Related
I'm trying to use GetDiskFreeSpaceEx in my C++ win32 application to get the total available bytes on the 'current' drive. I'm on Windows 7.
I'm using this sample code: http://support.microsoft.com/kb/231497
And it works! Well, almost. It works if I provide a drive, such as:
...
szDrive[0] = 'C'; // <-- specifying drive
szDrive[1] = ':';
szDrive[2] = '\\';
szDrive[3] = '\0';
pszDrive = szDrive;
...
fResult = pGetDiskFreeSpaceEx ((LPCTSTR)pszDrive,
(PULARGE_INTEGER)&i64FreeBytesToCaller,
(PULARGE_INTEGER)&i64TotalBytes,
(PULARGE_INTEGER)&i64FreeBytes);
fResult becomes true and i can go on to accurately calculate the number of free bytes available.
The problem, however, is that I was hoping to not have to specify the drive, but instead just use the 'current' one. The docs I found online (Here) state:
lpDirectoryName [in, optional]
A directory on the disk. If this parameter is NULL, the function uses the root of the current disk.
But if I pass in NULL for the Directory Name then GetDiskFreeSpaceEx ends up returning false and the data remains as garbage.
fResult = pGetDiskFreeSpaceEx (NULL,
(PULARGE_INTEGER)&i64FreeBytesToCaller,
(PULARGE_INTEGER)&i64TotalBytes,
(PULARGE_INTEGER)&i64FreeBytes);
//fResult == false
Is this odd? Surely I'm missing something? Any help is appreciated!
EDIT
As per JosephH's comment, I did a GetLastError() call. It returned the DWORD for:
ERROR_INVALID_NAME 123 (0x7B)
The filename, directory name, or volume label syntax is incorrect.
2nd EDIT
Buried down in the comments I mentioned:
I tried GetCurrentDirectory and it returns the correct absolute path, except it prefixes it with \\?\
it returns the correct absolute path, except it prefixes it with \\?\
That's the key to this mystery. What you got back is the name of the directory with the native api path name. Windows is an operating system that internally looks very different from what you are familiar with winapi programming. The Windows kernel has a completely different api, it resembles the DEC VMS operating system a lot. No coincidence, David Cutler used to work for DEC. On top of that native OS were originally three api layers, Win32, POSIX and OS/2. They made it easy to port programs from other operating systems to Windows NT. Nobody cared much for the POSIX and OS/2 layers, they were dropped at XP time.
One infamous restriction in Win32 is the value of MAX_PATH, 260. It sets the largest permitted size of a C string that stores a file path name. The native api permits much larger names, 32000 characters. You can bypass the Win32 restriction by using the path name using the native api format. Which is simply the same path name as you are familiar with, but prefixed with \\?\.
So surely the reason that you got such a string back from GetCurrentDirectory() is because your current directory name is longer than 259 characters. Extrapolating further, GetDiskFreeSpaceEx() failed because it has a bug, it rejects the long name it sees when you pass NULL. Somewhat understandable, it isn't normally asked to deal with long names. Everybody just passes the drive name.
This is fairly typical for what happens when you create directories with such long names. Stuff just starts falling over randomly. In general there is a lot of C code around that uses MAX_PATH and that code will fail miserably when it has to deal with path names that are longer than that. This is a pretty exploitable problem too for its ability to create stack buffer overflow in a C program, technically a carefully crafted file name could be used to manipulate programs and inject malware.
There is no real cure for this problem, that bug in GetDiskFreeSpaceEx() isn't going to be fixed any time soon. Delete that directory, it can cause lots more trouble, and write this off as a learning experience.
I am pretty sure you will have to retrieve the current drive and directory and pass that to the function. I remember attempting to use GetDiskFreeSpaceEx() with the directory name as ".", but that did not work.
Given a device instance ID for a network card, I would like to know its MAC address. Example device instance ID on my system for integrated Intel Gigabit card:
PCI\VEN_8086&DEV_10CC&SUBSYS_00008086&REV_00\3&33FD14CA&0&C8
So far, the algorithm I have used works as follows:
Call SetupDiGetClassDevs with DIGCF_DEVICEINTERFACE.
Call SetupDiEnumDeviceInfo to get the returned device in a SP_DEVINFO_DATA.
Call SetupDiEnumDeviceInterfaces with GUID_NDIS_LAN_CLASS to get a device interface.
