strncpy_from_user.c 文件参考

浏览源代码.

函数
INT32	LOS_StrncpyFromUser (CHAR *dst, const CHAR *src, INT32 count)

函数说明

LOS_StrncpyFromUser()

INT32 LOS_StrncpyFromUser	(	CHAR *	dst,
		const CHAR *	src,
		INT32	count
	)

在文件 strncpy_from_user.c 第 40 行定义.

{
    CHAR character;
    INT32 i;
    INT32 maxCount;
    size_t offset = 0;
 
    if ((!LOS_IsKernelAddress((VADDR_T)(UINTPTR)dst)) || (!LOS_IsUserAddress((VADDR_T)(UINTPTR)src)) || (count <= 0)) {
        return -EFAULT;//判断是否在各自空间
    }
 
    maxCount = (LOS_IsUserAddressRange((VADDR_T)(UINTPTR)src, (size_t)count)) ? \
                count : (INT32)(USER_ASPACE_TOP_MAX - (UINTPTR)src);//最大能拷贝的数据量,结束地址不能超过 USER_ASPACE_TOP_MAX
                                                            //USER_ASPACE_TOP_MAX 是用户空间能触及的最大虚拟内存空间地址
    for (i = 0; i < maxCount; ++i) {//一个个字符拷贝
        if (LOS_GetUser(&character, src + offset) != LOS_OK) {
            return -EFAULT;
        }
        *(CHAR *)(dst + offset) = character;
        if (character == '\0') {
            return offset;
        }
        ++offset;
    }
 
    return offset;
}

函数调用图:

这是这个函数的调用关系图: