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

1.1     ! root        1: /*
        !             2:  * Example of DOSCWAIT usage.
        !             3:  *
        !             4:  * Although a process can only call DOSCWAIT on its own child processes,
        !             5:  * it is possible to wait indirectly on subsequent generations of
        !             6:  * processes by use of the ProcessAndDescendents flag.  To wait for a
        !             7:  * collection of subprocesses to end, a process must call DOSCWAIT
        !             8:  * repeatedly, once for each of the subprocesses.  The result codes
        !             9:  * field is only valid for the one call first call against the child.
        !            10:  * Subsequent calls indicate that another descendent process has ended,
        !            11:  * but do not return exit or termination codes.
        !            12:  * 
        !            13:  * To wait for any child, rather that a specific one, the process
        !            14:  * should pass in a process id of 0.  The pid of the process that ended
        !            15:  * will be placed in the ProcessIdWord field.
        !            16:  *
        !            17:  * Compile as: cl -AL -G2 -Lp cwait.c
        !            18:  *
        !            19:  * Copyright (C) Microsoft Corp. 1986
        !            20:  */
        !            21: 
        !            22: #include <doscalls.h>
        !            23: #include <stdio.h>
        !            24: 
        !            25: #define ERRBUF_LEN     64
        !            26: #define ARG_LEN                128
        !            27: 
        !            28: main()
        !            29: {
        !            30:        struct ResultCodes child_status, child_pid;
        !            31:        unsigned ending_pid, res;
        !            32:        char errbuf[ERRBUF_LEN];
        !            33:        char child_arg[ARG_LEN];
        !            34:        char *child_env;
        !            35: 
        !            36:        /*
        !            37:         * Execute a program and wait for it to finish.
        !            38:         */
        !            39:        DOSEXECPGM((char *)0, 0, 2, (char *)0, (char *)0, &child_pid,
        !            40:                "child.exe");
        !            41:        printf("exec'd child, pid = %u\n", child_pid);
        !            42:        DOSCWAIT(0,0, &child_status, &ending_pid, child_pid.TermCode_PID);
        !            43:        if (child_status.TermCode_PID != 0)
        !            44:                printf("error: child's termination code was %u\n",
        !            45:                        child_status.TermCode_PID);
        !            46:        else
        !            47:                printf("child process returned %u\n", child_status.ExitCode);
        !            48: 
        !            49:        /*
        !            50:         * Execute a program and wait for it and all of its descendents
        !            51:         * to finish. In this case we specify the top pid to wait for.
        !            52:         */
        !            53:        DOSEXECPGM((char *)0, 0, 2, (char *)0, (char *)0, &child_pid,
        !            54:                "child.exe");
        !            55:        printf("exec'd child, pid = %u\n", child_pid);
        !            56:        do {
        !            57:                res = DOSCWAIT(1,0, &child_status, &ending_pid,
        !            58:                        child_pid.TermCode_PID);
        !            59:                if(res == 0)
        !            60:                        printf("cwait found pid = %u\n", ending_pid);
        !            61:                else
        !            62:                        printf("cwait found no more process\n");
        !            63:        } while (res == 0);
        !            64:        
        !            65:        /*
        !            66:         * Wait for any child to terminate. In this case we specify
        !            67:         * the pid as zero, which means wait for any child to finish.
        !            68:         */
        !            69:        DOSEXECPGM((char *)0, 0, 2, (char *)0, (char *)0, &child_pid,
        !            70:                "child.exe");
        !            71:        printf("exec'd child, pid = %u\n", child_pid);
        !            72:        do {
        !            73:                res = DOSCWAIT(1,0, &child_status, &ending_pid, 0);
        !            74:                if (res == 0)
        !            75:                        printf("child %u ended\n", ending_pid);
        !            76:        } while (res == 0);
        !            77: }

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