support/signal.c

   1 /*
   2  * <signal.h> wrapper functions.
   3  *
   4  * Authors:
   5  *   Jonathan Pryor (jonpryor@vt.edu)
   6  *   Jonathan Pryor (jpryor@novell.com)
   7  *   Tim Jenks (tim.jenks@realtimeworlds.com)
   8  *
   9  * Copyright (C) 2004-2005 Jonathan Pryor
  10  * Copyright (C) 2008 Novell, Inc.
  11  */
  12
  13 #include <signal.h>
  14
  15 #include "map.h"
  16 #include "mph.h"
  17
  18 #ifndef HOST_WIN32
  19 #include <sys/time.h>
  20 #include <sys/types.h>
  21 #if defined(__APPLE__)
  22 #include "fakepoll.h"
  23 #else
  24 #include <poll.h>
  25 #endif
  26 #include <unistd.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <pthread.h>
  30 #include <mono/utils/atomic.h>
  31 #include <mono/metadata/appdomain.h>
  32 #endif
  33
  34 G_BEGIN_DECLS
  35
  36 typedef void (*mph_sighandler_t)(int);
  37 typedef struct Mono_Unix_UnixSignal_SignalInfo signal_info;
  38
  39 #ifndef HOST_WIN32
  40 static int count_handlers (int signum);
  41 #endif
  42
  43 void*
  44 Mono_Posix_Stdlib_SIG_DFL (void)
  45 {
  46         return SIG_DFL;
  47 }
  48
  49 void*
  50 Mono_Posix_Stdlib_SIG_ERR (void)
  51 {
  52         return SIG_ERR;
  53 }
  54
  55 void*
  56 Mono_Posix_Stdlib_SIG_IGN (void)
  57 {
  58         return SIG_IGN;
  59 }
  60
  61 void
  62 Mono_Posix_Stdlib_InvokeSignalHandler (int signum, void *handler)
  63 {
  64         mph_sighandler_t _h = (mph_sighandler_t) handler;
  65         _h (signum);
  66 }
  67
  68 int Mono_Posix_SIGRTMIN (void)
  69 {
  70 #ifdef SIGRTMIN
  71         return SIGRTMIN;
  72 #else /* def SIGRTMIN */
  73         return -1;
  74 #endif /* ndef SIGRTMIN */
  75 }
  76
  77 int Mono_Posix_SIGRTMAX (void)
  78 {
  79 #ifdef SIGRTMAX
  80         return SIGRTMAX;
  81 #else /* def SIGRTMAX */
  82         return -1;
  83 #endif /* ndef SIGRTMAX */
  84 }
  85
  86 int Mono_Posix_FromRealTimeSignum (int offset, int *r)
  87 {
  88         if (NULL == r) {
  89                 errno = EINVAL;
  90                 return -1;
  91         }
  92         *r = 0;
  93 #if defined (SIGRTMIN) && defined (SIGRTMAX)
  94         if ((offset < 0) || (SIGRTMIN > SIGRTMAX - offset)) {
  95                 errno = EINVAL;
  96                 return -1;
  97         }
  98         *r = SIGRTMIN+offset;
  99         return 0;
 100 #else /* defined (SIGRTMIN) && defined (SIGRTMAX) */
 101 # ifdef ENOSYS
 102         errno = ENOSYS;
 103 # endif /* ENOSYS */
 104         return -1;
 105 #endif /* defined (SIGRTMIN) && defined (SIGRTMAX) */
 106 }
 107
 108 #ifndef HOST_WIN32
 109
 110 #ifndef WAPI_NO_ATOMIC_ASM
 111         #define mph_int_get(p)     InterlockedExchangeAdd ((p), 0)
 112         #define mph_int_inc(p)     InterlockedIncrement ((p))
 113         #define mph_int_dec_test(p)     (InterlockedDecrement ((p)) == 0)
 114         #define mph_int_set(p,o,n) InterlockedExchange ((p), (n))
 115 #elif GLIB_CHECK_VERSION(2,4,0)
 116         #define mph_int_get(p) g_atomic_int_get ((p))
 117         #define mph_int_inc(p) do {g_atomic_int_inc ((p));} while (0)
 118         #define mph_int_dec_test(p) g_atomic_int_dec_and_test ((p))
 119         #define mph_int_set(p,o,n) do {                                 \
 120                 while (!g_atomic_int_compare_and_exchange ((p), (o), (n))) {} \
 121         } while (0)
 122 #else
 123         #define mph_int_get(p) (*(p))
 124         #define mph_int_inc(p) do { (*(p))++; } while (0)
 125         #define mph_int_dec_test(p) (--(*(p)) == 0)
 126         #define mph_int_set(p,o,n) do { *(p) = n; } while (0)
 127 #endif
 128
 129 #if HAVE_PSIGNAL
 130 int
 131 Mono_Posix_Syscall_psignal (int sig, const char* s)
 132 {
 133         errno = 0;
 134         psignal (sig, s);
 135         return errno == 0 ? 0 : -1;
 136 }
 137 #endif  /* def HAVE_PSIGNAL */
 138
 139 #define NUM_SIGNALS 64
 140 static signal_info signals[NUM_SIGNALS];
 141
 142 static int acquire_mutex (pthread_mutex_t *mutex)
 143 {
 144         int mr;
 145         while ((mr = pthread_mutex_lock (mutex)) == EAGAIN) {
 146                 /* try to acquire again */
 147         }
 148         if ((mr != 0) && (mr != EDEADLK))  {
 149                 errno = mr;
 150                 return -1;
 151         }
 152         return 0;
 153 }
 154
 155 static void release_mutex (pthread_mutex_t *mutex)
 156 {
 157         int mr;
 158         while ((mr = pthread_mutex_unlock (mutex)) == EAGAIN) {
 159                 /* try to release mutex again */
 160         }
 161 }
 162
 163 static inline int
