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Annotation of os2sdk/demos/examples/exitlist/exitlist.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Example of DOSEXITLIST usage.
        !             3:  *
        !             4:  * Typically, exit list routines are used to free any resources that the
        !             5:  * process may have owned, and leave any shared resources in a consistent
        !             6:  * state. Semaphores and shared memory are the common cases. It is not
        !             7:  * necessary to close files, since the system does that automatically
        !             8:  * when a process terminates.
        !             9:  *
        !            10:  * When a process is in exit list processing, it is already in a
        !            11:  * half-terminated state, and should be very careful not to cause
        !            12:  * problems or execute too long.  Specifically, actions such as waiting
        !            13:  * on semaphores or for other processes to finish are extremely bad
        !            14:  * ideas.  It is not possible to create new threads or exec another
        !            15:  * process while in exit list processing.
        !            16:  *
        !            17:  * This example shows exit list processing routines being added and removed.
        !            18:  *
        !            19:  * Copyright (C) Microsoft Corp. 1986
        !            20:  */
        !            21: 
        !            22: #include <doscalls.h>
        !            23: 
        !            24: void e_handler1();                     /* two exit handler routines */
        !            25: void e_handler2();
        !            26: 
        !            27: #define        EXLIST_ADD      1               /* add routine to exit list */
        !            28: #define        EXLIST_REMOVE   2               /* remove routine from exit list */
        !            29: #define        EXLIST_DONE     3               /* terminate exit list handler */
        !            30: 
        !            31: void main()
        !            32: {
        !            33:        /* add a routine to the termination list */
        !            34:        DOSEXITLIST(EXLIST_ADD, e_handler1);
        !            35:        
        !            36:        /* add another routine to the termination list */
        !            37:        DOSEXITLIST(EXLIST_ADD, e_handler2);
        !            38: 
        !            39:        /* remove a routine from the termination list */
        !            40:        DOSEXITLIST(EXLIST_REMOVE, e_handler1);
        !            41:        
        !            42:        /* exit this process */
        !            43:        printf("about to exit\n");
        !            44:        DOSEXIT(1,0);
        !            45: }
        !            46: 
        !            47: /* first exit handler, not actually called in this example */
        !            48: void e_handler1()
        !            49: {
        !            50:        /* shared resource cleanup should be done here */
        !            51:        printf("this is exit handler 1\n");
        !            52: 
        !            53:        /* advance to next handler in exit list (if any) */
        !            54:        DOSEXITLIST(EXLIST_DONE, (char *)0);
        !            55: }
        !            56: 
        !            57: /* second exit handler - this one is called when the process terminates */
        !            58: void e_handler2()
        !            59: {
        !            60:        /* shared resource cleanup should be done here */
        !            61:        printf("this is exit handler 2\n");
        !            62: 
        !            63:        /* advance to next handler in exit list (if any) */
        !            64:        DOSEXITLIST(EXLIST_DONE, (char *)0);
        !            65: }

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