1/*
2 *   Copyright (c) International Business Machines  Corp., 2001
3 *
4 *   This program is free software;  you can redistribute it and/or modify
5 *   it under the terms of the GNU General Public License as published by
6 *   the Free Software Foundation; either version 2 of the License, or
7 *   (at your option) any later version.
8 *
9 *   This program is distributed in the hope that it will be useful,
10 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
11 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
12 *   the GNU General Public License for more details.
13 *
14 *   You should have received a copy of the GNU General Public License
15 *   along with this program;  if not, write to the Free Software
16 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 *
18 *
19 * NAME
20 *	fork12.c
21 *
22 * DESCRIPTION
23 *	Check that all children inherit parent's file descriptor
24 *
25 * ALGORITHM
26 *	Parent forks processes until -1 is returned.$
27 *
28 * USAGE
29 *	fork12
30 *	** CAUTION ** Can hang your machine, esp prior to 2.4.19
31 *
32 * HISTORY
33 *	07/2001 Ported by Wayne Boyer
34 *	07/2002 Split from fork07 as a test case to exhaust available pids.
35 *
36 * RESTRICTIONS
37 *	Should be run as root to avoid resource limits.$
38 *	Should not be run with other test programs because it tries to
39 *	  use all available pids.
40 */
41
42#include <stdio.h>
43#include <sys/wait.h>
44#include <errno.h>
45#include <string.h>
46#include "test.h"
47#include "safe_macros.h"
48
49char *TCID = "fork12";
50int TST_TOTAL = 1;
51
52static void setup(void);
53static void cleanup(void);
54static void fork12_sigs(int signum);
55
56int main(int ac, char **av)
57{
58	int forks, pid1, fork_errno, waitstatus;
59	int ret, status;
60	int lc;
61
62	tst_parse_opts(ac, av, NULL, NULL);
63
64	setup();
65
66	for (lc = 0; TEST_LOOPING(lc); lc++) {
67		tst_count = 0;
68
69		tst_resm(TINFO, "Forking as many kids as possible");
70		forks = 0;
71		while ((pid1 = fork()) != -1) {
72			if (pid1 == 0) {	/* child */
73				/*
74				 * Taunt the OOM killer so that it doesn't
75				 * kill system processes
76				 */
77				SAFE_FILE_PRINTF(NULL,
78					"/proc/self/oom_score_adj", "500");
79				pause();
80				exit(0);
81			}
82			forks++;
83			ret = SAFE_WAITPID(cleanup, -1, &status, WNOHANG);
84			if (ret > 0) {
85				/* a child may be killed by OOM killer */
86				if (WTERMSIG(status) == SIGKILL)
87					break;
88				tst_brkm(TBROK, cleanup,
89					 "child exit with error code %d or signal %d",
90					 WEXITSTATUS(status), WTERMSIG(status));
91			}
92		}
93		fork_errno = errno;
94
95		/* parent */
96		tst_resm(TINFO, "Number of processes forked is %d", forks);
97		tst_resm(TPASS, "fork() eventually failed with %d: %s",
98			 fork_errno, strerror(fork_errno));
99		/* collect our kids */
100		/*
101		 * Introducing a sleep(3) to make sure all children are
102		 * at pause() when SIGQUIT is sent to them
103		 */
104		sleep(3);
105		kill(0, SIGQUIT);
106		while (wait(&waitstatus) > 0) ;
107
108	}
109
110	cleanup();
111	tst_exit();
112}
113
114static void setup(void)
115{
116	tst_sig(FORK, fork12_sigs, cleanup);
117	TEST_PAUSE;
118}
119
120static void cleanup(void)
121{
122	int waitstatus;
123
124	/* collect our kids */
125	kill(0, SIGQUIT);
126	while (wait(&waitstatus) > 0) ;
127}
128
129static void fork12_sigs(int signum)
130{
131	if (signum == SIGQUIT) {
132		/* Children will continue, parent will ignore */
133	} else {
134		tst_brkm(TBROK, cleanup,
135			 "Unexpected signal %d received.", signum);
136	}
137}
138