90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
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/* This file is part of the sample code and exercises
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* used by the class "Advanced Programming in the UNIX
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* Environment" taught by Jan Schaumann
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* <jschauma@netmeister.org> at Stevens Institute of
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* Technology.
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*
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* This file is in the public domain.
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*
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* You don't have to, but if you feel like
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* acknowledging where you got this code, you may
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* reference me by name, email address, or point
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* people to the course website:
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* https://stevens.netmeister.org/631/
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*/
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/* This program creates as many worker children as
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* requested. To facilitate identification in the
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* process table, we self-exec with a fake argv[0].
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*/
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#include <sys/wait.h>
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#include <err.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <strings.h>
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#include <unistd.h>
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#define ARGV0_LENGTH 8 + 1 /* "worker" + 2 digits + NULL */
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#define MAXCHILDREN 32
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void
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work() {
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int i = 0;
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while (1) {
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i++;
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}
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}
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int
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main(int argc, char **argv) {
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int n;
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pid_t pid;
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if (argc == 1) {
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work();
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/* NOTREACHED */
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} else if (argc > 2) {
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(void)fprintf(stderr, "Usage: %s num\n", argv[0]);
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exit(EXIT_FAILURE);
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/* NOTREACHED */
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}
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n = atoi(argv[1]);
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if ((n < 1) || (n > MAXCHILDREN)) {
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(void)fprintf(stderr, "Please provide a number > 0 and <= %d.\n", MAXCHILDREN);
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exit(EXIT_FAILURE);
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/* NOTREACHED */
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}
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for (int i = 0; i < n; i++) {
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if ((pid = fork()) < 0) {
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err(EXIT_FAILURE, "fork");
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/* NOTREACHED */
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} else if (!pid) {
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char argv0[ARGV0_LENGTH];
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bzero(argv0, ARGV0_LENGTH);
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(void)snprintf(argv0, ARGV0_LENGTH, "worker%d", i);
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(void)printf("Created %s: %d\n", argv0, getpid());
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char * const args[] = { argv0, NULL };
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execve("./a.out", args, NULL);
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err(EXIT_FAILURE, "execve");
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/* NOTREACHED */
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}
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}
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while ((pid = wait(NULL)) > 0);
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if ((pid < 0) && errno != ECHILD) {
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err(EXIT_FAILURE, "wait");
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/* NOTREACHED */
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}
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return EXIT_SUCCESS;
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}
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