Call SetupDiGetDeviceInterfaceDetail for this returned device interface. This gets us the device path as a string: \\?\pci#ven_8086&dev_10cc&subsys_00008086&rev_00#3&33fd14ca&0&c8#{ad498944-762f-11d0-8dcb-00c04fc3358c}\{28fd5409-15bd-4c06-b62f-004d3a06f852}
At this point we have an address to the network card driver's interface. Open it with CreateFile using the result from #4.
Call DeviceIoControl with IOCTL_NDIS_QUERY_GLOBAL_STATS and OID of OID_802_3_PERMANENT_ADDRESS to get the MAC address.
This usually works, and has been used successfully on quite a large number of machines. However, it appears that a very select few machines have network drivers that aren't responding properly to the DeviceIoControl request in step #6; the problem persists even after updating network card drivers to the latest. These are newer, Windows 7-based computers. Specifically, DeviceIoControl completes successfully, but returns zero bytes instead of the expected six bytes containing the MAC address.
A clue seems to be on the MSDN page for IOCTL_NDIS_QUERY_GLOBAL_STATS:
This IOCTL will be deprecated in later operating system releases. You
should use WMI interfaces to query miniport driver information. For
more information see, NDIS Support for WMI.
-- perhaps newer network card drivers are no longer implementing this IOCTL?
So, how should I get this working? Is it possible there's an oversight in my approach and I'm doing something slightly wrong? Or do I need to take a much more different approach? Some alternate approaches seem to include:
Query Win32_NetworkAdapter WMI class: provides needed information but rejected due to horrible performance. See Fast replacement for Win32_NetworkAdapter WMI class for getting MAC address of local computer
Query MSNdis_EthernetPermanentAddress WMI class: appears to be the WMI replacement for IOCTL_NDIS_QUERY_GLOBAL_STATS and queries the OID directly from the driver - and this one works on the troublesome network driver. Unfortunately, the returned class instances only provide the MAC address and the InstanceName, which is a localized string like Intel(R) 82567LM-2 Gigabit Network Connection. Querying MSNdis_EnumerateAdapter yields a list which relates the InstanceName to a DeviceName, like \DEVICE\{28FD5409-15BD-4C06-B62F-004D3A06F852}. I'm not sure how to go from the DeviceName to the plug-and-play device instance ID (PCI\VEN_8086......).
Call GetAdaptersAddresses or GetAdaptersInfo (deprecated). The only non-localized identifier I can find in the return value is the adapter name, which is a string like {28FD5409-15BD-4C06-B62F-004D3A06F852} - same as the DeviceName returned by the WMI NDIS classes. So again, I can't figure out how to relate it to the device instance ID. I'm not sure if it would work 100% of the time either - e.g. for adapters without TCP/IP protocol configured.
NetBIOS method: requires specific protocols to be set up on the card so won't work 100% of time. Generally seems hack-ish, and not a way to relate to device instance ID anyway that I know of. I'd reject this approach.
UUID generation method: rejected for reasons I won't elaborate on here.
It seems like if I could find a way to get the "GUID" for the card from the device instance ID, I'd be well on my way with one of the remaining two ways of doing things. But I haven't figured out how yet. Otherwise, the WMI NDIS approach would seem most promising.
Getting a list of network cards and MAC addresses is easy, and there are several ways of doing it. Doing it in a fast way that lets me relate it to the device instance ID is apparently hard...
EDIT: Sample code of the IOCTL call if it helps anyone (ignore the leaked hFile handle):
HANDLE hFile = CreateFile(dosDevice.c_str(), 0, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
if (hFile == INVALID_HANDLE_VALUE) {
DWORD err = GetLastError();
wcout << "GetMACAddress: CreateFile on " << dosDevice << " failed." << endl;
return MACAddress();
}
BYTE address[6];
DWORD oid = OID_802_3_PERMANENT_ADDRESS, returned = 0;
//this fails too: DWORD oid = OID_802_3_CURRENT_ADDRESS, returned = 0;
if (!DeviceIoControl(hFile, IOCTL_NDIS_QUERY_GLOBAL_STATS, &oid, sizeof(oid), address, 6, &returned, NULL)) {
DWORD err = GetLastError();
wcout << "GetMACAddress: DeviceIoControl on " << dosDevice << " failed." << endl;
return MACAddress();
}
if (returned != 6) {
wcout << "GetMACAddress: invalid address length of " << returned << "." << endl;
return MACAddress();
}
The code fails, printing:
GetMACAddress: invalid address length of 0.
