self-extract

A Haskell library that can make an executable self-extracting.

Usage

.cabal file

...
build-type: Custom
...

custom-setup
  setup-depends: base, Cabal, self-extract

...

executable name-of-executable
  build-depends: self-extract, ...
  ...

Setup.hs

Basic:

import Codec.SelfExtract.Distribution (bundle)
import Distribution.Simple

main = defaultMainWithHooks simpleUserHooks
  { postBuild = \args bf pd lbi -> do
      postBuild simpleUserHooks args bf pd lbi
      bundle "name-of-executable" "dir-to-bundle" lbi
  }

Using the Path library:

import Codec.SelfExtract.Distribution (bundle')
import Distribution.Simple
import Path (reldir)

main = defaultMainWithHooks simpleUserHooks
  { postBuild = \args bf pd lbi -> do
      postBuild simpleUserHooks args bf pd lbi
      bundle' "name-of-executable" [reldir|dir-to-bundle|] lbi
  }

Executable file

Basic:

import Codec.SelfExtract (extractTo)

main = do
  extractTo "dir" -- will extract to $CWD/dir
  extractTo "/usr/local/lib"
  ...

Extract to a temporary directory:

import Codec.SelfExtract (withExtractToTemp)
import System.Directory (removeDirectory)

main = do
  withExtractToTemp $ \tmp -> do
    ...

Using the Path library:

import Codec.SelfExtract (extractTo', withExtractToTemp')
import Path (absdir, reldir)
import Path.IO (removeDir)

main = do
  extractTo' $ [reldir|dir|] -- will extract to $CWD/dir
  extractTo' $ [absdir|/usr/local/lib|]
  withExtractToTemp' $ \tmp -> do
    ...

Details

The above instructions should be a black box, but here is an explanation of the implementation if you need to know the details of how it works.

When the executable containing extractTo is built, some space will be allocated to contain the size of the binary.

bundle will find the executable from LocalBuildInfo's buildDir. It will take the directory specified and run tar on it. It will also get the size of the executable and write the size into the space allocated by extractTo. Then bundle will replace the executable with the executable itself concatenated with the tar archive.

When extractTo is called, it will read the size of the executable that was written in bundle. After seeking to the size of the binary, the tar archive can be extracted to the desired directory.