Drivers/Speech/GenericSay/speech.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>.
 */

/* GenericSay/speech.c - To use a generic 'say' command, like for the
 * rsynth package.
 */

#include "prologue.h"

#include <stdio.h>
#include <string.h>
#include <errno.h>

#include "log.h"

typedef enum {
   PARM_COMMAND
} DriverParameter;
#define SPKPARMS "command"

#include "spk_driver.h"
#include "speech.h"

static const char *commandPath;	/* default full path for the say command */
static FILE *commandStream = NULL;

static int
spk_construct (SpeechSynthesizer *spk, char **parameters)
{
  const char *command = parameters[PARM_COMMAND];
  commandPath = *command? command: SAY_CMD;
  logMessage(LOG_INFO, "Speech Command: %s", commandPath);
  return 1;
}

static void
spk_say (SpeechSynthesizer *spk, const unsigned char *buffer, size_t length, size_t count, const unsigned char *attributes) {
  if (!commandStream) {
    if (!(commandStream = popen(commandPath, "w"))) {
      logMessage(LOG_WARNING, "cannot start command: %s: %s",
                 commandPath, strerror(errno));
    }
  }

  if (commandStream) {
    if (fwrite(buffer, length, 1, commandStream)) {
      static const char trailer[] = {'\n'};

      if (fwrite(trailer, sizeof(trailer), 1, commandStream)) {
        if (fflush(commandStream) == EOF) {
        } else {
          logSystemError("fflush");
        }
      } else {
        logSystemError("fwrite");
      }
    } else {
      logSystemError("fwrite");
    }
  }
}

static void
spk_mute (SpeechSynthesizer *spk)
{
  if (commandStream)
    {
       pclose(commandStream);
       commandStream = NULL;
    }
}

static void
spk_destruct (SpeechSynthesizer *spk)
{
   spk_mute(spk);
}