ffi-php-examples-basic-9

  • Examples
  • Basic FFI usage

  • Basic FFI usage
  • Basic FFI usage

    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!
    

    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)