forked from acozzette/BUSE
-
Notifications
You must be signed in to change notification settings - Fork 4
/
fatfiles.c
390 lines (339 loc) · 13.5 KB
/
fatfiles.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
/*
* vsfat - virtual synthetic FAT filesystem on network block device from local folder
* Copyright (C) 2017 Sean Mollet
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>
#include "setup.h"
#include "utils.h"
#include "address.h"
#include "fatfiles.h"
#include "Fat32_Attr.h"
static unsigned const char fat_end[] = {0xFF, 0xFF, 0xFF, 0xFF};
//Advance the pointer to the next free sector in the fat
void fat_find_free()
{
while (fat[current_fat_position] != 0)
{
current_fat_position++;
//Bail if we go off the end
if (current_fat_position >= (bootentry.BPB_FATSz32 * bootentry.BPB_BytsPerSec) / 4)
{
return;
}
}
}
//Pass in either a memory segment or a filepath
//This will load the proper mappings and configure the fat
//Directory entries should be handled above here
//This assumes we have 0 fragmentation (which should always be true, since we don't allow deleting)
int fat_new_file(uint32_t file_fat_position, unsigned char *data, char *filepath, uint32_t length)
{
//length always has to be at least 1
if (length <= 0)
{
length = 1;
}
//Make sure we have enough space
uint32_t cluster_size = (bootentry.BPB_BytsPerSec * bootentry.BPB_SecPerClus);
uint32_t clusters_required = ceil_div(length, cluster_size); //Ceiling division
if (clusters_required >
((bootentry.BPB_FATSz32 * bootentry.BPB_BytsPerSec) / 4) - file_fat_position)
{ //Free clusters
return -1;
}
add_address_region(address_from_fatclus(file_fat_position), length, data, filepath);
//Remove the space for our first cluster
if (length > cluster_size)
{
length -= cluster_size;
}
else
{
length = 0;
}
//Mark any additional sectors in the FAT that we're using
while (length > 0)
{
fat[file_fat_position] = file_fat_position + 1;
file_fat_position++;
//Unsigned, so the subtraction could loop us around
if (length > cluster_size)
{
length -= cluster_size;
}
else
{
length = 0;
}
}
memcpy(&fat[file_fat_position], fat_end, sizeof(fat_end)); // Terminate this chain
return 0;
}
//Check if the current directory entry has space available
int dir_entry_sectors_needed(uint32_t entries_needed)
{
if (entries_needed == 0)
{
entries_needed = 1;
}
uint32_t cluster_size = (bootentry.BPB_BytsPerSec * bootentry.BPB_SecPerClus);
uint32_t entrys_per_cluster = cluster_size / sizeof(DirEntry);
if (current_dir->dirtables == 0)
{
return ceil_div(entries_needed, entrys_per_cluster);
}
uint32_t free_entries = entrys_per_cluster - (current_dir->current_dir_position % entrys_per_cluster);
if (free_entries > entries_needed)
{
return 0;
}
//Subtract the last of what we already have
entries_needed -= free_entries;
return ceil_div(entries_needed, entrys_per_cluster);
}
//This does accept multiple entries. However, it does not accept more than a single file worth
int dir_add_entry(unsigned char *entry, uint32_t length)
{
while (length > 0)
{
uint32_t cluster_size = (bootentry.BPB_BytsPerSec * bootentry.BPB_SecPerClus);
uint32_t entrys_per_cluster = cluster_size / sizeof(DirEntry);
uint32_t current_cluster_free = current_dir->current_dir_position % entrys_per_cluster;
//Make sure we have an initial entry
if (current_dir->dirtables == 0)
{
current_dir->dirtables = malloc(sizeof(DirTable));
current_dir->dirtables->next = 0;
current_dir->dirtables->dirtable = malloc(cluster_size);
memset(current_dir->dirtables->dirtable, 0, cluster_size);
uint64_t dest = address_from_fatclus(current_dir->dir_location);
add_address_region(dest, cluster_size, current_dir->dirtables->dirtable, 0);
