FFI::cast

(PHP 7 >= 7.4.0, PHP 8)

FFI::cast — Performs a C type cast

说明

FFI::cast() creates a new FFI\CData object, that references the same C data structure, but is associated with a different type. The resulting object does not own the C data, and the source ptr must survive the result. The C type may be specified as a string with any valid C type declaration or as FFI\CType object, created before. If this method is called statically, it must only use predefined C type names (e.g. int, char, etc.); if the method is called as instance method, any type declared for the instance is allowed.

参数

type: A valid C declaration as string, or an instance of FFI\CType which has already been created.
ptr: The handle of the pointer to a C data structure.

返回值

Returns the freshly created FFI\CData object.

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User Contributed Notes 1 note

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Yaner ¶

1 year ago

For example, stdlib.h headfile defines a function called "system()" in Linux:  extern int system (const char *__command) __wur;
And we can call it using FFI extension:

<?php
    $ffi_obj = FFI::cdef('int system(char *command);')
    $ffi_obj->system('whoami');
?>

Then execute the php script as if we were calling the real C  `system()`:

$ whoami
> root
$ php demo.php
> root

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