Finding the proper scope of a file collapse operation

I actually wrote something like that a few years ago, when I was a little kid. I called it offset_fs, instead of libnewfile. If a filename ended in -desc, it would be interpreted as
#comments
/path/to/file1: offset,length
/path/to/file2: offset,length
#etc
and the concatentation of the specified file slices would be obtained upon reading it back.

It's been useful occassionally.

src: http://ohcamacj.dyndns.org:8088/~jonathan/files-1e2a/offs...

However, it's been so long, I forgot how to compile it. -D_FILE_OFFSET_BITS=64 and -lpthread and maybe one or two other options. Sorry.