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390 lines
10 KiB
C
390 lines
10 KiB
C
/*
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mount.c (22.10.09)
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exFAT file system implementation library.
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Free exFAT implementation.
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Copyright (C) 2010-2018 Andrew Nayenko
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "exfat.h"
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <unistd.h>
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#include <sys/types.h>
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static uint64_t rootdir_size(const struct exfat* ef)
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{
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uint32_t clusters = 0;
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uint32_t clusters_max = le32_to_cpu(ef->sb->cluster_count);
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cluster_t rootdir_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
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/* Iterate all clusters of the root directory to calculate its size.
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It can't be contiguous because there is no flag to indicate this. */
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do
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{
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if (clusters == clusters_max) /* infinite loop detected */
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{
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exfat_error("root directory cannot occupy all %d clusters",
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clusters);
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return 0;
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}
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if (CLUSTER_INVALID(*ef->sb, rootdir_cluster))
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{
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exfat_error("bad cluster %#x while reading root directory",
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rootdir_cluster);
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return 0;
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}
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rootdir_cluster = exfat_next_cluster(ef, ef->root, rootdir_cluster);
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clusters++;
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}
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while (rootdir_cluster != EXFAT_CLUSTER_END);
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return (uint64_t) clusters * CLUSTER_SIZE(*ef->sb);
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}
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static const char* get_option(const char* options, const char* option_name)
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{
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const char* p;
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size_t length = strlen(option_name);
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for (p = strstr(options, option_name); p; p = strstr(p + 1, option_name))
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if ((p == options || p[-1] == ',') && p[length] == '=')
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return p + length + 1;
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return NULL;
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}
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static int get_int_option(const char* options, const char* option_name,
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int base, int default_value)
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{
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const char* p = get_option(options, option_name);
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if (p == NULL)
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return default_value;
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return strtol(p, NULL, base);
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}
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static bool match_option(const char* options, const char* option_name)
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{
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const char* p;
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size_t length = strlen(option_name);
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for (p = strstr(options, option_name); p; p = strstr(p + 1, option_name))
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if ((p == options || p[-1] == ',') &&
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(p[length] == ',' || p[length] == '\0'))
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return true;
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return false;
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}
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static void parse_options(struct exfat* ef, const char* options)
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{
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int opt_umask;
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opt_umask = get_int_option(options, "umask", 8, 0);
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ef->dmask = get_int_option(options, "dmask", 8, opt_umask);
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ef->fmask = get_int_option(options, "fmask", 8, opt_umask);
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ef->uid = get_int_option(options, "uid", 10, geteuid());
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ef->gid = get_int_option(options, "gid", 10, getegid());
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ef->noatime = match_option(options, "noatime");
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switch (get_int_option(options, "repair", 10, 0))
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{
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case 1:
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ef->repair = EXFAT_REPAIR_ASK;
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break;
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case 2:
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ef->repair = EXFAT_REPAIR_YES;
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break;
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default:
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ef->repair = EXFAT_REPAIR_NO;
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break;
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}
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}
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static bool verify_vbr_checksum(const struct exfat* ef, void* sector)
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{
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off_t sector_size = SECTOR_SIZE(*ef->sb);
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uint32_t vbr_checksum;
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int i;
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if (exfat_pread(ef->dev, sector, sector_size, 0) < 0)
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{
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exfat_error("failed to read boot sector");
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return false;
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}
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vbr_checksum = exfat_vbr_start_checksum(sector, sector_size);
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for (i = 1; i < 11; i++)
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{
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if (exfat_pread(ef->dev, sector, sector_size, i * sector_size) < 0)
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{
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exfat_error("failed to read VBR sector");
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return false;
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}
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vbr_checksum = exfat_vbr_add_checksum(sector, sector_size,
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vbr_checksum);
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}
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if (exfat_pread(ef->dev, sector, sector_size, i * sector_size) < 0)
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{
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exfat_error("failed to read VBR checksum sector");
