merge bug20342 into default

1 files changed, 45 insertions, 0 deletions

diff --git a/calculate-relative b/calculate-relative
new file mode 100755
index 0000000000..3c3e2b1ff6
--- /dev/null
+++ b/calculate-relative
@@ -0,0 +1,45 @@
+#!/usr/bin/python
+#
+# relpath.py
+# R.Barran 30/08/2004
+# Retrieved from http://code.activestate.com/recipes/302594/
+
+import os
+import sys
+
+def relpath(target, base=os.curdir):
+    """
+    Return a relative path to the target from either the current dir or an optional base dir.
+    Base can be a directory specified either as absolute or relative to current dir.
+    """
+
+    if not os.path.exists(target):
+        raise OSError, 'Target does not exist: '+target
+
+    if not os.path.isdir(base):
+        raise OSError, 'Base is not a directory or does not exist: '+base
+
+    base_list = (os.path.abspath(base)).split(os.sep)
+    target_list = (os.path.abspath(target)).split(os.sep)
+
+    # On the windows platform the target may be on a completely different drive from the base.
+    if os.name in ['nt','dos','os2'] and base_list[0] <> target_list[0]:
+        raise OSError, 'Target is on a different drive to base. Target: '+target_list[0].upper()+', base: '+base_list[0].upper()
+
+    # Starting from the filepath root, work out how much of the filepath is
+    # shared by base and target.
+    for i in range(min(len(base_list), len(target_list))):
+        if base_list[i] <> target_list[i]: break
+    else:
+        # If we broke out of the loop, i is pointing to the first differing path elements.
+        # If we didn't break out of the loop, i is pointing to identical path elements.
+        # Increment i so that in all cases it points to the first differing path elements.
+        i+=1
+
+    rel_list = [os.pardir] * (len(base_list)-i) + target_list[i:]
+    if (len(rel_list) == 0):
+        return "."
+    return os.path.join(*rel_list)
+
+if __name__ == "__main__":
+    print(relpath(sys.argv[1], sys.argv[2]))