PHP C++扩展从PHP5迁移至PHP7的完整升级指南

在没有怎么看明白php5 php7源码的情况下，接手一份基于php5写c++扩展，如何接手快速升级到php7环境下也能使用呢

这听起来像是个棘手的任务：对PHP5和PHP7的内核源码没有深入研究，却要接手一个用C++编写的、为PHP5设计的扩展，并让它平滑过渡到PHP7环境。通常，这意味着一场浩大的代码重写工程。但实际情况可能没想象中那么复杂。

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一个高效的策略是，建立抽象层。与其深入每个API的差异，不如先为那些变化最大的核心操作——尤其是对象处理——创建统一的接口。这样一来，核心业务逻辑的代码几乎无需改动。

事实上，仅仅通过修改所引用的一个关键头文件，就成功实现了目标：扩展被顺利编译，并且运行正常。这其中的关键，就在于下面这个精巧的版本适配设计。

phpobj.h 文件，定义版本选择

#ifndef _PHP_OBJ_H_2017
#define _PHP_OBJ_H_2017

#include 

#if PHP_MAJOR_VERSION < 7
#include "php5obj.h"
#else
#include "php7obj.h"
#endif

#endif //_PHP_OBJ_H_2017

这个头文件是整个方案的“调度中心”。它的逻辑清晰而直接：通过预处理器判断当前的PHP主版本号，从而自动包含对应版本的具体实现头文件。这确保了代码库只需维护一份，却能同时兼容两个大相径庭的PHP运行时。

php5obj.h 旧的

#define SW_RETURN_STRINGL RETURN_STRINGL
#define SW_RETVAL_STRINGL RETVAL_STRING
#define SW_RETVAL_STRING RETVAL_STRING
#define SW_RETURN_STRING RETURN_STRING
#define SW_ZVAL_STRINGL ZVAL_STRINGL
#define SW_ZVAL_STRING ZVAL_STRING
#define SW_MAKE_STD_ZVAL(p) MAKE_STD_ZVAL(p)
#define PZVAL_IS_REF(len) ZVAL_IS_REF(len)

// Register the class entry..
#define PHP5CPP_REGISTER_CLASS(name, obj_name) \
{ \
    zend_class_entry ce; \
    INIT_CLASS_ENTRY(ce, obj_name, php5cpp_ ## name ##_methods); \
    ce.create_object = php5cpp_object_new_ ## name; \
    php5cpp_ce_ ## name = zend_register_internal_class_ex(&ce, NULL, NULL TSRMLS_CC);\
    memcpy( &php5cpp_object_handlers_ ## name, \
        zend_get_std_object_handlers(), \
        sizeof(zend_object_handlers) ); \
    php5cpp_object_handlers_ ## name.clone_obj = NULL; \
    php5cpp_ce_ ## name->ce_flags |= ZEND_ACC_FINAL_CLASS; \
}

#define PHP5CPP_GET_THIS() \
    zval* object = getThis();

// Register resources. If we're using an object, put it into the object store.
#define PHP5CPP_REGISTER_RESOURCE(obj_type, return_value, res, le) \
{ \
    PHP5CPP_GET_THIS(); \
    int rsrc_id = ZEND_REGISTER_RESOURCE(object ? NULL : return_value, res, le); \
    if (object) { \
        php5cpp_obj *obj = (php5cpp_obj *)zend_object_store_get_object(object TSRMLS_CC); \
        obj->u.obj_type = res; \
        obj->rsrc_id = rsrc_id; \
        obj->type = is_ ## obj_type; \
    } \
}

// These are for parsing parameters and getting the actual object from the store.
#define PHP5CPP_SET_OBJ(type) \
{ \
    php5cpp_obj *obj = (php5cpp_obj *)zend_object_store_get_object( object TSRMLS_CC ); \
    type ## _instance = obj->u.type; \
}

// Deprecated
#define PHP5CPP_OBJ_PARAMS(type, params) \
{ \
    PHP5CPP_GET_THIS(); \
    if (object) { \
        if (params == FAILURE) { \
            RETURN_FALSE; \
        } \
        PHP5CPP_SET_OBJ(type) \
    } \
}

// Deprecated
#define PHP5CPP_OBJ_NO_PARAMS(type) \
{ \
    PHP5CPP_GET_THIS(); \
    if (object) { \
        if (ZEND_NUM_ARGS() != 0) { \
            php_error(E_WARNING, "didn't expect any arguments in %s()", get_active_function_name(TSRMLS_C)); \
        } \
        PHP5CPP_SET_OBJ(type) \
    } \
}

