_heapset
Go Up to malloc.h Index
Header File
malloc.h
Prototype
int _heapset(unsigned int fillvalue);
Description
Fills the free blocks on the heap with a constant value.
_heapset checks the heap for consistency using the same methods as _heapchk. It then fills each free block in the heap with the value contained in the least significant byte of fillvalue. This function can be used to find heap-related problems. It does not guarantee that subsequently allocated blocks will be filled with the specified value.
Return Value
One of the following values:
_HEAPOK | The heap appears to be uncorrupted |
_HEAPEMPTY | No heap exists |
_HEAPBADNODE | A corrupted heap block has been found |
Portability
POSIX | ANSI C | ANSI C++ | Win32 | Win64 | macOS | |
---|---|---|---|---|---|---|
_heapset | + |
Example
#include <windowsx.h>
#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>
BOOL InitApplication(HINSTANCE hInstance);
HWND InitInstance(HINSTANCE hInstance, int nCmdShow);
LRESULT FAR PASCAL _export MainWndProc(HWND hWnd, UINT message, WPARAM wParam,
LPARAM lParam);
void ExampleHeapSet(HWND hWnd);
#pragma argsused
int PASCAL WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow) {
MSG msg; // message
if (!InitApplication(hInstance)) // Initialize shared things
return (FALSE); // Exits if unable to initialize
/* Perform initializations that apply to a specific instance */
if (!(InitInstance(hInstance, nCmdShow)))
return (FALSE);
/* Acquire and dispatch messages until a WM_QUIT message is received. */
while (GetMessage(& msg, // message structure
NULL, // handle of window receiving the message
NULL, // lowest message to examine
NULL)) // highest message to examine
{
TranslateMessage(& msg); // Translates virtual key codes
DispatchMessage(& msg); // Dispatches message to window
}
return (msg.wParam); // Returns the value from PostQuitMessage
}
BOOL InitApplication(HINSTANCE hInstance) {
WNDCLASS wc;
// Fill in window class structure with parameters that describe the
// main window.
wc.style = CS_HREDRAW | CS_VREDRAW; // Class style(s).
wc.lpfnWndProc = (long(FAR PASCAL*)(void *, unsigned int, unsigned int,
long))MainWndProc; // Function to retrieve messages for
// windows of this class.
wc.cbClsExtra = 0; // No per-class extra data.
wc.cbWndExtra = 0; // No per-window extra data.
wc.hInstance = hInstance; // Application that owns the class.
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = GetStockObject(WHITE_BRUSH);
wc.lpszMenuName = NULL; // Name of menu resource in .RC file.
wc.lpszClassName = "Example"; // Name used in call to CreateWindow.
/* Register the window class and return success/failure code. */
return (RegisterClass(& wc));
}
HWND InitInstance(HINSTANCE hInstance, int nCmdShow) {
HWND hWnd; // Main window handle.
/* Create a main window for this application instance. */
hWnd = CreateWindow("Example", // See RegisterClass() call.
"Example _heapset 32 bit only", // Text for window title bar.
WS_OVERLAPPEDWINDOW, // Window style.
CW_USEDEFAULT, // Default horizontal position.
CW_USEDEFAULT, // Default vertical position.
CW_USEDEFAULT, // Default width.
CW_USEDEFAULT, // Default height.
NULL, // Overlapped windows have no parent.
NULL, // Use the window class menu.
hInstance, // This instance owns this window.
NULL // Pointer not needed.
);
/* If window could not be created, return "failure" */
if (!hWnd)
return (FALSE);
/* Make the window visible; update its client area; and return "success" */
ShowWindow(hWnd, nCmdShow); // Show the window
UpdateWindow(hWnd); // Sends WM_PAINT message
return (hWnd); // Returns the value from PostQuitMessage
}
void ExampleHeapSet(HWND hWnd) {
int hsts;
char *buffer;
if ((buffer = (char *)malloc(1)) == NULL)
exit(0);
hsts = _heapset('Z');
switch (hsts) {
case _HEAPOK:
MessageBox(hWnd, "Heap is OK", "Heap", MB_OK | MB_ICONINFORMATION);
break;
case _HEAPEMPTY:
MessageBox(hWnd, "Heap is empty", "Heap", MB_OK | MB_ICONINFORMATION);
break;
case _HEAPBADNODE:
MessageBox(hWnd, "Bad node in heap", "Heap",
MB_OK | MB_ICONINFORMATION);
break;
default:
break;
}
free(buffer);
}
#pragma argsused
LRESULT FAR PASCAL _export MainWndProc(HWND hWnd, UINT message, WPARAM wParam,
LPARAM lParam) {
switch (message) {
case WM_CREATE: {
// Example _heapset
ExampleHeapSet(hWnd);
return NULL;
}
case WM_QUIT:
case WM_DESTROY: // message: window being destroyed
PostQuitMessage(0);
break;
default: // Passes it on if unprocessed
return (DefWindowProc(hWnd, message, wParam, lParam));
}
}