gdb/ser-base.c

   1 /* Generic serial interface functions.
   2
   3    Copyright 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
   4    2003, 2004, 2005 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 2 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, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "serial.h"
  25 #include "ser-unix.h"
  26 #include "event-loop.h"
  27 #include <sys/time.h>
  28 #ifdef USE_WIN32API
  29 #include <winsock2.h>
  30 #endif
  31
  32 #include "gdb_string.h"
  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 void
  67 reschedule (struct serial *scb)
  68 {
  69   if (serial_is_async_p (scb))
  70     {
  71       int next_state;
  72       switch (scb->async_state)
  73         {
  74         case FD_SCHEDULED:
  75           if (scb->bufcnt == 0)
  76             next_state = FD_SCHEDULED;
  77           else
  78             {
  79               delete_file_handler (scb->fd);
  80               next_state = create_timer (0, push_event, scb);
  81             }
  82           break;
  83         case NOTHING_SCHEDULED:
  84           if (scb->bufcnt == 0)
  85             {
  86               add_file_handler (scb->fd, fd_event, scb);
  87               next_state = FD_SCHEDULED;
  88             }
  89           else
  90             {
  91               next_state = create_timer (0, push_event, scb);
  92             }
  93           break;
  94         default: /* TIMER SCHEDULED */
  95           if (scb->bufcnt == 0)
  96             {
  97               delete_timer (scb->async_state);
  98               add_file_handler (scb->fd, fd_event, scb);
  99               next_state = FD_SCHEDULED;
 100             }
 101           else
 102             next_state = scb->async_state;
 103           break;
 104         }
 105       if (serial_debug_p (scb))
 106         {
 107           switch (next_state)
 108             {
 109             case FD_SCHEDULED:
 110               if (scb->async_state != FD_SCHEDULED)
 111                 fprintf_unfiltered (gdb_stdlog, "[fd%d->fd-scheduled]\n",
 112                                     scb->fd);
 113               break;
 114             default: /* TIMER SCHEDULED */
 115               if (scb->async_state == FD_SCHEDULED)
 116                 fprintf_unfiltered (gdb_stdlog, "[fd%d->timer-scheduled]\n",
 117                                     scb->fd);
 118               break;
 119             }
 120         }
 121       scb->async_state = next_state;
 122     }
 123 }
 124
 125 /* FD_EVENT: This is scheduled when the input FIFO is empty (and there
 126    is no pending error).  As soon as data arrives, it is read into the
 127    input FIFO and the client notified.  The client should then drain
 128    the FIFO using readchar().  If the FIFO isn't immediatly emptied,
 129    push_event() is used to nag the client until it is. */
 130
 131 static void
 132 fd_event (int error, void *context)
 133 {
 134   struct serial *scb = context;
 135   if (error != 0)
 136     {
 137       scb->bufcnt = SERIAL_ERROR;
 138     }
 139   else if (scb->bufcnt == 0)
 140     {
 141       /* Prime the input FIFO.  The readchar() function is used to
 142          pull characters out of the buffer.  See also
 143          generic_readchar(). */
 144       int nr;
 145       nr = scb->ops->read_prim (scb, BUFSIZ);
 146       if (nr == 0)
 147         {
 148           scb->bufcnt = SERIAL_EOF;
 149         }
 150       else if (nr > 0)
 151         {
 152           scb->bufcnt = nr;
 153           scb->bufp = scb->buf;
 154         }
 155       else
 156         {
 157           scb->bufcnt = SERIAL_ERROR;
 158         }
 159     }
 160   scb->async_handler (scb, scb->async_context);
 161   reschedule (scb);
