managing dev/null file add and removal

.gitignore

@@ -0,0 +1 @@
+*.pyc

example/example.py

@@ -0,0 +1,42 @@
+import os
+import logging
+from patch import fromfile, fromstring
+
+class PatchLogHandler(logging.Handler):
+    def __init__(self):
+        logging.Handler.__init__(self, logging.DEBUG)
+
+    def emit(self, record):
+        logstr = self.format(record)
+        print logstr
+
+patchlog = logging.getLogger("patch")
+patchlog.handlers = []
+patchlog.addHandler(PatchLogHandler())
+
+patch = fromstring("""--- /dev/null
++++ b/newfile
+@@ -0,0 +0,3 @@
++New file1
++New file2
++New file3
+""")
+
+patch.apply(root=os.getcwd(), strip=0)
+
+
+with open("newfile", "rb") as f:
+    newfile = f.read()
+    assert "New file1\nNew file2\nNew file3\n" == newfile
+
+patch = fromstring("""--- a/newfile
++++ /dev/null
+@@ -0,3 +0,0 @@
+-New file1
+-New file2
+-New file3
+""")
+
+result = patch.apply(root=os.getcwd(), strip=0)
+
+assert os.path.exists("newfile") is False

patch.py

@@ -800,7 +800,6 @@ def diffstat(self):
                % (len(names), sum(insert), sum(delete), delta))
     return output
 
-
   def findfile(self, old, new):
     """ return name of file to be patched or None """
     if exists(old):
@@ -820,6 +819,10 @@ def findfile(self, old, new):
           return new
       return None
 
+  def _strip_prefix(self, filename):
+    if filename.startswith(b'a/') or filename.startswith(b'b/'):
+        return filename[2:]
+    return filename
 
   def apply(self, strip=0, root=None):
     """ Apply parsed patch, optionally stripping leading components
@@ -857,9 +860,22 @@ def apply(self, strip=0, root=None):
       filename = self.findfile(old, new)
 
       if not filename:
-          warning("source/target file does not exist:\n  --- %s\n  +++ %s" % (old, new))
-          errors += 1
-          continue
+          if "dev/null" in old:
+              # this is a file creation
+              filename = self._strip_prefix(new)
+              # I wish there would be something more clean to get the full contents
+              new_file = "".join(s[1:] for s in p.hunks[0].text)
+              with open(filename, "wb") as f:
+                  f.write(new_file)
+              continue
+          elif "dev/null" in new:
+              # this is a file removal
+              os.remove(self._strip_prefix(old))
+              continue
+          else:
+              warning("source/target file does not exist:\n  --- %s\n  +++ %s" % (old, new))
+              errors += 1
+              continue
       if not isfile(filename):
         warning("not a file - %s" % filename)
         errors += 1