App/FindHomes.py now computes the "real" path for SOFTWARE_HOME and

        INSTANCE_HOME, resolving any symlinks in any element within paths
        passed in via the INSTANCE_HOME or SOFTWARE_HOME envvars.  Paths that
        are computed by "dead reckoning" from os.getcwd and module paths are
        also "realpathed".  So for instance, if you use '/home/chrism/Instance'
        as your INSTANCE_HOME, and '/home/chrism' is a symlink to
        '/other/home/chrism', your INSTANCE_HOME will be computed as
        '/other/home/chrism/Instance'.  This is necessary to avoid
        weirdnesses while using "dead reckoning" from INSTANCE_HOME and
        SOFTWARE_HOME in other parts of the code.  POSIX systems only.

doc/CHANGES.txt

@@ -57,7 +57,18 @@ Zope Changes
       - Collector #304: several catalog optimisations
         
     Bugs:
-    
+
+      - App/FindHomes.py now computes the "real" path for SOFTWARE_HOME and
+        INSTANCE_HOME, resolving any symlinks in any element within paths
+        passed in via the INSTANCE_HOME or SOFTWARE_HOME envvars.  Paths that
+        are computed by "dead reckoning" from os.getcwd and module paths are
+        also "realpathed".  So for instance, if you use '/home/chrism/Instance'
+        as your INSTANCE_HOME, and '/home/chrism' is a symlink to
+        '/other/home/chrism', your INSTANCE_HOME will be computed as
+        '/other/home/chrism/Instance'.  This is necessary to avoid
+        weirdnesses while using "dead reckoning" from INSTANCE_HOME and
+        SOFTWARE_HOME in other parts of the code.  POSIX systems only.
+
       - Fixed PropertyManager/PropertySheets so that you can safely add a
         property named 'ids' without breaking your properties page.
 

lib/python/App/Common.py

@@ -13,7 +13,7 @@
 
 """Commonly used utility functions."""
 
-__version__='$Revision: 1.11 $'[11:-2]
+__version__='$Revision: 1.12 $'[11:-2]
 
 import sys, os, time
 
@@ -109,3 +109,26 @@ def attrget(o,name,default):
 
 def Dictionary(**kw): return kw # Sorry Guido
     
+def realpath(p):
+    """ Computes the 'real' path of a file or directory devoid of
+    any symlink in any element of the path """
+    p = os.path.abspath(p)
+    if os.name == 'posix':
+        path_list = p.split(os.sep)
+        orig_len = len(path_list)
+        changed = 0
+        i = 1
+        while not changed and i < orig_len:
+            head = path_list[:i]
+            tail = path_list[i:]
+            head_s = os.sep.join(head)
+            tail_s = os.sep.join(tail)
+            if os.path.islink(head_s):
+                head_s = os.readlink(head_s)
+                path_list = head_s.split(os.sep)
+                path_list.extend(tail)
+                p = os.sep.join(path_list)
+                p = realpath(p)
+                changed = 1
+            i = i + 1
+    return p

lib/python/App/FindHomes.py

@@ -13,10 +13,10 @@
 
 """Commonly used utility functions."""
 
-__version__='$Revision: 1.8 $'[11:-2]
+__version__='$Revision: 1.9 $'[11:-2]
 
 import os, sys, Products
-from Common import package_home
+from Common import package_home, realpath
 path_join = os.path.join
 path_split = os.path.split
 
@@ -31,10 +31,12 @@ except:
     if path_split(home)[1]=='..':
         home=path_split(path_split(home)[0])[0]
 
+home=realpath(home)
 sys.modules['__builtin__'].SOFTWARE_HOME=SOFTWARE_HOME=home
 
 try:
     chome=os.environ['INSTANCE_HOME']
+    chome = realpath(chome)
 except:
     chome=home
     d,e=path_split(chome)