saifali96 / sourcemapper

Extract JavaScript source trees from Sourcemap files

Sourcemapper

Sourcemapper is a bit of golang to parse a sourcemap, as generated by webpack or similar, and spit out the original JavaScript files, recreating the source tree based on the file paths in the sourcemap.

An article explaining its purpose is available here: https://pulsesecurity.co.nz/articles/javascript-from-sourcemaps

Usage

:~$ ./sourcemapper
Usage of ./sourcemapper:
  -help
        Show help
  -output string
        Source file output directory
  -url string
        URL to the Sourcemap file

Sourcemapper will download the map file at url, and then spit the sources out into the directory defined by output

doi@asov:~$ ./sourcemapper -o dhubsrc -u https://hub.docker.com/public/js/client.356c14916fb23f85707f.js.map
[+] Retriving Sourcemap from https://hub.docker.com/public/js/client.356c14916fb23f85707f.js.map
[+] Read 23045027 bytes, parsing JSON
[+] Retrieved Sourcemap with version 3, containing 1828 entries
[+] Writing 9076765 bytes to dhubsrc/webpack:/js/client.356c14916fb23f85707f.js
[+] Writing 1014 bytes to dhubsrc/webpack:/webpack/bootstrap 356c14916fb23f85707f
[+] Writing 3174 bytes to dhubsrc/webpack:/app/scripts/client.js
[+] Writing 281 bytes to dhubsrc/webpack:/~/babel-runtime/helpers/interop-require-default.js
[+] Writing 151 bytes to dhubsrc/webpack:/~/babel-core/polyfill.js
{snip}
[+] Writing 271 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/fn/object/set-prototype-of.js
[+] Writing 315 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/modules/es6.object.set-prototype-of.js
[+] Writing 1044 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/modules/_set-proto.js
[+] Writing 308 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/fn/object/create.js
[+] Writing 307 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/modules/es6.object.create.js
[+] Writing 360 bytes to dhubsrc/webpack:/~/rc-animate/~/core-js/library/fn/object/define-property.js
[+] Writing 371 bytes to dhubsrc/webpack:/~/rc-animate/~/core-js/library/modules/es6.object.define-property.js
[+] Writing 1041 bytes to dhubsrc/webpack:/~/rc-animate/~/babel-runtime/helpers/createClass.js
[+] done
doi@asov:~$ cd dhubsrc/
doi@asov:~/dhubsrc$ du -hs .
20M     .
doi@asov:~/dhubsrc$ cd webpack\:/
~/         app/       js/        webpack/   (webpack)/
doi@asov:~/dhubsrc$ cd webpack\:/app/scripts/
actions/     components/  middlewares/ reducers/    selectors/   stores/      vendor/
doi@asov:~/dhubsrc$ cd webpack\:/app/scripts/components/

Limitations

Paths such as 'webpack:/~/src/whatever/omg.js' are pretty common, so this tool will likely fail on NTFS file systems. EXT4 works fine though :D