tests/shunloadtest.c

   1 /*
   2  * Copyright (C) 2011, 2013 Red Hat, Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library 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 the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library.  If not, see
  16  * <http://www.gnu.org/licenses/>.
  17  *
  18  */
  19
  20 /*
  21  * When libvirt initializes, it creates a thread local for storing
  22  * the last virErrorPtr instance. It also registers a cleanup
  23  * callback for the thread local that will be invoked whenever
  24  * a thread exits.
  25  *
  26  * If the libvirt.so library was dlopen()'d and is dlclose()'d
  27  * while there is still a thread present, then when that thread
  28  * later exits, the libvirt cleanup callback will be invoked.
  29  * Unfortunately libvirt.so will no longer be in memory so the
  30  * callback SEGVs (if you're lucky), or invokes unlreated
  31  * code at the same address as the old callback (if you're
  32  * unlucky).
  33  *
  34  * To fix the problem libvirt is linked '-z nodelete' which
  35  * prevents the code being removed from memory at dlclose().
  36  *
  37  * This test case demonstrates this SEGV scenario. If this
  38  * test does not SEGV, then the '-z nodelete' fix is working
  39  */
  40
  41 #include <config.h>
  42
  43 #define NO_LIBVIRT /* This file intentionally does not link to libvirt */
  44 #include "testutils.h"
  45
  46 #ifdef linux
  47
  48 # include <dlfcn.h>
  49 # include <pthread.h>
  50 # include <unistd.h>
  51 # include <signal.h>
  52
  53 # include "internal.h"
  54
  55 pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  56 pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
  57 bool running = false;
  58 bool failstart = false;
  59 bool quit = false;
  60
  61 static void *threadMain(void *arg)
  62 {
  63     int (*startup)(void) = arg;
  64
  65     if (startup() < 0) {
  66         pthread_mutex_lock(&lock);
  67         failstart = true;
  68         pthread_cond_signal(&cond);
  69     } else {
  70         pthread_mutex_lock(&lock);
  71         running = true;
  72         pthread_cond_signal(&cond);
  73     }
  74
  75     while (!quit)
  76         pthread_cond_wait(&cond, &lock);
  77     pthread_mutex_unlock(&lock);
  78
  79     return NULL;
  80 }
  81
  82 static void sigHandler(int sig)
  83 {
  84     ignore_value(write(STDERR_FILENO, "FAIL\n", 5));
  85     signal(sig, SIG_DFL);
  86     raise(sig);
  87 }
  88
  89 /* We're not using the testutils.c main() wrapper because
  90  * we don't want  'shunloadtest' itself to link against
  91  * libvirt.so. We need to test dlopen()'ing of libvirt.so
  92  */
  93 int main(int argc ATTRIBUTE_UNUSED, char **argv)
  94 {
  95     void (*startup)(void);
  96     pthread_t t;
  97     void *lib;
  98     char *theprogname;
  99
 100     theprogname = argv[0];
 101     if (STRPREFIX(theprogname, "./"))
 102         theprogname += 2;
 103
 104     fprintf(stderr, "TEST: %s\n", theprogname);
 105     fprintf(stderr, "      .%*s 1   ", 39, "");
 106     signal(SIGSEGV, sigHandler);
 107
 108     if (!(lib = dlopen("./.libs/libshunload.so", RTLD_LAZY))) {
 109         fprintf(stderr, "Cannot load ./.libs/libshunload.so %s\n", dlerror());
 110         return 1;
 111     }
 112     if (!(startup = dlsym(lib, "shunloadStart"))) {
 113         fprintf(stderr, "Cannot find shunloadStart %s\n", dlerror());
 114         dlclose(lib);
 115         return 1;
 116     }
 117
 118     /*
 119      * Create a thread which is going to initialize libvirt
 120      * and raise an error
 121      */
 122     pthread_create(&t, NULL, threadMain, startup);
 123
 124     /* Wait for the thread to start and call libvirt */
 125     pthread_mutex_lock(&lock);
 126     while (!running && !failstart)
 127         pthread_cond_wait(&cond, &lock);
 128
 129     /* Close the shared library (and thus make libvirt.so
 130      * non-resident */
 131     dlclose(lib);
 132
 133     /* Tell the thread to quit */
 134     quit = true;
 135     pthread_cond_signal(&cond);
 136     pthread_mutex_unlock(&lock);
 137
 138     pthread_join(t, NULL);
 139
 140     /* If we got to here the thread successfully exited without
 141      * causing a SEGV !
 142      */
 143
 144     if (failstart)
 145         fprintf(stderr, "FAIL to initialize libvirt\n");
 146     else
 147         fprintf(stderr, "OK\n");
 148
 149     return 0;
 150 }
 151
 152 #else
 153
 154 int main(void)
 155 {
 156     return EXIT_AM_SKIP;
 157 }
 158
 159 #endif