memfile.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

          the_jnode->type == IMFS_LINEAR_FILE );
  if ( the_jnode->type != IMFS_MEMORY_FILE &&
       the_jnode->type != IMFS_LINEAR_FILE )
    rtems_set_errno_and_return_minus_one( EIO );

  /*
   *  Error checks on arguments
   */

  assert( dest );
  if ( !dest )
    rtems_set_errno_and_return_minus_one( EINVAL );

  /*
   *  If there is nothing to read, then quick exit.
   */

  my_length = length;
  if ( !my_length )
    rtems_set_errno_and_return_minus_one( EINVAL );

  /*
   *  Linear files (as created from a tar file are easier to handle
   *  than block files).
   */
  if (the_jnode->type == IMFS_LINEAR_FILE) {
    unsigned char  *file_ptr;

    file_ptr = (unsigned char *)the_jnode->info.linearfile.direct;

    if (my_length > (the_jnode->info.linearfile.size - start))
      my_length = the_jnode->info.linearfile.size - start;

    memcpy(dest, &file_ptr[start], my_length);

    IMFS_update_atime( the_jnode );

    return my_length;
  }

  /*
   *  If the last byte we are supposed to read is past the end of this
   *  in memory file, then shorten the length to read.
   */

  last_byte = start + length;
  if ( last_byte > the_jnode->info.file.size )
    my_length = the_jnode->info.file.size - start;

  copied = 0;

  /*
   *  Three phases to the read:
   *    + possibly the last part of one block
   *    + all of zero of more blocks
   *    + possibly the first part of one block
   */

  /*
   *  Phase 1: possibly the last part of one block
   */

  start_offset = start % IMFS_MEMFILE_BYTES_PER_BLOCK;
  block = start / IMFS_MEMFILE_BYTES_PER_BLOCK;
  if ( start_offset )  {
    to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK - start_offset;
    if ( to_copy > my_length )
      to_copy = my_length;
    block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
    assert( block_ptr );
    if ( !block_ptr )
      return copied;
    memcpy( dest, &(*block_ptr)[ start_offset ], to_copy );
    dest += to_copy;
    block++;
    my_length -= to_copy;
    copied += to_copy;
  }

  /*
   *  Phase 2: all of zero of more blocks
   */

  to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK;
  while ( my_length >= IMFS_MEMFILE_BYTES_PER_BLOCK ) {
    block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
    assert( block_ptr );
    if ( !block_ptr )
      return copied;
    memcpy( dest, &(*block_ptr)[ 0 ], to_copy );
    dest += to_copy;
    block++;
    my_length -= to_copy;
    copied += to_copy;
  }

  /*
   *  Phase 3: possibly the first part of one block
   */

  assert( my_length < IMFS_MEMFILE_BYTES_PER_BLOCK );

  if ( my_length ) {
    block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
    assert( block_ptr );
    if ( !block_ptr )
      return copied;
    memcpy( dest, &(*block_ptr)[ 0 ], my_length );
    copied += my_length;
  }

  IMFS_update_atime( the_jnode );

  return copied;
}

/*
 *  IMFS_memfile_write
 *
 *  This routine writes the specified data buffer into the in memory
 *  file pointed to by the_jnode.  The file is extended as needed.
 */

MEMFILE_STATIC ssize_t IMFS_memfile_write(
   IMFS_jnode_t          *the_jnode,
   off_t                  start,
   const unsigned char   *source,
   unsigned int           length
)
{
  block_p             *block_ptr;
  unsigned int         block;
  int                  status;
  unsigned int         my_length;
  unsigned int         to_copy = 0;
  unsigned int         last_byte;
  unsigned int         start_offset;
  int                  copied;
  const unsigned char *src;

  src = source;

  /*
   *  Perform internal consistency checks
   */

  assert( the_jnode );
  if ( !the_jnode )
    rtems_set_errno_and_return_minus_one( EIO );

  assert( the_jnode->type == IMFS_MEMORY_FILE );
  if ( the_jnode->type != IMFS_MEMORY_FILE )
    rtems_set_errno_and_return_minus_one( EIO );

  /*
   *  Error check arguments
   */

  assert( source );
  if ( !source )
    rtems_set_errno_and_return_minus_one( EINVAL );


  /*
   *  If there is nothing to write, then quick exit.
   */

  my_length = length;
  if ( !my_length )
    rtems_set_errno_and_return_minus_one( EINVAL );

  /*
   *  If the last byte we are supposed to write is past the end of this
   *  in memory file, then extend the length.
   */

  last_byte = start + length;
  if ( last_byte > the_jnode->info.file.size ) {
    status = IMFS_memfile_extend( the_jnode, last_byte );
    if ( status )
      rtems_set_errno_and_return_minus_one( ENOSPC );
  }

  copied = 0;

