Explaining Zend Module Entry

September 5, 2016


  1. Getting Started
  2. Hello World
  3. Explaining Zend Module Entry

In my last blog post I skirted past what zend_module_entry does, and just put the code there. I’m going to attempt to explain it with its many NULL values.

This is what I put in the Hello World extension:

zend_module_entry hello_module_entry = {  

This structure comes from here:

struct _zend_module_entry {
    unsigned short size;
    unsigned int zend_api;
    unsigned char zend_debug;
    unsigned char zts;
    const struct _zend_ini_entry *ini_entry;
    const struct _zend_module_dep *deps;
    const char *name;
    const struct _zend_function_entry *functions;
    int (*module_startup_func)(INIT_FUNC_ARGS);
    int (*module_shutdown_func)(SHUTDOWN_FUNC_ARGS);
    int (*request_startup_func)(INIT_FUNC_ARGS);
    int (*request_shutdown_func)(SHUTDOWN_FUNC_ARGS);
    void (*info_func)(ZEND_MODULE_INFO_FUNC_ARGS);
    const char *version;
    size_t globals_size;
#ifdef ZTS
    ts_rsrc_id* globals_id_ptr;
    void* globals_ptr;
    void (*globals_ctor)(void *global);
    void (*globals_dtor)(void *global);
    int (*post_deactivate_func)(void);
    int module_started;
    unsigned char type;
    void *handle;
    int module_number;
    const char *build_id;


This is a macro that fills in a few of the fields for us.

There are a few of these macros defined, these are:

These macros fill the fields size, zend_api, zend_debug, zts and, ini_entry and deps for the non _EX header

STANDARD_MODULE_HEADER is used when you don’t have any dependencies, if you have dependencies then use STANDARD_MODULE_HEADER_EX instead, and it will leave out a deps field that you can fill in.


This is the name of our extension. We registered this as a constant in hello.h, you could simply put a string in here. This field is required.


This is a reference to the structure of zend_function_entry that we put in

zend_function_entry hello_functions[] = {  
            PHP_FE(hello_world, NULL)

zend_function_entry is just a structure containing one or more function definitions, and ending with a PHP_FE_END source.

The next 5

Are ones you won’t touch often, unless you know what you’re doing.

They define, in order,

  • Module startup function
    • Module shutdown function
    • Request startup function
    • Request shutdown function
    • Info Function

Version Number

Next up is the version of the extension. This should be provided as a string, though we are using a constant that we defined in hello.h. There is also a constant NO_VERSION_YET, which just defines it as null.


The rest of the properties are filled in for you by using the STANDARD_MODULE_PROPERTIES. There should be no need for you to fill in these, unless you need to fill in some extension globals, in which case use STANDARD_MODULE_PROPERTIES\_EX.