FFI (Foreign Function Interface)

What is FFI?

The FFI (Foreign Function Interface) module in PHP enables direct interaction with C libraries without requiring compiled PHP extensions. Introduced in PHP 7.4, it allows calling C functions, accessing global variables, and working with native memory structures.

FFI is particularly useful for:

  • Using existing C libraries without writing PHP extensions.
  • Accessing low-level system APIs.
  • Optimizing performance-critical operations with native code execution.

Features of the PHP FFI Module

The FFI module allows:

  • Declaring and loading C libraries (FFI::cdef(), FFI::load()).
  • Calling C functions directly from PHP.
  • Interacting with C structures and types (struct, union, typedef).
  • Reading and modifying memory-shared variables.

Example Usage:

Calling a C standard library function

$ffi = FFI::cdef("
    int printf(const char *format, ...);
", "libc.so.6"); // Linux (use "msvcrt.dll" for Windows)

$ffi->printf("Hello from C!\n");

Working with C Structures

$ffi = FFI::cdef("
    typedef struct {
        int x;
        int y;
    } Point;
");

$point = $ffi->new("Point");
$point->x = 10;
$point->y = 20;

echo "Point: ({$point->x}, {$point->y})\n";

Advantages of FFI

  • Direct access to C libraries without requiring compiled PHP extensions.
  • Performance improvements for complex calculations and low-level processing.
  • Interoperability with other languages and system APIs.
  • Flexible memory manipulation and shared memory management.

Disadvantages of FFI

  • High security risk: Improper use can lead to memory errors or security vulnerabilities.
  • Platform-dependent: Requires different libraries for Linux, Windows, and macOS.
  • Disabled by default on some servers for security reasons.

Conclusion

The FFI module in PHP is a powerful tool for directly leveraging C libraries, improving performance, and interacting with system-level APIs. However, it must be used carefully, as improper memory access can cause serious errors.

🔗 References:

Catégories d’articles