1 /* 2 * Copyright (c) 2010 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Alex Hornung <ahornung@gmail.com 6 * and Ákos Kovács <akoskovacs@gmx.com> 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in 16 * the documentation and/or other materials provided with the 17 * distribution. 18 * 3. Neither the name of The DragonFly Project nor the names of its 19 * contributors may be used to endorse or promote products derived 20 * from this software without specific, prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 26 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 28 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 29 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 30 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 32 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include "libfsid.h" 37 38 #include <vfs/msdosfs/bootsect.h> 39 40 #define MSDOS_BOOT_BLOCK_SIZE 512 41 42 static char *get_volname(char *buf); 43 static char buffer[MSDOS_BOOT_BLOCK_SIZE * 4]; 44 45 fsid_t 46 msdosfs_probe(const char *dev) 47 { 48 if (fsid_dev_read(dev, 0L, sizeof(buffer), buffer) != 0) 49 return FSID_UNKNOWN; 50 51 if (get_volname(buffer) != NULL) 52 return FSID_MSDOSFS; 53 54 return FSID_MSDOSFS; 55 } 56 char * 57 msdosfs_volname(const char *dev) 58 { 59 char *volname; 60 61 if (fsid_dev_read(dev, 0L, sizeof(buffer), buffer) != 0) 62 return NULL; 63 64 volname = get_volname(buffer); 65 66 if (volname == NULL || volname[0] == '\0') 67 return NULL; 68 69 volname[sizeof(volname) - 1] = '\0'; 70 71 return volname; 72 } 73 74 /* 75 * This function used to get the offset address of 76 * the volume name, of the FAT partition. 77 * It also checks, that is a real FAT partition. 78 */ 79 static char * 80 get_volname(char *buff) 81 { 82 struct bootsector710 *bpb7; 83 struct bootsector50 *bpb4; 84 struct extboot *extb; 85 86 bpb7 = (struct bootsector710 *)buff; 87 bpb4 = (struct bootsector50 *)buff; 88 89 /* 90 * First, assume BPB v7 91 */ 92 extb = (struct extboot *)bpb7->bsExt; 93 if ((extb->exBootSignature == 0x28 || extb->exBootSignature == 0x29) && 94 strncmp(extb->exFileSysType, "FAT", 3) == 0) 95 return extb->exVolumeLabel; 96 97 /* 98 * If this is not a BPB v7, try it as a bpb v4. 99 */ 100 extb = (struct extboot *)bpb4->bsExt; 101 if ((extb->exBootSignature == EXBOOTSIG || 102 extb->exBootSignature == EXBOOTSIG2) && 103 strncmp(extb->exFileSysType, "FAT", 3) == 0) 104 return extb->exVolumeLabel; 105 106 /* 107 * If previous checks failed, it may not a FAT filesystem, or 108 * it may an older one without a volume name. 109 */ 110 return NULL; 111 } 112