luajit中。利用ffi能够嵌入C。眼下luajit的最新版是2.0.4，在这之前的版本号我还不清楚这个扩展库详细怎么样，只是在2.04中，真的非常爽。
既然是嵌入C代码。那么要说让lua支持面向对象。不如说是让C语言模拟面向对象编程。然后让luajit的ffi嵌入。要文字彻底来描写叙述清楚这个问题。我的表达能力非常有限，说不清楚，所以直接用代码来说吧。
//C++class foo_type{public: void foo1() { printf("%d", a + b); } void foo2(int n) { printf("%d", a + b + n); } int a; int b;};foo_type obj;obj.foo1();obj.foo2(100);//在C语言要做到相同的事。最简单的做法例如以下。typedef struct{ int a; int b;}foo_type;void foo1(foo_type *obj){ printf("%d", obj->a + obj->y);}void foo2(foo_type *obj, int n){ printf("%d", obj->a + obj->y + n);}foo_type obj;foo1(&obj);foo2(&obj, 100);/*****************************************//C++从汇编语言的角度看obj.foo1();lea ecx, objcall foo1-----------------------obj.foo2(100);push 100lea ecx, objcall foo1-----------------------//C语言从汇编语言的角度看foo1(&obj);lea eax, objpush eaxcall foo1-----------------------foo2(&obj, 100);push 100lea eax, objpush eaxcall foo2那么就能够看到，C和C++在实现这样的功能时的差别之处主要在于thiscall使用了ecx寄存器向下传递对象指针而在C语言。仅仅能把结构指针push下去，这就有点像微软的COM包装类的stdcall的类成员了。*****************************************///从汇编看到问题所在之后，要解决问题，也就在能够考虑写一个shellcode，这个shellcode实现将向下传递上层传入的參数。而且直接将结构指针以push參数的方式最后入栈。然后call就可以。typedef struct{ int a; int b;}foo_type;void foo1(foo_type *obj){ printf("%d", obj->a + obj->y);}void foo2(foo_type *obj, int n){ printf("%d", obj->a + obj->y + n);}typedef struct{ void (*foo1)(); void (*foo2)(int n);}foo_class;foo_type ft;foo_class obj;//与foo1相应的shellcode模板BYTE scT1[] = { 0x68, 0, 0, 0, 0, //push CONST 0xE8, 0, 0, 0, 0, //call CONST 0x83, 0xC4, 0x04, //add esp, 4 0xC3 //ret};BYTE *psc = (BYTE*)VirtualAlloc(NULL, sizeof(scT1), MEM_COMMIT, PAGE_EXECUTE_READWRITE);memcpy(psc, scT1, sizeof(scT1));*(ULONG*)(psc + 1) = (ULONG)&ft;*(ULONG*)(psc + 6) = (ULONG)&foo1 - (ULONG)(psc + 5) - 5;*(ULONG*)&(obj.foo1) = psc;//到这里之后，就已经能够这样用了obj.foo1();//与foo2相应的shellcode模板BYTE scT2[] = { 0xFF, 0x74, 0x24, 0x04, //push dword ptr [esp + 4] 0x68, 0, 0, 0, 0, //call CONST 0xE8, 0, 0, 0, 0, //call CONST 0x83, 0xC4, 0x08, //add esp, 8 0xC3 //ret};BYTE *psc = (BYTE*)VirtualAlloc(NULL, sizeof(scT2), MEM_COMMIT, PAGE_EXECUTE_READWRITE);memcpy(psc, scT2, sizeof(scT2));*(ULONG*)(psc + 5) = (ULONG)&ft;*(ULONG*)(psc + 10) = (ULONG)&foo2 - (ULONG)(psc + 5) - 5;*(ULONG*)&(obj.foo2) = psc;obj.foo2(100);//这样就模拟了面向对象形式的调用，之后就须要考虑的就是一些怎样整合管理资源之类的问题，还须要将代码尽可能的利用一些宏来简化，这些东西就不在这里说了，这个思路深入下去。相信大家都会知道该怎么做了。 以下是一套我封装的luajit使用ODBC訪问数据库的代码，没有凝视。将就着看吧。