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return false;
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}
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for (i = 0; i < sector_size / sizeof(vbr_checksum); i++)
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if (le32_to_cpu(((const le32_t*) sector)[i]) != vbr_checksum)
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{
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exfat_error("invalid VBR checksum 0x%x (expected 0x%x)",
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le32_to_cpu(((const le32_t*) sector)[i]), vbr_checksum);
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if (!EXFAT_REPAIR(invalid_vbr_checksum, ef, sector, vbr_checksum))
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return false;
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}
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return true;
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}
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static int commit_super_block(const struct exfat* ef)
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{
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if (exfat_pwrite(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
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{
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exfat_error("failed to write super block");
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return 1;
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}
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return exfat_fsync(ef->dev);
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}
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static int prepare_super_block(const struct exfat* ef)
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{
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if (le16_to_cpu(ef->sb->volume_state) & EXFAT_STATE_MOUNTED)
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exfat_warn("volume was not unmounted cleanly");
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if (ef->ro)
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return 0;
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ef->sb->volume_state = cpu_to_le16(
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le16_to_cpu(ef->sb->volume_state) | EXFAT_STATE_MOUNTED);
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return commit_super_block(ef);
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}
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static void exfat_free(struct exfat* ef)
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{
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exfat_close(ef->dev); /* first of all, close the descriptor */
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ef->dev = NULL; /* struct exfat_dev is freed by exfat_close() */
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free(ef->root);
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ef->root = NULL;
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free(ef->zero_cluster);
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ef->zero_cluster = NULL;
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free(ef->cmap.chunk);
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ef->cmap.chunk = NULL;
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free(ef->upcase);
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ef->upcase = NULL;
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free(ef->sb);
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ef->sb = NULL;
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}
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int exfat_mount(struct exfat* ef, const char* spec, const char* options)
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{
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int rc;
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enum exfat_mode mode;
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exfat_tzset();
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memset(ef, 0, sizeof(struct exfat));
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parse_options(ef, options);
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if (match_option(options, "ro"))
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mode = EXFAT_MODE_RO;
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else if (match_option(options, "ro_fallback"))
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mode = EXFAT_MODE_ANY;
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else
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mode = EXFAT_MODE_RW;
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ef->dev = exfat_open(spec, mode);
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if (ef->dev == NULL)
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return -EIO;
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if (exfat_get_mode(ef->dev) == EXFAT_MODE_RO)
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{
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if (mode == EXFAT_MODE_ANY)
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ef->ro = -1;
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else
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ef->ro = 1;
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}
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ef->sb = malloc(sizeof(struct exfat_super_block));
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if (ef->sb == NULL)
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{
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exfat_error("failed to allocate memory for the super block");
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exfat_free(ef);
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return -ENOMEM;
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}
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memset(ef->sb, 0, sizeof(struct exfat_super_block));
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if (exfat_pread(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
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{
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exfat_error("failed to read boot sector");
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exfat_free(ef);
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return -EIO;
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}
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if (memcmp(ef->sb->oem_name, "EXFAT ", 8) != 0)
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{
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exfat_error("exFAT file system is not found");
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exfat_free(ef);
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return -EIO;
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}
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/* sector cannot be smaller than 512 bytes */
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if (ef->sb->sector_bits < 9)
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{
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exfat_error("too small sector size: 2^%hhd", ef->sb->sector_bits);
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exfat_free(ef);
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return -EIO;
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}
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/* officially exFAT supports cluster size up to 32 MB */
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if ((int) ef->sb->sector_bits + (int) ef->sb->spc_bits > 25)
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{
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exfat_error("too big cluster size: 2^(%hhd+%hhd)",
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ef->sb->sector_bits, ef->sb->spc_bits);
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exfat_free(ef);
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return -EIO;
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}
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ef->zero_cluster = malloc(CLUSTER_SIZE(*ef->sb));
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if (ef->zero_cluster == NULL)
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{
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exfat_error("failed to allocate zero sector");
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exfat_free(ef);
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return -ENOMEM;
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}
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/* use zero_cluster as a temporary buffer for VBR checksum verification */
