searchdir.c

linux内核

#ident "$Id$"
/* ----------------------------------------------------------------------- *
 *   
 *   Copyright 2004 H. Peter Anvin - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * searchdir.c
 *
 * Search a FAT directory for a particular pre-mangled filename.
 * Copies the directory entry into direntry and returns the starting cluster
 * if found; returns -2 on not found, -1 on error, 0 on empty file.
 */

#include <string.h>
#include "libfatint.h"

int32_t libfat_searchdir(struct libfat_filesystem *fs, int32_t dirclust,
			 const void *name, struct libfat_direntry *direntry)
{
  struct fat_dirent *dep;
  int nent;
  libfat_sector_t s = libfat_clustertosector(fs, dirclust);

  while ( 1 ) {
    if ( s == 0 )
      return -2;		/* Not found */
    else if ( s == (libfat_sector_t)-1 )
      return -1;		/* Error */
    
    dep = libfat_get_sector(fs, s);
    if ( !dep )
      return -1;		/* Read error */

    for ( nent = 0 ; nent < LIBFAT_SECTOR_SIZE ;
	  nent += sizeof(struct fat_dirent) ) {
      if ( !memcmp(dep->name, name, 11) ) {
	if ( direntry ) {
	  memcpy(direntry->entry, dep, sizeof (*dep));
	  direntry->sector = s;
	  direntry->offset = nent;
	}
	if ( read32(&dep->size) == 0 )
	  return 0;		/* An empty file has no clusters */
	else
	  return read16(&dep->clustlo) + (read16(&dep->clusthi) << 16);
      }
      
      if ( dep->name[0] == 0 )
	return -2;		/* Hit high water mark */

      dep++;
    }   

    s = libfat_nextsector(fs, s);
  }
}