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    Basic FFI usage

    Before diving into the details of the FFI API, lets take a look at a few examples demonstrating the simplicity of the FFI API usage for regular tasks.

    Note:

    Some of these examples require libc.so.6 and as such will not work on systems where it is not available.

    Example #1 Calling a function from shared library

    <?php
    // create FFI object, loading libc and exporting function printf()
    $ffi = FFI::cdef(
    "int printf(const char *format, ...);", // this is a regular C declaration
    "libc.so.6");
    // call C's printf()
    $ffi->printf("Hello %s!\n", "world");
    ?>

    The above example will output:

    Hello world!

    Note:

    Note that some C functions need specific calling conventions, e.g. __fastcall, __stdcall or ,__vectorcall.

    Example #2 Calling a function, returning a structure through an argument

    <?php
    // create gettimeofday() binding
    $ffi = FFI::cdef("
    typedef unsigned int time_t;
    typedef unsigned int suseconds_t;

    struct timeval {
    time_t tv_sec;
    suseconds_t tv_usec;
    };

    struct timezone {
    int tz_minuteswest;
    int tz_dsttime;
    };

    int gettimeofday(struct timeval *tv, struct timezone *tz);
    "    , "libc.so.6");
    // create C data structures
    $tv = $ffi->new("struct timeval");
    $tz = $ffi->new("struct timezone");
    // call C's gettimeofday()
    var_dump($ffi->gettimeofday(FFI::addr($tv), FFI::addr($tz)));
    // access field of C data structure
    var_dump($tv->tv_sec);
    // print the whole C data structure
    var_dump($tz);
    ?>

    The above example will output something similar to:

    int(0)
int(1555946835)
object(FFI\CData:struct timezone)#3 (2) {
  ["tz_minuteswest"]=>
  int(0)
  ["tz_dsttime"]=>
  int(0)
}

    Example #3 Accessing existing C variables

    <?php
    // create FFI object, loading libc and exporting errno variable
    $ffi = FFI::cdef(
    "int errno;", // this is a regular C declaration
    "libc.so.6");
    // print C's errno
    var_dump($ffi->errno);
    ?>

    The above example will output:

    int(0)

    Example #4 Creating and Modifying C variables

    <?php
    // create a new C int variable
    $x = FFI::new("int");
    var_dump($x->cdata);

    // simple assignment
    $x->cdata = 5;
    var_dump($x->cdata);

    // compound assignment
    $x->cdata += 2;
    var_dump($x->cdata);
    ?>

    The above example will output:

    int(0)
int(5)
int(7)

    Example #5 Working with C arrays

    <?php
    // create C data structure
    $a = FFI::new("long[1024]");
    // work with it like with a regular PHP array
    for ($i = 0; $i < count($a); $i++) {
    $a[$i] = $i;
    }
    var_dump($a[25]);
    $sum = 0;
    foreach (    $a as $n) {
    $sum += $n;
    }
    var_dump($sum);
    var_dump(count($a));
    var_dump(FFI::sizeof($a));
    ?>

    The above example will output:

    int(25)
int(523776)
int(1024)
int(8192)

    Example #6 Working with C enums

    <?php
    $a     = FFI::cdef('typedef enum _zend_ffi_symbol_kind {
    ZEND_FFI_SYM_TYPE,
    ZEND_FFI_SYM_CONST = 2,
    ZEND_FFI_SYM_VAR,
    ZEND_FFI_SYM_FUNC
    } zend_ffi_symbol_kind;
    '    );
    var_dump($a->ZEND_FFI_SYM_TYPE);
    var_dump($a->ZEND_FFI_SYM_CONST);
    var_dump($a->ZEND_FFI_SYM_VAR);
    ?>

    The above example will output:

    int(0)
int(2)
int(3)

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    User Contributed Notes 1 note

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    1
    wowabbs+php at gmail dot com
    4 years ago
    <?
          if(!dl("ffi")) // Load the extension
              throw new Exception('Cound not load the FFI extension.');

      function     setWindowsDesktop($bmpFilePath)
      {
            define('SPI_SETDESKWALLPAPER'  , 0x14);
            define('SPIF_UPDATEINIFILE'    ,  0x1);
            define('SPIF_SENDWININICHANGE' ,  0x2);
            assert(File_Exists($bmpFilePath));
       
            // declare the Win32 API function used to change desktop settings.
            $User32 = FFI::cdef(<<<'IDL'
          int SystemParametersInfoA(int uAction, int uParam, char *lpvParam, int fuWinIni);
        IDL, 'User32.dll');
        $Kernel32 = FFI::cdef(<<<'IDL'
          int GetLastError();
        IDL, 'Kernel32.dll');
        // call the Windows API to update the desktop background.
        $Ret = $User32->SystemParametersInfoA(SPI_SETDESKWALLPAPER, 0, $bmpFilePath, SPIF_UPDATEINIFILE || SPIF_SENDWININICHANGE);
        if ($Ret == 0)
        {
          $Error = $Kernel32->GetLastError();
          throw new Exception("The call to the Windows API failed (error {$Error}).");
        }
      }
     
      $Url='https://www.php.net//images/news/phpkonf_2015.png';
      $Img=File_Get_Contents($Url);
      File_Put_Contents($File=basename($Url), $Img);
      setWindowsDesktop(realpath($File));
    ?>
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