source: rtems/c/src/lib/libc/imfs_directory.c @ 6693a68

/*
 *  XXX
 *
 *  COPYRIGHT (c) 1989-1998.
 *  On-Line Applications Research Corporation (OAR).
 *  Copyright assigned to U.S. Government, 1994.
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.OARcorp.com/rtems/license.html.
 *
 *  $Id$
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <chain.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <dirent.h>

#include "imfs.h"
#include "libio_.h"

/* -----------------------------------------------------------------------
 * This rountine will verify that the node being opened as a directory is
 * in fact a directory node. If it is then the offset into the directory 
 * will be set to 0 to position to the first directory entry.
 */

int imfs_dir_open( 
  rtems_libio_t  *iop,
  const char *pathname,
  unsigned32 flag,
  unsigned32 mode
)
{
  IMFS_jnode_t      *the_jnode;

  /* Is the node a directory ? */
  the_jnode = (IMFS_jnode_t *) iop->file_info;

  if ( the_jnode->type != IMFS_DIRECTORY )
     return -1;         /* It wasn't a directory --> return error */

  iop->offset = 0;
  return 0;
}



/* -----------------------------------------------------------------------
 * This routine will read the next directory entry based on the directory 
 * offset. The offset should be equal to -n- time the size of an individual
 * dirent structure. If n is not an integer multiple of the sizeof a 
 * dirent structure, an integer division will be performed to determine 
 * directory entry that will be returned in the buffer. Count should reflect
 * -m- times the sizeof dirent bytes to be placed in the buffer.
 * If there are not -m- dirent elements from the current directory position
 * to the end of the exisiting file, the remaining entries will be placed in 
 * the buffer and the returned value will be equal to -m actual- times the
 * size of a directory entry.
 */

int imfs_dir_read(
  rtems_libio_t  *iop,
  void *buffer,
  unsigned32 count
)
{
  /*
   *  Read up to element  iop->offset in the directory chain of the
   *  imfs_jnode_t struct for this file descriptor.
   */
   Chain_Node        *the_node;
   Chain_Control     *the_chain;
   IMFS_jnode_t      *the_jnode;
   int                bytes_transferred;
   int                current_entry;
   int                first_entry;
   int                last_entry;
   struct dirent      tmp_dirent;

   the_jnode = (IMFS_jnode_t *)iop->file_info;
   the_chain = &the_jnode->info.directory.Entries;
   
   if ( Chain_Is_empty( the_chain ) )
      return 0;

   /* Move to the first of the desired directory entries */
   the_node = the_chain->first;

   bytes_transferred = 0;
   first_entry = iop->offset;
   /* protect against using sizes that are not exact multiples of the */
   /* -dirent- size. These could result in unexpected results          */
   last_entry = first_entry + (count/sizeof(struct dirent)) * sizeof(struct dirent);

   /* The directory was not empty so try to move to the desired entry in chain*/
   for( 
      current_entry = 0; 
      current_entry < last_entry; 
      current_entry = current_entry + sizeof(struct dirent) ){

      if ( Chain_Is_tail( the_chain, the_node ) ){ 
         /* We hit the tail of the chain while trying to move to the first */
         /* entry in the read */
         return bytes_transferred;  /* Indicate that there are no more */
                                    /* entries to return */
      }
    
      if( current_entry >= first_entry ) {
         /* Move the entry to the return buffer */
         tmp_dirent.d_ino = 1;
         tmp_dirent.d_off = current_entry;
         tmp_dirent.d_reclen = sizeof( struct dirent );
         the_jnode = (IMFS_jnode_t *) the_node;
         tmp_dirent.d_namlen = strlen( the_jnode->name );
         strcpy( tmp_dirent.d_name, the_jnode->name );
         memcpy( 
            buffer + bytes_transferred, 
            (void *)&tmp_dirent, 
            sizeof( struct dirent ) 
         );
         iop->offset = iop->offset + sizeof(struct dirent);
         bytes_transferred = bytes_transferred + sizeof( struct dirent );
      }

