gdb/testsuite/gdb.threads/siginfo-threads.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2010-2022 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #define _GNU_SOURCE
  19 #include <pthread.h>
  20 #include <stdio.h>
  21 #include <limits.h>
  22 #include <errno.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <assert.h>
  26 #include <sys/types.h>
  27 #include <signal.h>
  28 #include <unistd.h>
  29 #include <asm/unistd.h>
  30
  31 #define gettid() syscall (__NR_gettid)
  32 #define tgkill(tgid, tid, sig) syscall (__NR_tgkill, tgid, tid, sig)
  33
  34 /* Terminate always in the main task.  It can lock up with SIGSTOPped
  35    GDB otherwise.  */
  36 #define TIMEOUT (gettid () == getpid() ? 10 : 15)
  37
  38 static pid_t thread1_tid;
  39 static pthread_cond_t thread1_tid_cond
  40   = PTHREAD_COND_INITIALIZER;
  41 static pthread_mutex_t thread1_tid_mutex
  42   = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;
  43 static int thread1_sigusr1_hit;
  44 static int thread1_sigusr2_hit;
  45
  46 static pid_t thread2_tid;
  47 static pthread_cond_t thread2_tid_cond
  48   = PTHREAD_COND_INITIALIZER;
  49 static pthread_mutex_t thread2_tid_mutex
  50   = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;
  51 static int thread2_sigusr1_hit;
  52 static int thread2_sigusr2_hit;
  53
  54 static pthread_mutex_t terminate_mutex
  55   = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;
  56
  57 static pthread_barrier_t threads_started_barrier;
  58
  59 /* Do not use alarm as it would create a ptrace event which would hang
  60    us up if we are being traced by GDB, which we stopped
  61    ourselves.  */
  62
  63 static void
  64 timed_mutex_lock (pthread_mutex_t *mutex)
  65 {
  66   int i;
  67   struct timespec start, now;
  68
  69   i = clock_gettime (CLOCK_MONOTONIC, &start);
  70   assert (i == 0);
  71
  72   do
  73     {
  74       i = pthread_mutex_trylock (mutex);
  75       if (i == 0)
  76         return;
  77       assert (i == EBUSY);
  78
  79       i = clock_gettime (CLOCK_MONOTONIC, &now);
  80       assert (i == 0);
  81       assert (now.tv_sec >= start.tv_sec);
  82     }
  83   while (now.tv_sec - start.tv_sec < TIMEOUT);
  84
  85   fprintf (stderr, "Timed out waiting for internal lock!\n");
  86   exit (EXIT_FAILURE);
  87 }
  88
  89 static void
  90 handler (int signo, siginfo_t *siginfo, void *exception)
  91 {
  92   int *varp;
  93
  94   assert (siginfo->si_signo == signo);
  95   assert (siginfo->si_code == SI_TKILL);
  96   assert (siginfo->si_pid == getpid ());
  97
  98   if (gettid () == thread1_tid)
  99     {
 100       if (signo == SIGUSR1)
 101         varp = &thread1_sigusr1_hit;
 102       else if (signo == SIGUSR2)
 103         varp = &thread1_sigusr2_hit;
 104       else
 105         assert (0);
 106     }
 107   else if (gettid () == thread2_tid)
 108     {
 109       if (signo == SIGUSR1)
 110         varp = &thread2_sigusr1_hit;
 111       else if (signo == SIGUSR2)
 112         varp = &thread2_sigusr2_hit;
 113       else
 114         assert (0);
 115     }
 116   else
 117     assert (0);
 118
 119   if (*varp)
 120     {
 121       fprintf (stderr, "Signal %d for TID %lu has been already hit!\n", signo,
 122                (unsigned long) gettid ());
 123       exit (EXIT_FAILURE);
 124     }
 125   *varp = 1;
 126 }
 127
 128 static void *
 129 thread1_func (void *unused)
 130 {
 131   int i;
 132
 133   pthread_barrier_wait (&threads_started_barrier);
 134
 135   timed_mutex_lock (&thread1_tid_mutex);
 136
 137   /* THREAD1_TID_MUTEX must be already locked to avoid a race.  */
