219 lines
6.4 KiB
C
219 lines
6.4 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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* Copyright (c) 2006 Tobias Reifenberger
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <geom/geom.h>
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#include <geom/geom_dbg.h>
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#include <geom/label/g_label.h>
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#include <geom/label/g_label_msdosfs.h>
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#define LABEL_NO_NAME "NO NAME "
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static void
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g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size)
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{
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struct g_provider *pp;
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FAT_BSBPB *pfat_bsbpb;
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FAT32_BSBPB *pfat32_bsbpb;
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FAT_DES *pfat_entry;
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uint8_t *sector0, *sector;
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g_topology_assert_not();
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pp = cp->provider;
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sector0 = NULL;
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sector = NULL;
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bzero(label, size);
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/* Check if the sector size of the medium is a valid FAT sector size. */
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switch(pp->sectorsize) {
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case 512:
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case 1024:
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case 2048:
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case 4096:
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break;
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default:
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G_LABEL_DEBUG(1, "MSDOSFS: %s: sector size %d not compatible.",
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pp->name, pp->sectorsize);
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return;
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}
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/* Load 1st sector with boot sector and boot parameter block. */
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sector0 = (uint8_t *)g_read_data(cp, 0, pp->sectorsize, NULL);
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if (sector0 == NULL)
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return;
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/* Check for the FAT boot sector signature. */
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if (sector0[510] != 0x55 || sector0[511] != 0xaa) {
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G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT signature found.",
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pp->name);
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goto error;
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}
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/*
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* Test if this is really a FAT volume and determine the FAT type.
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*/
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pfat_bsbpb = (FAT_BSBPB *)sector0;
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pfat32_bsbpb = (FAT32_BSBPB *)sector0;
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if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) {
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/*
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* If the BPB_FATSz16 field is not zero and the string "FAT" is
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* at the right place, this should be a FAT12 or FAT16 volume.
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*/
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if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
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G_LABEL_DEBUG(1,
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"MSDOSFS: %s: FAT12/16 volume not valid.",
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pp->name);
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goto error;
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}
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G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/FAT16 volume detected.",
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pp->name);
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/* A volume with no name should have "NO NAME " as label. */
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if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME,
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sizeof(pfat_bsbpb->BS_VolLab)) == 0) {
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G_LABEL_DEBUG(1,
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"MSDOSFS: %s: FAT12/16 volume has no name.",
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pp->name);
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goto error;
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}
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strlcpy(label, pfat_bsbpb->BS_VolLab,
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MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1));
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} else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) {
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uint32_t fat_FirstDataSector, fat_BytesPerSector, offset;
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/*
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* If the BPB_FATSz32 field is not zero and the string "FAT" is
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* at the right place, this should be a FAT32 volume.
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*/
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if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
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G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume not valid.",
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pp->name);
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goto error;
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}
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G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume detected.",
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pp->name);
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/*
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* If the volume label is not "NO NAME " we're done.
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*/
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if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME,
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sizeof(pfat32_bsbpb->BS_VolLab)) != 0) {
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strlcpy(label, pfat32_bsbpb->BS_VolLab,
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MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1));
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goto endofchecks;
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}
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/*
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* If the volume label "NO NAME " is in the boot sector, the
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* label of FAT32 volumes may be stored as a special entry in
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* the root directory.
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*/
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fat_FirstDataSector =
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UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) +
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(pfat32_bsbpb->BPB_NumFATs *
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UINT32BYTES(pfat32_bsbpb->BPB_FATSz32));
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fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec);
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G_LABEL_DEBUG(2,
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"MSDOSFS: FAT_FirstDataSector=0x%x, FAT_BytesPerSector=%d",
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fat_FirstDataSector, fat_BytesPerSector);
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for (offset = fat_BytesPerSector * fat_FirstDataSector;;
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offset += fat_BytesPerSector) {
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sector = (uint8_t *)g_read_data(cp, offset,
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fat_BytesPerSector, NULL);
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if (sector == NULL)
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goto error;
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pfat_entry = (FAT_DES *)sector;
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do {
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/* No more entries available. */
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if (pfat_entry->DIR_Name[0] == 0) {
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G_LABEL_DEBUG(1, "MSDOSFS: %s: "
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"FAT32 volume has no name.",
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pp->name);
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goto error;
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}
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/* Skip empty or long name entries. */
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if (pfat_entry->DIR_Name[0] == 0xe5 ||
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(pfat_entry->DIR_Attr &
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FAT_DES_ATTR_LONG_NAME) ==
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FAT_DES_ATTR_LONG_NAME) {
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continue;
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}
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/*
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* The name of the entry is the volume label if
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* ATTR_VOLUME_ID is set.
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*/
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if (pfat_entry->DIR_Attr &
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FAT_DES_ATTR_VOLUME_ID) {
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strlcpy(label, pfat_entry->DIR_Name,
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MIN(size,
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sizeof(pfat_entry->DIR_Name) + 1));
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goto endofchecks;
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}
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} while((uint8_t *)(++pfat_entry) <
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(uint8_t *)(sector + fat_BytesPerSector));
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g_free(sector);
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}
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} else {
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G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT volume detected.",
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pp->name);
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goto error;
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}
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endofchecks:
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g_label_rtrim(label, size);
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error:
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if (sector0 != NULL)
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g_free(sector0);
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if (sector != NULL)
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g_free(sector);
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}
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struct g_label_desc g_label_msdosfs = {
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.ld_taste = g_label_msdosfs_taste,
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.ld_dirprefix = "msdosfs/",
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.ld_enabled = 1
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};
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G_LABEL_INIT(msdosfs, g_label_msdosfs, "Create device nodes for MSDOSFS volumes");
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