DosExitList

Bindings:  C, MASM 

This call maintains a list of routines that execute when the current 
process ends. 

 DosExitList   (FcnCode_Order, RtnAddress) 
 

 FcnCode_Order (USHORT) - input 
    Two-byte fields. The low-order byte indicates the operation being 
    performed by DosExitList, which can be used to update the list of 
    routines, or to transfer to the next address on the termination list 
    at the completion of a routine. The values of the byte and their 
    meanings are: 

    Value     Definition 
    1         Add address to termination list. 
    2         Remove address from termination list. 
    3         Transfer to next address on termination list. 

   
    The high-order byte indicates the invocation order. This value is 
    valid only when the low-order byte is 1 (add an address).  For the 
    other low-order byte values, the high-order byte must be set to zero. 

   
    The invocation order determines the order in which routines are 
    invoked. Routines given a value of 0 are invoked first and routines 
    with a value of 255 are invoked last. If more than one routine is 
    added with the same invocation order value, the last routine to be 
    added is invoked first. The following values are used by OS/2 
    components: 

    Value       Definition 
    80H-88H     OS/2 Extended Edition Database Manager 
    90H-98H     OS/2 Extended Edition Communications Manager 
    A0H-A8H     OS/2 Presentation Manager 
    B0H         OS/2 KBD component 
    C0H         OS/2 VIO component 
    D0H         OS/2 IPC Queues component 

 RtnAddress (PFNEXITLIST) - input 
    The address of a routine to be executed. This address cannot be in an 
    IOPL segment. 

 rc (USHORT) - return 
    Return code descriptions are: 

    0         NO_ERROR 
    8         ERROR_NOT_ENOUGH_MEMORY 
    13        ERROR_INVALID_DATA 
 
 Remarks 

 DosExitList maintains a list of addresses to routines that receive 
 control when a process is terminated.  These addresses must be in the 
 address space of the terminating process. DosExitList routines perform 
 clean-up operations on resources. For example, DosExitList can be used in 
 a dynamic link library module to free resources and semaphores after a 
 client program has ended. 

 During DosExitList processing, the process is in a state of partial 
 termination.  All threads of the process are terminated, except for the 
 one executing the routines.  Ownership of any exclusive semaphores 
 created by the process with DosCreateSem was transferred to the 
 DosExitList thread, so the thread can access protected resources. 
 Termination routines should be short and fail-safe, so there is minimum 
 delay in completing process termination. 

 Before transferring control to the termination routines, OS/2 resets the 
 stack to its initial value. Transfer is by way of a JMP instruction. The 
 first parameter on the stack (located at SS:SP+4) contains an indicator 
 of why the process ended. The meanings of values returned are the same as 
 those for termination codes returned by DosCwait or  DosExecPgm requests. 
 These values are: 

 0         EXIT (normal exit) 
 1         Hard error abort 
 2         Trap operation 
 3         Unintercepted DosKillProcess. 
 

 Each routine on the list receives control in numeric order by function 
 high-order byte. For example, low (0) is first with high (0FFH) being 
 last.  In case of duplicate entries for the same value, the routines are 
 executed in LIFO order. 

 When a routine has completed its processing, it issues  DosExitList with 
 function = 3. Control is then transferred to the next address in the 
 invocation order. If a routine on the list does not issue DosExitList at 
 the completion of its processing, the process hangs, and OS/2 prevents 
 termination. When all addresses are serviced, the process completes 
 exiting. 

 Most OS/2 system calls are valid in a DosExitList routine; however, 
 certain functions such as DosCreateThread and DosExecPgm are not. 
 Functions requested in a routine must not be higher in the function code 
 order hierarchy than the invocation order specified for the routine.