node_file.cc

// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

#include "node.h"
#include "node_file.h"
#include "node_buffer.h"
#ifdef __POSIX__
# include "node_stat_watcher.h"
#endif
#include "req_wrap.h"

#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <assert.h>
#include <string.h>
#include <errno.h>
#include <limits.h>

#if defined(__MINGW32__) || defined(_MSC_VER)
# include <io.h>
# include <platform_win32.h>
#endif


namespace node {

using namespace v8;

#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define THROW_BAD_ARGS \
  ThrowException(Exception::TypeError(String::New("Bad argument")))

typedef class ReqWrap<uv_fs_t> FSReqWrap;

static Persistent<String> encoding_symbol;
static Persistent<String> errno_symbol;
static Persistent<String> buf_symbol;
static Persistent<String> oncomplete_sym;

Local<Value> FSError(int errorno,
                     const char *syscall = NULL,
                     const char *msg     = NULL,
                     const char *path    = NULL);


#ifdef _LARGEFILE_SOURCE
static inline int IsInt64(double x) {
  return x == static_cast<double>(static_cast<int64_t>(x));
}
#endif


static void After(uv_fs_t *req) {
  HandleScope scope;

  FSReqWrap* req_wrap = (FSReqWrap*) req->data;
  assert(&req_wrap->req_ == req);
  Local<Value> callback_v = req_wrap->object_->Get(oncomplete_sym);
  assert(callback_v->IsFunction());
  Local<Function> callback = Local<Function>::Cast(callback_v);

  // there is always at least one argument. "error"
  int argc = 1;

  // Allocate space for two args. We may only use one depending on the case.
  // (Feel free to increase this if you need more)
  Local<Value> argv[2];

  // NOTE: This may be needed to be changed if something returns a -1
  // for a success, which is possible.
  if (req->result == -1) {
    // If the request doesn't have a path parameter set.

    if (!req->path) {
      argv[0] = FSError(req->errorno);
    } else {
      argv[0] = FSError(req->errorno,
                        NULL,
                        NULL,
                        static_cast<const char*>(req->path));
    }
  } else {
    // error value is empty or null for non-error.
    argv[0] = Local<Value>::New(Null());

    // All have at least two args now.
    argc = 2;

    switch (req->fs_type) {
      // These all have no data to pass.
      case UV_FS_CLOSE:
      case UV_FS_RENAME:
      case UV_FS_UNLINK:
      case UV_FS_RMDIR:
      case UV_FS_MKDIR:
      case UV_FS_FTRUNCATE:
      case UV_FS_FSYNC:
      case UV_FS_FDATASYNC:
      case UV_FS_LINK:
      case UV_FS_SYMLINK:
      case UV_FS_CHMOD:
      case UV_FS_FCHMOD:
      case UV_FS_CHOWN:
      case UV_FS_FCHOWN:
        // These, however, don't.
        argc = 1;
        break;

      case UV_FS_UTIME:
      case UV_FS_FUTIME:
        argc = 0;
        break;

      case UV_FS_OPEN:
        /* pass thru */
      case UV_FS_SENDFILE:
        argv[1] = Integer::New(req->result);
        break;

      case UV_FS_WRITE:
        argv[1] = Integer::New(req->result);
        break;

      case UV_FS_STAT:
      case UV_FS_LSTAT:
      case UV_FS_FSTAT:
        {
          NODE_STAT_STRUCT *s = reinterpret_cast<NODE_STAT_STRUCT*>(req->ptr);
          argv[1] = BuildStatsObject(s);
        }
        break;

      case UV_FS_READLINK:
        argv[1] = String::New(static_cast<char*>(req->ptr));
        break;

      case UV_FS_READ:
        // Buffer interface
        argv[1] = Integer::New(req->result);
        break;

      case UV_FS_READDIR:
        {
          char *namebuf = static_cast<char*>(req->ptr);
          int nnames = req->result;

