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https://github.com/yquake2/pakextract.git
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89 lines
3.3 KiB
Text
89 lines
3.3 KiB
Text
pakextract
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----------
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pakextract is a small tool to extract the contents of
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a Quake II pak file into the current directory. Usage:
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./pakextract /path/to/pakfile.pak
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Only Quake II paks are supported. Other pak formats may
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work but it's untested and unsupported.
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-------------------------------------------------------
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The Quake II Pak File Format
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----------------------------
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A Quake II pak file consists of 3 parts:
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- Header
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- Directory
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- Data
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The header is written right after the start
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of the file and consists of 3 parts in the
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following order:
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- A 4 byte identification string "PACK" (in ASCII)
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- A 4 byte integer value defining the offset to the
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directory in bytes
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- A 4 byte iteger giving the length of the directory
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in bytes. Since every directory entry is 64 bytes
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long this value modulo 64 must be 0:
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(dir_length % 64) == 0;
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The directory can be anywere in the file but most times
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it's written to the end. In consists of datablocks,
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written one after the other without any space between
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them. A directory entry is 64 bytes long has entries
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in the following order:
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- A 56 byte file name (in ASCII)
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- A 4 byte integer value defining the position if the file
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as an offset in bytes to the start of the pak file.
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- A 4 byte integer giving the length of the file
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in bytes.
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-------------------------------------------------------
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The Daikatana Pak File Format
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-----------------------------
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The Daikatana pak file format is similar to the Quake II one, but
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additionally supports compressing files within the pak.
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Daikatana only did that for .tga .bmp .wal .pcx and .bsp files and might
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expect other files to be uncompressed (in case you want to write a compressor).
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In Daikatana directory entries are 72 bytes long, because they have to
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additional 4byte integer fields at the end:
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- A 4 byte integer giving the compressed length of the file in bytes,
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if it is compressed.
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- A 4 byte integer indicating whether the file is compressed
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(0: it's not compressed, else it's compressed)
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If the file is compressed, the file length field (the one also defined in
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Quake II pak) indicates the uncompressed length of the file, while the
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additional "compressed length" field indicates the number of bytes the
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compressed data of that file takes in the .pak.
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Compressed files are decompressed like this:
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while not done:
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read a byte (unsigned char) _x_.
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// x is never written to output, only used to determine what to do
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if x < 64:
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x+1 bytes of uncompressed data follow (just read+write them as they are)
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else if x < 128:
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// run-length encoded zeros
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write (x - 62) zero-bytes to output
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else if x < 192:
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// run-length encoded data
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read one byte, write it (x-126) times to output
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else if x < 254:
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// this references previously uncompressed data
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read one byte to get _offset_
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read (x-190) bytes from the already uncompressed and written output data,
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starting at (offset+2) bytes before the current write position
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(and add them to output, of course)
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else if x == 255:
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you're done decompressing (used as terminator)
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// but I'd also abort once compressed_length bytes are read, to be sure
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See also https://gist.github.com/DanielGibson/8bde6241c93e5efe8b75e5e00d0b9858
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("Description of Daikatana .pak format")
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