So the DeviceIoControl returns non-zero indicating success, but then returns zero bytes.
Here's one way to do it:
Call GetAdaptersAddresses to get a list of IP_ADAPTER_ADDRESSES structs
Iterate over each adapter and get its GUID from the AdapterName field (I'm not sure if this behaviour is guaranteed, but all the adapters in my system have a GUID here, and the documentation says the AdapterName is permanent)
For each adapter read the registry key from HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Network\{4D36E972-E325-11CE-BFC1-08002BE10318}\<the adapter GUID>\Connection\PnPInstanceID (if it exists) (got this idea from here; searching on Google that key seems to be well documented, so it's not likely to change)
From this key you get the device ID for the adapter (something like: PCI\VEN_14E4&DEV_16B1&SUBSYS_96B11849&REV_10\4&2B8260C3&0&00E4)
Do this for each adapter until you find a match. When you get your match just go back to the IP_ADAPTER_ADDRESSES and look at the PhysicalAddress field
Get a beer (optional)
It wouldn't be Windows if there weren't a million ways to do something!
I wound up using SetupDiGetDeviceRegistryProperty to read SPDRP_FRIENDLYNAME. If that's not found, then I read SPDRP_DEVICEDESC instead. Ultimately, this gets me a string like "VirtualBox Host-Only Ethernet Adapter #2". I then match this against the InstanceName property in the WMI NDIS classes (MSNdis_EthernetPermanentAddress WMI class). Both properties must be read in case there are multiple adapters sharing the same driver (i.e. "#2", "#3", etc.) - if there's only one adapter then SPDRP_FRIENDLYNAME isn't available, but if there is more than one then SPDRP_FRIENDLYNAME is required to differentiate them.
The method makes me a little nervous because I'm comparing what seems like a localized string, and there's no documentation that I've found that guarantees what I'm doing will always work. Unfortunately, I haven't found any better ways that are documented to work, either.
A couple other alternate methods involve groveling in undocumented registry locations. One method is spencercw's method, and the other would be to read SPDRP_DRIVER, which is the name of a subkey under HKLM\SYSTEM\CurrentControlSet\Control\Class. Underneath the driver key, look for the Linkage\Export value which then seems like it could be matched to the DeviceName property of the MSNdis_EnumerateAdapter class. But there's no documentation I could find that says these values can be legally matched. Furthermore, the only documentation I found about Linkage\Export was from the Win2000 registry reference and explicitly said that applications shouldn't rely on it.
Another method would be to look at my original question, step 4: "SetupDiGetDeviceInterfaceDetail for this returned device interface". The device interface path actually can be used to reconstruct the device path. Start with device interface path: \\?\pci#ven_8086&dev_10cc&subsys_00008086&rev_00#3&33fd14ca&0&c8#{ad498944-762f-11d0-8dcb-00c04fc3358c}\{28fd5409-15bd-4c06-b62f-004d3a06f852}. Then, remove everything before the final slash, leaving you with: {28fd5409-15bd-4c06-b62f-004d3a06f852}. Finally, prepend \Device\ to this string and match it against the WMI NDIS classes. Again, however, this seems to be undocumented and relying on an implementation detail of a device interface path.
In the end, the other methods I investigated had their own undocumented complications that sounded at least as serious as matching the SPDRP_FRIENDLYNAME / SPDRP_DEVICEDESC strings. So I opted for the simpler approach, which was to just match those strings against the WMI NDIS classes.
I guess you want to get the MAC address in order to implement some sort of DRM, inventory, or classification system, since you tried to get the permanent MAC address instead of the current one.
You seem to forget that there's even an administratively super-imposed MAC address (in other words: a "forced" MAC address).
Some drivers let you do this from the Device Property page, under the Advanced tab (for example: my Marvell network adapter let me do this), while some others don't let you do that (read: they don't support that property).
However, it all ends in a Registry value: HKLM\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\xxxx\NetworkAddress, with a REG_SZ type.
Here you can set a different MAC address than the original one, in the form "01020304abcd" (6 bytes, plain hexadecimal, without : separators or 0x prefix).
After you set it, reboot the machine, and on power-up the new MAC address will have effect.
I happen to have a motherboard with two Marvell integrated NICs, and a NETGEAR USB WiFi NIC. The Marvell one supports changing the MAC address: if you set the NetworkAddress value in the Registry, you see the new value in the driver properties page, too, and it has effect immediately, without the need to restart (if you change it from device Property Page).