 164 keep_trying (int r)
 165 {
 166         return r == -1 && errno == EINTR;
 167 }
 168
 169 static void
 170 default_handler (int signum)
 171 {
 172         int i;
 173         for (i = 0; i < NUM_SIGNALS; ++i) {
 174                 int fd;
 175                 signal_info* h = &signals [i];
 176                 if (mph_int_get (&h->signum) != signum)
 177                         continue;
 178                 mph_int_inc (&h->count);
 179                 fd = mph_int_get (&h->write_fd);
 180                 if (fd > 0) {
 181                         int j,pipecounter;
 182                         char c = signum;
 183                         pipecounter = mph_int_get (&h->pipecnt);
 184                         for (j = 0; j < pipecounter; ++j) {
 185                                 int r;
 186                                 do { r = write (fd, &c, 1); } while (keep_trying (r));
 187                                 fsync (fd); /* force */
 188                         }
 189                 }
 190         }
 191 }
 192
 193 static pthread_mutex_t signals_mutex = PTHREAD_MUTEX_INITIALIZER;
 194
 195 void*
 196 Mono_Unix_UnixSignal_install (int sig)
 197 {
 198         int i;
 199         signal_info* h = NULL;
 200         int have_handler = 0;
 201         void* handler = NULL;
 202
 203         if (acquire_mutex (&signals_mutex) == -1)
 204                 return NULL;
 205
 206 #if defined (SIGRTMIN) && defined (SIGRTMAX)
 207         /*The runtime uses some rt signals for itself so it's important to not override them.*/
 208         if (sig >= SIGRTMIN && sig <= SIGRTMAX && count_handlers (sig) == 0) {
 209                 struct sigaction sinfo;
 210                 sigaction (sig, NULL, &sinfo);
 211                 if (sinfo.sa_handler != SIG_DFL || (void*)sinfo.sa_sigaction != (void*)SIG_DFL) {
 212                         pthread_mutex_unlock (&signals_mutex);
 213                         errno = EADDRINUSE;
 214                         return NULL;
 215                 }
 216         }
 217 #endif /*defined (SIGRTMIN) && defined (SIGRTMAX)*/
 218
 219         for (i = 0; i < NUM_SIGNALS; ++i) {
 220                 if (h == NULL && signals [i].signum == 0) {
 221                         h = &signals [i];
 222                         h->handler = signal (sig, default_handler);
 223                         if (h->handler == SIG_ERR) {
 224                                 h->handler = NULL;
 225                                 h = NULL;
 226                                 break;
 227                         }
 228                         else {
 229                                 h->have_handler = 1;
 230                         }
 231                 }
 232                 if (!have_handler && signals [i].signum == sig &&
 233                                 signals [i].handler != default_handler) {
 234                         have_handler = 1;
 235                         handler = signals [i].handler;
 236                 }
 237                 if (h && have_handler)
 238                         break;
 239         }
 240
 241         if (h && have_handler) {
 242                 h->have_handler = 1;
 243                 h->handler      = handler;
 244         }
 245
 246         if (h) {
 247                 mph_int_set (&h->count, h->count, 0);
 248                 mph_int_set (&h->signum, h->signum, sig);
 249                 mph_int_set (&h->pipecnt, h->pipecnt, 0);
 250         }
 251
 252         release_mutex (&signals_mutex);
 253
 254         return h;
 255 }
 256
 257 static int
 258 count_handlers (int signum)
 259 {
 260         int i;
 261         int count = 0;
 262         for (i = 0; i < NUM_SIGNALS; ++i) {
 263                 if (signals [i].signum == signum)
 264                         ++count;
 265         }
 266         return count;
 267 }
 268
 269 int
 270 Mono_Unix_UnixSignal_uninstall (void* info)
 271 {
 272         signal_info* h;
 273         int r = -1;
 274
 275         if (acquire_mutex (&signals_mutex) == -1)
 276                 return -1;
 277
 278         h = info;
 279
 280         if (h == NULL || h < signals || h > &signals [NUM_SIGNALS])
 281                 errno = EINVAL;
 282         else {
 283                 /* last UnixSignal -- we can unregister */
 284                 if (h->have_handler && count_handlers (h->signum) == 1) {
 285                         mph_sighandler_t p = signal (h->signum, h->handler);
 286                         if (p != SIG_ERR)
 287                                 r = 0;
