I am working in Windows,using vc++2010 and MFC.
Following is my code:
CFile File;
TCHAR lpCause[1024];
CFileException eException;
CString strErrorMessage;
// a very long file path name means a file name over 255 characters
if (!File.Open(_T("a very long file path name"), CFile::modeCreate, &eException))
{
eException.GetErrorMessage(lpCause, 1024);
strErrorMessage = lpCause;
}
else
File.Close();
When I run the code, I got error message:"a very long file path name contains an incorrect path".
My questions are:
How to modify my code to make it work?
I learn that CreateFile() function can add "\\\\?\" in the beginning of file path, then it will extend this limit to 32767 wide characters.How can I do the same thing in MFC?
Cause
In the source of CFile::Open(), there is an explicit check if the path length exceeds _MAX_PATH:
if (lpszFileName != NULL && SUCCEEDED(StringCchLength(lpszFileName, _MAX_PATH, NULL)) )
If _MAX_PATH is exceeded, the function sets pException->m_cause = CFileException::badPath and returns FALSE.
This is true even for the MFC version that comes with VS2017.
So the standard technique to circumvent the _MAX_PATH limit, that is prefixing the path with \\?\ won't work.
Possible Solutions
Call CreateFileW() directly to pass it a path with \\?\ prefix. Use the CFile constructor that accepts a HANDLE to manage the file through a CFile object. The CFile object will take ownership of the handle so you must not call CloseHandle() on the handle.
HANDLE hFile = CreateFileW( L"\\\\?\\a very long file path name", GENERIC_WRITE, 0, nullptr, CREATE_ALWAYS, 0, NULL );
if( hFile != INVALID_HANDLE_VALUE )
{
// Manage the handle using CFile
CFile file( hFile );
// Use the file...
// The CFile destructor closes the handle here.
}
else
{
DWORD err = GetLastError();
// TODO: do your error handling...
}
Another possibility is to derive a class from CFile that overrides CFile::Open() (which is virtual). For the implementation copy/paste the MFC source, but leave out the _MAX_PATH check. For a big project, this class could be a drop-in replacement for CFile to enable long paths. You could even go so far to prepend the \\?\ prefix if it isn't already there (but that is more involved as the prefix also disables the regular transformations from a Win32 path to a NT-style path, like converting / to \, resolving dots and so on).
Related
I'm working on a little singleplayer cheat for a game and am planning on making it public, I have written the API and it all works well but I want to save the data that the user enters to a .ini file so that they will only have to log in one time unless their credentials change. I have done this and it works with a relative path C:\Users\Name\Documents\Cheat\Authorise.ini Although When check the result, it doesn't seem to save nor read the data in the file.
I'm wondering if there is a better way to get the Documents Directory.
Function:
std::string authFile = "C:\\Users\\%USERNAME%\\Documents\\Cheats\\Authorise.ini";
std::string username = GUI::Files::ReadStringFromIni(authFile, "Login", "Username");
std::string password = GUI::Files::ReadStringFromIni(authFile, "Login", "Password");`
Since you're on Windows, you should use the Windows API call available for this very purpose in <ShlObj.h> called SHGetKnownFolderPath. Note that you had best use a std::wstring instead for this purpose, since there is no variant of SHGetKnownFolderPath that accepts an MBCS or ANSI string. Also, this will get you the entire path to the user's profile directory, not just the username.
PWSTR path;
SHGetKnownFolderPath(FOLDERID_Documents, KF_FLAG_DEFAULT, NULL, &path);
std::wstring strpath(path);
CoTaskMemFree(path);
Also, once you're done with path, free it with CoTaskMemFree.
Different versions of Windows store user profiles in different locations, and even the default name of the Documents folder can differ. In fact, the name and location of the user's Documents folder is fully customizable by the user, and may not even be located under the user's profile at all. So, you should not assume the Documents folder is always located at C:\\Users\\%USERNAME%\\Documents.
