Remove most dangerous uses of 'chdir' syscall

Because chdir/getcwd is global to the whole process, it is not thread-safe
and may cause very serious bugs like data loss (for example when 'os.remove'
or 'shutil.rmtree' are called with relative paths).

There still remain uses of 'chdir' in ERP5 Subversion. A temporary quick change
is done to reduce the probability of race conditions, but this should really be
fixed.

product/ERP5/ERP5Site.py

@@ -1619,13 +1619,13 @@ class ERP5Generator(PortalGenerator):
 
   @classmethod
   def bootstrap(cls, context, bt_name, item_name, content_id_list):
-    cwd = os.getcwd()
-    try:
-      os.chdir(getBootstrapBusinessTemplateUrl(bt_name))
+    bt_path = getBootstrapBusinessTemplateUrl(bt_name)
     from Products.ERP5.Document.BusinessTemplate import quote
     traverse = context.unrestrictedTraverse
-      for root, dirs, files in os.walk(os.path.join(item_name, context.id)):
-        container_path = root.split(os.sep)[2:]
+    top = os.path.join(bt_path, item_name, context.id)
+    prefix_len = len(os.path.join(top, ''))
+    for root, dirs, files in os.walk(top):
+      container_path = root[prefix_len:]
       load = traverse(container_path)._importObjectFromFile
       if container_path:
         id_set = set(x[:-4] for x in files if x[-4:] == '.xml')
@@ -1636,8 +1636,6 @@ class ERP5Generator(PortalGenerator):
       for file in id_set:
         load(os.path.join(root, file + '.xml'),
              verify=False, set_owner=False, suppress_events=True)
-    finally:
-      os.chdir(cwd)
 
   def setupLastTools(self, p, **kw):
     """

product/ERP5/Tool/TemplateTool.py

@@ -256,27 +256,15 @@ class TemplateTool (BaseTool):
         Export the Business Template as a bt5 file and offer the user to
         download it.
       """
-      path = business_template.getTitle()
-      path = pathname2url(path)
-      # XXX Why is it necessary to create a temporary directory?
-      tmpdir_path = mkdtemp()
-      # XXX not thread safe
-      current_directory = os.getcwd()
-      os.chdir(tmpdir_path)
-      absolute_path = os.path.abspath(path)
-      export_string = business_template.export(path=absolute_path)
-      os.chdir(current_directory)
+      export_string = business_template.export()
+      try:
         if RESPONSE is not None:
           RESPONSE.setHeader('Content-type','tar/x-gzip')
-        RESPONSE.setHeader('Content-Disposition',
-                           'inline;filename=%s-%s.bt5' % \
-                               (path,
-                                business_template.getVersion()))
-      try:
+          RESPONSE.setHeader('Content-Disposition', 'inline;filename=%s-%s.bt5'
+            % (business_template.getTitle(), business_template.getVersion()))
         return export_string.getvalue()
       finally:
         export_string.close()
-        shutil.rmtree(tmpdir_path)
 
     security.declareProtected( 'Import/Export objects', 'publish' )
     def publish(self, business_template, url, username=None, password=None):

product/ERP5VCS/Subversion.py

@@ -30,15 +30,35 @@
 ##############################################################################
 
 import errno, glob, os, re, shutil
+import threading
 from ZTUtils import make_query
 from Products.ERP5Type.Message import translateString
+from Products.ERP5Type.Utils import simple_decorator
 from Products.ERP5.Document.BusinessTemplate import BusinessTemplateFolder
 from Products.ERP5VCS.WorkingCopy import \
-  WorkingCopy, Dir, File, chdir_working_copy, selfcached, \
+  WorkingCopy, Dir, File, selfcached, \
   NotAWorkingCopyError, NotVersionedError, VcsConflictError
 from Products.ERP5VCS.SubversionClient import \
   newSubversionClient, SubversionLoginError, SubversionSSLTrustError
 