 138   thread1_tid = gettid ();
 139
 140   i = pthread_cond_signal (&thread1_tid_cond);
 141   assert (i == 0);
 142   i = pthread_mutex_unlock (&thread1_tid_mutex);
 143   assert (i == 0);
 144
 145   /* Be sure the "t (tracing stop)" test can proceed for both
 146      threads.  */
 147   timed_mutex_lock (&terminate_mutex);
 148   i = pthread_mutex_unlock (&terminate_mutex);
 149   assert (i == 0);
 150
 151   if (!thread1_sigusr1_hit)
 152     {
 153       fprintf (stderr, "Thread 1 signal SIGUSR1 not hit!\n");
 154       exit (EXIT_FAILURE);
 155     }
 156   if (!thread1_sigusr2_hit)
 157     {
 158       fprintf (stderr, "Thread 1 signal SIGUSR2 not hit!\n");
 159       exit (EXIT_FAILURE);
 160     }
 161
 162   return NULL;
 163 }
 164
 165 static void *
 166 thread2_func (void *unused)
 167 {
 168   int i;
 169
 170   pthread_barrier_wait (&threads_started_barrier);
 171
 172   timed_mutex_lock (&thread2_tid_mutex);
 173
 174   /* THREAD2_TID_MUTEX must be already locked to avoid a race.  */
 175   thread2_tid = gettid ();
 176
 177   i = pthread_cond_signal (&thread2_tid_cond);
 178   assert (i == 0);
 179   i = pthread_mutex_unlock (&thread2_tid_mutex);
 180   assert (i == 0);
 181
 182   /* Be sure the "t (tracing stop)" test can proceed for both
 183      threads.  */
 184   timed_mutex_lock (&terminate_mutex);
 185   i = pthread_mutex_unlock (&terminate_mutex);
 186   assert (i == 0);
 187
 188   if (!thread2_sigusr1_hit)
 189     {
 190       fprintf (stderr, "Thread 2 signal SIGUSR1 not hit!\n");
 191       exit (EXIT_FAILURE);
 192     }
 193   if (!thread2_sigusr2_hit)
 194     {
 195       fprintf (stderr, "Thread 2 signal SIGUSR2 not hit!\n");
 196       exit (EXIT_FAILURE);
 197     }
 198
 199   return NULL;
 200 }
 201
 202 static const char *
 203 proc_string (const char *filename, const char *line)
 204 {
 205   FILE *f;
 206   static char buf[LINE_MAX];
 207   size_t line_len = strlen (line);
 208
 209   f = fopen (filename, "r");
 210   if (f == NULL)
 211     {
 212       fprintf (stderr, "fopen (\"%s\") for \"%s\": %s\n", filename, line,
 213                strerror (errno));
 214       exit (EXIT_FAILURE);
 215     }
 216   while (errno = 0, fgets (buf, sizeof (buf), f))
 217     {
 218       char *s;
 219
 220       s = strchr (buf, '\n');
 221       assert (s != NULL);
 222       *s = 0;
 223
 224       if (strncmp (buf, line, line_len) != 0)
 225         continue;
 226
 227       if (fclose (f))
 228         {
 229           fprintf (stderr, "fclose (\"%s\") for \"%s\": %s\n", filename, line,
 230                    strerror (errno));
 231           exit (EXIT_FAILURE);
 232         }
 233
 234       return &buf[line_len];
 235     }
 236   if (errno != 0)
 237     {
 238       fprintf (stderr, "fgets (\"%s\": %s\n", filename, strerror (errno));
 239       exit (EXIT_FAILURE);
 240     }
 241   fprintf (stderr, "\"%s\": No line \"%s\" found.\n", filename, line);
 242   exit (EXIT_FAILURE);
 243 }
 244
 245 static unsigned long
 246 proc_ulong (const char *filename, const char *line)
 247 {
 248   const char *s = proc_string (filename, line);
 249   long retval;
 250   char *end;
 251
 252   errno = 0;
 253   retval = strtol (s, &end, 10);
 254   if (retval < 0 || retval >= LONG_MAX || (end && *end))
 255     {
 256       fprintf (stderr, "\"%s\":\"%s\": %ld, %s\n", filename, line, retval,
 257                strerror (errno));
 258       exit (EXIT_FAILURE);
 259     }
 260   return retval;
 261 }
 262
 263 static void
 264 state_wait (pid_t process, const char *wanted)
 265 {
 266   char *filename;
 267   int i;
