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/* libguestfs
* Copyright (C) 2012 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* Regression test for RHBZ#790721.
*
* This bug involves locking issues when building the appliance in
* parallel from multiple threads in the same process. We use a read
* lock on the 'checksum' file, and it turns out this causes two
* problems: (1) locks don't have any effect on threads in the same
* process, and (2) because the PID is identical in different threads,
* the file we are trying to overwrite has the same name.
*
* To test this we want to create the appliance repeatedly from
* multiple threads, but we don't really care about launching the full
* qemu (a waste of time and memory for this test). Therefore replace
* qemu with a fake process and just look for the linking error.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
#include "guestfs.h"
#define STRNEQ(a,b) (strcmp((a),(b)) != 0)
/* Number of worker threads running the test. */
#define NR_THREADS 20
static pthread_barrier_t barrier;
static void *start_thread (void *);
int
main (int argc, char *argv[])
{
pthread_t thread[NR_THREADS];
int data[NR_THREADS];
int i, r, errors;
guestfs_h *g;
char *attach_method;
/* Test is only meaningful if the attach-method "appliance" is used. */
g = guestfs_create ();
if (!g) {
perror ("guestfs_create");
exit (EXIT_FAILURE);
}
attach_method = guestfs_get_attach_method (g);
if (attach_method == NULL) {
guestfs_close (g);
exit (EXIT_FAILURE);
}
if (STRNEQ (attach_method, "appliance")) {
fprintf (stderr, "%s: test skipped because attach method isn't 'appliance'.\n",
argv[0]);
free (attach_method);
guestfs_close (g);
exit (77);
}
free (attach_method);
guestfs_close (g);
/* Ensure error messages are not translated. */
setenv ("LC_ALL", "C", 1);
pthread_barrier_init (&barrier, NULL, NR_THREADS);
/* Create the other threads which will set up their own libguestfs
* handle then wait at a barrier before launching.
*/
for (i = 0; i < NR_THREADS; ++i) {
data[i] = i;
r = pthread_create (&thread[i], NULL, start_thread, &data[i]);
if (r != 0) {
fprintf (stderr, "pthread_create: %s\n", strerror (r));
exit (EXIT_FAILURE);
}
}
/* Wait for the threads to exit. */
errors = 0;
for (i = 0; i < NR_THREADS; ++i) {
int *ret;
r = pthread_join (thread[i], (void **) &ret);
if (r != 0) {
fprintf (stderr, "pthread_join: %s\n", strerror (r));
exit (EXIT_FAILURE);
}
if (*ret == -1)
errors++;
}
exit (errors == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
}
static void *
start_thread (void *vi)
{
guestfs_h *g;
int r, thread_id = *(int *)vi;
guestfs_error_handler_cb old_error_cb;
void *old_error_data;
const char *error;
g = guestfs_create ();
if (g == NULL) {
perror ("guestfs_create");
*(int *)vi = -1;
pthread_exit (vi);
}
if (guestfs_add_drive_opts (g, "/dev/null",
GUESTFS_ADD_DRIVE_OPTS_FORMAT, "raw",
GUESTFS_ADD_DRIVE_OPTS_READONLY, 1,
-1) == -1) {
*(int *)vi = -1;
pthread_exit (vi);
}
/* Fake out qemu. */
if (guestfs_set_qemu (g, "/bin/true") == -1) {
*(int *)vi = -1;
pthread_exit (vi);
}
/* Wait for the other threads to finish starting up. */
r = pthread_barrier_wait (&barrier);
if (r != 0 && r != PTHREAD_BARRIER_SERIAL_THREAD) {
fprintf (stderr, "pthread_barrier_wait: [thread %d]: %s\n",
thread_id, strerror (r));
*(int *)vi = -1;
pthread_exit (vi);
}
/* Launch the handle. Because of the faked out qemu, we expect this
* will fail with "child process died unexpectedly". We are
* interested in other failures.
*/
old_error_cb = guestfs_get_error_handler (g, &old_error_data);
guestfs_set_error_handler (g, NULL, NULL);
r = guestfs_launch (g);
error = guestfs_last_error (g);
if (r == 0) { /* This should NOT happen. */
fprintf (stderr, "rhbz790721: [thread %d]: "
"strangeness in test: expected launch to fail, but it didn't!\n",
thread_id);
*(int *)vi = -1;
pthread_exit (vi);
}
if (error == NULL) { /* This also should NOT happen. */
fprintf (stderr, "rhbz790721: [thread %d]: "
"strangeness in test: no error message!\n",
thread_id);
*(int *)vi = -1;
pthread_exit (vi);
}
/* If this happens, it indicates a bug/race in the appliance
* building code which is what this regression test is designed to
* spot.
*/
if (STRNEQ (error, "child process died unexpectedly")) {
fprintf (stderr, "rhbz790721: [thread %d]: error: %s\n", thread_id, error);
*(int *)vi = -1;
pthread_exit (vi);
}
guestfs_set_error_handler (g, old_error_cb, old_error_data);
/* Close the handle. */
guestfs_close (g);
*(int *)vi = 0;
pthread_exit (vi);
}
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