          Local<Array> names = Array::New(nnames);

          for (int i = 0; i < nnames; i++) {
            Local<String> name = String::New(namebuf);
            names->Set(Integer::New(i), name);
#ifndef NDEBUG
            namebuf += strlen(namebuf);
            assert(*namebuf == '\0');
            namebuf += 1;
#else
            namebuf += strlen(namebuf) + 1;
#endif
          }

          argv[1] = names;
        }
        break;

      default:
        assert(0 && "Unhandled eio response");
    }
  }

  TryCatch try_catch;

  callback->Call(req_wrap->object_, argc, argv);

  if (try_catch.HasCaught()) {
    FatalException(try_catch);
  }

  uv_fs_req_cleanup(&req_wrap->req_);
  delete req_wrap;
}

// This struct is only used on sync fs calls.
// For async calls FSReqWrap is used.
struct fs_req_wrap {
  fs_req_wrap() {}
  ~fs_req_wrap() { uv_fs_req_cleanup(&req); }
  // Ensure that copy ctor and assignment operator are not used.
  fs_req_wrap(const fs_req_wrap& req);
  fs_req_wrap& operator=(const fs_req_wrap& req);
  uv_fs_t req;
};


const char* errno_string(int errorno) {
  uv_err_t err;
  memset(&err, 0, sizeof err);
  err.code = (uv_err_code)errorno;
  return uv_err_name(err);
}


const char* errno_message(int errorno) {
  uv_err_t err;
  memset(&err, 0, sizeof err);
  err.code = (uv_err_code)errorno;
  return uv_strerror(err);
}


// hack alert! copy of ErrnoException in node.cc, tuned for uv errors
Local<Value> FSError(int errorno,
                     const char *syscall,
                     const char *msg,
                     const char *path) {
  static Persistent<String> syscall_symbol;
  static Persistent<String> errpath_symbol;
  static Persistent<String> code_symbol;

  if (syscall_symbol.IsEmpty()) {
    syscall_symbol = NODE_PSYMBOL("syscall");
    errno_symbol = NODE_PSYMBOL("errno");
    errpath_symbol = NODE_PSYMBOL("path");
    code_symbol = NODE_PSYMBOL("code");
  }

  if (!msg || !msg[0])
    msg = errno_message(errorno);

  Local<String> estring = String::NewSymbol(errno_string(errorno));
  Local<String> message = String::NewSymbol(msg);
  Local<String> cons1 = String::Concat(estring, String::NewSymbol(", "));
  Local<String> cons2 = String::Concat(cons1, message);

  Local<Value> e;

  if (path) {
    Local<String> cons3 = String::Concat(cons2, String::NewSymbol(" '"));
    Local<String> cons4 = String::Concat(cons3, String::New(path));
    Local<String> cons5 = String::Concat(cons4, String::NewSymbol("'"));
    e = Exception::Error(cons5);
  } else {
    e = Exception::Error(cons2);
  }

  Local<Object> obj = e->ToObject();

  // TODO errno should probably go
  obj->Set(errno_symbol, Integer::New(errorno));
  obj->Set(code_symbol, estring);
  if (path) obj->Set(errpath_symbol, String::New(path));
  if (syscall) obj->Set(syscall_symbol, String::NewSymbol(syscall));
  return e;
}


#define ASYNC_CALL(func, callback, ...)                           \
  FSReqWrap* req_wrap = new FSReqWrap();                          \
  int r = uv_fs_##func(uv_default_loop(), &req_wrap->req_,        \
      __VA_ARGS__, After);                                        \
  assert(r == 0);                                                 \
  req_wrap->object_->Set(oncomplete_sym, callback);               \
  req_wrap->Dispatched();                                         \
  return scope.Close(req_wrap->object_);

#define SYNC_CALL(func, path, ...)                                \
  fs_req_wrap req_wrap;                                           \
  int result = uv_fs_##func(uv_default_loop(), &req_wrap.req, __VA_ARGS__, NULL); \
  if (result < 0) {                                               \
    int code = uv_last_error(uv_default_loop()).code;             \
    return ThrowException(FSError(code, #func, "", path));        \
  }

#define SYNC_REQ req_wrap.req

#define SYNC_RESULT result


static Handle<Value> Close(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  if (args[1]->IsFunction()) {
    ASYNC_CALL(close, args[1], fd)
  } else {
    SYNC_CALL(close, 0, fd)
    return Undefined();
  }
}


static Persistent<FunctionTemplate> stats_constructor_template;

static Persistent<String> dev_symbol;
static Persistent<String> ino_symbol;
static Persistent<String> mode_symbol;
static Persistent<String> nlink_symbol;
static Persistent<String> uid_symbol;
static Persistent<String> gid_symbol;
static Persistent<String> rdev_symbol;
static Persistent<String> size_symbol;
static Persistent<String> blksize_symbol;
static Persistent<String> blocks_symbol;
static Persistent<String> atime_symbol;
static Persistent<String> mtime_symbol;
static Persistent<String> ctime_symbol;