//luaodbc.h**************************************************#pragma onceextern "C"{ typedef struct{ void (*close)(); bool (*set)(int i, int type, char *data, int size); bool (*get)(int i, int type); void *(*data)(); bool (*next)(); char *(*getstr)(int i); int (*getint)(int i); char *(*getstr_fn)(const char *name); char *(*getint_fn)(const char *name); bool (*setstr)(int i, const char *str); bool (*setint)(int i, int num); bool (*setstr_fn)(const char *name, const char *str); bool (*setint_fn)(const char *name, int num); }luastmt_class; typedef struct{ bool (*open)(const char*dsn); void (*close)(); luastmt_class *(*exec)(const char *sql); void (*tran_begin)(); void (*tran_end)(int ct); }luadbc_class; __declspec(dllexport) luadbc_class *luadbc_init(); __declspec(dllexport) void luadbc_exit(luadbc_class *obj);};//luaodbc.cpp**************************************************#include "stdafx.h"#include "luaodbc.h"#include #include #include #include #include extern "C"{#define LOS_CLOSED 0#define LOS_INITILZED 1#define LOS_CONNECTIONED 2#define LOS_TRAN 4#define LOS_STMTOPENED 8 typedef struct _ciType{ char name[68]; int type; int type_len; char *data; int data_size; int nds; }ciType; typedef struct _stmtType{ SQLHANDLE hstmt; ciType *cols; int col_count; int cp_size; unsigned int status; void *parent; luastmt_class thisobj; unsigned char *class_memory; int gci; _stmtType *next; }stmtType; typedef struct{ int (*open)(const char*dsn); void (*close)(); bool (*exec)(const char *sql); void (*tran_begin)(); void (*tran_end)(int ct); void *dbc_obj; }luadbc_class_ex; typedef struct _odbcType{ SQLHANDLE henv, hdbc; _stmtType *stmt_list; unsigned int status; luadbc_class_ex thisobj; unsigned char *class_memory; }odbcType; BYTE scT1[] = { 0x68, 0, 0, 0, 0, 0xE8, 0, 0, 0, 0, 0x83, 0xC4, 0x04, 0xC3 }; BYTE scT2[] = { 0xFF, 0x74, 0x24, 0x04, 0x68, 0, 0, 0, 0, 0xE8, 0, 0, 0, 0, 0x83, 0xC4, 0x08, 0xC3 }; BYTE scT3[] = { 0xFF, 0x74, 0x24, 0x08, 0xFF, 0x74, 0x24, 0x08, 0x68, 0, 0, 0, 0, 0xE8, 0, 0, 0, 0, 0x83, 0xC4, 0x0C, 0xC3 }; BYTE scT4[] = { 0xFF, 0x74, 0x24, 0x0C, 0xFF, 0x74, 0x24, 0x0C, 0xFF, 0x74, 0x24, 0x0C, 0x68, 0, 0, 0, 0, 0xE8, 0, 0, 0, 0, 0x83, 0xC4, 0x10, 0xC3 }; BYTE scT5[] = { 0xFF, 0x74, 0x24, 0x10, 0xFF, 0x74, 0x24, 0x10, 0xFF, 0x74, 0x24, 0x10, 0xFF, 0x74, 0x24, 0x10, 0x68, 0, 0, 0, 0, 0xE8, 0, 0, 0, 0, 0x83, 0xC4, 0x14, 0xC3 };#define SCTP1 1#define SCTP2 SCTP1 + 4#define SCTP3 SCTP2 + 4#define SCTP4 SCTP3 + 4#define SCTP5 SCTP4 + 4 std::list g_safe_luaodbc_list; CRITICAL_SECTION g_safe_luaodbc_cs; class luaodbc_startup{ public: luaodbc_startup() { InitializeCriticalSection(&g_safe_luaodbc_cs); static_link = 1; } int static_link; }; static luaodbc_startup g_luaodbc_link; static int ___g_static_link = g_luaodbc_link.static_link; void luastmt_close(stmtType *v) { if(v->status & LOS_STMTOPENED) { SQLFreeHandle(SQL_HANDLE_STMT, v->hstmt); v->hstmt = NULL; v->status ^= LOS_STMTOPENED; } } void luaodbc_coldata_realloc(stmtType *v, int i, int size) { delete v->cols[i].data; v->cols[i].data = new char[size]; } BOOL luastmt_set(stmtType *v, int i, int type, char *data, int size) { if(!data || i <= 0) return FALSE; if(!