current_cluster_free = entrys_per_cluster;
memcpy(&fat[current_dir->dir_location], fat_end, sizeof(fat_end)); // Terminate this chain in the FAT
}
//Make sure we don't exceed the 2Mb limit for directory size
if (current_dir->current_dir_position + 1 > (1024 * 1024 * 2) / sizeof(DirEntry))
{
return -1;
}
//Add another cluster if needed
if (current_cluster_free < 1)
{
fat_find_free();
//Add a new entry to the dirtables linked list
//Find the end of the list
DirTable *final_dir_table = current_dir->dirtables;
while (final_dir_table->next != 0)
{
final_dir_table = final_dir_table->next;
}
final_dir_table->next = malloc(sizeof(DirTable));
final_dir_table = final_dir_table->next;
final_dir_table->dirtable = malloc(cluster_size);
memset(final_dir_table->dirtable, 0, cluster_size);
final_dir_table->next = 0;
add_address_region(address_from_fatclus(current_fat_position), cluster_size, final_dir_table->dirtable, 0);
//Update the fat for the previous link in the chain to point to the new one
fat[current_dir->dir_location] = current_fat_position;
//Advance this pointer to the extended fat sector
current_dir->dir_location = current_fat_position;
memcpy(&fat[current_dir->dir_location], fat_end, sizeof(fat_end)); // Terminate this chain in the FAT
}
//Find the last dir_table in this chain and the last unused position
DirTable *final_dir_table = current_dir->dirtables;
uint32_t final_table_pos = current_dir->current_dir_position;
while (final_dir_table->next != 0)
{
final_dir_table = final_dir_table->next;
final_table_pos -= entrys_per_cluster;
}
//copy the data in
memcpy(final_dir_table->dirtable + final_table_pos * sizeof(DirEntry), entry, sizeof(DirEntry));
current_dir->current_dir_position++;
//Move to the next one
length--;
entry += sizeof(DirEntry);
}
//Profit!
return 0;
}
void up_dir()
{
//Free the current dir (we shouldn't be leaving until we're done with it)
//Commented out for debugging - will need to be removed for tracking if writing is desired
if (current_dir != &root_dir)
{
//I purposely don't free dirtables, because it's mapped
free(current_dir->path);
free(current_dir);
//Clear the filename entries as well
FileEntry *freeFile = current_dir->files;
while (freeFile != 0)
{
FileEntry *next = freeFile->next;
free(freeFile);
freeFile = next;
}
}
//If the parent is root, we just stay at the root
current_dir = current_dir->parent;
}
//Add a file to the mapping space
void add_file(char *name, char *filepath, uint32_t size, u_char isDirectory)
{
DirEntry entry;
unsigned char *lfn, *lfn_original;
unsigned int lfnlength = 0;
lfn = malloc(LFN_Max_length);
lfn_original = lfn;
//Make sure it's clear
memset(&entry, 0, sizeof(DirEntry));
//For now, just stupid 8.3
//Format uses unsigned char so it can potentially handle UTF-16 in the future
//We don't currently get 7 bit ascii input, so this cast clears the warning
//and will work correctly with the input we're given
format_name_83(current_dir, (unsigned char *)name, strlen(name), entry.DIR_Name, entry.DIR_Ext, lfn, &lfnlength);
//Add this filename to the 8.3 linked list to prevent colisions on LFNs
//If this directory is empty
if (current_dir->files == 0)
{
current_dir->files = malloc(sizeof(FileEntry));
current_dir->files->next = 0;
}
//Find the last entry (which is a new entry)
FileEntry *newFile = current_dir->files;
while (newFile->next != 0)
{
newFile = newFile->next;
}
newFile->next = malloc(sizeof(FileEntry));
memset(newFile->next, 0, sizeof(FileEntry));
memcpy(newFile->Filename, entry.DIR_Name, 8);
memcpy(newFile->Ext, entry.DIR_Ext, 3);
//Figure out how many lfn directory entries we'll need
int lfnEntryCount = ceil_div(lfnlength, LFN_Chars_Per_Entry);
