Class: Win32::NIO

Inherits:

Object

• Object
• Win32::NIO

Defined in:

ext/win32/nio.c

Constant Summary

VERSION =

The version of the win32-nio library

0.2.0

Class Method Summary

• .read(*args) ⇒ Object

  This method is similar to Ruby’s IO.read method except that it uses native function calls.

• .readlines(*args) ⇒ Object

  Reads the entire file specified by portname as individual lines, and returns those lines in an array.

Class Method Details

.read(*args) ⇒ Object

This method is similar to Ruby’s IO.read method except that it uses native function calls.

Examples:

# Read everything Win32::NIO.read(file)

# Read the first 100 bytes Win32::NIO.read(file, 100)

# Read 50 bytes starting at offset 10 Win32::NIO.read(file, 50, 10)

Note that the + options + that may be passed to this method are limited to :encoding, : mode and : event because we’re no longer using the open function internally.In the case of:mode the only thing that is checked for is the presence of the ‘b’ (binary)mode.

The :event option, if present, must be a Win32::Event object.

# File 'ext/win32/nio.c', line 40

static VALUE rb_nio_read(int argc, VALUE* argv, VALUE self){
  OVERLAPPED olap;
  HANDLE h;
  DWORD bytes_read;
  LARGE_INTEGER lsize;
  BOOL b;
  VALUE v_file, v_length, v_offset, v_options;
  VALUE v_event, v_mode, v_encoding, v_result;
  size_t length;
  int flags, error, size;
  wchar_t* file = NULL;
  char* buffer = NULL;

  memset(&olap, 0, sizeof(olap));

  // Paranoid initialization
  v_length = Qnil;
  v_offset = Qnil;
  v_options = Qnil;

  rb_scan_args(argc, argv, "13", &v_file, &v_length, &v_offset, &v_options);

  // Allow path-y objects.
  if (rb_respond_to(v_file, rb_intern("to_path")))
    v_file = rb_funcall(v_file, rb_intern("to_path"), 0, NULL);

  SafeStringValue(v_file);

  // If a length is provided it cannot be negative.
  if (!NIL_P(v_length)){
    length = NUM2SIZET(v_length);
    if ((int)length < 0)
      rb_raise(rb_eArgError, "negative length %i given", (int)length);
  }
  else{
    length = 0; // Mostly to make gcc stfu. We'll set this later.
  }

  // Unlike MRI, don't wait for an internal C function to fail on an invalid argument.
  if (!NIL_P(v_offset)){
    olap.Offset = NUM2ULONG(v_offset);
    if ((int)olap.Offset < 0)
      rb_raise(rb_eArgError, "negative offset %i given", (int)olap.Offset);
  }

  // Gotta do this for wide character function support.
  size = MultiByteToWideChar(CP_UTF8, 0, RSTRING_PTR(v_file), -1, NULL, 0);
  file = (wchar_t*)ruby_xmalloc(MAX_PATH * sizeof(wchar_t));

  if (!MultiByteToWideChar(CP_UTF8, 0, RSTRING_PTR(v_file), -1, file, size)){
    ruby_xfree(file);
    rb_raise_syserr("MultibyteToWideChar", GetLastError());
  }

  flags = FILE_FLAG_SEQUENTIAL_SCAN;

  // Possible options are :event, :mode and :encoding
  if (!NIL_P(v_options)){
    Check_Type(v_options, T_HASH);

    v_event = rb_hash_aref(v_options, ID2SYM(rb_intern("event")));
    v_encoding = rb_hash_aref(v_options, ID2SYM(rb_intern("encoding")));
    v_mode = rb_hash_aref(v_options, ID2SYM(rb_intern("mode")));

    if (!NIL_P(v_event)){
      flags |= FILE_FLAG_OVERLAPPED;
      olap.hEvent = (HANDLE)NUM2OFFT(rb_funcall(v_event, rb_intern("handle"), 0, 0));
    }
  }
  else{
    v_event = Qnil;
    v_encoding = Qnil;
    v_mode = Qnil;
  }

  h = CreateFileW(
    file,
    GENERIC_READ,
    FILE_SHARE_READ,
    NULL,
    OPEN_EXISTING,
    flags,
    NULL
  );

  if (h == INVALID_HANDLE_VALUE)
    rb_raise_syserr("CreateFile", GetLastError());

  // Get the file size. We may use this later to limit read length.
  if (!GetFileSizeEx(h, &lsize)){
    error = GetLastError();
    CloseHandle(h);
    rb_raise_syserr("GetFileSizeEx", error);
  }

  // If no length is specified, read the entire file
  if (NIL_P(v_length))
    length = (size_t)lsize.QuadPart;

  // Don't read past the end of the file
  if (olap.Offset + length > (size_t)lsize.QuadPart)
    length = (size_t)lsize.QuadPart - olap.Offset;

  buffer = (char*)ruby_xmalloc(length * sizeof(char));

  // If a block is given then treat it as a callback
  if (rb_block_given_p()){
    flags |= FILE_FLAG_OVERLAPPED;
    b = ReadFileEx(h, buffer, length, &olap, read_complete);
  }
  else{
    b = ReadFile(h, buffer, length, &bytes_read, &olap);
  }

  error = GetLastError();

  // Put in alertable wait state if overlapped IO
  if (flags & FILE_FLAG_OVERLAPPED)
    SleepEx(1, TRUE);

  if (!b){
    if(error == ERROR_IO_PENDING){
      DWORD bytes;
      if (!GetOverlappedResult(h, &olap, &bytes, TRUE)){
        ruby_xfree(buffer);
        CloseHandle(h);
        rb_raise_syserr("GetOverlappedResult", error);
      }
    }
    else{
      ruby_xfree(buffer);
      CloseHandle(h);
      rb_raise_syserr("ReadFile", error);
    }
  }

  CloseHandle(h);

  v_result = rb_str_new(buffer, length);
  ruby_xfree(buffer);

  // Convert CRLF to LF if text mode
  if (!NIL_P(v_mode) && strstr(RSTRING_PTR(v_mode), "t"))
    rb_funcall(v_result, rb_intern("gsub!"), 2, rb_str_new2("\r\n"), rb_gv_get("$/"));

  if (!NIL_P(v_encoding))
    rb_funcall(v_result, rb_intern("encode!"), 1, v_encoding);

  return v_result;
}

.readlines(*args) ⇒ Object

Reads the entire file specified by portname as individual lines, and returns those lines in an array. Lines are separated by sep.

