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/* Generic serial interface functions.

   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001, 2003,

   2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "serial.h"

#include "ser-base.h"

#include "event-loop.h"

#include "gdb_select.h"

#include "gdb_string.h"

#include <sys/time.h>

#ifdef USE_WIN32API

#include <winsock2.h>

#endif

static timer_handler_func push_event;

static handler_func fd_event;

/* Event handling for ASYNC serial code.

   At any time the SERIAL device either: has an empty FIFO and is

   waiting on a FD event; or has a non-empty FIFO/error condition and

   is constantly scheduling timer events.

   ASYNC only stops pestering its client when it is de-async'ed or it

   is told to go away. */

/* Value of scb->async_state: */

enum {

  /* >= 0 (TIMER_SCHEDULED) */

  /* The ID of the currently scheduled timer event. This state is

     rarely encountered.  Timer events are one-off so as soon as the

     event is delivered the state is shanged to NOTHING_SCHEDULED. */

  FD_SCHEDULED = -1,

  /* The fd_event() handler is scheduled.  It is called when ever the

     file descriptor becomes ready. */

  NOTHING_SCHEDULED = -2

  /* Either no task is scheduled (just going into ASYNC mode) or a

     timer event has just gone off and the current state has been

     forced into nothing scheduled. */

};

/* Identify and schedule the next ASYNC task based on scb->async_state

   and scb->buf* (the input FIFO).  A state machine is used to avoid

   the need to make redundant calls into the event-loop - the next

   scheduled task is only changed when needed. */

void

reschedule (struct serial *scb)

{

  if (serial_is_async_p (scb))

    {

      int next_state;

      switch (scb->async_state)

        {

        case FD_SCHEDULED:

          if (scb->bufcnt == 0)

            next_state = FD_SCHEDULED;

          else

            {

              delete_file_handler (scb->fd);

              next_state = create_timer (0, push_event, scb);

            }

          break;

        case NOTHING_SCHEDULED:

          if (scb->bufcnt == 0)

            {

              add_file_handler (scb->fd, fd_event, scb);

              next_state = FD_SCHEDULED;

            }

          else

            {

              next_state = create_timer (0, push_event, scb);

            }

          break;

        default: /* TIMER SCHEDULED */

          if (scb->bufcnt == 0)

            {

              delete_timer (scb->async_state);

              add_file_handler (scb->fd, fd_event, scb);

              next_state = FD_SCHEDULED;

            }

          else

            next_state = scb->async_state;

          break;

        }

      if (serial_debug_p (scb))

        {

          switch (next_state)

            {

            case FD_SCHEDULED:

              if (scb->async_state != FD_SCHEDULED)

                fprintf_unfiltered (gdb_stdlog, "[fd%d->fd-scheduled]\n",

                                    scb->fd);

              break;

            default: /* TIMER SCHEDULED */

              if (scb->async_state == FD_SCHEDULED)

                fprintf_unfiltered (gdb_stdlog, "[fd%d->timer-scheduled]\n",

                                    scb->fd);

              break;

            }

        }

      scb->async_state = next_state;

    }

}

/* FD_EVENT: This is scheduled when the input FIFO is empty (and there

   is no pending error).  As soon as data arrives, it is read into the

   input FIFO and the client notified.  The client should then drain

   the FIFO using readchar().  If the FIFO isn't immediatly emptied,

   push_event() is used to nag the client until it is. */

static void

fd_event (int error, void *context)

{

  struct serial *scb = context;

  if (error != 0)

    {

      scb->bufcnt = SERIAL_ERROR;

    }

  else if (scb->bufcnt == 0)

    {

      /* Prime the input FIFO.  The readchar() function is used to

         pull characters out of the buffer.  See also

         generic_readchar(). */

      int nr;

      nr = scb->ops->read_prim (scb, BUFSIZ);

      if (nr == 0)

        {

          scb->bufcnt = SERIAL_EOF;

        }

      else if (nr > 0)

        {

          scb->bufcnt = nr;

          scb->bufp = scb->buf;

        }

      else

        {

          scb->bufcnt = SERIAL_ERROR;

        }

    }

  scb->async_handler (scb, scb->async_context);

  reschedule (scb);

}

/* PUSH_EVENT: The input FIFO is non-empty (or there is a pending

   error).  Nag the client until all the data has been read.  In the

   case of errors, the client will need to close or de-async the

   device before naging stops. */

static void

push_event (void *context)