if (lfnEntryCount > LFN_Max_Entries)
{
lfnEntryCount = LFN_Max_Entries;
}
//No point adding entries if we don't have an LFN
if (lfnlength > 0)
{
//Build the LFN directory entries
LfnEntry *lfnEntries = malloc(sizeof(LfnEntry) * lfnEntryCount);
memset(lfnEntries, 0xFF, sizeof(LfnEntry) * lfnEntryCount);
for (int entryCount = 0; entryCount < lfnEntryCount; entryCount++)
{
int currentEntry = lfnEntryCount - entryCount - 1;
//Set the flag on the last entry
if (currentEntry == 0)
{
lfnEntries[currentEntry].LFN_Seq = ((entryCount + 1) & LFN_Seq_Mask) | LFN_First_Flag;
}
else
{
lfnEntries[currentEntry].LFN_Seq = (entryCount + 1) & LFN_Seq_Mask;
}
int chars = min(lfnlength, 5);
memset(&lfnEntries[currentEntry].LFN_Name, 0, 10);
memcpy(&lfnEntries[currentEntry].LFN_Name, lfn, chars * 2);
lfnlength -= chars;
lfn += chars * 2;
lfnEntries[currentEntry].LFN_Attributes = LFN_Attr;
lfnEntries[currentEntry].LFN_Type = 0x00;
lfnEntries[currentEntry].LFN_Checksum = fn_checksum(entry.DIR_Name, entry.DIR_Ext);
chars = min(lfnlength, 6);
memset(&lfnEntries[currentEntry].LFN_Name2, 0, 12);
memcpy(&lfnEntries[currentEntry].LFN_Name2, lfn, chars * 2);
lfnlength -= chars;
lfn += chars * 2;
lfnEntries[currentEntry].LFN_Cluster_HI = 0x00;
lfnEntries[currentEntry].LFN_Cluster_LO = 0x00;
chars = min(lfnlength, 2);
memset(&lfnEntries[currentEntry].LFN_Name3, 0, 4);
memcpy(&lfnEntries[currentEntry].LFN_Name3, lfn, chars * 2);
lfnlength -= chars;
lfn += chars * 2;
}
dir_add_entry((unsigned char *)lfnEntries, lfnEntryCount);
free(lfnEntries);
}
//If this is a directory, add the directory bit
if (isDirectory)
{
entry.DIR_Attr |= DIR_Attr_Directory;
}
else
{
//Set the "Archive" bit
entry.DIR_Attr = DIR_Attr_Archive;
}
//entry.DIR_NRRes = 0x08 | 0x10; //Everything is lowercase
fat_find_free();
//If the directory entry for this file will require a cluster
//Then our file will end up in the next cluster after that
//So, we need to increase this now to generate the correct entry
uint32_t filePosition = current_fat_position;
uint32_t clusters_needed = dir_entry_sectors_needed(lfnEntryCount);
filePosition += clusters_needed;
entry.DIR_FstClusLO = (uint16_t)(filePosition & 0xFFFF);
entry.DIR_FstClusHI = (uint16_t)((filePosition & 0xFFFF0000) >> 16);
entry.DIR_FileSize = size;
//dir_add_entry wants a byte array so it can have multiple entries chained together
//We just cast the struct pointer and tell it how many there are (1 for short filename)
if (dir_add_entry((unsigned char *)&entry, 1) == 0)
{
if (!isDirectory)
{
//Allocate the array for the actual data
fat_new_file(filePosition, 0, filepath, size);
}
else
{
//Make a new directory entry and change to it
Fat_Directory *new_dir = malloc(sizeof(Fat_Directory));
new_dir->path = filepath;
new_dir->dirtables = 0;
new_dir->current_dir_position = 0;
new_dir->parent = current_dir;
new_dir->dir_location = filePosition;
new_dir->files = 0;
current_dir = new_dir;
//Add the . and .. entries to this dir
DirEntry dotentry;
//Adding the . entry automatically maps the memory space for the first cluster of this
//dir entry
// .
memset(&dotentry, 0, sizeof(DirEntry));
dotentry.DIR_Attr = DIR_Attr_Archive | DIR_Attr_Directory;
dotentry.DIR_Name[0] = '.';
dotentry.DIR_FstClusLO = (uint16_t)(current_dir->dir_location & 0x00FF);
dotentry.DIR_FstClusHI = (uint16_t)(current_dir->dir_location & 0xFF00) >> 16;
dir_add_entry((unsigned char *)&dotentry, 1);
//..
dotentry.DIR_Name[1] = '.';
dotentry.DIR_FstClusLO = (uint16_t)(current_dir->parent->dir_location & 0x00FF);
dotentry.DIR_FstClusHI = (uint16_t)(current_dir->parent->dir_location & 0xFF00) >> 16;
dir_add_entry((unsigned char *)&dotentry, 1);
}
}
free(lfn_original);
}