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