Programs/ses.c

/*
 * BRLTTY - A background process providing access to the console screen (when in
 *          text mode) for a blind person using a refreshable braille display.
 *
 * Copyright (C) 1995-2023 by The BRLTTY Developers.
 *
 * BRLTTY comes with ABSOLUTELY NO WARRANTY.
 *
 * This is free software, placed 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. Please see the file LICENSE-LGPL for details.
 *
 * Web Page: http://brltty.app/
 *
 * This software is maintained by Dave Mielke <dave@mielke.cc>.
 */

#include "prologue.h"

#include <string.h>

#include "log.h"
#include "ses.h"
#include "defaults.h"

static const SessionEntry initialSessionEntry = {
  .number = 0,

  .trackScreenCursor = DEFAULT_TRACK_SCREEN_CURSOR,
  .hideScreenCursor = DEFAULT_HIDE_SCREEN_CURSOR,

  .ptrx = -1,
  .ptry = -1
};

static SessionEntry **sessionArray = NULL;
static unsigned int sessionLimit = 0;
static unsigned int sessionCount = 0;

SessionEntry *
getSessionEntry (int number) {
  int first = 0;
  int last = sessionCount - 1;

  while (first <= last) {
    int current = (first + last) / 2;
    SessionEntry *entry = sessionArray[current];
    if (number == entry->number) return entry;

    if (number < entry->number) {
      last = current - 1;
    } else {
      first = current + 1;
    }
  }

  if (sessionCount == sessionLimit) {
    unsigned int newLimit = sessionLimit? sessionLimit<<1: 0X10;
    SessionEntry **newArray;

    if ((newArray = realloc(sessionArray, ARRAY_SIZE(newArray, newLimit)))) {
      sessionArray = newArray;
      sessionLimit = newLimit;
    } else {
      logMallocError();
    }
  }

  if (sessionCount < sessionLimit) {
    SessionEntry *entry = malloc(sizeof(*entry));

    if (entry) {
      *entry = initialSessionEntry;
      entry->number = number;

      memmove(&sessionArray[first+1], &sessionArray[first],
              ARRAY_SIZE(sessionArray, sessionCount-first));
      sessionArray[first] = entry;
      sessionCount += 1;
      return entry;
    } else {
      logMallocError();
    }
  }

  {
    static SessionEntry fallbackEntry;
    static int initialized = 0;

    if (!initialized) {
      fallbackEntry = initialSessionEntry;
      initialized = 1;
    }

    return &fallbackEntry;
  }
}

void
deallocateSessionEntries (void) {
  if (sessionArray) {
    while (sessionCount > 0) free(sessionArray[--sessionCount]);
    free(sessionArray);
    sessionArray = NULL;
  } else {
    sessionCount = 0;
  }
  sessionLimit = 0;
}