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#!/usr/bin/env python
#
# Copyright (c) 2008 Martin Decky
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# - 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.
# - The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
#
"""
FAT creator
"""
import sys
import os
import random
import xstruct
import array
from imgutil import *
def subtree_size(root, cluster_size, dirent_size):
"Recursive directory walk and calculate size"
size = 0
files = 2
for item in listdir_items(root):
if item.is_file:
size += align_up(item.size, cluster_size)
files += 1
elif item.is_dir:
size += subtree_size(item.path, cluster_size, dirent_size)
files += 1
return size + align_up(files * dirent_size, cluster_size)
def root_entries(root):
"Return number of root directory entries"
return len(os.listdir(root))
def write_file(item, outf, cluster_size, data_start, fat, reserved_clusters):
"Store the contents of a file"
prev = -1
first = 0
for data in chunks(item, cluster_size):
empty_cluster = fat.index(0)
fat[empty_cluster] = 0xffff
if (prev != -1):
fat[prev] = empty_cluster
else:
first = empty_cluster
prev = empty_cluster
outf.seek(data_start + (empty_cluster - reserved_clusters) * cluster_size)
outf.write(data)
return first, item.size
def write_directory(directory, outf, cluster_size, data_start, fat, reserved_clusters, dirent_size, empty_cluster):
"Store the contents of a directory"
length = len(directory)
size = length * dirent_size
prev = -1
first = 0
i = 0
rd = 0;
while (rd < size):
if (prev != -1):
empty_cluster = fat.index(0)
fat[empty_cluster] = 0xffff
fat[prev] = empty_cluster
else:
first = empty_cluster
prev = empty_cluster
data = bytes()
data_len = 0
while ((i < length) and (data_len < cluster_size)):
if (i == 0):
directory[i].cluster = empty_cluster
data += directory[i].pack()
data_len += dirent_size
i += 1
outf.seek(data_start + (empty_cluster - reserved_clusters) * cluster_size)
outf.write(data)
rd += len(data)
return first, size
DIR_ENTRY = """little:
char name[8] /* file name */
char ext[3] /* file extension */
uint8_t attr /* file attributes */
uint8_t lcase /* file name case (NT extension) */
uint8_t ctime_fine /* create time (fine resolution) */
uint16_t ctime /* create time */
uint16_t cdate /* create date */
uint16_t adate /* access date */
padding[2] /* EA-index */
uint16_t mtime /* modification time */
uint16_t mdate /* modification date */
uint16_t cluster /* first cluster */
uint32_t size /* file size */
"""
DOT_DIR_ENTRY = """little:
uint8_t signature /* 0x2e signature */
char name[7] /* empty */
char ext[3] /* empty */
uint8_t attr /* file attributes */
padding[1] /* reserved for NT */
uint8_t ctime_fine /* create time (fine resolution) */
uint16_t ctime /* create time */
uint16_t cdate /* create date */
uint16_t adate /* access date */
padding[2] /* EA-index */
uint16_t mtime /* modification time */
uint16_t mdate /* modification date */
uint16_t cluster /* first cluster */
uint32_t size /* file size */
"""
DOTDOT_DIR_ENTRY = """little:
uint8_t signature[2] /* 0x2e signature */
char name[6] /* empty */
char ext[3] /* empty */
uint8_t attr /* file attributes */
padding[1] /* reserved for NT */
uint8_t ctime_fine /* create time (fine resolution) */
uint16_t ctime /* create time */
uint16_t cdate /* create date */
uint16_t adate /* access date */
padding[2] /* EA-index */
uint16_t mtime /* modification time */
uint16_t mdate /* modification date */
uint16_t cluster /* first cluster */
uint32_t size /* file size */
"""
LFN_DIR_ENTRY = """little:
uint8_t seq /* sequence number */
char name1[10] /* first part of the name */
uint8_t attr /* attributes */
uint8_t rec_type /* LFN record type */
uint8_t checksum /* LFN checksum */
char name2[12] /* second part of the name */
uint16_t cluster /* cluster */
char name3[4] /* third part of the name */
"""
lchars = set(['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'!', '#', '$', '%', '&', '\'', '(', ')', '-', '@',
'^', '_', '`', '{', '}', '~', '.'])
def fat_lchars(name):
"Filter FAT legal characters"
filtered_name = ''
filtered = False
for char in name.encode('ascii', 'replace').upper():
if char in lchars:
filtered_name += char
else:
filtered_name += b'_'
filtered = True
return (filtered_name, filtered)
def fat_name83(name, name83_list):
"Create a 8.3 name for the given name"
ascii_name, lfn = fat_lchars(name)
ascii_parts = ascii_name.split('.')
