/***************************************************************
  MPU-LOCK.C

       This file contains public stream locking functions.

       PART OF : MPUIO - library .

       USAGE   : External only .

       NOTE    : Stream locks are recursive, matching stdio
                 flockfile() ownership semantics.

       Copyright (C) 2000 - 2026  by Andrey V.Kosteltsev.
       All Rights Reserved.
 ***************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <libmpuio.h>
#include <mpu-symbols.h>
#include <mpu-libio.h>


/***************************************************************
  Lock STREAM for exclusive use by the calling thread.
 ***************************************************************/
void mpu_flockfile( mpu_FILE *stream )
{
  int  ret;

  if( !__mpu_IO_valid( stream ) )
    return;

  ret = pthread_mutex_lock( &stream->_lock );
  if( ret != 0 )
    errno = ret;

  return;

} /* End of mpu_flockfile() */


/***************************************************************
  Try to lock STREAM without waiting; return zero on success.
 ***************************************************************/
int mpu_ftrylockfile( mpu_FILE *stream )
{
  int  ret;

  if( !__mpu_IO_valid( stream ) )
    return( EINVAL );

  ret = pthread_mutex_trylock( &stream->_lock );
  if( ret != 0 )
    errno = ret;

  return( ret );

} /* End of mpu_ftrylockfile() */


/***************************************************************
  Release one STREAM lock held by the calling thread.
 ***************************************************************/
void mpu_funlockfile( mpu_FILE *stream )
{
  int  ret;

  if( !__mpu_IO_valid( stream ) )
    return;

  ret = pthread_mutex_unlock( &stream->_lock );
  if( ret != 0 )
    errno = ret;

  return;

} /* End of mpu_funlockfile() */