_str(), mode.c_str())), 0);
  if (!file_)
    FMT_THROW(SystemError(errno, "cannot open file {}", filename));
}

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

// A macro used to prevent expansion of fileno on broken versions of MinGW.
#define FMT_ARGS

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

fmt::File::File(fmt::CStringRef path, int oflag) {
  int mode = S_IRUSR | S_IWUSR;
#if defined(_WIN32) && !defined(__MINGW32__)
  fd_ = -1;
  FMT_POSIX_CALL(sopen_s(&fd_, path.c_str(), oflag, _SH_DENYNO, mode));
#else
  FMT_RETRY(fd_, FMT_POSIX_CALL(open(path.c_str(), oflag, mode)));
#endif
  if (fd_ == -1)
    FMT_THROW(SystemError(errno, "cannot open file {}", path));
}

fmt::File::~File() FMT_NOEXCEPT {
  // 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::report_system_error(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)
    FMT_THROW(SystemError(errno, "cannot close file"));
}

fmt::LongLong fmt::File::size() const {
#ifdef _WIN32
  // Use GetFileSize instead of GetFileSizeEx for the case when _WIN32_WINNT
  // is less than 0x0500 as is the case with some default MinGW builds.
  // Both functions support large file sizes.
  DWORD size_upper = 0;
  HANDLE handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd_));
  DWORD size_lower = FMT_SYSTEM(GetFileSize(handle, &size_upper));
  if (size_lower == INVALID_FILE_SIZE) {
    DWORD error = GetLastError();
    if (error != NO_ERROR)
      FMT_THROW(WindowsError(GetLastError(), "cannot get file size"));
  }
  fmt::ULongLong long_size = size_upper;
  return (long_size << sizeof(DWORD) * CHAR_BIT) | size_lower;
#else
  typedef struct stat Stat;
  Stat file_stat = Stat();
  if (FMT_POSIX_CALL(fstat(fd_, &file_stat)) == -1)
    FMT_THROW(SystemError(errno, "cannot get file attributes"));
  FMT_STATIC_ASSERT(sizeof(fmt::LongLong) >= sizeof(file_stat.st_size),
      "return type of File::size is not large enough");
  return file_stat.st_size;
#endif
}

std::size_t fmt::File::read(void *buffer, std::size_t count) {
  RWResult result = 0;
  FMT_RETRY(result, FMT_POSIX_CALL(read(fd_, buffer, convert_rwcount(count))));
  if (result < 0)
    FMT_THROW(SystemError(errno, "cannot read from file"));
  return internal::to_unsigned(result);
}

std::size_t fmt::File::write(const void *buffer, std::size_t count) {
  RWResult result = 0;
  FMT_RETRY(result, FMT_POSIX_CALL(write(fd_, buffer, convert_rwcount(count))));
  if (result < 0)
    FMT_THROW(SystemError(errno, "cannot write to file"));
  return internal::to_unsigned(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)
    FMT_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) {
    FMT_THROW(SystemError(errno,
      "cannot duplicate file descriptor {} to {}", fd_, fd));
  }
}

void fmt::File::dup2(int fd, ErrorCode &ec) FMT_NOEXCEPT {
  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)
    FMT_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)
    FMT_THROW(SystemError(errno, "cannot associate stream with file descriptor"));
  BufferedFile file(f);
  fd_ = -1;
  return file;
}

long fmt::getpagesize() {
#ifdef _WIN32
  SYSTEM_INFO si;
  GetSystemInfo(&si);
  return si.dwPageSize;
#else
  long size = FMT_POSIX_CALL(sysconf(_SC_PAGESIZE));
  if (size < 0)
    FMT_THROW(SystemError(errno, "cannot get memory page size"));
  return size;
#endif
}
