Issue 2956 - Ensure the correct version of jsshell is present

utils.py

 # coding: utf-8
 
 # This Source Code is subject to the terms of the Mozilla Public License
 # version 2.0 (the "License"). You can obtain a copy of the License at
 # http://mozilla.org/MPL/2.0/.
 
 import os
 import platform
+import re
 from StringIO import StringIO
+import shutil
+import subprocess
 import sys
 import urllib
 import zipfile
 
+JSSHELL_VERSION = "JavaScript-C31.5.0esrpre"
+JSSHELL_URL = ("https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly"
+               "/2015/02/2015-02-25-00-22-19-mozilla-esr31/jsshell-%s.zip")
+
 def ensureJSShell():
   baseDir = os.path.dirname(__file__)
   shell_dir = os.path.join(baseDir, 'mozilla')
+
   if not os.path.exists(shell_dir):
     os.makedirs(shell_dir)
   if sys.platform == 'win32':
     path = os.path.join(shell_dir, 'js.exe')
   else:
     path = os.path.join(shell_dir, 'js')
+
   if os.path.exists(path):
-    return path
+    # Return the path if jsshell is present and its version is correct
+    match = re.search(r"^Version: (.+)$",
+                      subprocess.check_output([path, "--help"]), re.MULTILINE)
+    if match and match.group(1) == JSSHELL_VERSION:
+      return path
+    # Otherwise remove the old / faulty version, we'll re-download
+    shutil.rmtree(shell_dir)

[Sebastian Noack, 2015/11/19 20:21:43]

I'm not sure whether this is a good idea. Imagine you work offline and switch to
a revision that requires a different version of jsshell, then the previous
version is deleted, the new one fails to download, and you cannot go back
either. 

[kzar, 2015/11/20 09:02:00]

That's true, but the current behaviour is to somewhat magically (and silently)
download jsshell in the background as well. When I had trouble connecting to the
Mozilla FTP server the other day my build was silently hanging while it tried to
download and it took me a while to pin down.

I don't mind changing that, but we need to agree on the desired behaviour. Any
ideas? (Also that should arguably be a separate issue.)

+    os.makedirs(shell_dir)
 
   supported_platforms = {
     'win32': 'win32',
     'linux2': {
       'i686': 'linux-i686',
       'x86_64': 'linux-x86_64'
     },
     'darwin': 'mac',
   }
   try:
     build = supported_platforms[sys.platform]
     if isinstance(build, dict):
       build = build[platform.machine()]
   except KeyError:
     raise Exception('Platform %s (%s) not supported by JS shell' % (
       sys.platform, platform.machine()
     ))
 
-  download_url = 'https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2015/02/2015-02-25-00-22-19-mozilla-esr31/jsshell-%s.zip' % build
-  data = StringIO(urllib.urlopen(download_url).read())
+  data = StringIO(urllib.urlopen(JSSHELL_URL % build).read())
   zip = zipfile.ZipFile(data)
   zip.extractall(shell_dir)
   zip.close()
 
   if not os.path.exists(path):
     raise Exception('Downloaded package didn\'t contain JS shell executable')
 
   try:
     os.chmod(path, 0700)
   except:
     pass
 
   return path