gdb/ser-base.c

   1 /* Generic serial interface functions.
   2
   3    Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001, 2003,
   4    2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "serial.h"
  23 #include "ser-base.h"
  24 #include "event-loop.h"
  25
  26 #include "gdb_select.h"
  27 #include "gdb_string.h"
  28 #include <sys/time.h>
  29 #ifdef USE_WIN32API
  30 #include <winsock2.h>
  31 #endif
  32
  33
  34 static timer_handler_func push_event;
  35 static handler_func fd_event;
  36
  37 /* Event handling for ASYNC serial code.
  38
  39    At any time the SERIAL device either: has an empty FIFO and is
  40    waiting on a FD event; or has a non-empty FIFO/error condition and
  41    is constantly scheduling timer events.
  42
  43    ASYNC only stops pestering its client when it is de-async'ed or it
  44    is told to go away. */
  45
  46 /* Value of scb->async_state: */
  47 enum {
  48   /* >= 0 (TIMER_SCHEDULED) */
  49   /* The ID of the currently scheduled timer event. This state is
  50      rarely encountered.  Timer events are one-off so as soon as the
  51      event is delivered the state is shanged to NOTHING_SCHEDULED. */
  52   FD_SCHEDULED = -1,
  53   /* The fd_event() handler is scheduled.  It is called when ever the
  54      file descriptor becomes ready. */
  55   NOTHING_SCHEDULED = -2
  56   /* Either no task is scheduled (just going into ASYNC mode) or a
  57      timer event has just gone off and the current state has been
  58      forced into nothing scheduled. */
  59 };
  60
  61 /* Identify and schedule the next ASYNC task based on scb->async_state
  62    and scb->buf* (the input FIFO).  A state machine is used to avoid
  63    the need to make redundant calls into the event-loop - the next
  64    scheduled task is only changed when needed. */
  65
  66 static void
  67 reschedule (struct serial *scb)
  68 {
  69   if (serial_is_async_p (scb))
  70     {
  71       int next_state;
  72
  73       switch (scb->async_state)
  74         {
  75         case FD_SCHEDULED:
  76           if (scb->bufcnt == 0)
  77             next_state = FD_SCHEDULED;
  78           else
  79             {
  80               delete_file_handler (scb->fd);
  81               next_state = create_timer (0, push_event, scb);
  82             }
  83           break;
  84         case NOTHING_SCHEDULED:
  85           if (scb->bufcnt == 0)
  86             {
  87               add_file_handler (scb->fd, fd_event, scb);
  88               next_state = FD_SCHEDULED;
  89             }
  90           else
  91             {
  92               next_state = create_timer (0, push_event, scb);
  93             }
  94           break;
  95         default: /* TIMER SCHEDULED */
  96           if (scb->bufcnt == 0)
  97             {
  98               delete_timer (scb->async_state);
  99               add_file_handler (scb->fd, fd_event, scb);
 100               next_state = FD_SCHEDULED;
 101             }
 102           else
 103             next_state = scb->async_state;
 104           break;
 105         }
 106       if (serial_debug_p (scb))
 107         {
 108           switch (next_state)
 109             {
 110             case FD_SCHEDULED:
 111               if (scb->async_state != FD_SCHEDULED)
 112                 fprintf_unfiltered (gdb_stdlog, "[fd%d->fd-scheduled]\n",
 113                                     scb->fd);
 114               break;
 115             default: /* TIMER SCHEDULED */
 116               if (scb->async_state == FD_SCHEDULED)
 117                 fprintf_unfiltered (gdb_stdlog, "[fd%d->timer-scheduled]\n",
 118                                     scb->fd);