Examples:

# Standard call
Win32::NIO.readlines('file.txt') # => ['line 1', 'line 2', 'line 3', 'line 4']

# Paragraph mode
Win32::NIO.readlines('file.txt', '') # => ['line 1\r\nline 2', 'line 3\r\nline 4']

# With event
event = Win32::Event.new
Win32::NIO.readlines('file.txt', nil, event)
p event.signaled? # => true

Superficially this method acts the same as the Ruby IO.readlines call, except that it does not transform line endings and accepts an optional event object. However, internally this method is using a scattered read to accomplish its goal. In practice this is only relevant in specific situations. Using it outside of those situations is unlikely to provide any practical benefit, and may even result in slower performance.

See information on vectored IO for more details.

# File 'ext/win32/nio.c', line 216

static VALUE rb_nio_readlines(int argc, VALUE* argv, VALUE self){
  HANDLE h;
  SYSTEM_INFO info;
  LARGE_INTEGER file_size;
  size_t length, page_size;
  double size;
  void* base_address;
  int error, page_num;
  wchar_t* file;
  VALUE v_file, v_sep, v_event, v_result;

  rb_scan_args(argc, argv, "12", &v_file, &v_sep, &v_event);

  SafeStringValue(v_file);

  if (NIL_P(v_sep))
    v_sep = rb_str_new2("\r\n");
  else
    SafeStringValue(v_sep);

  v_result = Qnil;

  length = MultiByteToWideChar(CP_UTF8, 0, RSTRING_PTR(v_file), -1, NULL, 0);
  file = (wchar_t*)ruby_xmalloc(MAX_PATH * sizeof(wchar_t));

  if (!MultiByteToWideChar(CP_UTF8, 0, RSTRING_PTR(v_file), -1, file, length)){
    ruby_xfree(file);
    rb_raise_syserr("MultibyteToWideChar", GetLastError());
  }

  h = CreateFileW(
    file,
    GENERIC_READ,
    FILE_SHARE_READ,
    NULL,
    OPEN_EXISTING,
    FILE_FLAG_OVERLAPPED | FILE_FLAG_NO_BUFFERING,
    NULL
  );

  if (h == INVALID_HANDLE_VALUE)
    rb_raise_syserr("CreateFile", GetLastError());

  if (!GetFileSizeEx(h, &file_size)){
    error = GetLastError();
    CloseHandle(h);
    rb_raise_syserr("GetFileSizeEx", error);
  }

  length = (size_t)file_size.QuadPart;

  GetSystemInfo(&info);
  page_size = info.dwPageSize;

  page_num = (int)ceil((double)length / page_size);

  size = page_num * page_size;

  base_address = VirtualAlloc(NULL, (size_t)size, MEM_COMMIT, PAGE_READWRITE);

  if (!base_address){
    error = GetLastError();
    CloseHandle(h);
    rb_raise_syserr("VirtualAlloc", error);
  }
  else{
    int i;
    OVERLAPPED olap;
    BOOL rv;
    FILE_SEGMENT_ELEMENT* fse;

    olap.Offset = 0;
    olap.OffsetHigh = 0;

    if (NIL_P(v_event))
      olap.hEvent = NULL;
    else
      olap.hEvent = (HANDLE)NUM2OFFT(rb_funcall(v_event, rb_intern("handle"), 0, 0));

    fse = (FILE_SEGMENT_ELEMENT*)malloc(sizeof(FILE_SEGMENT_ELEMENT) * (page_num + 1));
    memset(fse, 0, sizeof(FILE_SEGMENT_ELEMENT) * (page_num + 1));
    v_result = Qnil;

    for (i = 0; i < page_num; i++)
      fse[i].Alignment = (ULONGLONG)base_address + (page_size * i);

    rv = ReadFileScatter(h, fse, (DWORD)size, NULL, &olap);

    if (!rv){
      error = GetLastError();

      if (error == ERROR_IO_PENDING){
        while (!HasOverlappedIoCompleted(&olap))
          SleepEx(1, TRUE);
      }
      else{
        VirtualFree(base_address, 0, MEM_RELEASE);
        CloseHandle(h);
        rb_raise_syserr("ReadFileScatter", error);
      }
    }

    // Explicitly handle paragraph mode
    if (rb_equal(v_sep, rb_str_new2(""))){
      VALUE v_args[1];
      v_args[0] = rb_str_new2("(\r\n){2,}");
      v_sep = rb_class_new_instance(1, v_args, rb_cRegexp);
      v_result = rb_funcall(rb_str_new2(fse[0].Buffer), rb_intern("split"), 1, v_sep);
      rb_funcall(v_result, rb_intern("delete"), 1, rb_str_new2("\r\n"));
    }
    else{
      v_result = rb_funcall(rb_str_new2(fse[0].Buffer), rb_intern("split"), 1, v_sep);
    }

    VirtualFree(base_address, 0, MEM_RELEASE);
  }

  CloseHandle(h);

  return v_result;
}