（笔记）分配和释放虚拟内存

/* ************************************
*《精通Windows API》 
* 示例代码
* virtual.c
* 5.4.2  分配和释放可读可写的虚拟内存页面
**************************************/


/* 头文件　*/
#include <windows.h>
#include <stdio.h>


/*************************************
* int main(void)
* 功能 演示虚拟内存的使用
*
* 参数 未使用
**************************************/
int main(void)
{
SIZE_T sizeVirtual = 4000;//大小
LPVOID lpRound = (LPVOID)0x100000FF;//地址
MEMORY_BASIC_INFORMATION  mbi;//内存信息


//分配内存，直接分配已提交的内存
LPVOID lpAddress = VirtualAlloc(
lpRound,sizeVirtual,
MEM_COMMIT|MEM_RESERVE,PAGE_READWRITE
);
if(lpAddress == NULL)
{
printf("VirtualAlloc error: %d\n",GetLastError());
return 1;
}
printf("Alloc:MEM_COMMIT|MEM_RESERVE\n");
//复制数据到内存中
CopyMemory(lpAddress,"hello",strlen("hello"));
printf("分配、复制成功，地址：0x%.8x, 内容：%s\n",
lpAddress,lpAddress);
//获取内存信息并打印
VirtualQuery(lpAddress,&mbi,sizeof(mbi));                                  
printf("使用VirtualQuery获得的信息：\n"
"BaseAddress:0x%.8x\tAllocationBase:0x%.8x\t"
"AllocationProtect:0x%.8x\tRegionSize:%u\t"
"State:0x%.8x\tProtect:0x%.8x\tType:0x%.8x\n",
mbi.BaseAddress,mbi.AllocationBase,
mbi.AllocationProtect,mbi.RegionSize,
mbi.State,mbi.Protect,mbi.Type
);


////设置为READ-ONLY属性
//if(!VirtualProtect(lpAddress,0,PAGE_READONLY,NULL))
//{
// printf("VirtualProtect error: %d",GetLastError());
// return 1;
//}
////测试READ-ONLY属性,异常
//CopyMemory(lpAddress,"read only",lstrlen("read only"));
//printf(lpAddress);
////获取内存信息并打印
//VirtualQuery(lpAddress,&mbi,sizeof(mbi));
//printf("使用VirtualQuery获得的信息：\n"
// "BaseAddress:0x%.8x\tAllocationBase:0x%.8x\t"
// "AllocationProtect:0x%.8x\tRegionSize:%d\t"
// "State:0x%.8x\tProtect:0x%.8x\tType:0x%.8x\n",
// mbi.BaseAddress,mbi.AllocationBase,
// mbi.AllocationProtect,mbi.RegionSize,
// mbi.State,mbi.Protect,mbi.Type
// );


//DECOMMIT释放，页面将变为保留状态！！！！！！！！！！！
printf("Free: DECOMMIT\n");
if(!VirtualFree(lpRound,sizeVirtual,MEM_DECOMMIT))
{
printf("VirtualFree error: %d",GetLastError());
return 1;
}
//获取内存信息并打印
VirtualQuery(lpAddress,&mbi,sizeof(mbi));
printf("使用VirtualQuery获得的信息：\n"
"BaseAddress:0x%.8x\tAllocationBase:0x%.8x\t"
"AllocationProtect:0x%.8x\tRegionSize:%u\t"
"State:0x%.8x\tProtect:0x%.8x\tType:0x%.8x\n",
mbi.BaseAddress,mbi.AllocationBase,
mbi.AllocationProtect,mbi.RegionSize,
mbi.State,mbi.Protect,mbi.Type
);
//释放内存
printf("Free:RELEASE\n");
if(!VirtualFree( lpAddress,0,MEM_RELEASE ))
{
printf("VirtualFree error: %d",GetLastError());
return 1;
}
return 0;
}