#define PHP5CPP_GET_OBJ(type) \
{ \
    PHP5CPP_GET_THIS(); \
    if (object) { \
        PHP5CPP_SET_OBJ(type) \
    } \
    if (type ## _instance == NULL) { \
        php_error(E_WARNING, "Get object fall in %s()", get_active_function_name(TSRMLS_C)); \
    } \
}

#define PHP5CPP_GET_OBJ_ZVAL(type, obj) \
{ \
    zval* object = obj; \
    if (object) { \
        PHP5CPP_SET_OBJ(type) \
    } \
    if (type ## _instance == NULL) { \
        php_error(E_WARNING, "Get object fall in %s()", get_active_function_name(TSRMLS_C)); \
    } \
}

//static void php5cpp_object_free_storage_ ## type(zend_object *object TSRMLS_DC)
#define PHP5CPP_OBJ_FREE_FUNCTION(type) \
static void php5cpp_object_free_storage_ ## type(void *object TSRMLS_DC) \
{ \
    php5cpp_obj *obj = (php5cpp_obj *) object; \
    zend_hash_destroy(obj->std.properties); \
    FREE_HASHTABLE(obj->std.properties); \
    if ( obj->u.type ) { \
        zend_list_delete(obj->rsrc_id); \
    } \
    efree(obj); \
}

#define PHP5CPP_OBJ_NEW_FUNCTION(type) \
static zend_object_value php5cpp_object_new_ ## type(zend_class_entry *class_type TSRMLS_DC) \
{ \
    zend_object_value retval; \
    zval *tmp; \
    php5cpp_obj *obj = (php5cpp_obj *)emalloc( sizeof(php5cpp_obj) ); \
    memset( obj, 0, sizeof(php5cpp_obj) ); \
    obj->std.ce = class_type; \
    ALLOC_HASHTABLE( obj->std.properties ); \
    zend_hash_init( obj->std.properties, 0, NULL, ZVAL_PTR_DTOR, 0 ); \
    zend_hash_copy( obj->std.properties, \
        &class_type->properties_info, \
        (copy_ctor_func_t) zval_add_ref, \
        (void *) &tmp, \
        sizeof(zval *) ); \
    retval.handle = zend_objects_store_put( obj, \
        NULL, \
        (zend_objects_free_object_storage_t)php5cpp_object_free_storage_ ## type, \
        NULL TSRMLS_CC ); \
    retval.handlers = &php5cpp_object_handlers_ ## type; \
    return retval; \
}

#endif

这是PHP5时代的实现。可以看到，它严重依赖`zend_object_store_get_object`和`zend_objects_store_put`等API，并且内存管理和对象存储模型与PHP7有根本性不同。宏定义主要是对原有Zend API的简单包装，其内部逻辑是典型的PHP5扩展编写模式。

php7obj.h 新的

#define SW_RETURN_STRINGL(s, l, dup) RETURN_STRINGL(s, l)
#define SW_RETVAL_STRINGL(s, l, dup) do{ RETVAL_STRINGL(s, l); if (dup == 0) efree(s); }while(0)
#define SW_RETVAL_STRING(s, dup) do{ RETVAL_STRING(s); if (dup == 0) efree(s); }while(0)
#define SW_RETURN_STRING(val, duplicate) RETURN_STRING(val)
#define SW_ZVAL_STRINGL(z, s, l, dup) ZVAL_STRINGL(z, s, l)
#define SW_ZVAL_STRING(z,s,dup) ZVAL_STRING(z,s)
#define SW_MAKE_STD_ZVAL(p) zval _stack_zval_##p; p = &(_stack_zval_##p)
#define PZVAL_IS_REF(len) 0

static inline php5cpp_obj* php5obj_from_obj(zend_object *obj) {
    return (php5cpp_obj*)((char*)(obj) - XtOffsetOf(php5cpp_obj, std));
}
#define Z_PHP5OBJ_P(zv) php5obj_from_obj(Z_OBJ_P((zv)))

// Register the class entry..
#define PHP5CPP_REGISTER_CLASS(name, obj_name)\
{\
    zend_class_entry ce;\
    INIT_CLASS_ENTRY(ce, obj_name, php5cpp_##name##_methods);\
    ce.create_object = php5cpp_object_new_##name; \
    php5cpp_ce_##name = zend_register_internal_class_ex(&ce, NULL);\
    memcpy( &php5cpp_object_handlers_##name, zend_get_std_object_handlers(), sizeof(zend_object_handlers) );\
    php5cpp_object_handlers_##name.clone_obj = NULL;\
}

//#define ZEND_REGISTER_RESOURCE(return_value, result, le_result) ZVAL_RES(return_value, zend_register_resource(result, le_result))
#define PHP5CPP_GET_THIS() \
    zval* object = getThis();

// Register resources. If we're using an object, put it into the object store.
#define PHP5CPP_REGISTER_RESOURCE(obj_type, return_value, res, le) \
{\
    PHP5CPP_GET_THIS();\
    int rsrc_id =0;\
    /*zend_register_resource(res,le);*/\
    if (object) { \
        php5cpp_obj *obj = Z_PHP5OBJ_P(object);\
        obj->u.obj_type = res;\
        obj->rsrc_id = rsrc_id;\
        obj->type = is_##obj_type;\
    }\
}

// These are for parsing parameters and getting the actual object from the store.
#define PHP5CPP_SET_OBJ(type_name) \
{ \
    php5cpp_obj *obj = Z_PHP5OBJ_P(object) ; \
    type_name ## _instance = obj->u.type_name;\
}

// Deprecated
#define PHP5CPP_OBJ_PARAMS(type, params) \
{ \
    PHP5CPP_GET_THIS(); \
    if (object) { \
        if (params == FAILURE) { \
            RETURN_FALSE; \
        } \
        PHP5CPP_SET_OBJ(type) \
    } \
}

// Deprecated
#define PHP5CPP_OBJ_NO_PARAMS(type) \
{ \
    PHP5CPP_GET_THIS(); \
    if (object) { \
        if (ZEND_NUM_ARGS() != 0) { \
            php_error(E_WARNING, "didn't expect any arguments in %s()", get_active_function_name(TSRMLS_C)); \
        } \
        PHP5CPP_SET_OBJ(type) \
    } \
}

#define PHP5CPP_GET_OBJ(type) \
{\
    PHP5CPP_GET_THIS();\
    PHP5CPP_SET_OBJ(type);\
}

#define PHP5CPP_GET_OBJ_ZVAL(type, obj) \
{ \
    zval* object = obj; \
    if (object) { \
        PHP5CPP_SET_OBJ(type) \
    } \
    if (type ## _instance == NULL) { \
        php_error(E_WARNING, "Get object_zal fall in %s()", get_active_function_name(TSRMLS_C)); \
    } \
}

#define PHP5CPP_OBJ_FREE_FUNCTION(type) \
static void php5cpp_object_free_storage_ ## type(void *object TSRMLS_DC) \
{\
    php5cpp_obj *obj = Z_PHP5OBJ_P((zval *)object);\
    zend_object_std_dtor(&obj->std);\
}

#define PHP5CPP_OBJ_NEW_FUNCTION(type) \
static zend_object* php5cpp_object_new_ ## type(zend_class_entry *class_type TSRMLS_DC) \
{\
    int objsize = sizeof(php5cpp_obj);\
    php5cpp_obj *obj=(php5cpp_obj*)ecalloc(1,objsize); memset(obj,0,objsize);\
    php_error(E_WARNING, "create object %p in %s()", obj, get_active_function_name(TSRMLS_C));\
    zend_object_std_init(&obj->std, class_type TSRMLS_CC);\
    object_properties_init(&obj->std, class_type);\
    obj->std.handlers = &php5cpp_object_handlers_##type;\
    return &obj->std;\
}

#endif //_PHP7OBJ_H_

PHP7的实现则展现了完全不同的风貌。最核心的变化是对象模型的革新：PHP7中，`zend_object`被直接嵌入到自定义结构体中，通常放在首位。因此，获取自定义对象指针需要用到`Z_PHP5OBJ_P`这个关键宏，它通过`XtOffsetOf`计算偏移量来反向定位。

此外，字符串处理宏增加了对`dup`（复制）参数的处理逻辑，内存管理也转向使用`zend_object_std_init`和`object_properties_init`等新API。注册类时，不再需要传递`TSRMLS_CC`线程安全参数，这反映了PHP7在内部架构上的简化。

通过这样一组头文件的封装，C++扩展中的业务代码只需调用诸如`PHP5CPP_REGISTER_CLASS`、`PHP5CPP_GET_OBJ`这样的统一宏，而无需关心底层是PHP5还是PHP7。版本间的巨大差异被隔离在这薄薄的一层抽象之下，使得升级工作从“重写”变成了“适配”，效率自然大幅提升。