 268   struct timespec start, now;
 269   const char *state;
 270
 271   i = asprintf (&filename, "/proc/%lu/status", (unsigned long) process);
 272   assert (i > 0);
 273
 274   i = clock_gettime (CLOCK_MONOTONIC, &start);
 275   assert (i == 0);
 276
 277   do
 278     {
 279       state = proc_string (filename, "State:\t");
 280
 281       /* torvalds/linux-2.6.git 464763cf1c6df632dccc8f2f4c7e50163154a2c0
 282          has changed "T (tracing stop)" to "t (tracing stop)".  Make the GDB
 283          testcase backward compatible with older Linux kernels.  */
 284       if (strcmp (state, "T (tracing stop)") == 0)
 285         state = "t (tracing stop)";
 286
 287       if (strcmp (state, wanted) == 0)
 288         {
 289           free (filename);
 290           return;
 291         }
 292
 293       if (sched_yield ())
 294         {
 295           perror ("sched_yield()");
 296           exit (EXIT_FAILURE);
 297         }
 298
 299       i = clock_gettime (CLOCK_MONOTONIC, &now);
 300       assert (i == 0);
 301       assert (now.tv_sec >= start.tv_sec);
 302     }
 303   while (now.tv_sec - start.tv_sec < TIMEOUT);
 304
 305   fprintf (stderr, "Timed out waiting for PID %lu \"%s\" (now it is \"%s\")!\n",
 306            (unsigned long) process, wanted, state);
 307   exit (EXIT_FAILURE);
 308 }
 309
 310 static volatile pid_t tracer = 0;
 311 static pthread_t thread1, thread2;
 312
 313 static void
 314 cleanup (void)
 315 {
 316   printf ("Resuming GDB PID %lu.\n", (unsigned long) tracer);
 317
 318   if (tracer)
 319     {
 320       int i;
 321       int tracer_save = tracer;
 322
 323       tracer = 0;
 324
 325       i = kill (tracer_save, SIGCONT);
 326       assert (i == 0);
 327     }
 328 }
 329
 330 int
 331 main (int argc, char **argv)
 332 {
 333   int i;
 334   int standalone = 0;
 335   struct sigaction act;
 336
 337   if (argc == 2 && strcmp (argv[1], "-s") == 0)
 338     standalone = 1;
 339   else
 340     assert (argc == 1);
 341
 342   setbuf (stdout, NULL);
 343
 344   timed_mutex_lock (&thread1_tid_mutex);
 345   timed_mutex_lock (&thread2_tid_mutex);
 346
 347   timed_mutex_lock (&terminate_mutex);
 348
 349   errno = 0;
 350   memset (&act, 0, sizeof (act));
 351   act.sa_sigaction = handler;
 352   act.sa_flags = SA_RESTART | SA_SIGINFO;
 353   i = sigemptyset (&act.sa_mask);
 354   assert_perror (errno);
 355   assert (i == 0);
 356   i = sigaction (SIGUSR1, &act, NULL);
 357   assert_perror (errno);
 358   assert (i == 0);
 359   i = sigaction (SIGUSR2, &act, NULL);
 360   assert_perror (errno);
 361   assert (i == 0);
 362
 363   pthread_barrier_init (&threads_started_barrier, NULL, 3);
 364
 365   i = pthread_create (&thread1, NULL, thread1_func, NULL);
 366   assert (i == 0);
 367
 368   i = pthread_create (&thread2, NULL, thread2_func, NULL);
 369   assert (i == 0);
 370
 371   if (!standalone)
 372     {
 373       tracer = proc_ulong ("/proc/self/status", "TracerPid:\t");
 374       if (tracer == 0)
 375         {
 376           fprintf (stderr, "The testcase must be run by GDB!\n");
 377           exit (EXIT_FAILURE);
 378         }
 379       if (tracer != getppid ())
 380         {
 381           fprintf (stderr, "The testcase parent must be our GDB tracer!\n");
 382           exit (EXIT_FAILURE);
 383         }
 384     }
 385
 386   /* SIGCONT our debugger in the case of our crash as we would deadlock
 387      otherwise.  */
 388
 389   atexit (cleanup);
 390
 391   /* Wait until all threads are seen running.  On Linux (at least),
 392      new threads start stopped, and the debugger must resume them.