      the_node = the_node->next;
   }

   /* Success */
   return bytes_transferred;
}



/* -----------------------------------------------------------------------
 * This routine will be called by the generic close routine to cleanup any
 * resources that have been allocated for the management of the file
 */

int imfs_dir_close(
  rtems_libio_t  *iop
)
{
  /* The generic close routine handles the deallocation of the file control */
  /* and associated memory. At present the imfs_dir_close simply      */
  /* returns a successful completion status                                 */
 
  return 0;
}



/* -----------------------------------------------------------------------
 * This routine will behave in one of three ways based on the state of 
 * argument whence. Based on the state of its value the offset argument will
 * be interpreted using one of the following methods:
 *
 *      SEEK_SET - offset is the absolute byte offset from the start of the
 *                 logical start of the dirent sequence that represents the
 *                 directory
 *      SEEK_CUR - offset is used as the relative byte offset from the current
 *                 directory position index held in the iop structure
 *      SEEK_END - N/A --> This will cause an assert.
 */

int imfs_dir_lseek(
  rtems_libio_t  *iop,
  off_t           offset,
  int             whence
)
{
  off_t normal_offset;

  normal_offset = (offset/sizeof(struct dirent)) * sizeof(struct dirent);


  switch( whence )
  {
     case SEEK_SET:     /* absolute move from the start of the file */
        iop->offset = normal_offset;
        break;

     case SEEK_CUR:     /* relative move */
        iop->offset = iop->offset + normal_offset;
        break;

     case SEEK_END:     /* Movement past the end of the directory via lseek */
                        /* is not a permitted operation                     */
      default:
        set_errno_and_return_minus_one( EINVAL );
        break;

  }

  return 0;
}



/* -----------------------------------------------------------------------
 * This routine will obtain the following information concerning the current 
 * directory:
 *      st_dev          0ll
 *      st_ino          1
 *      st_mode         mode extracted from the jnode
 *      st_nlink        number of links to this node
 *      st_uid          uid extracted from the jnode
 *      st_gid          gid extracted from the jnode
 *      st_rdev         0ll
 *      st_size         the number of bytes in the directory 
 *                      This is calculated by taking the number of entries
 *                      in the directory and multiplying by the size of a 
 *                      dirent structure
 *      st_blksize      0
 *      st_blocks       0
 *      st_atime        time of last access
 *      st_mtime        time of last modification
 *      st_ctime        time of the last change
 *
 * This information will be returned to the calling function in a -stat- struct
 *      
 */

int imfs_dir_fstat(
  rtems_filesystem_location_info_t *loc,
  struct stat                      *buf
)
{
   Chain_Node        *the_node;
   Chain_Control     *the_chain;
   IMFS_jnode_t      *the_jnode;


   the_jnode = (IMFS_jnode_t *) loc->node_access;

   buf->st_dev = 0ll;
   buf->st_ino   = the_jnode->st_ino;
   buf->st_mode  = the_jnode->st_mode;
   buf->st_nlink = the_jnode->st_nlink;
   buf->st_uid   = the_jnode->st_uid;
   buf->st_gid   = the_jnode->st_gid;
   buf->st_rdev = 0ll;
   buf->st_blksize = 0;
   buf->st_blocks = 0;
   buf->st_atime = the_jnode->st_atime;
   buf->st_mtime = the_jnode->st_mtime;
   buf->st_ctime = the_jnode->st_ctime;

   buf->st_size = 0;

   the_chain = &the_jnode->info.directory.Entries;

   /* Run through the chain and count the number of directory entries */
   /* that are subordinate to this directory node                     */
   for ( the_node = the_chain->first ;
         !_Chain_Is_tail( the_chain, the_node ) ;
         the_node = the_node->next ) {
 
      buf->st_size = buf->st_size + sizeof( struct dirent );
   }

   return 0;
}