/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2004 Pawel Jakub Dawidek * Copyright (c) 2006 Tobias Reifenberger * All rights reserved. * * 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 #include #include #include #include #include #include #include #include #define LABEL_NO_NAME "NO NAME " static void g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size) { struct g_provider *pp; FAT_BSBPB *pfat_bsbpb; FAT32_BSBPB *pfat32_bsbpb; FAT_DES *pfat_entry; uint8_t *sector0, *sector; size_t copysize; g_topology_assert_not(); pp = cp->provider; sector0 = NULL; sector = NULL; bzero(label, size); /* Check if the sector size of the medium is a valid FAT sector size. */ switch(pp->sectorsize) { case 512: case 1024: case 2048: case 4096: break; default: G_LABEL_DEBUG(1, "MSDOSFS: %s: sector size %d not compatible.", pp->name, pp->sectorsize); return; } /* Load 1st sector with boot sector and boot parameter block. */ sector0 = (uint8_t *)g_read_data(cp, 0, pp->sectorsize, NULL); if (sector0 == NULL) return; /* Check for the FAT boot sector signature. */ if (sector0[510] != 0x55 || sector0[511] != 0xaa) { G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT signature found.", pp->name); 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) { G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/16 volume not valid.", pp->name); goto error; } G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/FAT16 volume detected.", pp->name); /* 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) { G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/16 volume has no name.", pp->name); goto error; } 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) { G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume not valid.", pp->name); goto error; } G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume detected.", pp->name); /* * 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); G_LABEL_DEBUG(2, "MSDOSFS: FAT_FirstDataSector=0x%x, FAT_BytesPerSector=%d", fat_FirstDataSector, fat_BytesPerSector); if (fat_BytesPerSector == 0 || fat_BytesPerSector % pp->sectorsize != 0) { G_LABEL_DEBUG(1, "MSDOSFS: %s: corrupted BPB", pp->name); goto error; } for (offset = fat_BytesPerSector * fat_FirstDataSector;; offset += fat_BytesPerSector) { sector = (uint8_t *)g_read_data(cp, offset, fat_BytesPerSector, NULL); if (sector == NULL) goto error; pfat_entry = (FAT_DES *)sector; do { /* No more entries available. */ if (pfat_entry->DIR_Name[0] == 0) { G_LABEL_DEBUG(1, "MSDOSFS: %s: " "FAT32 volume has no name.", pp->name); goto error; } /* 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)); g_free(sector); } } else { G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT volume detected.", pp->name); goto error; } endofchecks: g_label_rtrim(label, size); error: g_free(sector0); g_free(sector); } struct g_label_desc g_label_msdosfs = { .ld_taste = g_label_msdosfs_taste, .ld_dirprefix = "msdosfs/", .ld_enabled = 1 }; G_LABEL_INIT(msdosfs, g_label_msdosfs, "Create device nodes for MSDOSFS volumes");