{

  struct serial *scb = context;

  scb->async_state = NOTHING_SCHEDULED; /* Timers are one-off */

  scb->async_handler (scb, scb->async_context);

  /* re-schedule */

  reschedule (scb);

}

/* Wait for input on scb, with timeout seconds.  Returns 0 on success,

   otherwise SERIAL_TIMEOUT or SERIAL_ERROR. */

static int

ser_base_wait_for (struct serial *scb, int timeout)

{

  while (1)

    {

      int numfds;

      struct timeval tv;

      fd_set readfds, exceptfds;

      /* NOTE: Some OS's can scramble the READFDS when the select()

         call fails (ex the kernel with Red Hat 5.2).  Initialize all

         arguments before each call. */

      tv.tv_sec = timeout;

      tv.tv_usec = 0;

      FD_ZERO (&readfds);

      FD_ZERO (&exceptfds);

      FD_SET (scb->fd, &readfds);

      FD_SET (scb->fd, &exceptfds);

      if (timeout >= 0)

        numfds = gdb_select (scb->fd + 1, &readfds, 0, &exceptfds, &tv);

      else

        numfds = gdb_select (scb->fd + 1, &readfds, 0, &exceptfds, 0);

      if (numfds <= 0)

        {

          if (numfds == 0)

            return SERIAL_TIMEOUT;

          else if (errno == EINTR)

            continue;

          else

            return SERIAL_ERROR;        /* Got an error from select or poll */

        }

      return 0;

    }

}

/* Read a character with user-specified timeout.  TIMEOUT is number of seconds

   to wait, or -1 to wait forever.  Use timeout of 0 to effect a poll.  Returns

   char if successful.  Returns -2 if timeout expired, EOF if line dropped

   dead, or -3 for any other error (see errno in that case). */

static int

do_ser_base_readchar (struct serial *scb, int timeout)

{

  int status;

  int delta;

  /* We have to be able to keep the GUI alive here, so we break the

     original timeout into steps of 1 second, running the "keep the

     GUI alive" hook each time through the loop.

     Also, timeout = 0 means to poll, so we just set the delta to 0,

     so we will only go through the loop once.  */

  delta = (timeout == 0 ? 0 : 1);

  while (1)

    {

      /* N.B. The UI may destroy our world (for instance by calling

         remote_stop,) in which case we want to get out of here as

         quickly as possible.  It is not safe to touch scb, since

         someone else might have freed it.  The

         deprecated_ui_loop_hook signals that we should exit by

         returning 1.  */

      if (deprecated_ui_loop_hook)

        {

          if (deprecated_ui_loop_hook (0))

            return SERIAL_TIMEOUT;

        }

      status = ser_base_wait_for (scb, delta);

      if (timeout > 0)

        timeout -= delta;

      /* If we got a character or an error back from wait_for, then we can

         break from the loop before the timeout is completed. */

      if (status != SERIAL_TIMEOUT)

        break;

      /* If we have exhausted the original timeout, then generate

         a SERIAL_TIMEOUT, and pass it out of the loop. */

      else if (timeout == 0)

        {

          status = SERIAL_TIMEOUT;

          break;

        }

    }

  if (status < 0)

    return status;

  status = scb->ops->read_prim (scb, BUFSIZ);

  if (status <= 0)

    {

      if (status == 0)

        return SERIAL_EOF;

      else

        /* Got an error from read.  */

        return SERIAL_ERROR;

    }

  scb->bufcnt = status;

  scb->bufcnt--;

  scb->bufp = scb->buf;

  return *scb->bufp++;

}

/* Perform operations common to both old and new readchar. */

/* Return the next character from the input FIFO.  If the FIFO is

   empty, call the SERIAL specific routine to try and read in more

   characters.

   Initially data from the input FIFO is returned (fd_event()

   pre-reads the input into that FIFO.  Once that has been emptied,

   further data is obtained by polling the input FD using the device

   specific readchar() function.  Note: reschedule() is called after

   every read.  This is because there is no guarentee that the lower

   level fd_event() poll_event() code (which also calls reschedule())

   will be called. */

int

generic_readchar (struct serial *scb, int timeout,

                  int (do_readchar) (struct serial *scb, int timeout))

{

  int ch;

  if (scb->bufcnt > 0)

    {

      ch = *scb->bufp;

      scb->bufcnt--;

      scb->bufp++;

    }

  else if (scb->bufcnt < 0)