short_name = ''
short_ext = ''
if len(ascii_name) > 11:
lfn = True
if len(ascii_parts) > 0:
short_name = ascii_parts[0]
if len(short_name) > 8:
lfn = True
if len(ascii_parts) > 1:
short_ext = ascii_parts[-1]
if len(short_ext) > 3:
lfn = True
if len(ascii_parts) > 2:
lfn = True
if lfn == False:
name83_list.append(short_name + '.' + short_ext)
return (short_name.ljust(8)[0:8], short_ext.ljust(3)[0:3], False)
# For filenames with multiple extensions, we treat the last one
# as the actual extension. The rest of the filename is stripped
# of dots and concatenated to form the short name
for part in ascii_parts[1:-1]:
short_name += part
for number in range(1, 999999):
number_str = ('~' + str(number)).upper()
if len(short_name) + len(number_str) > 8:
short_name = short_name[0:8 - len(number_str)]
short_name += number_str;
if not (short_name + '.' + short_ext) in name83_list:
break
name83_list.append(short_name + '.' + short_ext)
return (short_name.ljust(8)[0:8], short_ext.ljust(3)[0:3], True)
def create_lfn_dirent(name, seq, checksum):
"Create LFN directory entry"
entry = xstruct.create(LFN_DIR_ENTRY)
name_rest = name[26:]
if len(name_rest) > 0:
entry.seq = seq
else:
entry.seq = seq | 0x40
entry.name1 = name[0:10]
entry.name2 = name[10:22]
entry.name3 = name[22:26]
entry.attr = 0x0F
entry.rec_type = 0
entry.checksum = checksum
entry.cluster = 0
return (entry, name_rest)
def lfn_checksum(name):
"Calculate LFN checksum"
checksum = 0
for i in range(0, 11):
checksum = (((checksum & 1) << 7) + (checksum >> 1) + ord(name[i])) & 0xFF
return checksum
def create_dirent(name, name83_list, directory, cluster, size):
short_name, short_ext, lfn = fat_name83(name, name83_list)
dir_entry = xstruct.create(DIR_ENTRY)
dir_entry.name = short_name
dir_entry.ext = short_ext
if (directory):
dir_entry.attr = 0x30
else:
dir_entry.attr = 0x20
dir_entry.lcase = 0x18
dir_entry.ctime_fine = 0 # FIXME
dir_entry.ctime = 0 # FIXME
dir_entry.cdate = 0 # FIXME
dir_entry.adate = 0 # FIXME
dir_entry.mtime = 0 # FIXME
dir_entry.mdate = 0 # FIXME
dir_entry.cluster = cluster
if (directory):
dir_entry.size = 0
else:
dir_entry.size = size
if not lfn:
return [dir_entry]
long_name = name.encode('utf_16_le')
entries = [dir_entry]
seq = 1
checksum = lfn_checksum(dir_entry.name + dir_entry.ext)
while len(long_name) > 0:
long_entry, long_name = create_lfn_dirent(long_name, seq, checksum)
entries.append(long_entry)
seq += 1
entries.reverse()
return entries
def create_dot_dirent(empty_cluster):
dir_entry = xstruct.create(DOT_DIR_ENTRY)
dir_entry.signature = 0x2e
dir_entry.name = b' '
dir_entry.ext = b' '
dir_entry.attr = 0x10
dir_entry.ctime_fine = 0 # FIXME
dir_entry.ctime = 0 # FIXME
dir_entry.cdate = 0 # FIXME
dir_entry.adate = 0 # FIXME
dir_entry.mtime = 0 # FIXME
dir_entry.mdate = 0 # FIXME
dir_entry.cluster = empty_cluster
dir_entry.size = 0
return dir_entry
def create_dotdot_dirent(parent_cluster):
dir_entry = xstruct.create(DOTDOT_DIR_ENTRY)
dir_entry.signature = [0x2e, 0x2e]
dir_entry.name = b' '
dir_entry.ext = b' '
dir_entry.attr = 0x10
dir_entry.ctime_fine = 0 # FIXME
dir_entry.ctime = 0 # FIXME
dir_entry.cdate = 0 # FIXME
dir_entry.adate = 0 # FIXME
dir_entry.mtime = 0 # FIXME
dir_entry.mdate = 0 # FIXME
dir_entry.cluster = parent_cluster
dir_entry.size = 0
return dir_entry
def recursion(head, root, outf, cluster_size, root_start, data_start, fat, reserved_clusters, dirent_size, parent_cluster):
"Recursive directory walk"
directory = []
name83_list = []
if not head:
# Directory cluster preallocation
empty_cluster = fat.index(0)
fat[empty_cluster] = 0xFFFF
directory.append(create_dot_dirent(empty_cluster))
directory.append(create_dotdot_dirent(parent_cluster))
else:
empty_cluster = 0
for item in listdir_items(root):
if item.is_file:
rv = write_file(item, outf, cluster_size, data_start, fat, reserved_clusters)
directory.extend(create_dirent(item.name, name83_list, False, rv[0], rv[1]))
elif item.is_dir:
rv = recursion(False, item.path, outf, cluster_size, root_start, data_start, fat, reserved_clusters, dirent_size, empty_cluster)
directory.extend(create_dirent(item.name, name83_list, True, rv[0], rv[1]))
if head:
outf.seek(root_start)
for dir_entry in directory:
outf.write(dir_entry.pack())
else:
return write_directory(directory, outf, cluster_size, data_start, fat, reserved_clusters, dirent_size, empty_cluster)
