/* wait.c 
   Copyright (C) 2000 Werner Koch (dd9jn)
   Copyright (C) 2001, 2002, 2003, 2004, 2005 g10 Code GmbH
 
   This file is part of GPGME.
 
   GPGME is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of
   the License, or (at your option) any later version.
   
   GPGME 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
   Lesser General Public License for more details.
   
   You should have received a copy of the GNU Lesser General Public
   License along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.  */

#if HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <sys/types.h>

#include "util.h"
#include "context.h"
#include "ops.h"
#include "wait.h"
#include "sema.h"
#include "priv-io.h"
#include "engine.h"
#include "debug.h"


void
_gpgme_fd_table_init (fd_table_t fdt)
{
  fdt->fds = NULL;
  fdt->size = 0;
}

void
_gpgme_fd_table_deinit (fd_table_t fdt)
{
  if (fdt->fds)
    free (fdt->fds);
}


/* XXX We should keep a marker and roll over for speed.  */
static gpgme_error_t
fd_table_put (fd_table_t fdt, int fd, int dir, void *opaque, int *idx)
{
  unsigned int i, j;
  struct io_select_fd_s *new_fds;

  for (i = 0; i < fdt->size; i++)
    {
      if (fdt->fds[i].fd == -1)
	break;
    }
  if (i == fdt->size)
    {
#define FDT_ALLOCSIZE 10
      new_fds = realloc (fdt->fds, (fdt->size + FDT_ALLOCSIZE)
			 * sizeof (*new_fds));
      if (!new_fds)
	return gpg_error_from_errno (errno);
      
      fdt->fds = new_fds;
      fdt->size += FDT_ALLOCSIZE;
      for (j = 0; j < FDT_ALLOCSIZE; j++)
	fdt->fds[i + j].fd = -1;
    }

  fdt->fds[i].fd = fd;
  fdt->fds[i].for_read = (dir == 1);
  fdt->fds[i].for_write = (dir == 0);
  fdt->fds[i].frozen = 0;
  fdt->fds[i].signaled = 0;
  fdt->fds[i].opaque = opaque;
  *idx = i;
  return 0;
}


/* Register the file descriptor FD with the handler FNC (which gets
   FNC_DATA as its first argument) for the direction DIR.  DATA should
   be the context for which the fd is added.  R_TAG will hold the tag
   that can be used to remove the fd.  */
gpgme_error_t
_gpgme_add_io_cb (void *data, int fd, int dir, gpgme_io_cb_t fnc,
		  void *fnc_data, void **r_tag)
{
  gpgme_error_t err;
  gpgme_ctx_t ctx = (gpgme_ctx_t) data;
  fd_table_t fdt;
  struct wait_item_s *item;
  struct tag *tag;

  assert (fnc);
  assert (ctx);

  fdt = &ctx->fdt;
  assert (fdt);

  tag = malloc (sizeof *tag);
  if (!tag)
    return gpg_error_from_errno (errno);
  tag->ctx = ctx;

  /* Allocate a structure to hold information about the handler.  */
  item = calloc (1, sizeof *item);
  if (!item)
    {
      int saved_errno = errno;
      free (tag);
      return gpg_error_from_errno (saved_errno);
    }
  item->ctx = ctx;
  item->dir = dir;
  item->handler = fnc;
  item->handler_value = fnc_data;

  err = fd_table_put (fdt, fd, dir, item, &tag->idx);
  if (err)
    {
      free (tag);
      free (item);
      return err;
    }

  *r_tag = tag;
  return 0;
}


void
_gpgme_remove_io_cb (void *data)
{
  struct tag *tag = data;
  gpgme_ctx_t ctx;
  fd_table_t fdt;
  int idx;

  assert (tag);
  ctx = tag->ctx;
  assert (ctx);
  fdt = &ctx->fdt;
  assert (fdt);
  idx = tag->idx;

  DEBUG2 ("setting fd %d (item=%p) done", fdt->fds[idx].fd,
	  fdt->fds[idx].opaque);
  free (fdt->fds[idx].opaque);
  free (tag);

  /* Free the table entry.  */
  fdt->fds[idx].fd = -1;
  fdt->fds[idx].for_read = 0;
  fdt->fds[idx].for_write = 0;
  fdt->fds[idx].opaque = NULL;
}


/* This is slightly embarrassing.  The problem is that running an I/O
   callback _may_ influence the status of other file descriptors.  Our
   own event loops could compensate for that, but the external event
   loops cannot.  FIXME: We may still want to optimize this a bit when
   we are called from our own event loops.  So if CHECKED is 1, the
   check is skipped.  */
gpgme_error_t
_gpgme_run_io_cb (struct io_select_fd_s *an_fds, int checked)
{
  struct wait_item_s *item;
  item = (struct wait_item_s *) an_fds->opaque;
  assert (item);

  if (!checked)
    {
      int nr;
      struct io_select_fd_s fds;

      fds = *an_fds;
      fds.signaled = 0;
      /* Just give it a quick poll.  */
      nr = _gpgme_io_select (&fds, 1, 1);
      assert (nr <= 1);
      if (nr < 0)
	return errno;
      else if (nr == 0)
	/* The status changed in the meantime, there is nothing left
	   to do.  */
	return 0;
    }

  return item->handler (item->handler_value, an_fds->fd);
}