 119               break;
 120             }
 121         }
 122       scb->async_state = next_state;
 123     }
 124 }
 125
 126 /* FD_EVENT: This is scheduled when the input FIFO is empty (and there
 127    is no pending error).  As soon as data arrives, it is read into the
 128    input FIFO and the client notified.  The client should then drain
 129    the FIFO using readchar().  If the FIFO isn't immediatly emptied,
 130    push_event() is used to nag the client until it is. */
 131
 132 static void
 133 fd_event (int error, void *context)
 134 {
 135   struct serial *scb = context;
 136   if (error != 0)
 137     {
 138       scb->bufcnt = SERIAL_ERROR;
 139     }
 140   else if (scb->bufcnt == 0)
 141     {
 142       /* Prime the input FIFO.  The readchar() function is used to
 143          pull characters out of the buffer.  See also
 144          generic_readchar(). */
 145       int nr;
 146       nr = scb->ops->read_prim (scb, BUFSIZ);
 147       if (nr == 0)
 148         {
 149           scb->bufcnt = SERIAL_EOF;
 150         }
 151       else if (nr > 0)
 152         {
 153           scb->bufcnt = nr;
 154           scb->bufp = scb->buf;
 155         }
 156       else
 157         {
 158           scb->bufcnt = SERIAL_ERROR;
 159         }
 160     }
 161   scb->async_handler (scb, scb->async_context);
 162   reschedule (scb);
 163 }
 164
 165 /* PUSH_EVENT: The input FIFO is non-empty (or there is a pending
 166    error).  Nag the client until all the data has been read.  In the
 167    case of errors, the client will need to close or de-async the
 168    device before naging stops. */
 169
 170 static void
 171 push_event (void *context)
 172 {
 173   struct serial *scb = context;
 174
 175   scb->async_state = NOTHING_SCHEDULED; /* Timers are one-off */
 176   scb->async_handler (scb, scb->async_context);
 177   /* re-schedule */
 178   reschedule (scb);
 179 }
 180
 181 /* Wait for input on scb, with timeout seconds.  Returns 0 on success,
 182    otherwise SERIAL_TIMEOUT or SERIAL_ERROR. */
 183
 184 static int
 185 ser_base_wait_for (struct serial *scb, int timeout)
 186 {
 187   while (1)
 188     {
 189       int numfds;
 190       struct timeval tv;
 191       fd_set readfds, exceptfds;
 192
 193       /* NOTE: Some OS's can scramble the READFDS when the select()
 194          call fails (ex the kernel with Red Hat 5.2).  Initialize all
 195          arguments before each call. */
 196
 197       tv.tv_sec = timeout;
 198       tv.tv_usec = 0;
 199
 200       FD_ZERO (&readfds);
 201       FD_ZERO (&exceptfds);
 202       FD_SET (scb->fd, &readfds);
 203       FD_SET (scb->fd, &exceptfds);
 204
 205       if (timeout >= 0)
 206         numfds = gdb_select (scb->fd + 1, &readfds, 0, &exceptfds, &tv);
 207       else
 208         numfds = gdb_select (scb->fd + 1, &readfds, 0, &exceptfds, 0);
 209
 210       if (numfds <= 0)
 211         {
 212           if (numfds == 0)
 213             return SERIAL_TIMEOUT;
 214           else if (errno == EINTR)
 215             continue;
 216           else
 217             return SERIAL_ERROR;        /* Got an error from select or poll */
 218         }
 219
 220       return 0;
 221     }
 222 }
 223
 224 /* Read a character with user-specified timeout.  TIMEOUT is number of seconds
 225    to wait, or -1 to wait forever.  Use timeout of 0 to effect a poll.  Returns
 226    char if successful.  Returns -2 if timeout expired, EOF if line dropped
 227    dead, or -3 for any other error (see errno in that case). */
 228
 229 static int
 230 do_ser_base_readchar (struct serial *scb, int timeout)
 231 {
 232   int status;
 233   int delta;
