Hey, im doing a little app for my smart phone, using Windows Mobile 6. I'm trying to get all currently running processec, but method CreateToolhelp32Snapshot always returns -1. So now im stuck. I tried to get error with invoking GetLastError() method, but that method returns 0 value. Here is a snippet of my code.
private const int TH32CS_SNAPPROCESS = 0x00000002;
[DllImport("toolhelp.dll")]
public static extern IntPtr CreateToolhelp32Snapshot(uint flags,
uint processid);
public static Process[] GetProcesses()
{
ArrayList procList = new ArrayList();
IntPtr handle = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if ((int)handle > 0)
{
try
{
PROCESSENTRY32 peCurr;
PROCESSENTRY32 pe32 = new PROCESSENTRY32();
// get byte array to pass to API call
byte[] peBytes = pe32.ToByteArray();
// get the first process
int retval = Process32First(handle, peBytes);
As a side note, the Smart Device Framework's OpenNETCF.ToolHelp namespace has all of this implemented and working (in case you'd rather not reinvent the wheel).
Instead of
CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
use
private const int TH32CS_SNAPNOHEAPS = 0x40000000;
CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS | TH32CS_SNAPNOHEAPS, 0);
By default CreateToolhelp32Snapshot will try to snapshot the heaps and that can cause an out of memory error.
Found this at https://social.msdn.microsoft.com/Forums/en-US/e91d845d-d51e-45ad-8acf-737e832c20d0/createtoolhelp32snapshot-windows-mobile-5?forum=vssmartdevicesnative and it solved my problem.
If you're not seeing valid "last error" information, perhaps you might need to add the "SetLastError" attribute on the API's DllImport attribute (MSDN reference with code examples). According to the documentation of this attribute, you should set SetLastError to...
...true to indicate that the callee will call SetLastError; otherwise, false. The default is false.
The runtime marshaler calls GetLastError and caches the value returned to prevent it from being overwritten by other API calls. You can retrieve the error code by calling GetLastWin32Error
As for the API failure you're seeing, I don't spot anything obvious offhand; the code you have seems very similar to the sample code here.
This is the proper implementation based on the MSDN documentation
private const int INVALID_HANDLE_VALUE = -1;
[Flags]
private enum SnapshotFlags : uint
{
HeapList = 0x00000001,
Process = 0x00000002,
Thread = 0x00000004,
Module = 0x00000008,
Module32 = 0x00000010,
Inherit = 0x80000000,
All = 0x0000001F,
NoHeaps = 0x40000000
}
[DllImport("toolhelp.dll"]
private static extern IntPtr CreateToolhelp32Snapshot(SnapshotFlags dwFlags, int th32ProcessID);
[StructLayout(LayoutKind.Sequential)]
public struct PROCESSENTRY32
{
public uint dwSize;
public uint cntUsage;
public uint th32ProcessID;
public IntPtr th32DefaultHeapID;
public uint th32ModuleID;
public uint cntThreads;
public uint th32ParentProcessID;
public int pcPriClassBase;
public uint dwFlags;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)] public string szExeFile;
};
IntPtr hSnap = CreateToolhelp32Snapshot(SnapshotFlags.Process, 0);
if (hSnap.ToInt64() != INVALID_HANDLE_VALUE)
{
PROCESSENTRY32 procEntry = new PROCESSENTRY32();
procEntry.dwSize = (uint)Marshal.SizeOf(typeof(PROCESSENTRY32));
if (Process32First(hSnap, ref procEntry))
{
do
{
//do whatever you want here
} while (Process32Next(hSnap, ref procEntry));
}
}
CloseHandle(hSnap);
Most importantly is this line, because you must set the size of the procEntry:
procEntry.dwSize = (uint)Marshal.SizeOf(typeof(PROCESSENTRY32));
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