Brew afsctool on your own for Mac OS Sierra

Recently, I came across an error message while compressing the document with HFS+ compression using open source tool afsctool. The repository on Homebrew project is still on version 1.6.4.

Message comes up every time: "Unable to compress file."

Someone on Github has figured out what's happening and has a solution. The Github user has pointed out that the filesystem on Sierra returns a different value of file type than its predecessor. This renders afsctool useless and return error message at all time. But the suggested change has never been updated on the original source repository of afsctool.

With a little patience for not using this tool, I made up my mind. I think it's time to homebrew our software tool before the Author patches the source code for this.

Here's the recipe:

Before your own compiling work, you might want to uninstall the outdated brew formula for afsctool:

$
$ brew uninstall afsctool

Make sure gcc is installed properly on your Mac.

Take a look at the Hombrew formulas for afsctool via http://brewformulas.org/Afsctool

Take a look at the source file from there: https://github.com/Homebrew/homebrew-core/tree/master/Formula/afsctool.rb

We found a URL from there: https://docs.google.com/uc?export=download&id=0BwQlnXqL939ZQjBQNEhRQUo0aUk

Also, take a look at the parameters called from the def() function call. Highlighted parameters will be useful for compiling:

def install
    cd "afsctool_34" do
      system ENV.cc, ENV.cflags, "-lz",
         "-framework", "CoreServices", "-o", "afsctool", "afsctool.c"
      bin.install "afsctool"
    end
end

Grab the source code ZIP of afsctool from the above URL.

Extract the ZIP file to a temporary location.

Find afsctool.c and amend the file according to this Github post.

Try compiling the .c file afsctool.c with GCC compiler using the aforementioned parameters from brew formula:

$
$ gcc -lz -framework CoreServices -o afsctool afsctool.c

Copy the compile file afsctool to the common bin folder for easy access:

$
$ cp ./afsctool /usr/local/bin/afsctool

Well, it's time to have a try on our new compiled tool:

$ afsctool -cv ./afsctool.c
/afsctool_34/afsctool.c:
File content type: public.c-source
File size (uncompressed data fork; reported size by Mac OS 10.6+ Finder): 79339 bytes / 79 KB (kilobytes) / 77 KiB (kibibytes)
File size (compressed data fork - decmpfs xattr; reported size by Mac OS 10.0-10.5 Finder): 13396 bytes / 16 KB (kilobytes) / 16 KiB (kibibytes)
File size (compressed data fork): 13412 bytes / 16 KB (kilobytes) / 16 KiB (kibibytes)
Compression savings: 83.1%
Number of extended attributes: 4
Total size of extended attribute data: 50 bytes
Approximate overhead of extended attributes: 1608 bytes
Approximate total file size (compressed data fork + EA + EA overhead + file overhead): 18306 bytes / 18 KB (kilobytes) / 18 KiB (kibibytes)

Finally, the compression works again.

By the way, we may need to keep watching until one day an updated brew formula is available to tackle this problem for Sierra.