 234
 235   /* We have to be able to keep the GUI alive here, so we break the
 236      original timeout into steps of 1 second, running the "keep the
 237      GUI alive" hook each time through the loop.
 238
 239      Also, timeout = 0 means to poll, so we just set the delta to 0,
 240      so we will only go through the loop once.  */
 241
 242   delta = (timeout == 0 ? 0 : 1);
 243   while (1)
 244     {
 245       /* N.B. The UI may destroy our world (for instance by calling
 246          remote_stop,) in which case we want to get out of here as
 247          quickly as possible.  It is not safe to touch scb, since
 248          someone else might have freed it.  The
 249          deprecated_ui_loop_hook signals that we should exit by
 250          returning 1.  */
 251
 252       if (deprecated_ui_loop_hook)
 253         {
 254           if (deprecated_ui_loop_hook (0))
 255             return SERIAL_TIMEOUT;
 256         }
 257
 258       status = ser_base_wait_for (scb, delta);
 259       if (timeout > 0)
 260         timeout -= delta;
 261
 262       /* If we got a character or an error back from wait_for, then we can
 263          break from the loop before the timeout is completed. */
 264       if (status != SERIAL_TIMEOUT)
 265         break;
 266
 267       /* If we have exhausted the original timeout, then generate
 268          a SERIAL_TIMEOUT, and pass it out of the loop. */
 269       else if (timeout == 0)
 270         {
 271           status = SERIAL_TIMEOUT;
 272           break;
 273         }
 274     }
 275
 276   if (status < 0)
 277     return status;
 278
 279   status = scb->ops->read_prim (scb, BUFSIZ);
 280
 281   if (status <= 0)
 282     {
 283       if (status == 0)
 284         return SERIAL_EOF;
 285       else
 286         /* Got an error from read.  */
 287         return SERIAL_ERROR;
 288     }
 289
 290   scb->bufcnt = status;
 291   scb->bufcnt--;
 292   scb->bufp = scb->buf;
 293   return *scb->bufp++;
 294 }
 295
 296 /* Perform operations common to both old and new readchar. */
 297
 298 /* Return the next character from the input FIFO.  If the FIFO is
 299    empty, call the SERIAL specific routine to try and read in more
 300    characters.
 301
 302    Initially data from the input FIFO is returned (fd_event()
 303    pre-reads the input into that FIFO.  Once that has been emptied,
 304    further data is obtained by polling the input FD using the device
 305    specific readchar() function.  Note: reschedule() is called after
 306    every read.  This is because there is no guarentee that the lower
 307    level fd_event() poll_event() code (which also calls reschedule())
 308    will be called. */
 309
 310 int
 311 generic_readchar (struct serial *scb, int timeout,
 312                   int (do_readchar) (struct serial *scb, int timeout))
 313 {
 314   int ch;
 315   if (scb->bufcnt > 0)
 316     {
 317       ch = *scb->bufp;
 318       scb->bufcnt--;
 319       scb->bufp++;
 320     }
 321   else if (scb->bufcnt < 0)
 322     {
 323       /* Some errors/eof are are sticky. */
 324       ch = scb->bufcnt;
 325     }
 326   else
 327     {
 328       ch = do_readchar (scb, timeout);
 329       if (ch < 0)
 330         {
 331           switch ((enum serial_rc) ch)
 332             {
 333             case SERIAL_EOF:
 334             case SERIAL_ERROR:
 335               /* Make the error/eof stick. */
 336               scb->bufcnt = ch;
 337               break;
 338             case SERIAL_TIMEOUT:
 339               scb->bufcnt = 0;
 340               break;
 341             }
 342         }
 343     }
 344   /* Read any error output we might have.  */
 345   if (scb->error_fd != -1)
 346     {
 347       ssize_t s;
 348       char buf[81];
 349
 350       for (;;)
 351         {
 352           char *current;
 353           char *newline;
 354           int to_read = 80;
 355
 356           int num_bytes = -1;
 357           if (scb->ops->avail)
 358             num_bytes = (scb->ops->avail)(scb, scb->error_fd);
 359           if (num_bytes != -1)
 360             to_read = (num_bytes < to_read) ? num_bytes : to_read;
 361
 362           if (to_read == 0)
 363             break;
 364
 365           s = read (scb->error_fd, &buf, to_read);
 366           if (s == -1)
 367             break;
 368           if (s == 0)
 369             {
 370               /* EOF */
 371               close (scb->error_fd);
 372               scb->error_fd = -1;
 373               break;
 374             }
 375
 376           /* In theory, embedded newlines are not a problem.