The best way to get the correct path to a user's Documents folder on all versions of Windows is to simply ask Windows itself. Use SHGetFolderPath(CSIDL_MYDOCUMENTS) (pre-Vista) or SHGetKnownFolderPath(FOLDERID_Documents) (Vista+) for that, eg:
#include <shlobj.h>
#include <shlwapi.h>
std::string GetDocumentsFolder()
{
std::string path;
char szPath[MAX_PATH+1] = {};
if (SHGetFolderPathA(NULL, CSIDL_MYDOCUMENTS, NULL, SHGFP_TYPE_CURRENT, szPath) == S_OK)
path = PathAddBackslashA(szPath);
/*
PWSTR pPath = NULL;
if (SHGetKnownFolderPath(FOLDERID_Documents, KF_FLAG_DEFAULT, NULL, &pPath) == S_OK)
{
int wlen = lstrlenW(pPath);
int len = WideCharToMultiByte(CP_ACP, 0, pPath, wlen, NULL, 0, NULL, NULL);
if (len > 0)
{
path.resize(len+1);
WideCharToMultiByte(CP_ACP, 0, pPath, wlen, &path[0], len, NULL, NULL);
path[len] = '\\';
}
CoTaskMemFree(pPath);
}
*/
return path;
}
std::string GetAuthFilePath()
{
std::string path = GetDocumentsFolder();
if (!path.empty())
path += "Cheats\\Authorise.ini";
return path;
}
std::string authFile = GetAuthFilePath();
...
There is a short example:
WIN32_FIND_DATA fd;
HANDLE h = FindFirstFile(L"C:", &fd);
if (h == INVALID_HANDLE_VALUE)
{
wprintf(L"Err = %d\n", GetLastError());
return 1;
}
do {
std::wstring fullPath(fd.cFileName);
wprintf(L"FullPath = %s\n", fullPath.c_str());
} while (FindNextFile(h, &fd));
FindClose(h);
I'm confused since
HANDLE h = FindFirstFile(L"C:", &fd); // OK
HANDLE h = FindFirstFile(L"E:", &fd); // INVALID_HANDLE_VALUE
HANDLE h = FindFirstFile(L"F:", &fd); // INVALID_HANDLE_VALUE
But E and F are real, existing volumes.
I do so because I need all information from the WIN32_FIND_DATA structure which will be passed to the kernel mode.
This question seems to be based on a misunderstanding. You say:
I do not want to examine the files and directories in "E:*", I want to get information about this volume.
and
I need all information from the WIN32_FIND_DATA structure.
Well, the find data information is meaningful for file and directory objects, but not for volume objects.
You'll need to use some other means to obtain volume information. Perhaps GetVolumeInformation, WMI, or maybe something else depending on your needs.
I think you have to put "E:\\*" not only the volume. Or you want to find the volume entry? Also, it is good to clean fd structure memset( &fd, 0, sizeof fd ).
On my machine (Win7 x64) FindFirstFile(L"C:", &fd) returns -1 (C: is system disc), GetLastError() is 2 (i.e. "file not found").
I've checked how FindFirstFile is working. It converts winapi like path to nt path at some stage using RtlDosPathNameToRelativeNtPathName_U and then checks whether PartName is empty or not.
If it's empty it returns mentioned error code.
if it's a mask, it continues and enumerates entries that match: that's why FindFirstFile(L"C:\\*.*", &fd) returns valid handle. Thus if you need to enumerate all files in C: using form C:\\*.*.
In case if you need a volume information use special function GetVolumeInformation.
I have a win32 console application in C++, Visual Studio 2012. I cannot get the config parameter from the ini file. I tried different possibilities with file path,like placing the .ini file in source folder, write the full path to is, placing in the folder with generated .exe file. The output on the console after executing of the .exe file is 0 or (null) for string in every case. What I am doing wrong? How can I read the parameters?
v1:
LPCTSTR path = L".\\config.ini";
TCHAR protocolChar[32];
int port = GetPrivateProfileString(_T("PORT"), _T("SETTINGS"), _T(""), protocolChar, 32, path);
printf("***%d***\n", port);
v2:
int port = GetPrivateProfileInt(_T("PORT"), _T("SETTINGS"), 0, _T("config.ini"));
config.ini contains:
[SETTINGS]
USER_NUM_MAX = 256 ; Maximum number of users
PORT = 8080;
Oups, under Windows hitting a ini file in not that easy. In both tries (v1 and v2), you look for the file in current directory and then in Windows directory but not in the directory where the executable file is.