BOOT_SECTOR = """little:
uint8_t jmp[3] /* jump instruction */
char oem[8] /* OEM string */
uint16_t sector /* bytes per sector */
uint8_t cluster /* sectors per cluster */
uint16_t reserved /* reserved sectors */
uint8_t fats /* number of FATs */
uint16_t rootdir /* root directory entries */
uint16_t sectors /* total number of sectors */
uint8_t descriptor /* media descriptor */
uint16_t fat_sectors /* sectors per single FAT */
uint16_t track_sectors /* sectors per track */
uint16_t heads /* number of heads */
uint32_t hidden /* hidden sectors */
uint32_t sectors_big /* total number of sectors (if sectors == 0) */
/* Extended BIOS Parameter Block */
uint8_t drive /* physical drive number */
padding[1] /* reserved (current head) */
uint8_t extboot_signature /* extended boot signature */
uint32_t serial /* serial number */
char label[11] /* volume label */
char fstype[8] /* filesystem type */
padding[448] /* boot code */
uint8_t boot_signature[2] /* boot signature */
"""
EMPTY_SECTOR = """little:
padding[512] /* empty sector data */
"""
FAT_ENTRY = """little:
uint16_t next /* FAT16 entry */
"""
def usage(prname):
"Print usage syntax"
print(prname + " <EXTRA_BYTES> <PATH> <IMAGE>")
def main():
if (len(sys.argv) < 4):
usage(sys.argv[0])
return
if (not sys.argv[1].isdigit()):
print("<EXTRA_BYTES> must be a number")
return
extra_bytes = int(sys.argv[1])
path = os.path.abspath(sys.argv[2].decode())
if (not os.path.isdir(path)):
print("<PATH> must be a directory")
return
fat16_clusters = 4096
sector_size = 512
cluster_size = 4096
dirent_size = 32
fatent_size = 2
fat_count = 2
reserved_clusters = 2
# Make sure the filesystem is large enough for FAT16
size = subtree_size(path, cluster_size, dirent_size) + reserved_clusters * cluster_size + extra_bytes
while (size // cluster_size < fat16_clusters):
if (cluster_size > sector_size):
cluster_size = cluster_size // 2
size = subtree_size(path, cluster_size, dirent_size) + reserved_clusters * cluster_size + extra_bytes
else:
size = fat16_clusters * cluster_size + reserved_clusters * cluster_size
root_size = align_up(root_entries(path) * dirent_size, cluster_size)
fat_size = align_up(align_up(size, cluster_size) // cluster_size * fatent_size, sector_size)
sectors = (cluster_size + fat_count * fat_size + root_size + size) // sector_size
root_start = cluster_size + fat_count * fat_size
data_start = root_start + root_size
outf = open(sys.argv[3], "wb")
boot_sector = xstruct.create(BOOT_SECTOR)
boot_sector.jmp = [0xEB, 0x3C, 0x90]
boot_sector.oem = b'MSDOS5.0'
boot_sector.sector = sector_size
boot_sector.cluster = cluster_size // sector_size
boot_sector.reserved = cluster_size // sector_size
boot_sector.fats = fat_count
boot_sector.rootdir = root_size // dirent_size
if (sectors <= 65535):
boot_sector.sectors = sectors
else:
boot_sector.sectors = 0
boot_sector.descriptor = 0xF8
boot_sector.fat_sectors = fat_size // sector_size
boot_sector.track_sectors = 63
boot_sector.heads = 6
boot_sector.hidden = 0
if (sectors > 65535):
boot_sector.sectors_big = sectors
else:
boot_sector.sectors_big = 0
boot_sector.drive = 0x80
boot_sector.extboot_signature = 0x29
boot_sector.serial = random.randint(0, 0x7fffffff)
boot_sector.label = b'HELENOS'
boot_sector.fstype = b'FAT16 '
boot_sector.boot_signature = [0x55, 0xAA]
outf.write(boot_sector.pack())
empty_sector = xstruct.create(EMPTY_SECTOR)
# Reserved sectors
for i in range(1, cluster_size // sector_size):
outf.write(empty_sector.pack())
# FAT tables
for i in range(0, fat_count):
for j in range(0, fat_size // sector_size):
outf.write(empty_sector.pack())
# Root directory
for i in range(0, root_size // sector_size):
outf.write(empty_sector.pack())
# Data
for i in range(0, size // sector_size):
outf.write(empty_sector.pack())
fat = array.array('L', [0] * (fat_size // fatent_size))
fat[0] = 0xfff8
fat[1] = 0xffff
recursion(True, path, outf, cluster_size, root_start, data_start, fat, reserved_clusters, dirent_size, 0)
# Store FAT
fat_entry = xstruct.create(FAT_ENTRY)
for i in range(0, fat_count):
outf.seek(cluster_size + i * fat_size)
for j in range(0, fat_size // fatent_size):
fat_entry.next = fat[j]
outf.write(fat_entry.pack())
outf.close()
if __name__ == '__main__':
main()
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