Browser Console Snippet to decompress mozlz4 and jsonlz4 files

decompress-mozlz4-snippet.js

/* Decompression Script for the Browser Console

   NOTE: BEFORE RUNNING THIS SCRIPT, CHECK THIS SETTING:
   Type or paste about:config into the address bar and press Enter
   Click the button promising to be careful
   In the search box type devt and pause while Firefox filters the list
   If devtools.chrome.enabled is false, double-click it to toggle to true

Paste this entire script into the command line at the bottom of the Browser Console (Windows: Ctrl+Shift+j)
Then press Enter to run the script. A file picker should promptly open.

See: http://forums.mozillazine.org/viewtopic.php?p=14111285#p14111285
*/
var {utils:Cu} = Components;
// Set up file chooser
var fp = Components.classes["@mozilla.org/filepicker;1"].createInstance(Components.interfaces.nsIFilePicker);
var fu = Cu.import("resource://gre/modules/FileUtils.jsm").FileUtils
try { // Fx125+
  fp.init(window.browsingContext, 'Open File', Components.interfaces.nsIFilePicker.modeOpen);
} catch(e) { // Fx124 and earlier
  fp.init(window, 'Open File', Components.interfaces.nsIFilePicker.modeOpen);
}
fp.appendFilter("LZ4 Compressed Files", "*.mozlz4;*.jsonlz4*");
//fp.displayDirectory = fu.File(OS.Constants.Path.profileDir);
fp.displayDirectory = fu.File(PathUtils.profileDir); // Fx104
// Call file chooser
fp.open((aResult) => {
  if (aResult == Components.interfaces.nsIFilePicker.returnOK) {
    if (fp.file.exists() && fp.file.isFile() && fp.file.isReadable()) {
      var oldfile = fp.file.path;
      // Construct output file name
      var newfile = oldfile + "_converted.json";
      try {
        //Cu.import("resource://gre/modules/osfile.jsm");
        //let promise = OS.File.read(oldfile,{compression:"lz4"}); 
        let promise = IOUtils.readUTF8(oldfile, { decompress: true }); // Fx104
        promise = promise.then(jsonString => {
          //OS.File.writeAtomic(newfile, jsonString);
          IOUtils.writeUTF8(newfile, jsonString); // Fx104
        });
        promise = promise.then(retval => {
          console.log('Saved as: "' + newfile + '"');
        });
      }
        catch (err) {
          console.log(err);
      }
    }
  }
});

I created a pair of webapps that are simpler to use:

• Bookmarks: https://www.jeffersonscher.com/ffu/bookbackreader.html
• Session History: https://www.jeffersonscher.com/ffu/scrounger.html

Updates for Firefox 104:

• OS.Constants.Path.profileDir to PathUtils.profileDir
• OS.File.read() to IOUtils.readUTF8()
• OS.File.writeAtomic() to IOUtils.writeUTF8()

Try/catch added for Firefox 125 (currently in Nightly), at lines 18-20, 22.

Commented out Line 34 which broke in Firefox 132 or earlier.