  /*
   *  Three phases to the write:
   *    + possibly the last part of one block
   *    + all of zero of more blocks
   *    + possibly the first part of one block
   */

  /*
   *  Phase 1: possibly the last part of one block
   */

  start_offset = start % IMFS_MEMFILE_BYTES_PER_BLOCK;
  block = start / IMFS_MEMFILE_BYTES_PER_BLOCK;
  if ( start_offset )  {
    to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK - start_offset;
    if ( to_copy > my_length )
      to_copy = my_length;
    block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
    assert( block_ptr );
    if ( !block_ptr )
      return copied;
#if 0
printf( "write %d at %d in %d: %*s\n", to_copy, start_offset, block, to_copy, src );
#endif
    memcpy( &(*block_ptr)[ start_offset ], src, to_copy );
    src += to_copy;
    block++;
    my_length -= to_copy;
    copied += to_copy;
  }

  /*
   *  Phase 2: all of zero of more blocks
   */

  to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK;
  while ( my_length >= IMFS_MEMFILE_BYTES_PER_BLOCK ) {
    block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
    assert( block_ptr );
    if ( !block_ptr )
      return copied;
#if 0
printf( "write %d in %d: %*s\n", to_copy, block, to_copy, src );
#endif
    memcpy( &(*block_ptr)[ 0 ], src, to_copy );
    src += to_copy;
    block++;
    my_length -= to_copy;
    copied += to_copy;
  }

  /*
   *  Phase 3: possibly the first part of one block
   */

  assert( my_length < IMFS_MEMFILE_BYTES_PER_BLOCK );

  to_copy = my_length;
  if ( my_length ) {
    block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
    assert( block_ptr );
    if ( !block_ptr )
      return copied;
#if 0
printf( "write %d in %d: %*s\n", to_copy, block, to_copy, src );
#endif
    memcpy( &(*block_ptr)[ 0 ], src, my_length );
    my_length = 0;
    copied += to_copy;
  }

  IMFS_atime_mtime_update( the_jnode );

  return copied;
}

/*
 *  IMFS_memfile_get_block_pointer
 *
 *  This routine looks up the block pointer associated with the given block
 *  number.  If that block has not been allocated and "malloc_it" is
 *  TRUE, then the block is allocated.  Otherwise, it is an error.
 */

#if 0
block_p *IMFS_memfile_get_block_pointer_DEBUG(
   IMFS_jnode_t   *the_jnode,
   unsigned int    block,
   int             malloc_it
);

block_p *IMFS_memfile_get_block_pointer(
   IMFS_jnode_t   *the_jnode,
   unsigned int    block,
   int             malloc_it
)
{
  block_p *p;

  p = IMFS_memfile_get_block_pointer_DEBUG( the_jnode, block, malloc_it );
  printf( "(%d -> %p) ", block, p );
  return p;
}

block_p *IMFS_memfile_get_block_pointer_DEBUG(
#else
block_p *IMFS_memfile_get_block_pointer(
#endif
   IMFS_jnode_t   *the_jnode,
   unsigned int    block,
   int             malloc_it
)
{
  unsigned int    my_block;
  IMFS_memfile_t *info;
  unsigned int    singly;
  unsigned int    doubly;
  unsigned int    triply;
  block_p        *p;
  block_p        *p1;
  block_p        *p2;

  /*
   *  Perform internal consistency checks
   */

  assert( the_jnode );
  if ( !the_jnode )
    return NULL;

  assert( the_jnode->type == IMFS_MEMORY_FILE );
  if ( the_jnode->type != IMFS_MEMORY_FILE )
    return NULL;

  info = &the_jnode->info.file;

  my_block = block;

  /*
   *  Is the block number in the simple indirect portion?
   */

  if ( my_block <= LAST_INDIRECT ) {
#if 0
printf( "(s %d) ", block );
fflush(stdout);
#endif
    p = info->indirect;

    if ( malloc_it ) {

      if ( !p ) {
        p = memfile_alloc_block();
        if ( !p )
           return 0;
        info->indirect = p;
      }
      return &info->indirect[ my_block ];
    }

    if ( !p )
      return 0;

    return &info->indirect[ my_block ];
  }

  /*
   *  Is the block number in the doubly indirect portion?
   */

  if ( my_block <= LAST_DOUBLY_INDIRECT ) {
#if 0
printf( "(d %d) ", block );
fflush(stdout);
#endif

    my_block -= FIRST_DOUBLY_INDIRECT;

    singly = my_block % IMFS_MEMFILE_BLOCK_SLOTS;
    doubly = my_block / IMFS_MEMFILE_BLOCK_SLOTS;

    p = info->doubly_indirect;
    if ( malloc_it ) {

      if ( !p ) {
        p = memfile_alloc_block();
        if ( !p )
           return 0;
        info->doubly_indirect = p;
      }

      p1 = (block_p *)p[ doubly ];
      if ( !p1 ) {
        p1 = memfile_alloc_block();
        if ( !p1 )
           return 0;
        p[ doubly ] = (block_p) p1;
      }

      return (block_p *)&p1[ singly ];
    }

    if ( !p )
      return 0;

    p = (block_p *)p[ doubly ];
    if ( !p ) 
      return 0;