The easy way is to put all ini files under Windows directory. If you find cleaner to have the ini file along with the exe one, you have some more work to do :
find the executable file full path
replace the exe end with ini
use that full path to get access to your private ini file
To get the name of the executable file, simply use GetModuleFileName with a NULL HMODULE :
LPCTSTR getExecPath() {
DWORD len = 64;
for (;;) {
LPTSTR fileName = new TCHAR[len];
if (len == ::GetModuleFileName(NULL, fileName, len)) {
delete fileName;
len *= 2;
}
else {
return fileName;
}
}
}
or if you prefere to directly get the ini file name :
LPCTSTR getIniName() {
DWORD len = 4;
for (;;) {
LPTSTR fileName = new TCHAR[len];
if (len == ::GetModuleFileName(NULL, fileName, len)) {
delete fileName;
len *= 2;
}
else {
::lstrcpy(fileName + lstrlen(fileName) - 3, "ini");
return fileName;
}
}
}
and to not forget to delete the file name when done since it is allocated with new ...
Edit per comment :
For reference, the windows directory may depend on windows version. But it can always be retrieved by the API function GetWindowsDirectory. Extract from the reference page :
UINT WINAPI GetWindowsDirectory(
_Out_ LPTSTR lpBuffer,
_In_ UINT uSize
);
Parameters
lpBuffer [out] A pointer to a buffer that receives the path. This path does not end with a backslash unless the Windows directory is the root directory. For example, if the Windows directory is named Windows on drive C, the path of the Windows directory retrieved by this function is C:\Windows. If the system was installed in the root directory of drive C, the path retrieved is C:.
uSize [in] The maximum size of the buffer specified by the lpBuffer parameter, in TCHARs. This value should be set to MAX_PATH.
Return value
If the function succeeds, the return value is the length of the string copied to the buffer, in TCHARs, not including the terminating null character.
If the length is greater than the size of the buffer, the return value is the size of the buffer required to hold the path.
If the function fails, the return value is zero. To get extended error information, call GetLastError. *
I faced this problem when I updated from VS2010 to VS2012.
On VS 2010 I simply called the function with the file name of the .ini-file as argument for lpFileName (see MSDN Documentation).
This was not working for VS 2012 any more, so I changed to go for the complete path like this:
char directoryPath[MAX_PATH];
char readParameter[MAX_STR_LEN];
GetCurrentDirectory( directoryPath, MAX_PATH );
string directoryPathAsString(directoryPath);
directoryPathAsString = directoryPathAsString + "\\" + filename;
GetPrivateProfileString("section","parameter","0",readParameter,MAX_STR_LEN, directoryPathAsString.c_str());
I'm trying to create an xml file using pugixml. The code is;
//Open the save as diolog
TCHAR szFilters[]= _T("Files (*.abc)|*.abc|All Files (*.*)|*.*||");
// Create an SaveAs dialog; the default file name extension is ".abc".
CFileDialog fileDlg(FALSE, _T("abc"), NULL,
OFN_OVERWRITEPROMPT |OFN_CREATEPROMPT| OFN_PATHMUSTEXIST, szFilters);
// Display the file dialog.
CString pathName;
CString fileName;
if(fileDlg.DoModal() == IDOK)
{
pathName = fileDlg.GetPathName();
fileName = fileDlg.GetFileName();
::CreateFile(pathName,GENERIC_WRITE,0,NULL,CREATE_NEW, FILE_ATTRIBUTE_NORMAL|FILE_FLAG_SEQUENTIAL_SCAN,NULL);
} //File is created in explorer
else
return;
//[code_modify_add
// add node with some name
pugi::xml_document xmlDoc;
pugi::xml_parse_result result = xmlDoc.load_file(fileName);
The problem is result always gives out a 'file_not_found' status, but I can see that the file is created in windows explorer. When I try to select the same file during the execution of the program it still returns 'file_not_found'.
