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  1. #!/usr/bin/env python
  2. #
  3. # Copyright (c) 2008 Martin Decky
  4. # All rights reserved.
  5. #
  6. # Redistribution and use in source and binary forms, with or without
  7. # modification, are permitted provided that the following conditions
  8. # are met:
  9. #
  10. # - Redistributions of source code must retain the above copyright
  11. #   notice, this list of conditions and the following disclaimer.
  12. # - Redistributions in binary form must reproduce the above copyright
  13. #   notice, this list of conditions and the following disclaimer in the
  14. #   documentation and/or other materials provided with the distribution.
  15. # - The name of the author may not be used to endorse or promote products
  16. #   derived from this software without specific prior written permission.
  17. #
  18. # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19. # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20. # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21. # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22. # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23. # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24. # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25. # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26. # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27. # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28. #
  29. """
  30. FAT creator
  31. """
  32.  
  33. import sys
  34. import os
  35. import random
  36. import xstruct
  37. import array
  38.  
  39. def align_up(size, alignment):
  40.     "Return size aligned up to alignment"
  41.    
  42.     if (size % alignment == 0):
  43.         return size
  44.    
  45.     return (((size / alignment) + 1) * alignment)
  46.  
  47. def subtree_size(root, cluster_size, dirent_size):
  48.     "Recursive directory walk and calculate size"
  49.    
  50.     size = 0
  51.     files = 0
  52.    
  53.     for name in os.listdir(root):
  54.         canon = os.path.join(root, name)
  55.        
  56.         if (os.path.isfile(canon)):
  57.             size += align_up(os.path.getsize(canon), cluster_size)
  58.             files += 1
  59.        
  60.         if (os.path.isdir(canon)):
  61.             size += subtree_size(canon, cluster_size, dirent_size)
  62.             files += 1
  63.    
  64.     return size + align_up(files * dirent_size, cluster_size)
  65.  
  66. def root_entries(root):
  67.     "Return number of root directory entries"
  68.    
  69.     return len(os.listdir(root))
  70.  
  71. def write_file(path, outf, cluster_size, data_start, fat):
  72.     "Store the contents of a file"
  73.    
  74.     size = os.path.getsize(path)
  75.     prev = -1
  76.     first = -1
  77.    
  78.     inf = file(path, "r")
  79.     rd = 0;
  80.     while (rd < size):
  81.         data = inf.read(cluster_size);
  82.        
  83.         empty_cluster = fat.index(0)
  84.        
  85.         fat[empty_cluster] = 0xffff
  86.         if (prev != -1):
  87.             fat[prev] = empty_cluster
  88.         else:
  89.             first = empty_cluster
  90.        
  91.         prev = empty_cluster
  92.        
  93.         outf.seek(data_start + empty_cluster * cluster_size)
  94.         outf.write(data)
  95.         rd += len(data)
  96.     inf.close()
  97.    
  98.     return first, size
  99.  
  100. DIR_ENTRY = """little:
  101.     char name[8]               /* file name */
  102.     char ext[3]                /* file extension */
  103.     uint8_t attr               /* file attributes */
  104.     padding[1]                 /* reserved for NT */
  105.     uint8_t ctime_fine         /* create time (fine resolution) */
  106.     uint16_t ctime             /* create time */
  107.     uint16_t cdate             /* create date */
  108.     uint16_t adate             /* access date */
  109.     padding[2]                 /* EA-index */
  110.     uint16_t mtime             /* modification time */
  111.     uint16_t mdate             /* modification date */
  112.     uint16_t cluster           /* first cluster */
  113.     uint32_t size              /* file size */
  114. """
  115.  
  116. def mangle_fname(name):
  117.     # FIXME: filter illegal characters
  118.     fname = (name.split('.')[0] + '          ').upper()[0:8]
  119.     return fname
  120.  
