libfat/searchdir.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * searchdir.c
  15  *
  16  * Search a FAT directory for a particular pre-mangled filename.
  17  * Copies the directory entry into direntry and returns the starting cluster
  18  * if found; returns -2 on not found, -1 on error, 0 on empty file.
  19  */
  20
  21 #include <string.h>
  22 #include "libfatint.h"
  23
  24 int32_t libfat_searchdir(struct libfat_filesystem *fs, int32_t dirclust,
  25                          const void *name, struct libfat_direntry *direntry)
  26 {
  27   struct fat_dirent *dep;
  28   int nent;
  29   libfat_sector_t s = libfat_clustertosector(fs, dirclust);
  30
  31   while ( 1 ) {
  32     if ( s == 0 )
  33       return -2;                /* Not found */
  34     else if ( s == (libfat_sector_t)-1 )
  35       return -1;                /* Error */
  36
  37     dep = libfat_get_sector(fs, s);
  38     if ( !dep )
  39       return -1;                /* Read error */
  40
  41     for ( nent = 0 ; nent < LIBFAT_SECTOR_SIZE ;
  42           nent += sizeof(struct fat_dirent) ) {
  43       if ( !memcmp(dep->name, name, 11) ) {
  44         if ( direntry ) {
  45           memcpy(direntry->entry, dep, sizeof (*dep));
  46           direntry->sector = s;
  47           direntry->offset = nent;
  48         }
  49         if ( read32(&dep->size) == 0 )
  50           return 0;             /* An empty file has no clusters */
  51         else
  52           return read16(&dep->clustlo) + (read16(&dep->clusthi) << 16);
  53       }
  54
  55       if ( dep->name[0] == 0 )
  56         return -2;              /* Hit high water mark */
  57
  58       dep++;
  59     }
  60
  61     s = libfat_nextsector(fs, s);
  62   }
  63 }