    {

      /* Some errors/eof are are sticky. */

      ch = scb->bufcnt;

    }

  else

    {

      ch = do_readchar (scb, timeout);

      if (ch < 0)

        {

          switch ((enum serial_rc) ch)

            {

            case SERIAL_EOF:

            case SERIAL_ERROR:

              /* Make the error/eof stick. */

              scb->bufcnt = ch;

              break;

            case SERIAL_TIMEOUT:

              scb->bufcnt = 0;

              break;

            }

        }

    }

  /* Read any error output we might have.  */

  if (scb->error_fd != -1)

    {

      ssize_t s;

      char buf[81];

      for (;;)

        {

          char *current;

          char *newline;

          int to_read = 80;

          int num_bytes = -1;

          if (scb->ops->avail)

            num_bytes = (scb->ops->avail)(scb, scb->error_fd);

          if (num_bytes != -1)

            to_read = (num_bytes < to_read) ? num_bytes : to_read;

          if (to_read == 0)

            break;

          s = read (scb->error_fd, &buf, to_read);

          if (s == -1)

            break;

          /* In theory, embedded newlines are not a problem.

             But for MI, we want each output line to have just

             one newline for legibility.  So output things

             in newline chunks.  */

          buf[s] = '\0';

          current = buf;

          while ((newline = strstr (current, "\n")) != NULL)

            {

              *newline = '\0';

              fputs_unfiltered (current, gdb_stderr);

              fputs_unfiltered ("\n", gdb_stderr);

              current = newline + 1;

            }

          fputs_unfiltered (current, gdb_stderr);

        }

    }

  reschedule (scb);

  return ch;

}

int

ser_base_readchar (struct serial *scb, int timeout)

{

  return generic_readchar (scb, timeout, do_ser_base_readchar);

}

int

ser_base_write (struct serial *scb, const char *str, int len)

{

  int cc;

  while (len > 0)

    {

      cc = scb->ops->write_prim (scb, str, len);

      if (cc < 0)

        return 1;

      len -= cc;

      str += cc;

    }

  return 0;

}

int

ser_base_flush_output (struct serial *scb)

{

  return 0;

}

int

ser_base_flush_input (struct serial *scb)

{

  if (scb->bufcnt >= 0)

    {

      scb->bufcnt = 0;

      scb->bufp = scb->buf;

      return 0;

    }

  else

    return SERIAL_ERROR;

}

int

ser_base_send_break (struct serial *scb)

{

  return 0;

}

int

ser_base_drain_output (struct serial *scb)

{

  return 0;

}

void

ser_base_raw (struct serial *scb)

{

  return;                       /* Always in raw mode */

}

serial_ttystate

ser_base_get_tty_state (struct serial *scb)

{

  /* allocate a dummy */

  return (serial_ttystate) XMALLOC (int);

}

int

ser_base_set_tty_state (struct serial *scb, serial_ttystate ttystate)

{

  return 0;

}

int

ser_base_noflush_set_tty_state (struct serial *scb,

                                serial_ttystate new_ttystate,

                                serial_ttystate old_ttystate)

{

  return 0;

}

void

ser_base_print_tty_state (struct serial *scb,

                          serial_ttystate ttystate,

                          struct ui_file *stream)

{

  /* Nothing to print.  */

  return;

}

int

ser_base_setbaudrate (struct serial *scb, int rate)

{

  return 0;                      /* Never fails! */

}

int

ser_base_setstopbits (struct serial *scb, int num)

{

  return 0;                      /* Never fails! */

}

/* Put the SERIAL device into/out-of ASYNC mode.  */

void

ser_base_async (struct serial *scb,

                int async_p)

{

  if (async_p)

    {

      /* Force a re-schedule. */

      scb->async_state = NOTHING_SCHEDULED;

      if (serial_debug_p (scb))

        fprintf_unfiltered (gdb_stdlog, "[fd%d->asynchronous]\n",

                            scb->fd);

      reschedule (scb);

    }

  else

    {

      if (serial_debug_p (scb))

        fprintf_unfiltered (gdb_stdlog, "[fd%d->synchronous]\n",

                            scb->fd);

      /* De-schedule whatever tasks are currently scheduled. */

      switch (scb->async_state)

        {

        case FD_SCHEDULED:

          delete_file_handler (scb->fd);

          break;

        case NOTHING_SCHEDULED:

          break;

        default: /* TIMER SCHEDULED */

          delete_timer (scb->async_state);

          break;

        }

    }

}