wadfs – WAD file system


wadfs [ -Dr ] [ -m mtpt ] [ -S srvname ] [ WAD ]


Wadfs serves a file tree mounted at mtpt (default /mnt/wad) that provides access to a WAD file’s contents.

The command line options are:


Enable 9P debugging messages.  


Set read-only file tree.  

-S srvname

Post channel on /srv/srvname.  

-m mtpt

Set mountpoint.  

A WAD is a concatenation of uncompressed files, referred to as lumps. A lump may contain either data, or be used as a marker to indicate the beginning or end of a section, segregating lumps of the same format.

Wadfs represents section start markers as directories, and regular lumps and end markers as files. For convenience, lump file names are in lower case, and are translated to the upper case internally.

At startup, if the path to a WAD file is provided as argument, wadfs will attempt to parse it and construct a file tree. Otherwise, wadfs starts with a blank tree instead.

Two additional files are provided in the file system’s root directory: SIG and WAD. Reading from and writing to SIG allows accessing and changing the WAD’s type. The only possible values are PWAD (the default) and IWAD.

WAD returns the new WAD file resulting from the recompilation of the lump tree.

WAD file structure

There are few restrictions on the structure of WAD files. Excepting maps, sections can nest and may have no end marker, or one named differently than the section itself. Regular sections typically have one-letter names, and nested sections use the same name appended by a digit. By convention, lump names may only contain visible printing ASCII characters, excepting lower-case letters. Map sections do not end at a marker but at the next non map lump, and use hardcoded names, depending on game version.

Wadfs imposes a number of additional restrictions on structure and naming:

Lump names may not contain upper-case letters and the / character.  

A map section may only contain map lumps, which use hardcoded names. Ordering is significant, but is handled automatically. Map sections may not nest.  

Regular sections may not nest beyond one level, and may not contain more than one end marker. End markers may not exist outside of a section. Directory names omit the start marker’s _START suffix.  

Excepting map lumps, no two lumps, including markers, may have the same name.  

Once created, a lump may not be renamed so as to change its type.  

Error recovery

Upon parsing the initial WAD file, if one of the restrictions for WAD file structure outlined in the sections above is not respected, a warning is issued, and the offending lump is potentially skipped. Some recovery is attempted, but one must systematically recheck the tree. When duplicate non marker lumps are encountered, each will overwrite the previous entry.


Open doom2.wad and play a MUS file:


% games/wadfs /sys/games/lib/doom/doom2.wad
createfile SW18_7: file already exists
% games/mus /mnt/wad/d_romero | games/midi

Now create a blank WAD, then one section FF; copy a flat from doom2.wad to the directory, then rename the end marker to F_END to have the doom engine find the flat; finally, compile and save the new WAD file.


% games/wadfs -m /mnt/wad2
% cd /mnt/wad2
% mkdir ff
adding end marker FF_END
% cp ../wad/f/f1/f_sky1 ff/
% mv ff/ff_end ff/f_end
% cp WAD /sys/games/lib/doom/sky.wad




games(1), mus(1)


Wadfs first appeared in 9front (August, 2017).


Many WAD files in the wild do not conform to all the rules exposed above, in particular ones using DeHackEd engine modifications. WAD’s using end markers outside of a section, typically F_END, will lose them.

Repairing broken WAD files can be a pain.