fork12.c revision d59a659cd639ca2780b00049d102acd2a783d585 
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 "usctest.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	char *msg;
62
63	msg = parse_opts(ac, av, NULL, NULL);
64	if (msg != NULL)
65		tst_brkm(TBROK, NULL, "OPTION PARSING ERROR - %s", msg);
66
67	setup();
68
69	for (lc = 0; TEST_LOOPING(lc); lc++) {
70		tst_count = 0;
71
72		tst_resm(TINFO, "Forking as many kids as possible");
73		forks = 0;
74		while ((pid1 = fork()) != -1) {
75			if (pid1 == 0) {	/* child */
76				pause();
77				exit(0);
78			}
79			forks++;
80			ret = waitpid(-1, &status, WNOHANG);
81			if (ret < 0)
82				tst_brkm(TBROK, cleanup,
83					 "waitpid failed %d: %s\n", errno,
84					 strerror(errno));
85			if (ret > 0) {
86				/* a child may be killed by OOM killer */
87				if (WTERMSIG(status) == SIGKILL)
88					break;
89				tst_brkm(TBROK, cleanup,
90					 "child exit with error code %d or signal %d",
91					 WEXITSTATUS(status), WTERMSIG(status));
92			}
93		}
94		fork_errno = errno;
95
96		/* parent */
97		tst_resm(TINFO, "Number of processes forked is %d", forks);
98		tst_resm(TPASS, "fork() eventually failed with %d: %s",
99			 fork_errno, strerror(fork_errno));
100		/* collect our kids */
101		/*
102		 * Introducing a sleep(3) to make sure all children are
103		 * at pause() when SIGQUIT is sent to them
104		 */
105		sleep(3);
106		kill(0, SIGQUIT);
107		while (wait(&waitstatus) > 0) ;
108
109	}
110
111	cleanup();
112	tst_exit();
113}
114
115static void setup()
116{
117	tst_sig(FORK, fork12_sigs, cleanup);
118	TEST_PAUSE;
119}
120
121static void cleanup()
122{
123	int waitstatus;
124
125	/* collect our kids */
126	kill(0, SIGQUIT);
127	while (wait(&waitstatus) > 0) ;
128	TEST_CLEANUP;
129}
130
131static void fork12_sigs(int signum)
132{
133	if (signum == SIGQUIT) {
134		/* Children will continue, parent will ignore */
135	} else {
136		tst_brkm(TBROK, cleanup,
137			 "Unexpected signal %d received.", signum);
138	}
139}
140