(v->status & LOS_STMTOPENED)) return FALSE; SQLINTEGER ncb = size; //printf("data:%s, i:%d, len:%d, type:%d\n", data,i, size, type); SQLFreeStmt(v->hstmt, SQL_UNBIND); SQLRETURN rc = SQLBindCol(v->hstmt, (SQLUSMALLINT)i, (SQLSMALLINT)type, (SQLPOINTER)data, (SQLINTEGER)size, &ncb); if(rc == SQL_SUCCESS || rc == SQL_SUCCESS_WITH_INFO) SQLSetPos(v->hstmt, 1, SQL_UPDATE, SQL_LOCK_NO_CHANGE); //printf("update:%d, %d\n", rc, ncb); SQLFreeStmt(v->hstmt, SQL_UNBIND); return TRUE; } BOOL luastmt_get(stmtType *v, int i, int type) { if(i <= 0) return FALSE; if(!(v->status & LOS_STMTOPENED)) return FALSE; SQLRETURN rc; for(;;) { if(v->gci == i) SQLSetPos(v->hstmt, 1, SQL_POSITION, SQL_LOCK_NO_CHANGE); else v->gci = i; rc = SQLGetData(v->hstmt, i, type, v->cols[i - 1].data, v->cols[i - 1].data_size, (SQLINTEGER*)&(v->cols[i - 1].nds)); if(rc == SQL_SUCCESS || rc == SQL_SUCCESS_WITH_INFO) return TRUE; if(v->cols[i - 1].data_size < v->cols[i - 1].nds) luaodbc_coldata_realloc(v, i - 1, v->cols[i - 1].nds + 1); else return FALSE; } return false; } void *luastmt_dataptr(stmtType *v, int i) { if(i <= 0) return false; return v->cols[i - 1].data; } BOOL luastmt_next(stmtType *v) { if(!(v->status & LOS_STMTOPENED)) return false; v->gci = 0; SQLRETURN rc = SQLFetch(v->hstmt); return (rc != SQL_NO_DATA_FOUND); } const char *luastmt_getstr(stmtType *v, int i) { if(!luastmt_get(v, i, SQL_C_CHAR)) return ""; return v->cols[i - 1].data; } int luastmt_getint(stmtType *v, int i) { if(!luastmt_get(v, i, SQL_C_SLONG)) return -1; return *(int*)(v->cols[i - 1].data); } int _colindexfromename(stmtType *v, const char *name) { std::string str = name; std::transform(str.begin(), str.end(), str.begin(), tolower); for(short i = 0; i < v->col_count; i++) { if(str == (v->cols)[i].name) return i + 1; } return -1; } const char *luastmt_getstr_fn(stmtType *v, const char *name) { if(!name) return ""; return luastmt_getstr(v, _colindexfromename(v, name)); } int luastmt_getint_fn(stmtType *v, const char *name) { if(!name) return -1; return luastmt_getint(v, _colindexfromename(v, name)); } BOOL luastmt_setstr(stmtType *v, int i, const char *str) { if(i <= 0 || !str) return FALSE; return luastmt_set(v, i, SQL_C_CHAR, (char*)str, strlen(str) + 1); } BOOL luastmt_setint(stmtType *v, int i, int num) { if(!v || i <= 0) return FALSE; return luastmt_set(v, i, SQL_C_SLONG, (char*)&num, sizeof(int)); } BOOL luastmt_setstr_fn(stmtType *v, const char *name, const char *str) { if(!v || !name) return false; return luastmt_setstr(v, _colindexfromename(v, name), str); } BOOL luastmt_setint_fn(stmtType *v, const char *name, int num) { if(!name) return