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if (!verify_vbr_checksum(ef, ef->zero_cluster))
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{
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exfat_free(ef);
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return -EIO;
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}
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memset(ef->zero_cluster, 0, CLUSTER_SIZE(*ef->sb));
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if (ef->sb->version.major != 1 || ef->sb->version.minor != 0)
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{
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exfat_error("unsupported exFAT version: %hhu.%hhu",
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ef->sb->version.major, ef->sb->version.minor);
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exfat_free(ef);
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return -EIO;
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}
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if (ef->sb->fat_count != 1)
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{
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exfat_error("unsupported FAT count: %hhu", ef->sb->fat_count);
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exfat_free(ef);
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return -EIO;
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}
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if (le64_to_cpu(ef->sb->sector_count) * SECTOR_SIZE(*ef->sb) >
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exfat_get_size(ef->dev))
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{
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/* this can cause I/O errors later but we don't fail mounting to let
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user rescue data */
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exfat_warn("file system in sectors is larger than device: "
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"%"PRIu64" * %d > %"PRIu64,
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le64_to_cpu(ef->sb->sector_count), SECTOR_SIZE(*ef->sb),
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exfat_get_size(ef->dev));
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}
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if ((off_t) le32_to_cpu(ef->sb->cluster_count) * CLUSTER_SIZE(*ef->sb) >
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exfat_get_size(ef->dev))
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{
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exfat_error("file system in clusters is larger than device: "
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"%u * %d > %"PRIu64,
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le32_to_cpu(ef->sb->cluster_count), CLUSTER_SIZE(*ef->sb),
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exfat_get_size(ef->dev));
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exfat_free(ef);
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return -EIO;
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}
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ef->root = malloc(sizeof(struct exfat_node));
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if (ef->root == NULL)
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{
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exfat_error("failed to allocate root node");
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exfat_free(ef);
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return -ENOMEM;
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}
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memset(ef->root, 0, sizeof(struct exfat_node));
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ef->root->attrib = EXFAT_ATTRIB_DIR;
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ef->root->start_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
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ef->root->fptr_cluster = ef->root->start_cluster;
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ef->root->name[0] = cpu_to_le16('\0');
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ef->root->size = rootdir_size(ef);
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if (ef->root->size == 0)
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{
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exfat_free(ef);
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return -EIO;
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}
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/* exFAT does not have time attributes for the root directory */
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ef->root->mtime = 0;
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ef->root->atime = 0;
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/* always keep at least 1 reference to the root node */
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exfat_get_node(ef->root);
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rc = exfat_cache_directory(ef, ef->root);
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if (rc != 0)
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goto error;
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if (ef->upcase == NULL)
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{
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exfat_error("upcase table is not found");
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goto error;
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}
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if (ef->cmap.chunk == NULL)
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{
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exfat_error("clusters bitmap is not found");
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goto error;
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}
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if (prepare_super_block(ef) != 0)
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goto error;
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return 0;
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error:
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exfat_put_node(ef, ef->root);
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exfat_reset_cache(ef);
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exfat_free(ef);
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return -EIO;
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}
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static void finalize_super_block(struct exfat* ef)
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{
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if (ef->ro)
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return;
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ef->sb->volume_state = cpu_to_le16(
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le16_to_cpu(ef->sb->volume_state) & ~EXFAT_STATE_MOUNTED);
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/* Some implementations set the percentage of allocated space to 0xff
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on FS creation and never update it. In this case leave it as is. */
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if (ef->sb->allocated_percent != 0xff)
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{
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uint32_t free, total;
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free = exfat_count_free_clusters(ef);
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total = le32_to_cpu(ef->sb->cluster_count);
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ef->sb->allocated_percent = ((total - free) * 100 + total / 2) / total;
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}
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commit_super_block(ef); /* ignore return code */
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}
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void exfat_unmount(struct exfat* ef)
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{
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exfat_flush_nodes(ef); /* ignore return code */
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exfat_flush(ef); /* ignore return code */
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exfat_put_node(ef, ef->root);
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exfat_reset_cache(ef);
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finalize_super_block(ef);
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exfat_free(ef); /* will close the descriptor */
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}
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