  121. def mangle_ext(name):
  122.     # FIXME: filter illegal characters
  123.     ext = (name.split('.')[1] + '  ').upper()[0:3]
  124.     return ext
  125.  
  126. def create_dirent(name, directory, cluster, size):
  127.     dir_entry = xstruct.create(DIR_ENTRY)
  128.    
  129.     dir_entry.name = mangle_fname(name)
  130.     dir_entry.ext = mangle_ext(name)
  131.    
  132.     if (directory):
  133.         dir_entry.attr = 0x30
  134.     else:
  135.         dir_entry.attr = 0x20
  136.    
  137.     dir_entry.ctime_fine = 0 # FIXME
  138.     dir_entry.ctime = 0 # FIXME
  139.     dir_entry.cdate = 0 # FIXME
  140.     dir_entry.adate = 0 # FIXME
  141.     dir_entry.mtime = 0 # FIXME
  142.     dir_entry.mdate = 0 # FIXME
  143.     dir_entry.cluster = cluster
  144.     dir_entry.size = size
  145.    
  146.     return dir_entry
  147.  
  148. def recursion(head, root, outf, cluster_size, root_start, data_start, fat):
  149.     "Recursive directory walk"
  150.    
  151.     directory = []
  152.     for name in os.listdir(root):
  153.         canon = os.path.join(root, name)
  154.        
  155.         if (os.path.isfile(canon)):
  156.             rv = write_file(canon, outf, cluster_size, data_start, fat)
  157.             directory.append(create_dirent(name, False, rv[0], rv[1]))
  158.    
  159.     if (head):
  160.         outf.seek(root_start)
  161.         for dir_entry in directory:
  162.             outf.write(dir_entry.pack())
  163.  
  164. BOOT_SECTOR = """little:
  165.     uint8_t jmp[3]             /* jump instruction */
  166.     char oem[8]                /* OEM string */
  167.     uint16_t sector            /* bytes per sector */
  168.     uint8_t cluster            /* sectors per cluster */
  169.     uint16_t reserved          /* reserved sectors */
  170.     uint8_t fats               /* number of FATs */
  171.     uint16_t rootdir           /* root directory entries */
  172.     uint16_t sectors           /* total number of sectors */
  173.     uint8_t descriptor         /* media descriptor */
  174.     uint16_t fat_sectors       /* sectors per single FAT */
  175.     uint16_t track_sectors     /* sectors per track */
  176.     uint16_t heads             /* number of heads */
  177.     uint32_t hidden            /* hidden sectors */
  178.     uint32_t sectors_big       /* total number of sectors (if sectors == 0) */
  179.    
  180.     /* Extended BIOS Parameter Block */
  181.     uint8_t drive              /* physical drive number */
  182.     padding[1]                 /* reserved (current head) */
  183.     uint8_t extboot_signature  /* extended boot signature */
  184.     uint32_t serial            /* serial number */
  185.     char label[11]             /* volume label */
  186.     char fstype[8]             /* filesystem type */
  187.     padding[448]               /* boot code */
  188.     uint8_t boot_signature[2]  /* boot signature */
  189. """
  190.  
  191. EMPTY_SECTOR = """little:
  192.     padding[512]               /* empty sector data */
  193. """
  194.  
  195. FAT_ENTRY = """little:
  196.     uint16_t next              /* FAT16 entry */
  197. """
  198.  
  199. def usage(prname):
  200.     "Print usage syntax"
  201.     print prname + " <PATH> <IMAGE>"
  202.  
  203. def main():
  204.     if (len(sys.argv) < 3):
  205.         usage(sys.argv[0])
  206.         return
  207.    
  208.     path = os.path.abspath(sys.argv[1])
  209.     if (not os.path.isdir(path)):
  210.         print "<PATH> must be a directory"
  211.         return
  212.    
  213.     fat16_clusters = 4096
  214.    
  215.     sector_size = 512
  216.     cluster_size = 4096
  217.     dirent_size = 32
  218.     fatent_size = 2
  219.     fat_count = 2
  220.     reserved_clusters = 2
  221.    
