Using Named Objects

The following example illustrates the use of object names by creating and opening a named mutex.

First Process

The first process uses the CreateMutex function to create the mutex object. Note that this function succeeds even if there is an existing object with the same name.

#include <windows.h>
#include <stdio.h>
#include <conio.h>

// This process creates the mutex object.

int main(void)
{
 HANDLE hMutex; 

 hMutex = CreateMutex( 
 NULL, // default security descriptor
 FALSE, // mutex not owned
 TEXT("NameOfMutexObject")); // object name

 if (hMutex == NULL) 
 printf("CreateMutex error: %d\n", GetLastError() ); 
 else 
 if ( GetLastError() == ERROR_ALREADY_EXISTS ) 
 printf("CreateMutex opened an existing mutex\n"); 
 else printf("CreateMutex created a new mutex.\n");

 // Keep this process around until the second process is run
 _getch();

 CloseHandle(hMutex);

 return 0;
}

Second Process

The second process uses the OpenMutex function to open a handle to the existing mutex. This function fails if a mutex object with the specified name does not exist. The access parameter requests full access to the mutex object, which is necessary for the handle to be used in any of the wait functions.

#include <windows.h>
#include <stdio.h>

// This process opens a handle to a mutex created by another process.

int main(void)
{
 HANDLE hMutex; 

 hMutex = OpenMutex( 
 MUTEX_ALL_ACCESS, // request full access
 FALSE, // handle not inheritable
 TEXT("NameOfMutexObject")); // object name

 if (hMutex == NULL) 
 printf("OpenMutex error: %d\n", GetLastError() );
 else printf("OpenMutex successfully opened the mutex.\n");

 CloseHandle(hMutex);

 return 0;
}

Related topics

Object Names

Using Mutex Objects