1 | #!/usr/bin/perl |
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2 | ###################################################################### |
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3 | # |
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4 | # File : split_bootimg.pl |
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5 | # Author(s) : William Enck <enck@cse.psu.edu> |
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6 | # Description : Split appart an Android boot image created |
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7 | # with mkbootimg. The format can be found in |
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8 | # android-src/system/core/mkbootimg/bootimg.h |
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9 | # |
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10 | # Thanks to alansj on xda-developers.com for |
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11 | # identifying the format in bootimg.h and |
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12 | # describing initial instructions for splitting |
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13 | # the boot.img file. |
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14 | # |
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15 | # Last Modified : Tue Dec 2 23:36:25 EST 2008 |
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16 | # By : William Enck <enck@cse.psu.edu> |
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17 | # |
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18 | # Copyright (c) 2008 William Enck |
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19 | # |
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20 | ###################################################################### |
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21 | |
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22 | use strict; |
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23 | use warnings; |
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24 | |
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25 | # Turn on print flushing |
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26 | $|++; |
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27 | |
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28 | ###################################################################### |
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29 | ## Global Variables and Constants |
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30 | |
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31 | my $SCRIPT = __FILE__; |
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32 | my $IMAGE_FN = undef; |
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33 | |
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34 | # Constants (from bootimg.h) |
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35 | use constant BOOT_MAGIC => 'ANDROID!'; |
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36 | use constant BOOT_MAGIC_SIZE => 8; |
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37 | use constant BOOT_NAME_SIZE => 16; |
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38 | use constant BOOT_ARGS_SIZE => 512; |
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39 | |
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40 | # Unsigned integers are 4 bytes |
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41 | use constant UNSIGNED_SIZE => 4; |
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42 | |
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43 | # Parsed Values |
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44 | my $PAGE_SIZE = undef; |
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45 | my $KERNEL_SIZE = undef; |
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46 | my $RAMDISK_SIZE = undef; |
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47 | my $SECOND_SIZE = undef; |
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48 | |
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49 | ###################################################################### |
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50 | ## Main Code |
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51 | |
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52 | &parse_cmdline(); |
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53 | &parse_header($IMAGE_FN); |
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54 | |
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55 | =format (from bootimg.h) |
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56 | ** +-----------------+ |
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57 | ** | boot header | 1 page |
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58 | ** +-----------------+ |
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59 | ** | kernel | n pages |
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60 | ** +-----------------+ |
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61 | ** | ramdisk | m pages |
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62 | ** +-----------------+ |
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63 | ** | second stage | o pages |
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64 | ** +-----------------+ |
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65 | ** |
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66 | ** n = (kernel_size + page_size - 1) / page_size |
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67 | ** m = (ramdisk_size + page_size - 1) / page_size |
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68 | ** o = (second_size + page_size - 1) / page_size |
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69 | =cut |
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70 | |
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71 | my $n = int(($KERNEL_SIZE + $PAGE_SIZE - 1) / $PAGE_SIZE); |
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72 | my $m = int(($RAMDISK_SIZE + $PAGE_SIZE - 1) / $PAGE_SIZE); |
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73 | my $o = int(($SECOND_SIZE + $PAGE_SIZE - 1) / $PAGE_SIZE); |
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74 | |
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75 | my $k_offset = $PAGE_SIZE; |
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76 | my $r_offset = $k_offset + ($n * $PAGE_SIZE); |
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77 | my $s_offset = $r_offset + ($m * $PAGE_SIZE); |
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78 | |
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79 | (my $base = $IMAGE_FN) =~ s/.*\/(.*)$/$1/; |
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80 | my $k_file = $base . "-kernel"; |
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81 | my $r_file = $base . "-ramdisk.gz"; |
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82 | my $s_file = $base . "-second.gz"; |
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83 | |
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84 | # The kernel is always there |
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85 | print "Writing $k_file ..."; |
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86 | &dump_file($IMAGE_FN, $k_file, $k_offset, $KERNEL_SIZE); |
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87 | print " complete.\n"; |
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88 | |
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89 | # The ramdisk is always there |
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90 | print "Writing $r_file ..."; |
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91 | &dump_file($IMAGE_FN, $r_file, $r_offset, $RAMDISK_SIZE); |
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92 | print " complete.\n"; |
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93 | |
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94 | # The Second stage bootloader is optional |
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95 | unless ($SECOND_SIZE == 0) { |
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96 | print "Writing $s_file ..."; |
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97 | &dump_file($IMAGE_FN, $s_file, $s_offset, $SECOND_SIZE); |
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98 | print " complete.\n"; |
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99 | } |
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100 | |
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101 | ###################################################################### |
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102 | ## Supporting Subroutines |
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103 | |
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104 | =header_format (from bootimg.h) |
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105 | struct boot_img_hdr |
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106 | { |
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107 | unsigned char magic[BOOT_MAGIC_SIZE]; |
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108 | |
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109 | unsigned kernel_size; /* size in bytes */ |
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110 | unsigned kernel_addr; /* physical load addr */ |
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111 | |
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112 | unsigned ramdisk_size; /* size in bytes */ |