 162 }
 163
 164 /* PUSH_EVENT: The input FIFO is non-empty (or there is a pending
 165    error).  Nag the client until all the data has been read.  In the
 166    case of errors, the client will need to close or de-async the
 167    device before naging stops. */
 168
 169 static void
 170 push_event (void *context)
 171 {
 172   struct serial *scb = context;
 173   scb->async_state = NOTHING_SCHEDULED; /* Timers are one-off */
 174   scb->async_handler (scb, scb->async_context);
 175   /* re-schedule */
 176   reschedule (scb);
 177 }
 178
 179 /* Wait for input on scb, with timeout seconds.  Returns 0 on success,
 180    otherwise SERIAL_TIMEOUT or SERIAL_ERROR. */
 181
 182 static int
 183 ser_base_wait_for (struct serial *scb, int timeout)
 184 {
 185   while (1)
 186     {
 187       int numfds;
 188       struct timeval tv;
 189       fd_set readfds, exceptfds;
 190
 191       /* NOTE: Some OS's can scramble the READFDS when the select()
 192          call fails (ex the kernel with Red Hat 5.2).  Initialize all
 193          arguments before each call. */
 194
 195       tv.tv_sec = timeout;
 196       tv.tv_usec = 0;
 197
 198       FD_ZERO (&readfds);
 199       FD_ZERO (&exceptfds);
 200       FD_SET (scb->fd, &readfds);
 201       FD_SET (scb->fd, &exceptfds);
 202
 203       if (timeout >= 0)
 204         numfds = select (scb->fd + 1, &readfds, 0, &exceptfds, &tv);
 205       else
 206         numfds = select (scb->fd + 1, &readfds, 0, &exceptfds, 0);
 207
 208       if (numfds <= 0)
 209         {
 210           if (numfds == 0)
 211             return SERIAL_TIMEOUT;
 212           else if (errno == EINTR)
 213             continue;
 214           else
 215             return SERIAL_ERROR;        /* Got an error from select or poll */
 216         }
 217
 218       return 0;
 219     }
 220 }
 221
 222 /* Read a character with user-specified timeout.  TIMEOUT is number of seconds
 223    to wait, or -1 to wait forever.  Use timeout of 0 to effect a poll.  Returns
 224    char if successful.  Returns -2 if timeout expired, EOF if line dropped
 225    dead, or -3 for any other error (see errno in that case). */
 226
 227 static int
 228 do_ser_base_readchar (struct serial *scb, int timeout)
 229 {
 230   int status;
 231   int delta;
 232
 233   /* We have to be able to keep the GUI alive here, so we break the
 234      original timeout into steps of 1 second, running the "keep the
 235      GUI alive" hook each time through the loop.
 236
 237      Also, timeout = 0 means to poll, so we just set the delta to 0,
 238      so we will only go through the loop once.  */
 239
 240   delta = (timeout == 0 ? 0 : 1);
 241   while (1)
 242     {
 243       /* N.B. The UI may destroy our world (for instance by calling
 244          remote_stop,) in which case we want to get out of here as
 245          quickly as possible.  It is not safe to touch scb, since
 246          someone else might have freed it.  The
 247          deprecated_ui_loop_hook signals that we should exit by
 248          returning 1.  */
 249
 250       if (deprecated_ui_loop_hook)
 251         {
 252           if (deprecated_ui_loop_hook (0))
 253             return SERIAL_TIMEOUT;
 254         }
 255
 256       status = ser_base_wait_for (scb, delta);
 257       if (timeout > 0)
 258         timeout -= delta;
 259
 260       /* If we got a character or an error back from wait_for, then we can
 261          break from the loop before the timeout is completed. */
 262       if (status != SERIAL_TIMEOUT)
 263         break;
 264
 265       /* If we have exhausted the original timeout, then generate
 266          a SERIAL_TIMEOUT, and pass it out of the loop. */
 267       else if (timeout == 0)
 268         {