false; return luastmt_setint(v, _colindexfromename(v, name), num); } void luastmt_class_init(stmtType *v) { BYTE *psc = v->class_memory;#define make_luastmt_shellcode(_member_, _sc_t_, _pup_, _proc_) *(DWORD*)&(v->thisobj._member_) = (DWORD)psc; \ memcpy_s(psc, sizeof(_sc_t_), _sc_t_, sizeof(_sc_t_)); \ *(DWORD*)(psc + _pup_) = (DWORD)v; \ *(DWORD*)(psc + _pup_ + 5) = (DWORD)_proc_ - (DWORD)(psc + _pup_ + 5 - 1) - 5; \ psc += sizeof(_sc_t_) make_luastmt_shellcode(close, scT1, SCTP1, luastmt_close); make_luastmt_shellcode(set, scT5, SCTP5, luastmt_set); make_luastmt_shellcode(get, scT3, SCTP3, luastmt_get); make_luastmt_shellcode(data, scT1, SCTP1, luastmt_dataptr); make_luastmt_shellcode(next, scT1, SCTP1, luastmt_next); make_luastmt_shellcode(getstr, scT2, SCTP2, luastmt_getstr); make_luastmt_shellcode(getint, scT2, SCTP2, luastmt_getint); make_luastmt_shellcode(getstr_fn, scT2, SCTP2, luastmt_getstr_fn); make_luastmt_shellcode(getint_fn, scT2, SCTP2, luastmt_getint_fn); make_luastmt_shellcode(setstr, scT3, SCTP3, luastmt_setstr); make_luastmt_shellcode(setint, scT3, SCTP3, luastmt_setint); make_luastmt_shellcode(setstr_fn, scT3, SCTP3, luastmt_setstr_fn); make_luastmt_shellcode(setint_fn, scT3, SCTP3, luastmt_setint_fn); } void luastmt_colinfo_release(stmtType *v) { for(int i = 0; i < v->cp_size; i++) { if(v->cols[i].data) { delete v->cols[i].data; v->cols[i].data = NULL; } } delete v->cols; } void luastmt_colinfo_init(stmtType *v) { short count; SQLNumResultCols(v->hstmt, &count); if(count > v->cp_size) { luastmt_colinfo_release(v); v->cp_size = count; v->cols = new ciType[count]; memset(v->cols, 0, sizeof(ciType) * count); } v->col_count = count; char szColName[68]; SQLSMALLINT cbColName, sqlColType, ibScale, fNullable; SQLUINTEGER cbColDef; for(short i = 0; i < count; i++) { SQLDescribeColA(v->hstmt, i + 1, (SQLCHAR*)szColName, 68, &cbColName, &sqlColType, &cbColDef, &ibScale, &fNullable); for(short j = 0; j < cbColName; j++)szColName[j] = tolower(szColName[j]); memcpy_s(v->cols[i].name, 68, szColName, cbColName + 1); if(v->cols[i].data_size < (int)cbColDef + 1) { if(v->cols[i].data) delete v->cols[i].data; v->cols[i].data_size = cbColDef + 1; v->cols[i].data = new char[cbColDef + 1]; } v->cols[i].type = sqlColType; v->cols[i].type_len = cbColDef; } } void luastmt_release(stmtType *v) { luastmt_colinfo_release(v); VirtualFree(v->class_memory, 0, MEM_RELEASE); delete v; } stmtType *luaodbc_newstmt(_odbcType *parent) { stmtType *v = new stmtType; memset(v, 0, sizeof(stmtType)); v->cp_size = 64; v->cols = new ciType[64]; memset(v->cols, 0, sizeof(ciType) * 64); v->status = LOS_CLOSED; v->next = NULL; v->parent = parent; v->class_memory = (unsigned char *)VirtualAlloc(NULL, 