可以';t在屏幕上打开日志中的内存映射文件
本文关键字:日志 内存 文件 映射 屏幕 可以 | 更新日期: 2023-09-27 18:26:28
我正在尝试使用内存映射文件在windows(用C#编写)服务和用C++编写的屏幕保护程序之间共享数据。
虽然如果屏幕保护程序在登录用户的上下文中运行,这很好,但如果屏幕保护软件在登录屏幕上运行,则不起作用。相反,OpenFileMapping
由于未经授权的访问错误而失败。很明显,我缺少了一个访问规则(或者系统设置,也许是为了让它发挥作用),但我不知道是哪一个。
我的c#端代码:
public CreateMemMappedFile(string fileName)
{
this.rootName = fileName;
var security = new MemoryMappedFileSecurity();
security.AddAccessRule(new System.Security.AccessControl.AccessRule<MemoryMappedFileRights>(
new SecurityIdentifier(WellKnownSidType.WorldSid, null),
MemoryMappedFileRights.FullControl, System.Security.AccessControl.AccessControlType.Allow));
security.AddAccessRule(new System.Security.AccessControl.AccessRule<MemoryMappedFileRights>(
new SecurityIdentifier(WellKnownSidType.AnonymousSid, null),
MemoryMappedFileRights.FullControl, System.Security.AccessControl.AccessControlType.Allow));
security.AddAccessRule(new System.Security.AccessControl.AccessRule<MemoryMappedFileRights>(
new SecurityIdentifier(WellKnownSidType.NullSid, null),
MemoryMappedFileRights.FullControl, System.Security.AccessControl.AccessControlType.Allow));
// printing the SID from the screensaver shows that we are running as Local Service
security.AddAccessRule(new System.Security.AccessControl.AccessRule<MemoryMappedFileRights>(
new SecurityIdentifier(WellKnownSidType.LocalServiceSid, null),
MemoryMappedFileRights.FullControl, System.Security.AccessControl.AccessControlType.Allow));
this.handle = MemoryMappedFile.CreateOrOpen(
"Global''" + fileName, 1024 * 1024,
MemoryMappedFileAccess.ReadWriteExecute
,MemoryMappedFileOptions.DelayAllocatePages,
security, System.IO.HandleInheritability.Inheritable
);
}
我的屏幕保护程序代码:
TCHAR* myFileName = _T("Global''myfile");
ipcBufferHandle = OpenFileMapping(FILE_MAP_READ,FALSE,myFileName);
if(ipcBufferHandle == NULL)
{
_tprintf(_T("couldn't open file '"%s'" with error code %d'n"),myFileName,GetLastError());
}
else
{
_tprintf(_T("opened file %s'n"),myFileName);
}
其输出couldn't open file "Global'myfile" with error code 5
如msdn所述,OpenFileMapping定义为
HANDLE WINAPI OpenFileMapping(
_In_ DWORD dwDesiredAccess,
_In_ BOOL bInheritHandle,
_In_ LPCTSTR lpName
);
因此,当使用FALSE
调用bInheritHandle
时,句柄不会与其他进程共享。尝试TRUE
,就像您在C#中使用System.IO.HandleInheritability.Inheritable
一样。
ipcBufferHandle = OpenFileMapping(FILE_MAP_READ, TRUE, myFileName);