 288                         h->handler      = NULL;
 289                         h->have_handler = 0;
 290                 }
 291                 h->signum = 0;
 292         }
 293
 294         release_mutex (&signals_mutex);
 295
 296         return r;
 297 }
 298
 299 static int
 300 setup_pipes (signal_info** signals, int count, struct pollfd *fd_structs, int *currfd)
 301 {
 302         int i;
 303         int r = 0;
 304         for (i = 0; i < count; ++i) {
 305                 signal_info* h;
 306                 int filedes[2];
 307
 308                 h = signals [i];
 309
 310                 if (mph_int_get (&h->pipecnt) == 0) {
 311                         if ((r = pipe (filedes)) != 0) {
 312                                 break;
 313                         }
 314                         h->read_fd  = filedes [0];
 315                         h->write_fd = filedes [1];
 316                 }
 317                 mph_int_inc (&h->pipecnt);
 318                 fd_structs[*currfd].fd = h->read_fd;
 319                 fd_structs[*currfd].events = POLLIN;
 320                 ++(*currfd);
 321         }
 322         return r;
 323 }
 324
 325 static void
 326 teardown_pipes (signal_info** signals, int count)
 327 {
 328         int i;
 329         for (i = 0; i < count; ++i) {
 330                 signal_info* h = signals [i];
 331
 332                 if (mph_int_dec_test (&h->pipecnt)) {
 333                         if (h->read_fd != 0)
 334                                 close (h->read_fd);
 335                         if (h->write_fd != 0)
 336                                 close (h->write_fd);
 337                         h->read_fd  = 0;
 338                         h->write_fd = 0;
 339                 }
 340         }
 341 }
 342
 343 static int
 344 wait_for_any (signal_info** signals, int count, int *currfd, struct pollfd* fd_structs, int timeout, Mono_Posix_RuntimeIsShuttingDown shutting_down)
 345 {
 346         int r, idx;
 347         do {
 348                 struct timeval tv;
 349                 struct timeval *ptv = NULL;
 350                 if (timeout != -1) {
 351                         tv.tv_sec  = timeout / 1000;
 352                         tv.tv_usec = (timeout % 1000)*1000;
 353                         ptv = &tv;
 354                 }
 355                 r = poll (fd_structs, count, timeout);
 356         } while (keep_trying (r) && !shutting_down ());
 357
 358         idx = -1;
 359         if (r == 0)
 360                 idx = timeout;
 361         else if (r > 0) {
 362                 int i;
 363                 for (i = 0; i < count; ++i) {
 364                         signal_info* h = signals [i];
 365                         if (fd_structs[i].revents & POLLIN) {
 366                                 int r;
 367                                 char c;
 368                                 do {
 369                                         r = read (h->read_fd, &c, 1);
 370                                 } while (keep_trying (r) && !shutting_down ());
 371                                 if (idx == -1)
 372                                         idx = i;
 373                         }
 374                 }
 375         }
 376
 377         return idx;
 378 }
 379
 380 /*
 381  * returns: -1 on error:
 382  *          timeout on timeout
 383  *          index into _signals array of signal that was generated on success
 384  */
 385 int
 386 Mono_Unix_UnixSignal_WaitAny (void** _signals, int count, int timeout /* milliseconds */, Mono_Posix_RuntimeIsShuttingDown shutting_down)
 387 {
 388         int r;
 389         int currfd = 0;
 390         struct pollfd fd_structs[NUM_SIGNALS];
 391
 392         signal_info** signals = (signal_info**) _signals;
 393
 394         if (count > NUM_SIGNALS)
 395                 return -1;
 396
 397         if (acquire_mutex (&signals_mutex) == -1)
 398                 return -1;
 399
 400         r = setup_pipes (signals, count, &fd_structs[0], &currfd);
 401
 402         release_mutex (&signals_mutex);
 403
 404         if (r == 0) {
 405                 r = wait_for_any (signals, count, &currfd, &fd_structs[0], timeout, shutting_down);
 406         }
 407
 408         if (acquire_mutex (&signals_mutex) == -1)
 409                 return -1;
 410
 411         teardown_pipes (signals, count);
 412
 413         release_mutex (&signals_mutex);
 414
 415         return r;
 416 }
 417
 418 #endif /* ndef HOST_WIN32 */
 419
 420
 421 G_END_DECLS
 422
 423 /*
 424  * vim: noexpandtab
 425  */