Here follows the results of reading the MAC address with different methods:
GetAdaptersInfo: new MAC address
IOCTL_NDIS_QUERY_GLOBAL_STATS: original MAC address
MSNdis_EthernetPermanentAddress: original MAC address
I tried adding the NetworkAddress value in the Registry for the NETGEAR USB WiFi NIC, and the results are:
GetAdaptersInfo: new MAC address
IOCTL_NDIS_QUERY_GLOBAL_STATS: new MAC address
MSNdis_EthernetPermanentAddress: new MAC address
The original MAC addres is gone.
So, in order to not be fooled by a "malicious" user, you always need to check the HKLM\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\xxxx\NetworkAddress Registry value. If that is set, i guess it's better to not trust that Network Adapter at all, since it is up to the driver implementation to decide what will be presented to you using the different methods.
Some background for getting to that Registry key:
Microsoft documentation about the HKLM\SYSTEM\CurrentControlSet\Class key
According to the Microsoft documentation on that page,
There is a subkey for each class that is named using the GUID of the
setup class
So we choose the {4D36E972-E325-11CE-BFC1-08002BE10318} subkey (aka GUID_DEVCLASS_NET, defined in <devguid.h>, and further documented here)
Again, according to Microsoft documentation,
Each class subkey contains other subkeys known as software keys (or, driver keys) for each device instance of that class installed in the system. Each of these software keys is named by using a device instance ID, which is a base-10, four-digit ordinal value
The xxxx part is a 4-character textual representation of a positive integer, starting from 0
So, you can traverse the subkeys up from 0000, 0001, 0002, up to the number of network adapters in your system.
The documentation stops here: I didn't find any other documentation about the different registry values, or such.
However, in each of these subkeys, you can find REG_SZ values that can help you link the GetAdaptersInfo(), MSNdis_EthernetPermanentAddress, Win32_NetworkAdapter, and Device Instance ID worlds (and this answers your question).
The Registry values are:
DeviceInstanceID: its value is, no surprise, the Device Instance ID
NetCfgInstanceId: its value is the AdapterName member of the IP_ADAPTER_INFO struct, returned by GetAdaptersInfo(). It is also the GUID member of the Win32_NetworkAdapter WMI class.
Don't forget the NetworkAddress one: should a valid MAC address exist here, a driver may report it as the MAC address in use by GetAdaptersInfo(), MSNdis_EthernetPermanentAddress, and IOCTL_NDIS_QUERY_GLOBAL_STATS!
Then, as you already said, the only connection between the MSNdis_EthernetPermanentAddress WMI Class and the rest of the "world" is by its InstanceName member. You can relate it to the Description member of the IP_ADAPTER_INFO struct, returned by GetAdaptersInfo(). Although it may be a localized name, it seems to be unique for the system (For my two integrated Marvell NICs, the second one has a " #2" appended to its name).
Final note:
Said all the above, the user could choose to disable WMI...
HRESULT CreatePartitionEx(ULONGLONG ullOffset, ULONGLONG ullSize, ULONG ulAlign, [in] CREATE_PARTITION_PARAMETERS *para, IVdsAsync **ppAsync
)
When i am passing parameter ppAsync = NULL , perticular call is failing and returned INVALIED argument.
Please help me to solve this issue.
According to the documentation, concerning the last parameter - ppAsync:
The address of an IVdsAsync interface pointer, which VDS initializes
on return. Callers must release the interface. Use this pointer to
cancel, wait for, or query the status of the operation.
This means that you should provide an actual pointer as a last parameter when calling the function. Since you are providing NULL, probably that is causing the problem.
EDIT:
Use like this:
IVdsAsync *pAsync; // Declare a pointer
// Then use it like this (take a look at the last parameter)
CreatePartitionEx(
ullOffset,
ullSize,
ulAlign,
para,
&pAsync); // You pass it with a leading &, which gives you the address of the pointer
And that should do it.
Remember that you should release the pAsync after you are finished with it, as the documentation states.
I am doing the same thing with Createvolume() , buts its returning hResult= E_InvalidArg . The fourth parameter is stripe size .The Windows implementation requires the stripe size to be 65536 if the type is VDS_VT_STRIPE or VDS_VT_PaARITY. Other volume types are not striped and the stripe size is 0.
