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Annotation of os2sdk/demos/examples/cwait/cwait.c, revision 1.1.1.1

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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