However if I close the program and run again and then select the file, result returns true.
I noticed that while the program is executing I cannot open the newly created file, but when the program is closed I can open it.
What could be the matter with it?
Thanks.
You are creating a file and leaving it open write only with a share mode of zero (meaning it can not be shared) and throwing away its handle and then trying to reopen the file for reading with the xml parser.
You probably want to CloseHandle() on the return value for ::CreateFile()
HANDLE hFile = ::CreateFile(pathName,GENERIC_WRITE,0,NULL,CREATE_NEW, FILE_ATTRIBUTE_NORMAL|FILE_FLAG_SEQUENTIAL_SCAN,NULL);
if (hFile == INVALID_HANDLE_VALUE) {
// Call GetLastError() to figure out why the file creation failed.
}
else
{
CloseHandle(hFile);
}
am facing two problems one big problem and one small problem :)
problem # 1 : am unable to read Machine ID from below path ... i get my processor name like intel i7 #2.2ghz like that , i do not know why , i should get machine id , long integer string but i not get it , so please help
reg_path="SOFTWARE\\Microsoft\\Cryptography";
rvalue="MachineGuid"; // data value
my registery reading function
string read_reg_sz(char rpath[],char rdata[]) // read registery Loaction
{
REGSAM flag = KEY_WOW64_32KEY or KEY_WOW64_64KEY;
char buffer[MAX];
char Buffer[MAX];
DWORD BufSize = _MAX_PATH;
char dwMHz[MAX];
DWORD dataType = REG_SZ;
HKEY hKey;
long lError = RegOpenKeyEx(HKEY_LOCAL_MACHINE,rpath,NULL, KEY_READ | KEY_WRITE | flag,&hKey);
if(lError != ERROR_SUCCESS)
{// if the key is not found, tell the user why:
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
NULL,
lError,
0,
Buffer,
_MAX_PATH,
0);
cout<<"\n reg erro : "<<Buffer;
return "N/A";
}
// query the key:
RegQueryValueEx(hKey,rdata,NULL,&dataType,(LPBYTE) &dwMHz,&BufSize);
RegCloseKey(hKey); // close open handle ....
cout<<"\n reg data read: "<<dwMHz;
return dwMHz;
}
second problem :
currently i have function which can totally clean recycle bin :)
SHEmptyRecycleBin(NULL, NULL, SHERB_NOCONFIRMATION | SHERB_NOPROGRESSUI | SHERB_NOSOUND);
but i want to delete single file from recycle bin like passing filename
You should really post it as two different questions, but I'll try to answer both.
1. Get MachineGuid
I think your issue is in this line:
// query the key:
RegQueryValueEx(hKey,rdata,NULL,&dataType,(LPBYTE) &dwMHz,&BufSize);
You should change it to:
// query the key:
RegQueryValueEx(hKey,rvalue,NULL,&dataType,(LPBYTE) &dwMHz,&BufSize);
By the way, dhMHz does not sound like right variable name - change it to reflect reality.
Also, you should have this:
DWORD BufSize = sizeof(Buffer) - 1;
And, it would be nice to NOT have both buffer and Buffer variables.
2. Delete one file from recycle bin
According to Microsoft documentation on SHFileOperation, you should just use DeleteFile on filename like C:\$Recycle.Bin\file.txt:
When used to delete a file, SHFileOperation permanently deletes the file unless you set the FOF_ALLOWUNDO flag in the fFlags member of the SHFILEOPSTRUCT structure pointed to by lpFileOp. Setting that flag sends the file to the Recycle Bin. If you want to simply delete a file and guarantee that it is not placed in the Recycle Bin, use DeleteFile.
To delete a single file from the Recycle Bin, use SHGetSpecialFolderLocation(CSIDL_BITBUCKET) or SHGetKnownFolderIDList(FOLDERID_RecycleBinFolder) to get the absolute PIDL of the Recycle Bin, then use SHBindToObject() to get the IShellFolder interface for it and call its ParseDisplayName() method to convert the desired filename into a relative PIDL, then use SHBindToObject() to get the IContextMenu interface for the file and call its InvokeCommand() method to execute the file's "delete" verb.