I use this code to delete a file from my local system:
bool Delete(const ::CComPtr<IShellItem>& pShellItem, bool permanently)
{
::CComPtr<IFileOperation> pFileOperation;
// initialize the file operation
HRESULT hr = ::CoCreateInstance(CLSID_FileOperation, NULL, CLSCTX_ALL, IID_PPV_ARGS(&pFileOperation));
if (FAILED(hr))
return false;
// don't show any system error message to user, but returns an error code if delete failed. Also show elevation prompt if required
DWORD fileOpFlags = FOF_SILENT | FOF_NO_UI | FOF_NOERRORUI | FOF_NOCONFIRMATION | FOFX_EARLYFAILURE | FOFX_SHOWELEVATIONPROMPT;
// do move file on Recycle Bin instead of deleting it permanently?
if (!permanently)
if (WOSHelper_MSWindows::GetWindowsVersion() >= WOSHelper_MSWindows::IEVersion::IE_Win8)
// Windows 8 introduces the FOFX_RECYCLEONDELETE flag and deprecates the FOF_ALLOWUNDO in favor of FOFX_ADDUNDORECORD
fileOpFlags |= FOFX_ADDUNDORECORD | FOFX_RECYCLEONDELETE;
else
// for Windows 7 and Vista, RecycleOnDelete is the default behavior
fileOpFlags |= FOF_ALLOWUNDO;
// prepare the delete operation flags
hr = pFileOperation->SetOperationFlags(fileOpFlags);
if (FAILED(hr))
return false;
// mark item for deletion
hr = pFileOperation->DeleteItem(pShellItem, nullptr);
if (FAILED(hr))
return false;
// delete the item
hr = pFileOperation->PerformOperations();
if (FAILED(hr))
return false;
return true;
}
On my local computer I also mounted an alias disk using this command:
subst V: "C:\MyData"
Now, using my above alias, I need to move a file to the Recycle Bin (this is done by setting the permanently parameter to false while I call my function) from the following path:
V:\MyProject\MyFileToDel.txt
Doing that, the file is well deleted from its containing folder, but it is never moved to the Recycle Bin. On the other hand, when I try to delete my file from its original path:
C:\MyData\MyProject\MyFileToDel.txt
The file is well deleted from its containing folder AND moved to the Recycle Bin, as expected.
However this is the exact same file in the exact same location in the both cases, the only difference is that one is deleted from an alias, and the other from its complete path.
What should I change to make the function to work in the both cases?
Related
I am trying to create a program that any normal user can run on windows and generate a process list of all processes, including the executable location. I have used CreateToolhelp32Snapshot() to get all process names, pid, ppid. But having issues getting the image path. Everything I do results in pretty much Access Denied.
I have tried ZwQueryInformationProcess, GetProcessImageFileName, etc. and also using OpenProcess to get the handle to each process. I can get the handle by using PROCESS_QUERY_LIMITED_INFORMATION, but any other option doesn't work. I am lost and have been at this for a few days. Can anyone point me in the right direction?
This is the code that works for non-admin user on Windows. Use the szExeFile member of PROCESSENTRY32 to get the path:
HANDLE hProcessSnap = NULL;
HANDLE hProcess = NULL;
PROCESSENTRY32 pe32;
DWORD dwPriorityClass = 0;
// Take a snapshot of all processes in the system.
hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (hProcessSnap == INVALID_HANDLE_VALUE)
{
return;
}
// Set the size of the structure before using it.
pe32.dwSize = sizeof(PROCESSENTRY32);
// Retrieve information about the first process,
// and exit if unsuccessful
if (!Process32First(hProcessSnap, &pe32))
{
CloseHandle(hProcessSnap); // clean the snapshot object
return;
}
// Now walk the snapshot of processes, and
// display information about each process in turn
do
{
// do something with the pe32 struct.
// pe32.szExeFile -> path of the file
} while (Process32Next(hProcessSnap, &pe32));
CloseHandle(hProcessSnap);
I am trying to delete all the temporary files created by my application during uninstall. I use the following code:
bool DeleteFileNow( QString filenameStr )
{
wchar_t* filename;
filenameStr.toWCharArray(filename);
QFileInfo info(filenameStr);
// don't do anything if the file doesn't exist!
if (!info.exists())
return false;
// determine the path in which to store the temp filename
wchar_t* path;
info.absolutePath().toWCharArray(path);
TRACE( "Generating temporary name" );
// generate a guaranteed to be unique temporary filename to house the pending delete
wchar_t tempname[MAX_PATH];
if (!GetTempFileNameW(path, L".xX", 0, tempname))
return false;
TRACE( "Moving real file name to dummy" );
// move the real file to the dummy filename
if (!MoveFileExW(filename, tempname, MOVEFILE_REPLACE_EXISTING))
{
// clean up the temp file
DeleteFileW(tempname);
return false;
}
TRACE( "Queueing the OS" );
// queue the deletion (the OS will delete it when all handles (ours or other processes) close)
return DeleteFileW(tempname) != FALSE;
}
My application is crashing. I think its due to some missing windows dll for the operations performed. Is there any other way to perform the same operation using Qt alone?