512, MEM_COMMIT, PAGE_EXECUTE_READWRITE); luastmt_class_init(v); return v; } void luaodbc_tran_begin(odbcType *v) { SQLSetConnectAttrA(v->hdbc, SQL_ATTR_AUTOCOMMIT, (SQLPOINTER)SQL_FALSE, NULL); v->status |= LOS_TRAN; } void luaodbc_tran_end(odbcType *v, int ct) { SQLEndTran(SQL_HANDLE_DBC, v->hdbc, (short)ct); SQLSetConnectAttrA(v->hdbc, SQL_ATTR_AUTOCOMMIT, (SQLPOINTER)SQL_TRUE, NULL); v->status ^= LOS_TRAN; } void luaodbc_close(odbcType *v) { if(v->status & LOS_CONNECTIONED) { stmtType *s = v->stmt_list; do{ luastmt_close(s); s = s->next; }while(s); if(v->status & LOS_TRAN) luaodbc_tran_end(v, SQL_ROLLBACK); SQLDisconnect(v->hdbc); SQLFreeHandle(SQL_HANDLE_DBC, v->hdbc); v->status ^= LOS_CONNECTIONED; v->hdbc = NULL; } } BOOL luaodbc_open(odbcType *v, const char *dsn) { luaodbc_close(v); SQLHANDLE hdbc; SQLRETURN rc = SQLAllocHandle(SQL_HANDLE_DBC, v->henv, &hdbc); if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) return FALSE; rc = SQLConnectA(hdbc, (SQLCHAR*)dsn, SQL_NTS, NULL, 0, NULL, 0); if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) { SQLFreeHandle(SQL_HANDLE_DBC, hdbc); return FALSE; } v->hdbc = hdbc; v->status |= LOS_CONNECTIONED; return TRUE; } luastmt_class *luaodbc_exec(odbcType *v, const char *sql) { stmtType *s = v->stmt_list; stmtType *b = s; do{ if(!(s->status & LOS_STMTOPENED)) break; b = s; s = s->next; }while(s); if(!s) { s = luaodbc_newstmt(v); b->next = s; } SQLHANDLE hstmt; SQLRETURN rc; if(!(v->status & LOS_CONNECTIONED)) return NULL; rc = SQLAllocHandle(SQL_HANDLE_STMT, v->hdbc, &hstmt); if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) return FALSE; SQLCancel(hstmt);#if(_MSC_VER < 1300) SQLSetStmtOption(hStmt, SQL_CONCURRENCY, SQL_CONCUR_VALUES); SQLSetStmtOption(hStmt, SQL_CURSOR_TYPE, SQL_CURSOR_KEYSET_DRIVEN);#else SQLSetStmtAttr(hstmt, SQL_ATTR_CONCURRENCY, (SQLPOINTER)SQL_CONCUR_VALUES, 0); SQLSetStmtAttr(hstmt, SQL_ATTR_CURSOR_TYPE, (SQLPOINTER)SQL_CURSOR_KEYSET_DRIVEN, 0);#endif rc = SQLExecDirectA(hstmt, (SQLCHAR*)sql, SQL_NTS); if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) { //printf("ERROR:[ODBC::Connection::Execute]->%s\n", sql); SQLFreeHandle(SQL_HANDLE_STMT, hstmt); return FALSE; } s->hstmt = hstmt; luastmt_colinfo_init(s); s->status |= LOS_STMTOPENED; return &(s->thisobj); } void luaodbc_class_init(odbcType *v) { BYTE *psc = v->class_memory;#define make_luaodbc_shellcode(_member_, _sc_t_, _pup_, _proc_) *(DWORD*)&(v->thisobj._member_) = (DWORD)psc; \ memcpy_s(psc, sizeof(_sc_t_), _sc_t_, sizeof(_sc_t_)); \ *(DWORD*)(psc + _pup_) = (DWORD)v; \ *(DWORD*)(psc + _pup_ + 5) = (DWORD)_proc_ - (DWORD)(psc + _pup_ + 5 - 1) - 5; \ psc += sizeof(_sc_t_) make_luaodbc_shellcode(open, scT2, SCTP2, luaodbc_open); make_luaodbc_shellcode(close, scT1, SCTP1, luaodbc_close); make_luaodbc_shellcode(exec, scT2, SCTP2, luaodbc_exec); make_luaodbc_shellcode(tran_begin, scT1, SCTP1, luaodbc_tran_begin); make_luaodbc_shellcode(tran_end, scT2, SCTP2, luaodbc_tran_end); } __declspec(dllexport) luadbc_class *luadbc_init() { odbcType *v = new odbcType; memset(v, 0, sizeof(odbcType)); SQLRETURN rc; rc = SQLAllocHandle(SQL_HANDLE_ENV, NULL, &(v->henv)); if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) return NULL; rc = SQLSetEnvAttr(v->henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, SQL_IS_INTEGER); if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) { SQLFreeHandle(SQL_HANDLE_ENV, v->henv); v->henv = NULL; return NULL; } v->stmt_list = luaodbc_newstmt(v); v->status = LOS_INITILZED; v->class_memory = (unsigned char *)VirtualAlloc(NULL, 512, MEM_COMMIT, PAGE_EXECUTE_READWRITE); luaodbc_class_init(v); v->thisobj.dbc_obj = v; EnterCriticalSection(&g_safe_luaodbc_cs); g_safe_luaodbc_list.push_back((int)&(v->thisobj)); LeaveCriticalSection(&g_safe_luaodbc_cs); return (luadbc_class*)&(v->thisobj); } __declspec(dllexport) void luadbc_exit(luadbc_class *obj) { EnterCriticalSection(&g_safe_luaodbc_cs); auto it = std::find(g_safe_luaodbc_list.begin(), g_safe_luaodbc_list.end(), (int)obj); if(it == g_safe_luaodbc_list.end()) { LeaveCriticalSection(&g_safe_luaodbc_cs); return; } g_safe_luaodbc_list.erase(it); LeaveCriticalSection(&g_safe_luaodbc_cs); odbcType *v = (odbcType*)(((luadbc_class_ex*)obj)->dbc_obj); VirtualFree(v->class_memory, 0, MEM_RELEASE); luaodbc_close(v); stmtType *s = v->stmt_list; stmtType *b; do{ b = s; s = s->next; luastmt_release(b); }while(s); SQLFreeHandle(SQL_HANDLE_ENV, v->henv); delete v; }}
--luajit中这样调用local ffi = require("ffi")ffi.cdef[[ typedef struct{ void (*close)(); bool (*set)(int i, int type, char *data, int size); bool (*get)(int i, int type); void *(*data)(); bool (*next)(); char *(*getstr)(int i); int (*getint)(int i); char *(*getstr_fn)(const char *name); char *(*getint_fn)(const char *name); bool (*setstr)(int i, const char *str); bool (*setint)(int i, int num); bool (*setstr_fn)(const char *name, const char *str); bool (*setint_fn)(const char *name, int num); }luastmt_class; typedef struct{ bool (*open)(const char*dsn); void (*close)(); luastmt_class *(*exec)(const char *sql); void (*tran_begin)(); void (*tran_end)(int ct); }luadbc_class; luadbc_class *luadbc_init(); void luadbc_exit(luadbc_class *obj);]]local conn = ffi.C.luadbc_init();if conn.open("USERDSN") ~= false then print("已连接!") local rs = conn.exec("SELECT * FROM characters") if rs ~= nil then print("開始遍历数据!") while rs.next() do print(ffi.string(rs.getstr(3))) end rs.close() end conn.close()end