/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> * Copyright (c) 2006 Tobias Reifenberger * Copyright (c) 2014 The FreeBSD Foundation * All rights reserved. * * This software was developed by Edward Tomasz Napierala under sponsorship * from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <sys/cdefs.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "fstyp.h" #include "msdosfs.h" #define LABEL_NO_NAME "NO NAME " /* * XXX the signature 0x55 0xAA as the last two bytes of 512 is not required * by specifications, but was historically required by fstyp. This check * should be removed, with a more comprehensive BPB validation instead. */ static bool check_signature(uint8_t sector0[512]) { /* Check for the FAT boot sector signature. */ if (sector0[510] == 0x55 && sector0[511] == 0xaa) return (true); /* Special case for Raspberry Pi Pico bootloader. */ if (sector0[510] == 0 && sector0[511] == 0 && sector0[0] == 0xeb && sector0[1] == 0x3c && sector0[2] == 0x90) return (true); return (false); } int fstyp_msdosfs(FILE *fp, char *label, size_t size) { FAT_BSBPB *pfat_bsbpb; FAT32_BSBPB *pfat32_bsbpb; FAT_DES *pfat_entry; uint8_t *sector0, *sector; size_t copysize; sector0 = NULL; sector = NULL; /* Load 1st sector with boot sector and boot parameter block. */ sector0 = (uint8_t *)read_buf(fp, 0, 512); if (sector0 == NULL) return (1); if (!check_signature(sector0)) { goto error; } /* * Test if this is really a FAT volume and determine the FAT type. */ pfat_bsbpb = (FAT_BSBPB *)sector0; pfat32_bsbpb = (FAT32_BSBPB *)sector0; if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) { /* * If the BPB_FATSz16 field is not zero and the string "FAT" is * at the right place, this should be a FAT12 or FAT16 volume. */ if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) { goto error; } /* A volume with no name should have "NO NAME " as label. */ if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME, sizeof(pfat_bsbpb->BS_VolLab)) == 0) { goto endofchecks; } copysize = MIN(size - 1, sizeof(pfat_bsbpb->BS_VolLab)); memcpy(label, pfat_bsbpb->BS_VolLab, copysize); label[copysize] = '\0'; } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; /* * If the BPB_FATSz32 field is not zero and the string "FAT" is * at the right place, this should be a FAT32 volume. */ if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { goto error; } /* * If the volume label is not "NO NAME " we're done. */ if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { copysize = MIN(size - 1, sizeof(pfat32_bsbpb->BS_VolLab)); memcpy(label, pfat32_bsbpb->BS_VolLab, copysize); label[copysize] = '\0'; goto endofchecks; } /* * If the volume label "NO NAME " is in the boot sector, the * label of FAT32 volumes may be stored as a special entry in * the root directory. */ fat_FirstDataSector = UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + (pfat32_bsbpb->BPB_NumFATs * UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); // fat_FirstDataSector, fat_BytesPerSector); for (offset = fat_BytesPerSector * fat_FirstDataSector;; offset += fat_BytesPerSector) { sector = (uint8_t *)read_buf(fp, offset, fat_BytesPerSector); if (sector == NULL) goto error; pfat_entry = (FAT_DES *)sector; do { /* No more entries available. */ if (pfat_entry->DIR_Name[0] == 0) { goto endofchecks; } /* Skip empty or long name entries. */ if (pfat_entry->DIR_Name[0] == 0xe5 || (pfat_entry->DIR_Attr & FAT_DES_ATTR_LONG_NAME) == FAT_DES_ATTR_LONG_NAME) { continue; } /* * The name of the entry is the volume label if * ATTR_VOLUME_ID is set. */ if (pfat_entry->DIR_Attr & FAT_DES_ATTR_VOLUME_ID) { copysize = MIN(size - 1, sizeof(pfat_entry->DIR_Name)); memcpy(label, pfat_entry->DIR_Name, copysize); label[copysize] = '\0'; goto endofchecks; } } while((uint8_t *)(++pfat_entry) < (uint8_t *)(sector + fat_BytesPerSector)); free(sector); } } else { goto error; } endofchecks: rtrim(label, size); free(sector0); free(sector); return (0); error: free(sector0); free(sector); return (1); }
