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https://github.com/limine-bootloader/limine
synced 2024-12-12 09:44:04 +03:00
We can now get file records from the MFT
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10caa22bbc
commit
66564de7e0
@ -40,6 +40,9 @@ struct ntfs_file_handle {
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uint64_t mft_offset;
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uint64_t file_record_size;
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uint64_t sectors_per_file_record;
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uint32_t size_bytes;
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};
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@ -4,6 +4,10 @@
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#include <stdbool.h>
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// This is the total size of a file record, including the attributes
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// TODO: calculate this
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#define MIN_FILE_RECORD_SIZE 1024
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struct mft_file_record {
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char name[4];
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uint16_t update_seq_offset;
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@ -98,12 +102,124 @@ int ntfs_check_signature(struct volume *part) {
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return 1;
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}
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/**
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* Gets a count and cluster from the runlist, if next is true then it updates the list intenrally
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* so the next call will return the next element
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*
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* if returned false we got to the end of the file.
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*/
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static bool ntfs_get_next_run_list_element(uint8_t **runlist, uint64_t *out_cluster_count, uint64_t *out_cluster, bool next) {
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uint8_t *runlist_ptr = *runlist;
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// we have reached the end of the file
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if (runlist_ptr[0] == 0) {
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return false;
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}
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uint8_t low = runlist_ptr[0] & 0xF;
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uint8_t high = (runlist_ptr[0] >> 4) & 0xF;
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runlist_ptr++;
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// get the run length
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uint64_t count = 0;
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for (int i = low; i > 0; i--) {
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count <<= 8;
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count |= runlist_ptr[i - 1];
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}
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runlist_ptr += low;
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// get the high byte first
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int8_t high_byte = (int8_t)runlist_ptr[high - 1];
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// get the run offset
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uint64_t cluster = 0;
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for (int i = high; i > 0; i--) {
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cluster <<= 8;
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cluster |= runlist_ptr[i - 1];
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}
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runlist_ptr += high;
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// if the offset is negative, fill the empty bytes with 0xff
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if (high_byte < 0 && high < 8) {
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uint64_t fill = 0;
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for (int i = 8; i > high; i--) {
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fill >>= 8;
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fill |= 0xFF00000000000000;
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}
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cluster |= fill;
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}
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// out it
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*out_cluster = cluster;
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*out_cluster_count = count;
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// update it
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if (next) {
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*runlist = runlist_ptr;
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}
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return true;
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}
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static bool ntfs_get_file_record(struct ntfs_file_handle *handle, uint64_t mft_record_no, uint8_t *file_record_buffer) {
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uint8_t *runlist = handle->mft_run_list;
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// get the
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uint64_t count = 0;
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uint64_t cluster = 0;
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if (!ntfs_get_next_run_list_element(&runlist, &count, &cluster, true)) {
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return false;
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}
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size_t bytes_per_cluster = handle->bpb.bytes_per_sector * handle->bpb.sectors_per_cluster;
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uint64_t byte_count = count * bytes_per_cluster;
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uint64_t sector = cluster * handle->bpb.sectors_per_cluster;
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uint64_t record_count = 0;
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do {
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// consume the items from the current runlist
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if (byte_count > 0) {
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sector += handle->sectors_per_file_record;
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byte_count -= handle->file_record_size;
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} else {
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// get the next run list...
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if (!ntfs_get_next_run_list_element(&runlist, &count, &cluster, true)) {
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// reached the end of the mft, did not find it...
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return false;
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}
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byte_count = count * bytes_per_cluster;
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sector = cluster * handle->bpb.sectors_per_cluster;
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continue;
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}
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record_count++;
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} while (record_count < mft_record_no);
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// we found the sector of the file record!
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uint64_t offset = sector * handle->bpb.bytes_per_sector;
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if(!volume_read(handle->part, file_record_buffer, offset, handle->file_record_size))
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panic("NTFS: Failed to read file record from mft");
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// make sure this is a valid file record
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struct mft_file_record* fr = (struct mft_file_record*)file_record_buffer;
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if (strncmp(fr->name, "FILE", SIZEOF_ARRAY(fr->name)))
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panic("NTFS: File record has invalid signature (got %c%c%c%c, should be FILE)!",
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fr->name[0], fr->name[1], fr->name[2], fr->name[3]);
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// we good!
