Bug 1164443 - Mozinstall should only install in an empty dir; r=ahal

--HG--
extra : commitid : 9jTgPYAbTt0
extra : rebase_source : 89a108164c90062f2534a06d1edd466d4185c711

testing/mozbase/mozinstall/mozinstall/mozinstall.py

@@ -10,6 +10,7 @@ import sys
 import tarfile
 import time
 import zipfile
+import tempfile
 
 import mozfile
 import mozinfo
@@ -93,8 +94,7 @@ def install(src, dest):
     the installation folder.
 
     :param src: Path to the install file
-    :param dest: Path to install to (to ensure we do not overwrite any existent
-                 files the folder should not exist yet)
+    :param dest: Path to install to
     """
     src = os.path.realpath(src)
     dest = os.path.realpath(dest)
@@ -102,14 +102,15 @@ def install(src, dest):
     if not is_installer(src):
         raise InvalidSource(src + ' is not valid installer file.')
 
-    did_we_create = False
     if not os.path.exists(dest):
-        did_we_create = True
         os.makedirs(dest)
+    else:
+        # create a subfolder to prevent data loss
+        dest = tempfile.mkdtemp(prefix="mozinstall", dir=dest)
 
     trbk = None
-    try:
     install_dir = None
+    try:
         if zipfile.is_zipfile(src) or tarfile.is_tarfile(src):
             install_dir = mozfile.extract(src, dest)[0]
         elif src.lower().endswith('.dmg'):
@@ -121,13 +122,13 @@ def install(src, dest):
 
     except:
         cls, exc, trbk = sys.exc_info()
-        if did_we_create:
-            try:
         # try to uninstall this properly
-                uninstall(dest)
+        try:
+            if install_dir:
+                uninstall(install_dir)
         except:
-                # uninstall may fail, let's just try to clean the folder
-                # in this case
+            pass
+        # remove the dest folder anyway
         try:
             mozfile.remove(dest)
         except: