tests/test-lockfile.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2014 Nicira, Inc.
   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
  17 #include <config.h>
  18
  19 #include "lockfile.h"
  20
  21 #include <errno.h>
  22 #include <stdlib.h>
  23 #include <sys/stat.h>
  24 #include <sys/wait.h>
  25 #include <unistd.h>
  26
  27 #include "process.h"
  28 #include "timeval.h"
  29 #include "util.h"
  30 #include "vlog.h"
  31 #include "ovstest.h"
  32
  33 struct test {
  34     const char *name;
  35     void (*function)(void);
  36 };
  37
  38 static const struct test tests[];
  39
  40 #define CHECK(A, B) check(A, B, #A, #B, __FILE__, __LINE__)
  41 static void
  42 check(int a, int b,
  43       const char *a_string, const char *b_string, const char *file, int line)
  44 {
  45     if (a != b) {
  46         fprintf(stderr, "%s:%d: expected %s == %s but %d != %d\n",
  47                 file, line, a_string, b_string, a, b);
  48         fflush(stderr);
  49         abort();
  50     }
  51 }
  52
  53 static void
  54 run_lock_and_unlock(void)
  55 {
  56     struct lockfile *lockfile;
  57
  58     CHECK(lockfile_lock("file", &lockfile), 0);
  59     lockfile_unlock(lockfile);
  60 }
  61
  62 static void
  63 run_lock_and_unlock_twice(void)
  64 {
  65     struct lockfile *lockfile;
  66
  67     CHECK(lockfile_lock("file", &lockfile), 0);
  68     lockfile_unlock(lockfile);
  69
  70     CHECK(lockfile_lock("file", &lockfile), 0);
  71     lockfile_unlock(lockfile);
  72 }
  73
  74 static void
  75 run_lock_blocks_same_process(void)
  76 {
  77     struct lockfile *lockfile;
  78
  79     CHECK(lockfile_lock("file", &lockfile), 0);
  80     CHECK(lockfile_lock("file", &lockfile), EDEADLK);
  81     lockfile_unlock(lockfile);
  82 }
  83
  84 static void
  85 run_lock_blocks_same_process_twice(void)
  86 {
  87     struct lockfile *lockfile;
  88
  89     CHECK(lockfile_lock("file", &lockfile), 0);
  90     CHECK(lockfile_lock("file", &lockfile), EDEADLK);
  91     CHECK(lockfile_lock("file", &lockfile), EDEADLK);
  92     lockfile_unlock(lockfile);
  93 }
  94
  95 static enum { PARENT, CHILD }
  96 do_fork(void)
  97 {
  98     switch (fork()) {
  99     case 0:
 100         lockfile_postfork();
 101         return CHILD;
 102
 103     default:
 104         return PARENT;
 105
 106     case -1:
 107         /* Error. */
 108         ovs_fatal(errno, "fork failed");
 109     }
 110 }
 111
 112 static void
 113 run_lock_blocks_other_process(void)
 114 {
 115     /* Making this static prevents a memory leak warning from valgrind for the
 116      * parent process, which cannot easily unlock (and free) 'lockfile' because
 117      * it can only do so after the child has exited, and it's the caller of
 118      * this function that does the wait() call. */
 119     static struct lockfile *lockfile;
 120
 121     CHECK(lockfile_lock("file", &lockfile), 0);
 122     if (do_fork() == CHILD) {
 123         lockfile_unlock(lockfile);
 124         CHECK(lockfile_lock("file", &lockfile), EAGAIN);
 125         exit(11);
 126     }
 127 }
 128
 129 static void
 130 run_lock_twice_blocks_other_process(void)
 131 {
 132     struct lockfile *lockfile, *dummy;
 133
 134     CHECK(lockfile_lock("file", &lockfile), 0);
 135     CHECK(lockfile_lock("file", &dummy), EDEADLK);
 136     if (do_fork() == CHILD) {
 137         CHECK(lockfile_lock("file", &dummy), EAGAIN);
 138         exit(11);
 139     }
 140 }
 141
 142 static void
 143 run_lock_and_unlock_allows_other_process(void)
 144 {
 145     struct lockfile *lockfile;
 146
 147     CHECK(lockfile_lock("file", &lockfile), 0);
 148     lockfile_unlock(lockfile);
 149
 150     if (do_fork() == CHILD) {
 151         CHECK(lockfile_lock("file", &lockfile), 0);
 152         exit(11);
 153     }
 154 }
 155
 156 static void
 157 run_lock_multiple(void)
 158 {
 159     struct lockfile *a, *b, *c, *dummy;
 160
 161     CHECK(lockfile_lock("a", &a), 0);
 162     CHECK(lockfile_lock("b", &b), 0);
 163     CHECK(lockfile_lock("c", &c), 0);
 164
 165     lockfile_unlock(a);
 166     CHECK(lockfile_lock("a", &a), 0);
 167     CHECK(lockfile_lock("a", &dummy), EDEADLK);
 168     lockfile_unlock(a);
 169
 170     lockfile_unlock(b);
 171     CHECK(lockfile_lock("a", &a), 0);
 172
 173     lockfile_unlock(c);
 174     lockfile_unlock(a);
 175 }
 176
 177 /* Checks that locking a dangling symlink works OK.  (It used to hang.) */
 178 static void
 179 run_lock_symlink(void)
 180 {
 181     struct lockfile *a, *b, *dummy;
 182     struct stat s;
 183
 184     /* Create a symlink .a.~lock~ pointing to .b.~lock~. */
 185     CHECK(symlink(".b.~lock~", ".a.~lock~"), 0);
 186     CHECK(lstat(".a.~lock~", &s), 0);
 187     CHECK(S_ISLNK(s.st_mode) != 0, 1);
 188     CHECK(stat(".a.~lock~", &s), -1);
 189     CHECK(errno, ENOENT);
 190     CHECK(stat(".b.~lock~", &s), -1);
 191     CHECK(errno, ENOENT);
 192
 193     CHECK(lockfile_lock("a", &a), 0);
 194     CHECK(lockfile_lock("a", &dummy), EDEADLK);
 195     CHECK(lockfile_lock("b", &dummy), EDEADLK);
 196     lockfile_unlock(a);
 197
 198     CHECK(lockfile_lock("b", &b), 0);
 199     CHECK(lockfile_lock("b", &dummy), EDEADLK);
 200     CHECK(lockfile_lock("a", &dummy), EDEADLK);
 201     lockfile_unlock(b);
 202
 203     CHECK(lstat(".a.~lock~", &s), 0);
 204     CHECK(S_ISLNK(s.st_mode) != 0, 1);
 205     CHECK(stat(".a.~lock~", &s), 0);
 206     CHECK(S_ISREG(s.st_mode) != 0, 1);
 207     CHECK(stat(".b.~lock~", &s), 0);
 208     CHECK(S_ISREG(s.st_mode) != 0, 1);
 209 }
 210
 211 /* Checks that locking a file that is itself a symlink yields a lockfile in the
 212  * directory that the symlink points to, named for the target of the
 213  * symlink.
 214  *
 215  * (That is, if "a" is a symlink to "dir/b", then "a"'s lockfile is named
 216  * "dir/.b.~lock".) */
 217 static void
 218 run_lock_symlink_to_dir(void)
 219 {
 220     struct lockfile *a, *dummy;
 221     struct stat s;
 222
 223     /* Create a symlink "a" pointing to "dir/b". */
 224     CHECK(mkdir("dir", 0700), 0);
 225     CHECK(symlink("dir/b", "a"), 0);
 226     CHECK(lstat("a", &s), 0);
 227     CHECK(S_ISLNK(s.st_mode) != 0, 1);
 228
 229     /* Lock 'a'. */
 230     CHECK(lockfile_lock("a", &a), 0);
 231     CHECK(lstat("dir/.b.~lock~", &s), 0);
 232     CHECK(S_ISREG(s.st_mode) != 0, 1);
 233     CHECK(lstat(".a.~lock~", &s), -1);
 234     CHECK(errno, ENOENT);
 235     CHECK(lockfile_lock("dir/b", &dummy), EDEADLK);
 236
 237     lockfile_unlock(a);
 238 }
 239
 240 static void
 241 run_help(void)
 242 {
 243     size_t i;
 244
 245     printf("usage: %s TESTNAME\n"
 246            "where TESTNAME is one of the following:\n",
 247            program_name);
 248     for (i = 0; tests[i].name; i++) {
 249         fprintf(stderr, "\t%s\n", tests[i].name);
 250     }
 251 }
 252
 253 static const struct test tests[] = {
 254 #define TEST(NAME) { #NAME, run_##NAME }
 255     TEST(lock_and_unlock),
 256     TEST(lock_and_unlock_twice),
 257     TEST(lock_blocks_same_process),
 258     TEST(lock_blocks_same_process_twice),
 259     TEST(lock_blocks_other_process),
 260     TEST(lock_twice_blocks_other_process),
 261     TEST(lock_and_unlock_allows_other_process),
 262     TEST(lock_multiple),
 263     TEST(lock_symlink),
 264     TEST(lock_symlink_to_dir),
 265     TEST(help),
 266     { NULL, NULL }
 267 #undef TEST
 268 };
 269
 270 static void
 271 test_lockfile_main(int argc, char *argv[])
 272 {
 273     size_t i;
 274
 275     set_program_name(argv[0]);
 276     vlog_set_pattern(VLF_CONSOLE, "%c|%p|%m");
 277     vlog_set_levels(NULL, VLF_SYSLOG, VLL_OFF);
 278
 279     if (argc != 2) {
 280         ovs_fatal(0, "exactly one argument required; use \"%s help\" for help",
 281                   program_name);
 282     }
 283
 284     for (i = 0; tests[i].name; i++) {
 285         if (!strcmp(argv[1], tests[i].name)) {
 286             int n_children;
 287             int status;
 288
 289             (tests[i].function)();
 290
 291             n_children = 0;
 292             while (wait(&status) > 0) {
 293                 if (WIFEXITED(status) && WEXITSTATUS(status) == 11) {
 294                     n_children++;
 295                 } else {
 296                     ovs_fatal(0, "child exited in unexpected way: %s",
 297                               process_status_msg(status));
 298                 }
 299             }
 300             if (errno != ECHILD) {
 301                 ovs_fatal(errno, "wait");
 302             }
 303
 304             printf("%s: success (%d child%s)\n",
 305                    tests[i].name, n_children, n_children != 1 ? "ren" : "");
 306             exit(0);
 307         }
 308     }
 309     ovs_fatal(0, "unknown test \"%s\"; use \"%s help\" for help",
 310               argv[1], program_name);
 311 }
 312
 313 OVSTEST_REGISTER("test-lockfile", test_lockfile_main);