Roku have already told your problem in manipulating with QString and wchar_t*.
See the documentation: QString Class Reference, method toWCharArray:
int QString::toWCharArray ( wchar_t * array ) const
Fills the array with the data contained in this QString object. The array is encoded in utf16 on platforms where wchar_t is 2 bytes wide (e.g. windows) and in ucs4 on platforms where wchar_t is 4 bytes wide (most Unix systems).
array has to be allocated by the caller and contain enough space to hold the complete string (allocating the array with the same length as the string is always sufficient).
returns the actual length of the string in array.
If you are simply looking for a way to remove a file using Qt, use QFile::remove:
QFile file(fileNameStr);
file.remove(); // Returns a bool; true if successful
If you want Qt to manage the entire life cycle of a temporary file for you, take a look at QTemporaryFile:
QTemporaryFile tempFile(fileName);
if (tempFile.open())
{
// Do stuff with file here
}
// When tempFile falls out of scope, it is automatically deleted.
I want to measure/optimize the "cold boot" startup performance of an application, and it's difficult to do this without an actual reboot, which is obviously not an ideal solution.
Is there a way I could invalidate entire system's file cache, so that mapped page accesses actually cause a disk access, so that I can measure the time my program takes to start up?
Information:
I pretty much need FSCTL_DISMOUNT_VOLUME's functionality, but for the system volume.
At least on Windows 7, it seems that attempting to open a volume handle without FILE_SHARE_WRITE sharing permissions causes the file system cache to be invalidated, even if the creation fails.
Thus I made a program that simply calls CreateFile to this end.
Download the program* from its Base64 version here:
<!-- Click "Run Snippet", then Right-Click -> Save As... -->
FlushFileSystemCache.exe
Source
// Usage: ClearCache C: D:
#include <tchar.h>
#include <stdio.h>
#include <windows.h>
int _tmain(int argc, LPTSTR argv[]) {
LPCTSTR DOS_PREFIX = _T("\\\\.\\");
for (int i = 1; i < argc; i++) {
LPTSTR arg = argv[i];
LPTSTR path = (LPTSTR)calloc(
_tcslen(arg) + _tcslen(DOS_PREFIX) + 1, sizeof(*arg));
__try {
if (_istalpha(arg[0]) && arg[1] == _T(':') &&
(arg[2] == _T('\0') ||
arg[2] == _T('\\') && arg[3] == _T('\0')))
{ _tcscat(path, DOS_PREFIX); }
_tcscat(path, arg);
HANDLE hFile = CreateFile(path,
FILE_READ_DATA, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
if (hFile != INVALID_HANDLE_VALUE) { CloseHandle(hFile); }
else {
DWORD le = GetLastError();
if (le != ERROR_SHARING_VIOLATION && le != ERROR_ACCESS_DENIED)
{
_ftprintf(stderr, _T("Error %d clearing %s\n"), le, argv[i]);
return le;
}
}
} __finally { free(path); }
}
return 0;
}
* Just for fun, see if you can figure out what the executable does by disassembling it. It's not your typical executable. :)
I've written a simple command-line utility to do that: FlushFileCache
It relies on the undocumented NtSetSystemInformation functions, and can flush the various other memory pools as well.
This solution worked great: Clear file cache to repeat performance testing
More specifically, I'm doing this:
// Open with FILE_FLAG_NO_BUFFERING
auto hFile = CreateFile(path.c_str(),
GENERIC_READ,
FILE_SHARE_READ,
nullptr,
OPEN_EXISTING,
FILE_FLAG_NO_BUFFERING,
nullptr);
/// Check
if (hFile == INVALID_HANDLE_VALUE){
//_tprintf(TEXT("Terminal failure: unable to open file \"%s\" for read.\n"), argv[1]);
cout << "error" << endl;
return;
}
// Close
CloseHandle(hFile);
// Now open file with regular C++ API, and caching disabled
ifstream file(path, ios::binary | ios::ate);
What David said. Create a large file, however many GB you need, and each time you want to reset your file cache, make a copy of the file. Then make sure you delete the old file.
So, create BIGFILE1.DAT, copy it to BIGFILE2.DAT, and then delete BIGFILE1.DAT (which removes it from the disk and the cache). Next time, just reverse the process.
Addenda:
Well, the other option is to take the files that are mapped, and copy them to new files, delete the old ones, and rename the new files back to the old ones. The cache is backed by a file. If the file "goes away" so does the cache.
If you can identify these files, and they're not shared by the system/other running programs, this should be simple to script and, ideally, run faster than copy 6 GB of files around.
You can use a VM and take a snapshot right after the VM boots. Resuming from a snapshot will be faster than a reboot.
I'm having an issue with using SHGetFileInfo on the public desktop and files in the public desktop. I'll focus on the actual desktop folder (CSIDL_COMMON_DESKTOPDIRECTORY or usually "C:\Users\Public\Desktop"). Also - I've started seeing this behavior only recently, but I can't pinpoint the exact change which made it faulty. The actual call to ShGetFileInfo has not changed (as far as I can tell).
