source: bootcd/isolinux/syslinux-6.03/libfat/searchdir.c @ 26ffad7

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2004-2008 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);
    }
}