Is there a way ( or an API ) to know when a text file is edited ( by a program or by a person ) and do a specific action ?
For example: I want to show a MessageBox when the file c:\Users\john\free.txt is edited.
Depends on when you exactly want to know it.
is your application running continuously and do you want to see any change as soon as possible?
is your application a simple command-line application that needs to check for changes once?
In the second case, you could check the modification dates of the file (as suggested by PoweRoy and Michal) or use a hash (as suggested by PoweRoy).
If your application is running continuously, you should use the FindFirstChangeNotification and ReadDirectoryChanges functions. You can read more about it on the following pages:
http://msdn.microsoft.com/en-us/library/windows/desktop/aa364417(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365465(v=vs.85).aspx.
Simplest: compare modification dates. But this can be manipulated.
Or make a hash of the original file and compare it with the current file.
GetFileTime should help you.
http://msdn.microsoft.com/en-us/library/ms724320%28v=vs.85%29.aspx
and there is GetFileAttributesEx as well.
check the file's last modify datetime.
This method retrieves status information related to a given CFile object instance or a given file path.
BOOL GetStatus(
CFileStatus& rStatus
) const;
static BOOL PASCAL GetStatus(
LPCTSTR lpszFileName,
CFileStatus& rStatus
);
Parameters
rStatus
A reference to a user-supplied CFileStatus structure that will receive the status information. The CFileStatus structure has the following fields:
CTime m_ctime The date and time the file was created.
CTime m_mtime The date and time the file was last modified.
CTime m_atime The date and time the file was last accessed for reading.
ULONGLONG m_size The logical size of the file in bytes, as reported by the DIR command.
BYTE m_attribute The attribute byte of the file.
char m_szFullName[_MAX_PATH] The absolute filename in the Windows character set.
lpszFileName
A string in the Windows character set that is the path to the desired file. The path can be relative or absolute, or it can contain a network path name.
Return Value
TRUE if the status information for the specified file is successfully obtained; otherwise, FALSE.
PS:information from MSDN
I posted a question earlier regarding obtaining GPU clock speeds, but I guess the thread appeared as already answered since someone had replied to it.
I'd been advised by one of your members to try extracting GPU clock speeds using SetupDiEnumDeviceInfo.
However, I looked around at some examples, like this one: http://www.codeproject.com/KB/system/DevMgr.aspx
and nothing seemed to be displayed about the clock speed.
Could someone please elaborate on how to achieve this, if at all possible?
Thanks again
You will want to check out this msdn article:
http://msdn.microsoft.com/en-us/library/bb742655.aspx
Specifically, follow these steps:
Call SetupDiGetDeviceRegistryProperty to retrieve the size, in bytes, of the property value. Supply the following parameter values:
Set DeviceInfoSet to a handle to a device information set that contains the device instance for which to retrieve the requested property value.
Set DeviceInfoData to a pointer to an SP_DEVINFO_DATA structure that represents the device instance for which to retrieve the requested property value.
Set Property to an SPDRP_Xxx identifier. For a list of these identifiers and a description of the corresponding device properties, see the description of the Property parameter that is included with SetupDiSetDeviceRegistryProperty.
Set PropertyRegDataType to a pointer to a DWORD-typed variable.
Set PropertyBuffer to NULL.
Set PropertyBufferSize to zero.
Set RequiredSize to a pointer to a DWORD-typed variable that receives, the size, in bytes of the property value.
In response to the call to SetupDiSetDeviceRegistryProperty, SetupDiGetDeviceRegistryProperty sets *RequiredSize to the size, in bytes, of the buffer that is required to retrieve the property value, logs the error code ERROR_INSUFFICIENT_BUFFER, and returns FALSE. A subsequent call to GetLastError will return the most recently logged error code.
Call SetupDiGetDeviceRegistryProperty again and supply the same parameter values that were supplied in the first call, except for the following changes:
Set PropertyBuffer to a pointer to a BYTE-typed buffer that receives the requested property value.
Set PropertyBufferSize to the the size, in bytes, of the PropertyBuffer buffer. The first call to SetupDiGetDeviceRegistryProperty retrieved the required size of the PropertyBuffer buffer in *RequiredSize.
This link shows how to get to the point where you've got the required strucutres to call SetupDiGetDeviceRegistryProperty.
http://www.pinvoke.net/default.aspx/setupapi/SetupDiEnumDeviceInfo.html