Local<Object> BuildStatsObject(NODE_STAT_STRUCT *s) {
  HandleScope scope;

  if (dev_symbol.IsEmpty()) {
    dev_symbol = NODE_PSYMBOL("dev");
    ino_symbol = NODE_PSYMBOL("ino");
    mode_symbol = NODE_PSYMBOL("mode");
    nlink_symbol = NODE_PSYMBOL("nlink");
    uid_symbol = NODE_PSYMBOL("uid");
    gid_symbol = NODE_PSYMBOL("gid");
    rdev_symbol = NODE_PSYMBOL("rdev");
    size_symbol = NODE_PSYMBOL("size");
    blksize_symbol = NODE_PSYMBOL("blksize");
    blocks_symbol = NODE_PSYMBOL("blocks");
    atime_symbol = NODE_PSYMBOL("atime");
    mtime_symbol = NODE_PSYMBOL("mtime");
    ctime_symbol = NODE_PSYMBOL("ctime");
  }

  Local<Object> stats =
    stats_constructor_template->GetFunction()->NewInstance();

  /* ID of device containing file */
  stats->Set(dev_symbol, Integer::New(s->st_dev));

  /* inode number */
  stats->Set(ino_symbol, Integer::New(s->st_ino));

  /* protection */
  stats->Set(mode_symbol, Integer::New(s->st_mode));

  /* number of hard links */
  stats->Set(nlink_symbol, Integer::New(s->st_nlink));

  /* user ID of owner */
  stats->Set(uid_symbol, Integer::New(s->st_uid));

  /* group ID of owner */
  stats->Set(gid_symbol, Integer::New(s->st_gid));

  /* device ID (if special file) */
  stats->Set(rdev_symbol, Integer::New(s->st_rdev));

  /* total size, in bytes */
  stats->Set(size_symbol, Number::New(s->st_size));

#ifdef __POSIX__
  /* blocksize for filesystem I/O */
  stats->Set(blksize_symbol, Integer::New(s->st_blksize));

  /* number of blocks allocated */
  stats->Set(blocks_symbol, Integer::New(s->st_blocks));
#endif

  /* time of last access */
  stats->Set(atime_symbol, NODE_UNIXTIME_V8(s->st_atime));

  /* time of last modification */
  stats->Set(mtime_symbol, NODE_UNIXTIME_V8(s->st_mtime));

  /* time of last status change */
  stats->Set(ctime_symbol, NODE_UNIXTIME_V8(s->st_ctime));

  return scope.Close(stats);
}

static Handle<Value> Stat(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());

  if (args[1]->IsFunction()) {
    ASYNC_CALL(stat, args[1], *path)
  } else {
    SYNC_CALL(stat, *path, *path)
    return scope.Close(BuildStatsObject((NODE_STAT_STRUCT*)SYNC_REQ.ptr));
  }
}

static Handle<Value> LStat(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());

  if (args[1]->IsFunction()) {
    ASYNC_CALL(lstat, args[1], *path)
  } else {
    SYNC_CALL(lstat, *path, *path)
    return scope.Close(BuildStatsObject((NODE_STAT_STRUCT*)SYNC_REQ.ptr));
  }
}

static Handle<Value> FStat(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  if (args[1]->IsFunction()) {
    ASYNC_CALL(fstat, args[1], fd)
  } else {
    SYNC_CALL(fstat, 0, fd)
    return scope.Close(BuildStatsObject((NODE_STAT_STRUCT*)SYNC_REQ.ptr));
  }
}

static Handle<Value> Symlink(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 2 || !args[0]->IsString() || !args[1]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value dest(args[0]->ToString());
  String::Utf8Value path(args[1]->ToString());
  int flags = 0;

  if (args[2]->IsString()) {
    String::Utf8Value mode(args[2]->ToString());
    if (memcmp(*mode, "dir\0", 4) == 0) {
      flags |= UV_FS_SYMLINK_DIR;
    }
  }

