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Processes and Threads

Information about running processes and threads is crucial for system monitoring and management.

Key Functions:

• OpenProcess: Retrieves a handle to an existing process object.
• EnumProcesses: Retrieves the process identifier for each of the system's processes.
• GetProcessTimes: Retrieves timing information for the specified process.
• CreateToolhelp32Snapshot: Takes a snapshot of the specified set of processes, modules, or threads.

Related Structures:

• PROCESSENTRY32: Describes an entry in the process table.

// Example: Get process ID
HANDLE hProcess = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, pid);
if (hProcess != NULL) {
    // ... use process handle
    CloseHandle(hProcess);
}
                    

Memory Management

Understand memory usage, allocation, and system memory status.

Key Functions:

• GlobalMemoryStatusEx: Fills the structure specified by the lpBuffer parameter with information about the current memory utilization of the computer.
• VirtualQueryEx: Retrieves detailed information about a range of pages in the virtual address space of the calling process.
• GetSystemInfo: Populates the specified structure with information about the current system.

Related Structures:

• MEMORYSTATUSEX: Contains information about the current memory status of the computer.
• SYSTEM_INFO: Contains information about the current computer system.

MEMORYSTATUSEX memInfo;
memInfo.dwLength = sizeof(MEMORYSTATUSEX);
GlobalMemoryStatusEx(&memInfo);
// Access memInfo.ullTotalPhys, memInfo.ullAvailPhys, etc.
                    

Performance Counters

Access real-time performance data for various system components.

Key Functions:

• PdhOpenLog: Opens a performance data log file.
• PdhCollectQueryData: Collects data for the specified counter query.
• PdhGetFormattedCounterValue: Retrieves the formatted value of a counter.

Note:

For more direct kernel access to performance data, consider using Windows Management Instrumentation (WMI) or specific performance driver interfaces.

Environment Variables

Retrieve system-wide and user-specific environment variables.

Key Functions:

• GetEnvironmentVariable: Retrieves the value of the specified environment variable for the current process.
• SetEnvironmentVariable: Sets the value of an environment variable for the current process.

Example:

TCHAR userName[256];
DWORD len = GetEnvironmentVariable(TEXT("USERNAME"), userName, 256);
if (len > 0 && len < 256) {
    wcout << L"Current User: " << userName << endl;
}
                    

System Limits

Query system-defined limits and configurations.

Key Functions:

• GetSystemMetrics: Retrieves the specified system metric (sometimes referred to as a user interface element or feature).
• GetNativeSystemInfo: Populates the structure specified by lpSystemInfo with information about the current computer.

Common Metrics:

• SM_CXSCREEN: Width of the screen.
• SM_CYSCREEN: Height of the screen.
• SM_NUMBEROFPROCESSORS: Number of logical processors.