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113 | unsigned ramdisk_addr; /* physical load addr */ |
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114 | |
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115 | unsigned second_size; /* size in bytes */ |
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116 | unsigned second_addr; /* physical load addr */ |
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117 | |
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118 | unsigned tags_addr; /* physical addr for kernel tags */ |
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119 | unsigned page_size; /* flash page size we assume */ |
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120 | unsigned unused[2]; /* future expansion: should be 0 */ |
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121 | |
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122 | unsigned char name[BOOT_NAME_SIZE]; /* asciiz product name */ |
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123 | |
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124 | unsigned char cmdline[BOOT_ARGS_SIZE]; |
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125 | |
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126 | unsigned id[8]; /* timestamp / checksum / sha1 / etc */ |
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127 | }; |
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128 | =cut |
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129 | sub parse_header { |
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130 | my ($fn) = @_; |
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131 | my $buf = undef; |
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132 | |
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133 | open INF, $fn or die "Could not open $fn: $!\n"; |
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134 | binmode INF; |
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135 | |
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136 | # Read the Magic |
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137 | read(INF, $buf, BOOT_MAGIC_SIZE); |
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138 | unless ($buf eq BOOT_MAGIC) { |
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139 | die "Android Magic not found in $fn. Giving up.\n"; |
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140 | } |
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141 | |
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142 | # Read kernel size and address (assume little-endian) |
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143 | read(INF, $buf, UNSIGNED_SIZE * 2); |
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144 | my ($k_size, $k_addr) = unpack("VV", $buf); |
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145 | |
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146 | # Read ramdisk size and address (assume little-endian) |
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147 | read(INF, $buf, UNSIGNED_SIZE * 2); |
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148 | my ($r_size, $r_addr) = unpack("VV", $buf); |
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149 | |
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150 | # Read second size and address (assume little-endian) |
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151 | read(INF, $buf, UNSIGNED_SIZE * 2); |
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152 | my ($s_size, $s_addr) = unpack("VV", $buf); |
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153 | |
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154 | # Ignore tags_addr |
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155 | read(INF, $buf, UNSIGNED_SIZE); |
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156 | |
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157 | # get the page size (assume little-endian) |
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158 | read(INF, $buf, UNSIGNED_SIZE); |
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159 | my ($p_size) = unpack("V", $buf); |
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160 | |
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161 | # Ignore unused |
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162 | read(INF, $buf, UNSIGNED_SIZE * 2); |
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163 | |
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164 | # Read the name (board name) |
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165 | read(INF, $buf, BOOT_NAME_SIZE); |
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166 | my $name = $buf; |
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167 | |
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168 | # Read the command line |
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169 | read(INF, $buf, BOOT_ARGS_SIZE); |
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170 | my $cmdline = $buf; |
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171 | |
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172 | # Ignore the id |
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173 | read(INF, $buf, UNSIGNED_SIZE * 8); |
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174 | |
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175 | # Close the file |
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176 | close INF; |
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177 | |
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178 | # Print important values |
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179 | printf "Page size: %d (0x%08x)\n", $p_size, $p_size; |
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180 | printf "Kernel size: %d (0x%08x)\n", $k_size, $k_size; |
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181 | printf "Kernel addr: %d (0x%08x)\n", $k_addr, $k_addr; |
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182 | printf "Ramdisk size: %d (0x%08x)\n", $r_size, $r_size; |
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183 | printf "Ramdisk addr: %d (0x%08x)\n", $r_addr, $r_addr; |
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184 | printf "Second size: %d (0x%08x)\n", $s_size, $s_size; |
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185 | printf "Second addr: %d (0x%08x)\n", $s_addr, $s_addr; |
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186 | printf "Board name: $name\n"; |
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187 | printf "Command line: $cmdline\n"; |
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188 | |
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189 | # Save the values |
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190 | $PAGE_SIZE = $p_size; |
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191 | $KERNEL_SIZE = $k_size; |
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192 | $RAMDISK_SIZE = $r_size; |
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193 | $SECOND_SIZE = $s_size; |
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194 | } |
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195 | |
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196 | sub dump_file { |
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197 | my ($infn, $outfn, $offset, $size) = @_; |
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198 | my $buf = undef; |
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199 | |
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200 | open INF, $infn or die "Could not open $infn: $!\n"; |
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201 | open OUTF, ">$outfn" or die "Could not open $outfn: $!\n"; |
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202 | |
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203 | binmode INF; |
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204 | binmode OUTF; |
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205 | |
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206 | seek(INF, $offset, 0) or die "Could not seek in $infn: $!\n"; |
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207 | read(INF, $buf, $size) or die "Could not read $infn: $!\n"; |
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208 | print OUTF $buf or die "Could not write $outfn: $!\n"; |
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209 | |
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210 | close INF; |
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211 | close OUTF; |
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212 | } |
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213 | |
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214 | ###################################################################### |
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215 | ## Configuration Subroutines |
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216 | |
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217 | sub parse_cmdline { |
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218 | unless ($#ARGV == 0) { |
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219 | die "Usage: $SCRIPT boot.img\n"; |
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220 | } |
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221 | $IMAGE_FN = $ARGV[0]; |
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222 | } |
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223 | |
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224 | |
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