  if (args[3]->IsFunction()) {
    ASYNC_CALL(symlink, args[3], *dest, *path, flags)
  } else {
    SYNC_CALL(symlink, *path, *dest, *path, flags)
    return Undefined();
  }
}

static Handle<Value> Link(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 2 || !args[0]->IsString() || !args[1]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value orig_path(args[0]->ToString());
  String::Utf8Value new_path(args[1]->ToString());

  if (args[2]->IsFunction()) {
    ASYNC_CALL(link, args[2], *orig_path, *new_path)
  } else {
    SYNC_CALL(link, *orig_path, *orig_path, *new_path)
    return Undefined();
  }
}

static Handle<Value> ReadLink(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());

  if (args[1]->IsFunction()) {
    ASYNC_CALL(readlink, args[1], *path)
  } else {
    SYNC_CALL(readlink, *path, *path)
    return scope.Close(String::New((char*)SYNC_REQ.ptr));
  }
}

static Handle<Value> Rename(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 2 || !args[0]->IsString() || !args[1]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value old_path(args[0]->ToString());
  String::Utf8Value new_path(args[1]->ToString());

  if (args[2]->IsFunction()) {
    ASYNC_CALL(rename, args[2], *old_path, *new_path)
  } else {
    SYNC_CALL(rename, *old_path, *old_path, *new_path)
    return Undefined();
  }
}

#ifndef _LARGEFILE_SOURCE
#define ASSERT_TRUNCATE_LENGTH(a) \
  if (!(a)->IsUndefined() && !(a)->IsNull() && !(a)->IsUInt32()) { \
    return ThrowException(Exception::TypeError(String::New("Not an integer"))); \
  }
#define GET_TRUNCATE_LENGTH(a) ((a)->UInt32Value())
#else
#define ASSERT_TRUNCATE_LENGTH(a) \
  if (!(a)->IsUndefined() && !(a)->IsNull() && !IsInt64((a)->NumberValue())) { \
    return ThrowException(Exception::TypeError(String::New("Not an integer"))); \
  }
#define GET_TRUNCATE_LENGTH(a) ((a)->IntegerValue())
#endif

static Handle<Value> Truncate(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 2 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  ASSERT_TRUNCATE_LENGTH(args[1]);
  off_t len = GET_TRUNCATE_LENGTH(args[1]);

  if (args[2]->IsFunction()) {
    ASYNC_CALL(ftruncate, args[2], fd, len)
  } else {
    SYNC_CALL(ftruncate, 0, fd, len)
    return Undefined();
  }
}

static Handle<Value> Fdatasync(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  if (args[1]->IsFunction()) {
    ASYNC_CALL(fdatasync, args[1], fd)
  } else {
    SYNC_CALL(fdatasync, 0, fd)
    return Undefined();
  }
}

static Handle<Value> Fsync(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  if (args[1]->IsFunction()) {
    ASYNC_CALL(fsync, args[1], fd)
  } else {
    SYNC_CALL(fsync, 0, fd)
    return Undefined();
  }
}

static Handle<Value> Unlink(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());

  if (args[1]->IsFunction()) {
    ASYNC_CALL(unlink, args[1], *path)
  } else {
    SYNC_CALL(unlink, *path, *path)
    return Undefined();
  }
}

static Handle<Value> RMDir(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());

  if (args[1]->IsFunction()) {
    ASYNC_CALL(rmdir, args[1], *path)
  } else {
    SYNC_CALL(rmdir, *path, *path)
    return Undefined();
  }
}

static Handle<Value> MKDir(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 2 || !args[0]->IsString() || !args[1]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());
  int mode = static_cast<int>(args[1]->Int32Value());

  if (args[2]->IsFunction()) {
    ASYNC_CALL(mkdir, args[2], *path, mode)
  } else {
    SYNC_CALL(mkdir, *path, *path, mode)
    return Undefined();
  }
}

static Handle<Value> SendFile(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 4 ||
      !args[0]->IsUint32() ||
      !args[1]->IsUint32() ||
      !args[2]->IsUint32() ||
      !args[3]->IsUint32()) {
    return THROW_BAD_ARGS;
  }