#if 0
printf( "(d %d %d %d %d %p %p) ", block, my_block, doubly,
                                       singly, p, &p[singly] );
fflush(stdout);
#endif
    return (block_p *)&p[ singly ];
  }

#if 0
printf( "(t %d) ", block );
fflush(stdout);
#endif
  /*
   *  Is the block number in the triply indirect portion?
   */

  if ( my_block <= LAST_TRIPLY_INDIRECT ) {
    my_block -= FIRST_TRIPLY_INDIRECT;

    singly = my_block % IMFS_MEMFILE_BLOCK_SLOTS;
    doubly = my_block / IMFS_MEMFILE_BLOCK_SLOTS;
    triply = doubly / IMFS_MEMFILE_BLOCK_SLOTS;
    doubly %= IMFS_MEMFILE_BLOCK_SLOTS;

    p = info->triply_indirect;

    if ( malloc_it ) {
      if ( !p ) {
        p = memfile_alloc_block();
        if ( !p )
           return 0;
        info->triply_indirect = p;
      }

      p1 = (block_p *) p[ triply ];
      if ( !p1 ) {
        p1 = memfile_alloc_block();
        if ( !p1 )
           return 0;
        p[ triply ] = (block_p) p1;
      }

      p2 = (block_p *)p1[ doubly ];
      if ( !p2 ) {
        p2 = memfile_alloc_block();
        if ( !p2 )
           return 0;
        p1[ doubly ] = (block_p) p2;
      }
      return (block_p *)&p2[ singly ];
    }

    if ( !p )
      return 0;

#if 0
printf( "(t %d %d %d %d %d) ", block, my_block, triply, doubly, singly );
fflush(stdout);
#endif
    p1 = (block_p *) p[ triply ];
    if ( !p1 )
      return 0;

    p2 = (block_p *)p1[ doubly ];
    if ( !p )
      return 0;

    return (block_p *)&p2[ singly ];
  }

  /*
   *  This means the requested block number is out of range.
   */

  return 0;
}

/*
 *  memfile_alloc_block
 *
 *  Allocate a block for an in-memory file.
 */

int memfile_blocks_allocated = 0;

void *memfile_alloc_block(void)
{
  void *memory;

  memory = (void *)calloc(1, IMFS_MEMFILE_BYTES_PER_BLOCK);
  if ( memory )
    memfile_blocks_allocated++;

  return memory;
}

/*
 *  memfile_free_block
 *
 *  Free a block from an in-memory file.
 */

void memfile_free_block(
  void *memory
)
{
#if 0
printf( "(d %p) ", memory );
fflush(stdout);
#endif
  free(memory);
  memfile_blocks_allocated--;
}


/*
 *  memfile_rmnod
 *
 *  This routine is available from the optable to remove a node 
 *  from the IMFS file system.
 */

int memfile_rmnod(
  rtems_filesystem_location_info_t      *pathloc       /* IN */
)
{
  IMFS_jnode_t *the_jnode;  

  the_jnode = (IMFS_jnode_t *) pathloc->node_access;

  /* 
   * Take the node out of the parent's chain that contains this node 
   */

  if ( the_jnode->Parent != NULL ) {
    Chain_Extract( (Chain_Node *) the_jnode );
    the_jnode->Parent = NULL;
  }

  /*
   * Decrement the link counter and see if we can free the space.
   */

  the_jnode->st_nlink--;
  IMFS_update_ctime( the_jnode );

  return memfile_check_rmnod( the_jnode );
}


int  memfile_check_rmnod( IMFS_jnode_t *the_jnode ){

  /*
   * The file cannot be open and the link must be less than 1 to free.
   */

  if ( !rtems_libio_is_file_open( the_jnode ) && (the_jnode->st_nlink < 1) ) {

    /* 
     * Is the rtems_filesystem_current is this node?
     */

    if ( rtems_filesystem_current.node_access == the_jnode )
       rtems_filesystem_current.node_access = NULL;

    /*
     * Free memory associated with a memory file.
     */
    if (the_jnode->type != IMFS_LINEAR_FILE)
      IMFS_memfile_remove( the_jnode );

    free( the_jnode );
  }

  return 0;
}