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) +
  53                         (read16(&dep->clusthi) << 16);
  54             }
  55
  56             if (dep->name[0] == 0)
  57                 return -2;      /* Hit high water mark */
  58
  59             dep++;
  60         }
  61
  62         s = libfat_nextsector(fs, s);
  63     }
  64 }