  int out_fd = args[0]->Uint32Value();
  int in_fd = args[1]->Uint32Value();
  off_t in_offset = args[2]->Uint32Value();
  size_t length = args[3]->Uint32Value();

  if (args[4]->IsFunction()) {
    ASYNC_CALL(sendfile, args[4], out_fd, in_fd, in_offset, length)
  } else {
    SYNC_CALL(sendfile, 0, out_fd, in_fd, in_offset, length)
    return scope.Close(Integer::New(SYNC_RESULT));
  }
}

static Handle<Value> ReadDir(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());

  if (args[1]->IsFunction()) {
    ASYNC_CALL(readdir, args[1], *path, 0 /*flags*/)
  } else {
    SYNC_CALL(readdir, *path, *path, 0 /*flags*/)

    char *namebuf = static_cast<char*>(SYNC_REQ.ptr);
    int nnames = req_wrap.req.result;
    Local<Array> names = Array::New(nnames);

    for (int i = 0; i < nnames; i++) {
      Local<String> name = String::New(namebuf);
      names->Set(Integer::New(i), name);
#ifndef NDEBUG
      namebuf += strlen(namebuf);
      assert(*namebuf == '\0');
      namebuf += 1;
#else
      namebuf += strlen(namebuf) + 1;
#endif
    }

    return scope.Close(names);
  }
}

static Handle<Value> Open(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 3 ||
      !args[0]->IsString() ||
      !args[1]->IsInt32() ||
      !args[2]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  String::Utf8Value path(args[0]->ToString());
  int flags = args[1]->Int32Value();
  int mode = static_cast<int>(args[2]->Int32Value());

  if (args[3]->IsFunction()) {
    ASYNC_CALL(open, args[3], *path, flags, mode)
  } else {
    SYNC_CALL(open, *path, *path, flags, mode)
    int fd = SYNC_RESULT;
    return scope.Close(Integer::New(fd));
  }
}

#ifndef _LARGEFILE_SOURCE
#define ASSERT_OFFSET(a) \
  if (!(a)->IsUndefined() && !(a)->IsNull() && !(a)->IsInt32()) { \
    return ThrowException(Exception::TypeError(String::New("Not an integer"))); \
  }
#define GET_OFFSET(a) ((a)->IsNumber() ? (a)->Int32Value() : -1)
#else
#define ASSERT_OFFSET(a) \
  if (!(a)->IsUndefined() && !(a)->IsNull() && !IsInt64((a)->NumberValue())) { \
    return ThrowException(Exception::TypeError(String::New("Not an integer"))); \
  }
#define GET_OFFSET(a) ((a)->IsNumber() ? (a)->IntegerValue() : -1)
#endif

// bytesWritten = write(fd, data, position, enc, callback)
// Wrapper for write(2).
//
// 0 fd        integer. file descriptor
// 1 buffer    the data to write
// 2 offset    where in the buffer to start from
// 3 length    how much to write
// 4 position  if integer, position to write at in the file.
//             if null, write from the current position
static Handle<Value> Write(const Arguments& args) {
  HandleScope scope;

  if (!args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  if (!Buffer::HasInstance(args[1])) {
    return ThrowException(Exception::Error(
                String::New("Second argument needs to be a buffer")));
  }

  Local<Object> buffer_obj = args[1]->ToObject();
  char *buffer_data = Buffer::Data(buffer_obj);
  size_t buffer_length = Buffer::Length(buffer_obj);

  size_t off = args[2]->Int32Value();
  if (off >= buffer_length) {
    return ThrowException(Exception::Error(
          String::New("Offset is out of bounds")));
  }

  ssize_t len = args[3]->Int32Value();
  if (off + len > buffer_length) {
    return ThrowException(Exception::Error(
          String::New("Length is extends beyond buffer")));
  }

  ASSERT_OFFSET(args[4]);
  off_t pos = GET_OFFSET(args[4]);

  char * buf = (char*)buffer_data + off;
  Local<Value> cb = args[5];

  if (cb->IsFunction()) {
    ASYNC_CALL(write, cb, fd, buf, len, pos)
  } else {
    SYNC_CALL(write, 0, fd, buf, len, pos)
    return scope.Close(Integer::New(SYNC_RESULT));
  }
}

