cpueater.c revision e16cb84e2324f05334d18dcf5956f20f44262b62 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 *
16 * Simple cpu eater busy loop. Runs as a daemon. prints the child PID to
17 * std so you can easily kill it later.
18 */
19
20#include <stdio.h>
21#include <unistd.h>
22#include <stdlib.h>
23#include <fcntl.h>
24#include <sys/types.h>
25#include <sys/stat.h>
26
27
28int main(int argc, char *argv[])
29{
30    pid_t pid;
31    int life_universe_and_everything;
32    int fd;
33
34    switch(fork()) {
35        case -1:
36            perror(argv[0]);
37            exit(1);
38            break;
39        case 0: /* child */
40            chdir("/");
41            umask(0);
42            setpgrp();
43            setsid();
44            /* fork again to fully detach from controlling terminal. */
45            switch(pid = fork()) {
46                case -1:
47                    break;
48                case 0: /* second child */
49                    /* redirect to /dev/null */
50                    close(0);
51                    open("/dev/null", 0);
52                    close(1);
53                    if(open("/dev/null", O_WRONLY) < 0) {
54                        perror("/dev/null");
55                        exit(1);
56                    }
57                    fflush(stdout);
58                    close(2);
59                    dup(1);
60                    for (fd = 3; fd < 256; fd++) {
61                        close(fd);
62                    }
63                    /* busy looper */
64                    while (1) {
65                        life_universe_and_everything = 42 * 2;
66                    }
67                  default:
68                      /* so caller can easily kill it later. */
69                      printf("%d\n", pid);
70                      exit(0);
71                      break;
72                }
73                break;
74          default:
75              exit(0);
76              break;
77    }
78  return 0;
79}
80
81
82/* vim:ts=4:sw=4:softtabstop=4:smarttab:expandtab */
83
84