Subversion Repositories HelenOS

#!/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

def align_up(size, alignment):

    "Return size aligned up to alignment"

    if (size % alignment == 0):

        return size

    return (((size / alignment) + 1) * alignment)

def subtree_size(root, cluster_size):

    "Recursive directory walk and calculate size"

    size = 0

    files = 0

    for name in os.listdir(root):

        canon = os.path.join(root, name)

        if (os.path.isfile(canon)):

            size += align_up(os.path.getsize(canon), cluster_size)

            files += 1

        if (os.path.isdir(canon)):

            size += subtree_size(canon, cluster_size)

            files += 1

    return size + align_up(files * 32, cluster_size)

def root_entries(root):

    "Return number of root directory entries"

    return len(os.listdir(root))

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]

"""

def usage(prname):

    "Print usage syntax"

    print prname + " <PATH> <IMAGE>"

def main():

    if (len(sys.argv) < 3):

        usage(sys.argv[0])

        return

    path = os.path.abspath(sys.argv[1])

    if (not os.path.isdir(path)):

        print "<PATH> must be a directory"

        return

    sector_size = 512

    cluster_size = 4096

    root_size = align_up(root_entries(sys.argv[1]) * 32, sector_size)

    size = subtree_size(sys.argv[1], cluster_size)

    fat_size = align_up(size / cluster_size * 2, sector_size)

    sectors = (cluster_size + 2 * fat_size + root_size + size) / sector_size

    outf = file(sys.argv[2], "w")

    boot_sector = xstruct.create(BOOT_SECTOR)

    boot_sector.jmp = [0xEB, 0x3C, 0x90]

    boot_sector.oem = "MSDOS5.0"

    boot_sector.sector = sector_size

    boot_sector.cluster = cluster_size / sector_size

    boot_sector.reserved = cluster_size / sector_size

    boot_sector.fats = 2

    boot_sector.rootdir = root_size / 32

    boot_sector.sectors = (sectors if (sectors <= 65535) else 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

    boot_sector.sectors_big = (sectors if (sectors > 65535) else 0)

    boot_sector.drive = 0x80

    boot_sector.extboot_signature = 0x29

    boot_sector.serial = random.randint(0, 0xFFFFFFFF)

    boot_sector.label = "HELENOS"

    boot_sector.fstype = "FAT16   "

    boot_sector.boot_signature = [0x55, 0xAA]

    outf.write(boot_sector.pack())

    empty_sector = xstruct.create(EMPTY_SECTOR)

    # Reserved sectors (boot_sector.reserved - boot_sector)

    for i in range(1, boot_sector.reserved):

        outf.write(empty_sector.pack())

    # FAT tables

    for i in range(0, boot_sector.fats):

        for j in range(0, boot_sector.fat_sectors):

            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())

    outf.close()

if __name__ == '__main__':

    main()