/*
 * Wrapper for read(2).
 *
 * bytesRead = fs.read(fd, buffer, offset, length, position)
 *
 * 0 fd        integer. file descriptor
 * 1 buffer    instance of Buffer
 * 2 offset    integer. offset to start reading into inside buffer
 * 3 length    integer. length to read
 * 4 position  file position - null for current position
 *
 */
static Handle<Value> Read(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 2 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  int fd = args[0]->Int32Value();

  Local<Value> cb;

  size_t len;
  off_t pos;

  char * buf = NULL;

  if (!Buffer::HasInstance(args[1])) {
    return ThrowException(Exception::Error(
                String::New("Second argument needs to be a buffer")));
  }

  Local<Object> buffer_obj = args[1]->ToObject();
  char *buffer_data = Buffer::Data(buffer_obj);
  size_t buffer_length = Buffer::Length(buffer_obj);

  size_t off = args[2]->Int32Value();
  if (off >= buffer_length) {
    return ThrowException(Exception::Error(
          String::New("Offset is out of bounds")));
  }

  len = args[3]->Int32Value();
  if (off + len > buffer_length) {
    return ThrowException(Exception::Error(
          String::New("Length is extends beyond buffer")));
  }

  pos = GET_OFFSET(args[4]);

  buf = buffer_data + off;

  cb = args[5];

  if (cb->IsFunction()) {
    ASYNC_CALL(read, cb, fd, buf, len, pos);
  } else {
    SYNC_CALL(read, 0, fd, buf, len, pos)
    Local<Integer> bytesRead = Integer::New(SYNC_RESULT);
    return scope.Close(bytesRead);
  }
}


/* fs.chmod(path, mode);
 * Wrapper for chmod(1) / EIO_CHMOD
 */
static Handle<Value> Chmod(const Arguments& args) {
  HandleScope scope;

  if(args.Length() < 2 || !args[0]->IsString() || !args[1]->IsInt32()) {
    return THROW_BAD_ARGS;
  }
  String::Utf8Value path(args[0]->ToString());
  int mode = static_cast<int>(args[1]->Int32Value());

  if(args[2]->IsFunction()) {
    ASYNC_CALL(chmod, args[2], *path, mode);
  } else {
    SYNC_CALL(chmod, *path, *path, mode);
    return Undefined();
  }
}


/* fs.fchmod(fd, mode);
 * Wrapper for fchmod(1) / EIO_FCHMOD
 */
static Handle<Value> FChmod(const Arguments& args) {
  HandleScope scope;

  if(args.Length() < 2 || !args[0]->IsInt32() || !args[1]->IsInt32()) {
    return THROW_BAD_ARGS;
  }
  int fd = args[0]->Int32Value();
  int mode = static_cast<int>(args[1]->Int32Value());

  if(args[2]->IsFunction()) {
    ASYNC_CALL(fchmod, args[2], fd, mode);
  } else {
    SYNC_CALL(fchmod, 0, fd, mode);
    return Undefined();
  }
}


/* fs.chown(path, uid, gid);
 * Wrapper for chown(1) / EIO_CHOWN
 */
static Handle<Value> Chown(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 3 || !args[0]->IsString()) {
    return THROW_BAD_ARGS;
  }

  if (!args[1]->IsInt32() || !args[2]->IsInt32()) {
    return ThrowException(Exception::Error(String::New("User and Group IDs must be an integer.")));
  }

  String::Utf8Value path(args[0]->ToString());
  int uid = static_cast<int>(args[1]->Int32Value());
  int gid = static_cast<int>(args[2]->Int32Value());

  if (args[3]->IsFunction()) {
    ASYNC_CALL(chown, args[3], *path, uid, gid);
  } else {
    SYNC_CALL(chown, *path, *path, uid, gid);
    return Undefined();
  }
}