So I have this (I've omitted intermediate error checks to shorten - the function calls return with success):
SHFILEINFOW info;
uint32_t return_value = 0;
uint32_t flags = SHGFI_TYPENAME|SHGFI_ICON|SHGFI_SMALLICON|SHGFI_SYSICONINDEX;
uint32_t attributes = FILE_ATTRIBUTE_NORMAL;
wchar_t *path = L"C:\\Users\\Public\\Desktop";
return_value = SHGetFileInfoW(path, attributes, &info, sizeof(SHFILEINFOW), flags);
printf("[%ls] %u ", path, return_value);
This returns 0 as the return value. If I populate path using:
SHGetFolderPathW(NULL, CSIDL_COMMON_DESKTOPDIRECTORY, NULL, 0, path)
I get the same result. But if I use the pidl, as in:
LPITEMIDLIST pidl = NULL;
SHGetSpecialFolderLocation(NULL, CSIDL_COMMON_DESKTOPDIRECTORY, &pidl);
return_value = SHGetFileInfoW((LPCWSTR) pidl, attributes, &info, sizeof(SHFILEINFOW), flags | SHGFI_PIDL);
Then I get something which I expect, a handle to the system small icon list.
I can't tell what I'm doing wrong - and it only happens on this specific folder. I actually need icons for the items inside the directory, so using the pidl doesn't seem to be an option right now. Any ideas on what is the expected way to retrieve icons from the common desktop?
--
I should mention this behavior happens on Windows Vista - using the path populated by SHGetFolderPathW on XP works fine
I had the same problem. It can be fixed by calling the function CoInitialize from OLE32.DLL when the program starts.
CoInitialize(0);
return_value = SHGetFileInfoW(path, attributes, &info, sizeof(SHFILEINFOW), flags);
What are the Win32 APIs to use to programically delete files and folders?
Edit
DeleteFile and RemoveDirectory are what I was looking for.
However, for this project I ended up using SHFileOperation.
I found the sample code at CodeGuru helpful.
There are two ways to approach this. One is through the File Services (using commands such as DeleteFile and RemoveDirectory) and the other is through the Windows Shell (using SHFileOperation). The latter is recommended if you want to delete non-empty directories or if you want explorer style feedback (progress dialogs with flying files, for example). The quickest way of doing this is to create a SHFILEOPSTRUCT, initialise it and call SHFileOperation, thus:
void silently_remove_directory(LPCTSTR dir) // Fully qualified name of the directory being deleted, without trailing backslash
{
SHFILEOPSTRUCT file_op = {
NULL,
FO_DELETE,
dir,
"",
FOF_NOCONFIRMATION |
FOF_NOERRORUI |
FOF_SILENT,
false,
0,
"" };
SHFileOperation(&file_op);
}
This silently deletes the entire directory. You can add feedback and prompts by varying the SHFILEOPSTRUCT initialisation - do read up on it.
I think you want DeleteFile and RemoveDirectory
See uvgroovy's comment above. You need 2 nulls at the end of the 'dir' field.
int silently_remove_directory(LPCTSTR dir) // Fully qualified name of the directory being deleted, without trailing backslash
{
int len = strlen(dir) + 2; // required to set 2 nulls at end of argument to SHFileOperation.
char* tempdir = (char*) malloc(len);
memset(tempdir,0,len);
strcpy(tempdir,dir);
SHFILEOPSTRUCT file_op = {
NULL,
FO_DELETE,
tempdir,
NULL,
FOF_NOCONFIRMATION |
FOF_NOERRORUI |
FOF_SILENT,
false,
0,
"" };
int ret = SHFileOperation(&file_op);
free(tempdir);
return ret; // returns 0 on success, non zero on failure.
}
I believe DeleteFile does not send the file to the Recycle Bin. Also, RemoveDirectory removes only empty dirs. SHFileOperation would give you the most control over what and how to delete and would show the standard Windows UI dialog boxes (e.g. "Preparing to delete etc.) if needed.
/* function used to send files and folder to recycle bin in win32 */
int fn_Send_Item_To_RecycleBin(TCHAR newpath[])
{
_tcscat_s(newpath, MAX_PATH,_T("|"));
TCHAR* Lastptr = _tcsrchr(newpath, _T('|'));
*Lastptr = _T('\0'); // Replace last pointer with Null for double null termination
SHFILEOPSTRUCT shFileStruct;
ZeroMemory(&shFileStruct,sizeof(shFileStruct));
shFileStruct.hwnd=NULL;
shFileStruct.wFunc= FO_DELETE;
shFileStruct.pFrom= newpath;
shFileStruct.fFlags = FOF_ALLOWUNDO | FOF_NOCONFIRMATION | FOF_NOERRORUI | FOF_SILENT;
return SHFileOperation(&shFileStruct);
}
For C++ programming, if you're willing to work with third-party libraries,
boost::filesystem::remove_all(yourPath)
is much simpler than SHFileOperation.