 377              But for MI, we want each output line to have just
 378              one newline for legibility.  So output things
 379              in newline chunks.  */
 380           buf[s] = '\0';
 381           current = buf;
 382           while ((newline = strstr (current, "\n")) != NULL)
 383             {
 384               *newline = '\0';
 385               fputs_unfiltered (current, gdb_stderr);
 386               fputs_unfiltered ("\n", gdb_stderr);
 387               current = newline + 1;
 388             }
 389           fputs_unfiltered (current, gdb_stderr);
 390         }
 391     }
 392
 393   reschedule (scb);
 394   return ch;
 395 }
 396
 397 int
 398 ser_base_readchar (struct serial *scb, int timeout)
 399 {
 400   return generic_readchar (scb, timeout, do_ser_base_readchar);
 401 }
 402
 403 int
 404 ser_base_write (struct serial *scb, const char *str, int len)
 405 {
 406   int cc;
 407
 408   while (len > 0)
 409     {
 410       cc = scb->ops->write_prim (scb, str, len);
 411
 412       if (cc < 0)
 413         return 1;
 414       len -= cc;
 415       str += cc;
 416     }
 417   return 0;
 418 }
 419
 420 int
 421 ser_base_flush_output (struct serial *scb)
 422 {
 423   return 0;
 424 }
 425
 426 int
 427 ser_base_flush_input (struct serial *scb)
 428 {
 429   if (scb->bufcnt >= 0)
 430     {
 431       scb->bufcnt = 0;
 432       scb->bufp = scb->buf;
 433       return 0;
 434     }
 435   else
 436     return SERIAL_ERROR;
 437 }
 438
 439 int
 440 ser_base_send_break (struct serial *scb)
 441 {
 442   return 0;
 443 }
 444
 445 int
 446 ser_base_drain_output (struct serial *scb)
 447 {
 448   return 0;
 449 }
 450
 451 void
 452 ser_base_raw (struct serial *scb)
 453 {
 454   return;                       /* Always in raw mode */
 455 }
 456
 457 serial_ttystate
 458 ser_base_get_tty_state (struct serial *scb)
 459 {
 460   /* allocate a dummy */
 461   return (serial_ttystate) XMALLOC (int);
 462 }
 463
 464 int
 465 ser_base_set_tty_state (struct serial *scb, serial_ttystate ttystate)
 466 {
 467   return 0;
 468 }
 469
 470 int
 471 ser_base_noflush_set_tty_state (struct serial *scb,
 472                                 serial_ttystate new_ttystate,
 473                                 serial_ttystate old_ttystate)
 474 {
 475   return 0;
 476 }
 477
 478 void
 479 ser_base_print_tty_state (struct serial *scb,
 480                           serial_ttystate ttystate,
 481                           struct ui_file *stream)
 482 {
 483   /* Nothing to print.  */
 484   return;
 485 }
 486
 487 int
 488 ser_base_setbaudrate (struct serial *scb, int rate)
 489 {
 490   return 0;                     /* Never fails! */
 491 }
 492
 493 int
 494 ser_base_setstopbits (struct serial *scb, int num)
 495 {
 496   return 0;                     /* Never fails! */
 497 }
 498
 499 /* Put the SERIAL device into/out-of ASYNC mode.  */
 500
 501 void
 502 ser_base_async (struct serial *scb,
 503                 int async_p)
 504 {
 505   if (async_p)
 506     {
 507       /* Force a re-schedule. */
 508       scb->async_state = NOTHING_SCHEDULED;
 509       if (serial_debug_p (scb))
 510         fprintf_unfiltered (gdb_stdlog, "[fd%d->asynchronous]\n",
 511                             scb->fd);
 512       reschedule (scb);
 513     }
 514   else
 515     {
 516       if (serial_debug_p (scb))
 517         fprintf_unfiltered (gdb_stdlog, "[fd%d->synchronous]\n",
 518                             scb->fd);
 519       /* De-schedule whatever tasks are currently scheduled. */
 520       switch (scb->async_state)
 521         {
 522         case FD_SCHEDULED:
 523           delete_file_handler (scb->fd);
 524           break;
 525         case NOTHING_SCHEDULED:
 526           break;
 527         default: /* TIMER SCHEDULED */
 528           delete_timer (scb->async_state);
 529           break;
 530         }
 531     }
 532 }