/* fs.fchown(fd, uid, gid);
 * Wrapper for fchown(1) / EIO_FCHOWN
 */
static Handle<Value> FChown(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 3 || !args[0]->IsInt32()) {
    return THROW_BAD_ARGS;
  }

  if (!args[1]->IsInt32() || !args[2]->IsInt32()) {
    return ThrowException(Exception::Error(String::New("User and Group IDs must be an integer.")));
  }

  int fd = args[0]->Int32Value();
  int uid = static_cast<int>(args[1]->Int32Value());
  int gid = static_cast<int>(args[2]->Int32Value());

  if (args[3]->IsFunction()) {
    ASYNC_CALL(fchown, args[3], fd, uid, gid);
  } else {
    SYNC_CALL(fchown, 0, fd, uid, gid);
    return Undefined();
  }
}


static Handle<Value> UTimes(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 3
      || !args[0]->IsString()
      || !args[1]->IsNumber()
      || !args[2]->IsNumber())
  {
    return THROW_BAD_ARGS;
  }

  const String::Utf8Value path(args[0]->ToString());
  const double atime = static_cast<double>(args[1]->NumberValue());
  const double mtime = static_cast<double>(args[2]->NumberValue());

  if (args[3]->IsFunction()) {
    ASYNC_CALL(utime, args[3], *path, atime, mtime);
  } else {
    SYNC_CALL(utime, *path, *path, atime, mtime);
    return Undefined();
  }
}

static Handle<Value> FUTimes(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 3
      || !args[0]->IsInt32()
      || !args[1]->IsNumber()
      || !args[2]->IsNumber())
  {
    return THROW_BAD_ARGS;
  }

  const int fd = args[0]->Int32Value();
  const double atime = static_cast<double>(args[1]->NumberValue());
  const double mtime = static_cast<double>(args[2]->NumberValue());

  if (args[3]->IsFunction()) {
    ASYNC_CALL(futime, args[3], fd, atime, mtime);
  } else {
    SYNC_CALL(futime, 0, fd, atime, mtime);
    return Undefined();
  }
}


void File::Initialize(Handle<Object> target) {
  HandleScope scope;

  NODE_SET_METHOD(target, "close", Close);
  NODE_SET_METHOD(target, "open", Open);
  NODE_SET_METHOD(target, "read", Read);
  NODE_SET_METHOD(target, "fdatasync", Fdatasync);
  NODE_SET_METHOD(target, "fsync", Fsync);
  NODE_SET_METHOD(target, "rename", Rename);
  NODE_SET_METHOD(target, "truncate", Truncate);
  NODE_SET_METHOD(target, "rmdir", RMDir);
  NODE_SET_METHOD(target, "mkdir", MKDir);
  NODE_SET_METHOD(target, "sendfile", SendFile);
  NODE_SET_METHOD(target, "readdir", ReadDir);
  NODE_SET_METHOD(target, "stat", Stat);
  NODE_SET_METHOD(target, "lstat", LStat);
  NODE_SET_METHOD(target, "fstat", FStat);
  NODE_SET_METHOD(target, "link", Link);
  NODE_SET_METHOD(target, "symlink", Symlink);
  NODE_SET_METHOD(target, "readlink", ReadLink);
  NODE_SET_METHOD(target, "unlink", Unlink);
  NODE_SET_METHOD(target, "write", Write);

  NODE_SET_METHOD(target, "chmod", Chmod);
  NODE_SET_METHOD(target, "fchmod", FChmod);
  //NODE_SET_METHOD(target, "lchmod", LChmod);

  NODE_SET_METHOD(target, "chown", Chown);
  NODE_SET_METHOD(target, "fchown", FChown);
  //NODE_SET_METHOD(target, "lchown", LChown);

  NODE_SET_METHOD(target, "utimes", UTimes);
  NODE_SET_METHOD(target, "futimes", FUTimes);

  errno_symbol = NODE_PSYMBOL("errno");
  encoding_symbol = NODE_PSYMBOL("node:encoding");
  buf_symbol = NODE_PSYMBOL("__buf");
}

void InitFs(Handle<Object> target) {
  HandleScope scope;
  // Initialize the stats object
  Local<FunctionTemplate> stat_templ = FunctionTemplate::New();
  stats_constructor_template = Persistent<FunctionTemplate>::New(stat_templ);
  target->Set(String::NewSymbol("Stats"),
               stats_constructor_template->GetFunction());
  File::Initialize(target);

  oncomplete_sym = NODE_PSYMBOL("oncomplete");

#ifdef __POSIX__
  StatWatcher::Initialize(target);
#endif
}

}  // end namespace node

NODE_MODULE(node_fs, node::InitFs);