+# XXX Still not thread safe !!! Proper fix is to never use 'os.chdir'
+#     Using a RLock is a temporary quick change that only protects against
+#     concurrent uses of ERP5 Subversion.
+_chdir_lock = threading.RLock()
+@simple_decorator
+def chdir_working_copy(func):
+  def decorator(self, *args, **kw):
+    _chdir_lock.acquire()
+    try:
+      cwd = os.getcwd()
+      try:
+        os.chdir(self.working_copy)
+        return func(self, *args, **kw)
+      finally:
+        os.chdir(cwd)
+    finally:
+      _chdir_lock.release()
+  return decorator
 
 class Subversion(WorkingCopy):
 
@@ -238,6 +258,7 @@ class Subversion(WorkingCopy):
         'Files committed successfully in revision ${revision}',
         mapping=dict(revision=getRevisionNumber(revision))))))
 
+  @chdir_working_copy
   def _export(self, business_template):
     bta = BusinessTemplateWorkingCopy(creation=1, client=self._getClient())
     bta.export(business_template)

product/ERP5VCS/WorkingCopy.py

@@ -42,17 +42,6 @@ from ZTUtils import make_query
 from Products.ERP5.Document.BusinessTemplate import BusinessTemplateFolder
 from Products.ERP5Type.Utils import simple_decorator
 
-@simple_decorator
-def chdir_working_copy(func):
-  def decorator(self, *args, **kw):
-    cwd = os.getcwd()
-    try:
-      os.chdir(self.working_copy)
-      return func(self, *args, **kw)
-    finally:
-      os.chdir(cwd)
-  return decorator
-
 @simple_decorator
 def selfcached(func):
   """Return a function which stores a computed value in an instance
@@ -202,15 +191,10 @@ class WorkingCopy(Implicit):
     business_template.build()
     # XXX: Big hack to make export work as expected.
     transaction.commit()
-    old_cwd = os.getcwd()
-    try:
-      os.chdir(self.working_copy)
     self._export(business_template)
-    finally:
-      os.chdir(old_cwd)
 
   def _export(self, business_template):
-    bta = BusinessTemplateWorkingCopy(creation=1)
+    bta = BusinessTemplateWorkingCopy(creation=1, path=self.working_copy)
     self.addremove(*bta.export(business_template))
 
   def showOld(self, path):
@@ -386,6 +370,7 @@ class BusinessTemplateWorkingCopy(BusinessTemplateFolder):
   def _writeString(self, obj, path):
     self.file_set.add(path)
     self._makeParent(path)
+    path = os.path.join(self.path, path)
     # write file unless unchanged
     file = None
     try:
@@ -412,8 +397,9 @@ class BusinessTemplateWorkingCopy(BusinessTemplateFolder):
     path = os.path.dirname(path)
     if path and path not in self.dir_set:
       self._makeParent(path)
-      if not os.path.exists(path):
-        os.mkdir(path)
+      real_path = os.path.join(self.path, path)
+      if not os.path.exists(real_path):
+        os.mkdir(real_path)
       self.dir_set.add(path)
 
   def export(self, business_template):
@@ -423,8 +409,8 @@ class BusinessTemplateWorkingCopy(BusinessTemplateFolder):
     business_template.export(bta=self)
     # Remove dangling files/dirs
     removed_set = set()
-    prefix_length = len(os.path.join('.', ''))
-    for dirpath, dirnames, filenames in os.walk('.'):
+    prefix_length = len(os.path.join(self.path, ''))
+    for dirpath, dirnames, filenames in os.walk(self.path):
       dirpath = dirpath[prefix_length:]
       for i in xrange(len(dirnames) - 1, -1, -1):
         d = dirnames[i]
@@ -432,13 +418,13 @@ class BusinessTemplateWorkingCopy(BusinessTemplateFolder):
           d = os.path.join(dirpath, d)
           if d in self.dir_set:
             continue
-          shutil.rmtree(d)
+          shutil.rmtree(os.path.join(self.path, d))
           removed_set.add(d)
         del dirnames[i]
       for f in filenames:
         f = os.path.join(dirpath, f)
         if f not in self.file_set:
-          os.remove(f)
+          os.remove(os.path.join(self.path, f))
           removed_set.add(f)
     return self.file_set, removed_set