# eio_fallocate

(PECL eio >= 0.0.1dev)

eio_fallocate — Allows the caller to directly manipulate the allocated disk space for a file

### 说明

eio_fallocate ( mixed `$fd` , int `$mode` , int `$offset` , int `$length` [, int `$pri` = EIO_PRI_DEFAULT [, callable `$callback` = NULL [, mixed `$data` = NULL ]]] ) : resource

eio_fallocate() allows the caller to directly manipulate the allocated disk space for the file specified by `fd` file descriptor for the byte range starting at `offset` and continuing for `length` bytes.

> Note: File should be opened for writing

> `EIO_O_CREAT` should be logically OR'd with `EIO_O_WRONLY`, or `EIO_O_RDWR`

### 参数

`fd`

  Stream, Socket resource, or numeric file descriptor, e.g. returned by eio_open().

`mode`

  Currently only one flag is supported for mode: `EIO_FALLOC_FL_KEEP_SIZE` (the same as POSIX constant `FALLOC_FL_KEEP_SIZE`).

`offset`

  Specifies start of the byte range.

`length`

  Specifies length the byte range.

`pri`

  请求的优先级：`EIO_PRI_DEFAULT`，`EIO_PRI_MIN`，`EIO_PRI_MAX` 或 `NULL`。如果是 `NULL`，`pri` 将设为 `EIO_PRI_DEFAULT`。

`callback`

  `callback` 函数在请求完成时被调用。其应匹配一下原型：

      void callback(mixed $data, int $result[, resource $req]);

  `data`

    传递给请求的用户数据。

  `result`

    针对请求的结果的值。通常是相应的系统调用返回的值。

  `req`

    可选的请求资源，可被 eio_get_last_error() 之类的函数使用。

`data`

  Arbitrary variable passed to `callback`.

### 返回值

eio_fallocate() returns request resource on success or `FALSE` on error.