 393      Need to wait for that before stopping GDB.  */
 394   pthread_barrier_wait (&threads_started_barrier);
 395
 396   printf ("Stopping GDB PID %lu.\n", (unsigned long) tracer);
 397
 398   if (tracer)
 399     {
 400       i = kill (tracer, SIGSTOP);
 401       assert (i == 0);
 402       state_wait (tracer, "T (stopped)");
 403     }
 404
 405   /* Threads are now waiting at timed_mutex_lock (thread1_tid_mutex)
 406      and so they could not trigger the signals before GDB is unstopped
 407      later.  Threads get resumed by the pthread_cond_wait below.  Use
 408      `while' loops for protection against spurious pthread_cond_wait
 409      wakeups.  */
 410
 411   printf ("Waiting till the threads initialize their TIDs.\n");
 412
 413   while (thread1_tid == 0)
 414     {
 415       i = pthread_cond_wait (&thread1_tid_cond, &thread1_tid_mutex);
 416       assert (i == 0);
 417     }
 418
 419   while (thread2_tid == 0)
 420     {
 421       i = pthread_cond_wait (&thread2_tid_cond, &thread2_tid_mutex);
 422       assert (i == 0);
 423     }
 424
 425   printf ("Thread 1 TID = %lu, thread 2 TID = %lu, PID = %lu.\n",
 426           (unsigned long) thread1_tid, (unsigned long) thread2_tid,
 427           (unsigned long) getpid ());
 428
 429   errno = 0;
 430   i = tgkill (getpid (), thread1_tid, SIGUSR1);
 431   assert_perror (errno);
 432   assert (i == 0);
 433   i = tgkill (getpid (), thread1_tid, SIGUSR2);
 434   assert_perror (errno);
 435   assert (i == 0);
 436   i = tgkill (getpid (), thread2_tid, SIGUSR1);
 437   assert_perror (errno);
 438   assert (i == 0);
 439   i = tgkill (getpid (), thread2_tid, SIGUSR2);
 440   assert_perror (errno);
 441   assert (i == 0);
 442
 443   printf ("Waiting till the threads are trapped by the signals.\n");
 444
 445   if (tracer)
 446     {
 447       /* s390x-unknown-linux-gnu will fail with "R (running)".  */
 448
 449       state_wait (thread1_tid, "t (tracing stop)");
 450
 451       state_wait (thread2_tid, "t (tracing stop)");
 452     }
 453
 454   cleanup ();
 455
 456   printf ("Joining the threads.\n");
 457
 458   i = pthread_mutex_unlock (&terminate_mutex);
 459   assert (i == 0);
 460
 461   i = pthread_join (thread1, NULL);
 462   assert (i == 0);
 463
 464   i = pthread_join (thread2, NULL);
 465   assert (i == 0);
 466
 467   printf ("Exiting.\n");        /* break-at-exit */
 468
 469   return EXIT_SUCCESS;
 470 }