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return true;
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}
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/**
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* Read the the directory's file record from the mft
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*/
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// static int ntfs_read_directory(struct ntfs_file_handle *handle, uint64_t mft_record, char *file_record) {
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static bool ntfs_read_directory(struct ntfs_file_handle *handle, uint64_t mft_record, uint8_t *file_record) {
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// get the record of the directory
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if (!ntfs_get_file_record(handle, mft_record, file_record))
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return false;
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// }
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return true;
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}
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/**
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* Get an attribute from the given file record
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@ -115,8 +231,9 @@ static bool ntfs_get_file_record_attr(uint8_t* file_record, uint32_t attr_type,
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uint8_t* cur_attr_ptr = file_record + fr->attribute_offset;
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while (true) {
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if (cur_attr_ptr + sizeof(struct file_record_attr_header) > file_record + 4096)
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panic("File record attribute is outside of file record");
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// TODO: don't check for the min size, but for the actual size...
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if (cur_attr_ptr + sizeof(struct file_record_attr_header) > file_record + MIN_FILE_RECORD_SIZE)
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panic("NTFS: File record attribute is outside of file record");
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struct file_record_attr_header *cur_attr = (struct file_record_attr_header *)cur_attr_ptr;
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@ -130,7 +247,7 @@ static bool ntfs_get_file_record_attr(uint8_t* file_record, uint32_t attr_type,
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return false;
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if (cur_attr->length == 0)
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panic("File record attribute has zero length");
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panic("NTFS: File record attribute has zero length");
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cur_attr_ptr += cur_attr->length;
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}
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@ -144,39 +261,50 @@ static void ntfs_read_root(struct ntfs_file_handle *handle) {
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handle->mft_offset = (uint64_t)handle->bpb.mft_cluster * (uint64_t)handle->bpb.sectors_per_cluster * (uint64_t)handle->bpb.bytes_per_sector;
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// read the mft file record, this should be the size of a sector
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// but we will use 4096 since it should cover it
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uint8_t file_record_buffer[4096];
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uint8_t file_record_buffer[handle->file_record_size];
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if (!volume_read(handle->part, file_record_buffer, handle->mft_offset, sizeof(file_record_buffer)))
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panic("Failed to read MFT file record");
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panic("NTFS: Failed to read MFT file record");
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// get the file attribute
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struct file_record_attr_header_non_res *attr;
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if (!ntfs_get_file_record_attr(file_record_buffer, FR_ATTRIBUTE_DATA, (uint8_t **)&attr))
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panic("MFT file record missing DATA attribute");
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panic("NTFS: MFT file record missing DATA attribute");
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// verify the attr and run list are in the buffer
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if ((uint8_t *)attr + sizeof(*attr) > file_record_buffer + sizeof(file_record_buffer))
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panic("MFT file record attribute is outside of file record");
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panic("NTFS: MFT file record attribute is outside of file record");
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if ((uint8_t *)attr + attr->run_offset + 256 > file_record_buffer + sizeof(file_record_buffer))
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panic("MFT Run list is outside of file record");
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panic("NTFS: MFT Run list is outside of file record");
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// save the run list
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memcpy(handle->mft_run_list, (uint8_t *)attr + attr->run_offset, sizeof(handle->mft_run_list));
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// TODO: read the root directory
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// read the root directory record, which has the number 5
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if (!ntfs_read_directory(handle, 5, file_record_buffer))
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panic("NTFS: Missing root directory file record!");
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}
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// static int ntfs_find_file_in_directory(char *dir, size_t dir_size, short *name, struct index_entry* entry) {
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// }
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int ntfs_open(struct ntfs_file_handle *ret, struct volume *part, const char *path) {
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// save the part
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ret->part = part;
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// start by reading the bpb so we can access it later on
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if (!volume_read(part, &ret->bpb, 0, sizeof(ret->bpb)))
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panic("Failed to read the BPB");
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panic("NTFS: Failed to read the BPB");
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// in NTFS sector size can be 512 to 4096 bytes, file records are
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// at least 1024 bytes, in here calculate the sectors per file record
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// and the file record size
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if (ret->bpb.bytes_per_sector <= MIN_FILE_RECORD_SIZE) {
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// this has multiple sectors
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ret->sectors_per_file_record = MIN_FILE_RECORD_SIZE / ret->bpb.bytes_per_sector;
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ret->file_record_size = MIN_FILE_RECORD_SIZE;
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} else {
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// this has a single sector
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ret->sectors_per_file_record = 1;
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ret->file_record_size = ret->bpb.bytes_per_sector;
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}
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// now prepare the root directory so we can search for
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// the rest of the stuff
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ntfs_read_root(ret);
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