  222.     # Make sure the filesystem is large enought for FAT16
  223.     size = subtree_size(path, cluster_size, dirent_size) + reserved_clusters * cluster_size
  224.     while (size / cluster_size < fat16_clusters):
  225.         if (cluster_size > sector_size):
  226.             cluster_size /= 2
  227.             size = subtree_size(path, cluster_size, dirent_size) + reserved_clusters * cluster_size
  228.         else:
  229.             size = fat16_clusters * cluster_size + reserved_clusters * cluster_size
  230.    
  231.     root_size = align_up(root_entries(path) * dirent_size, cluster_size)
  232.    
  233.     fat_size = align_up(align_up(size, cluster_size) / cluster_size * fatent_size, sector_size)
  234.    
  235.     sectors = (cluster_size + fat_count * fat_size + root_size + size) / sector_size
  236.     root_start = cluster_size + fat_count * fat_size
  237.     data_start = root_start + root_size
  238.    
  239.     outf = file(sys.argv[2], "w")
  240.    
  241.     boot_sector = xstruct.create(BOOT_SECTOR)
  242.     boot_sector.jmp = [0xEB, 0x3C, 0x90]
  243.     boot_sector.oem = "MSDOS5.0"
  244.     boot_sector.sector = sector_size
  245.     boot_sector.cluster = cluster_size / sector_size
  246.     boot_sector.reserved = cluster_size / sector_size
  247.     boot_sector.fats = fat_count
  248.     boot_sector.rootdir = root_size / dirent_size
  249.     boot_sector.sectors = (sectors if (sectors <= 65535) else 0)
  250.     boot_sector.descriptor = 0xF8
  251.     boot_sector.fat_sectors = fat_size / sector_size
  252.     boot_sector.track_sectors = 63
  253.     boot_sector.heads = 6
  254.     boot_sector.hidden = 0
  255.     boot_sector.sectors_big = (sectors if (sectors > 65535) else 0)
  256.    
  257.     boot_sector.drive = 0x80
  258.     boot_sector.extboot_signature = 0x29
  259.     boot_sector.serial = random.randint(0, 0xFFFFFFFF)
  260.     boot_sector.label = "HELENOS"
  261.     boot_sector.fstype = "FAT16   "
  262.     boot_sector.boot_signature = [0x55, 0xAA]
  263.    
  264.     outf.write(boot_sector.pack())
  265.    
  266.     empty_sector = xstruct.create(EMPTY_SECTOR)
  267.    
  268.     # Reserved sectors
  269.     for i in range(1, cluster_size / sector_size):
  270.         outf.write(empty_sector.pack())
  271.    
  272.     # FAT tables
  273.     for i in range(0, fat_count):
  274.         for j in range(0, boot_sector.fat_sectors):
  275.             outf.write(empty_sector.pack())
  276.    
  277.     # Root directory
  278.     for i in range(0, root_size / sector_size):
  279.         outf.write(empty_sector.pack())
  280.    
  281.     # Data
  282.     for i in range(0, size / sector_size):
  283.         outf.write(empty_sector.pack())
  284.    
  285.     fat = array.array('L', [0] * (fat_size / fatent_size))
  286.     fat[0] = 0xfff8
  287.     fat[1] = 0xffff
  288.    
  289.     recursion(True, path, outf, cluster_size, root_start, data_start, fat)
  290.    
  291.     # Store FAT
  292.     fat_entry = xstruct.create(FAT_ENTRY)
  293.     for i in range(0, fat_count):
  294.         outf.seek(cluster_size + i * fat_size)
  295.         for j in range(0, fat_size / fatent_size):
  296.             fat_entry.next = fat[j]
  297.             outf.write(fat_entry.pack())
  298.    
  299.     outf.close()
  300.    
  301. if __name__ == '__main__':
  302.     main()
  303.