 269           status = SERIAL_TIMEOUT;
 270           break;
 271         }
 272     }
 273
 274   if (status < 0)
 275     return status;
 276
 277   status = scb->ops->read_prim (scb, BUFSIZ);
 278
 279   if (status <= 0)
 280     {
 281       if (status == 0)
 282         /* 0 chars means timeout.  (We may need to distinguish between EOF
 283            & timeouts someday.)  */
 284         return SERIAL_TIMEOUT;
 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   reschedule (scb);
 345   return ch;
 346 }
 347
 348 int
 349 ser_base_readchar (struct serial *scb, int timeout)
 350 {
 351   return generic_readchar (scb, timeout, do_ser_base_readchar);
 352 }
 353
 354 int
 355 ser_base_write (struct serial *scb, const char *str, int len)
 356 {
 357   int cc;
 358
 359   while (len > 0)
 360     {
 361       cc = scb->ops->write_prim (scb, str, len);
 362
 363       if (cc < 0)
 364         return 1;
 365       len -= cc;
 366       str += cc;
 367     }
 368   return 0;
 369 }
 370
 371 int
 372 ser_base_flush_output (struct serial *scb)
 373 {
 374   return 0;
 375 }
 376
 377 int
 378 ser_base_flush_input (struct serial *scb)
 379 {
 380   if (scb->bufcnt >= 0)
 381     {
 382       scb->bufcnt = 0;
 383       scb->bufp = scb->buf;
 384       return 0;
 385     }
 386   else
 387     return SERIAL_ERROR;
 388 }
 389
 390 int
 391 ser_base_send_break (struct serial *scb)
 392 {
 393   return 0;
 394 }
 395
 396 int
 397 ser_base_drain_output (struct serial *scb)
 398 {
 399   return 0;
 400 }
 401
 402 void
 403 ser_base_raw (struct serial *scb)
 404 {
 405   return;                       /* Always in raw mode */
 406 }
 407
 408 serial_ttystate
 409 ser_base_get_tty_state (struct serial *scb)
 410 {
 411   /* allocate a dummy */
 412   return (serial_ttystate) XMALLOC (int);
 413 }
 414
 415 int
 416 ser_base_set_tty_state (struct serial *scb, serial_ttystate ttystate)
 417 {
 418   return 0;
 419 }
 420
 421 int
 422 ser_base_noflush_set_tty_state (struct serial *scb,
 423                                 serial_ttystate new_ttystate,
 424                                 serial_ttystate old_ttystate)
 425 {
 426   return 0;
 427 }
 428
 429 void
 430 ser_base_print_tty_state (struct serial *scb,
 431                           serial_ttystate ttystate,
 432                           struct ui_file *stream)
 433 {
 434   /* Nothing to print.  */
 435   return;
 436 }
 437
 438 int
 439 ser_base_setbaudrate (struct serial *scb, int rate)
 440 {
 441   return 0;                     /* Never fails! */
 442 }
 443
 444 int
 445 ser_base_setstopbits (struct serial *scb, int num)
 446 {
 447   return 0;                     /* Never fails! */
 448 }
 449
 450 /* Put the SERIAL device into/out-of ASYNC mode.  */
 451
 452 void
 453 ser_base_async (struct serial *scb,
 454                 int async_p)
 455 {
 456   if (async_p)
 457     {
 458       /* Force a re-schedule. */
 459       scb->async_state = NOTHING_SCHEDULED;
 460       if (serial_debug_p (scb))
 461         fprintf_unfiltered (gdb_stdlog, "[fd%d->asynchronous]\n",
 462                             scb->fd);
 463       reschedule (scb);
 464     }
 465   else
 466     {
 467       if (serial_debug_p (scb))
 468         fprintf_unfiltered (gdb_stdlog, "[fd%d->synchronous]\n",
 469                             scb->fd);
 470       /* De-schedule whatever tasks are currently scheduled. */
 471       switch (scb->async_state)
 472         {
 473         case FD_SCHEDULED:
 474           delete_file_handler (scb->fd);
 475           break;
 476         case NOTHING_SCHEDULED:
 477           break;
 478         default: /* TIMER SCHEDULED */
 479           delete_timer (scb->async_state);
 480           break;
 481         }
 482     }
 483 }