Refactor le_util, 100% cover

letsencrypt/le_util.py

@@ -54,8 +54,25 @@ def check_permissions(filepath, mode, uid=0):
     return stat.S_IMODE(file_stat.st_mode) == mode and file_stat.st_uid == uid
 
 
+def _safely_attempt_open(fname, mode):
+    file_d = os.open(fname, os.O_CREAT | os.O_EXCL | os.O_RDWR, mode)
+    return os.fdopen(file_d, "w"), fname
+
+
+def _unique_file(path, filename_pat, count, mode):
+    while True:
+        try:
+            return _safely_attempt_open(
+                os.path.join(path, filename_pat(count)), mode)
+        except OSError as err:
+            # "File exists," is okay, try a different name.
+            if err.errno != errno.EEXIST:
+                raise
+        count += 1
+
+
 def unique_file(path, mode=0o777):
-    """Safely finds a unique file for writing only (by default).
+    """Safely finds a unique file.
 
     :param str path: path/filename.ext
     :param int mode: File mode
@@ -64,52 +81,35 @@ def unique_file(path, mode=0o777):
 
     """
     path, tail = os.path.split(path)
-    count = 0
-    while True:
-        fname = os.path.join(path, "%04d_%s" % (count, tail))
-        try:
-            file_d = os.open(fname, os.O_CREAT | os.O_EXCL | os.O_RDWR, mode)
-            return os.fdopen(file_d, "w"), fname
-        except OSError as exception:
-            # "File exists," is okay, try a different name.
-            if exception.errno != errno.EEXIST:
-                raise
-        count += 1
+    return _unique_file(
+        path, filename_pat=(lambda count: "%04d_%s" % (count, tail)),
+        count=0, mode=mode)
 
 
 def unique_lineage_name(path, filename, mode=0o777):
-    """Safely finds a unique file for writing only (by default).  Uses a
-    file lineage convention.
+    """Safely finds a unique file using lineage convention.
 
     :param str path: directory path
     :param str filename: proposed filename
     :param int mode: file mode
 
-    :returns: tuple of file object and file name (which may be modified from
-        the requested one by appending digits to ensure uniqueness)
+    :returns: tuple of file object and file name (which may be modified
+        from the requested one by appending digits to ensure uniqueness)
 
     :raises OSError: if writing files fails for an unanticipated reason,
-        such as a full disk or a lack of permission to write to specified
-        location.
+        such as a full disk or a lack of permission to write to
+        specified location.
 
     """
-    fname = os.path.join(path, "%s.conf" % (filename))
     try:
-        file_d = os.open(fname, os.O_CREAT | os.O_EXCL | os.O_RDWR, mode)
-        return os.fdopen(file_d, "w"), fname
+        return _safely_attempt_open(
+            os.path.join(path, "%s.conf" % (filename)), mode=mode)
     except OSError as err:
         if err.errno != errno.EEXIST:
-            raise err
-    count = 1
-    while True:
-        fname = os.path.join(path, "%s-%04d.conf" % (filename, count))
-        try:
-            file_d = os.open(fname, os.O_CREAT | os.O_EXCL | os.O_RDWR, mode)
-            return os.fdopen(file_d, "w"), fname
-        except OSError as err:
-            if err.errno != errno.EEXIST:
-                raise err
-        count += 1
+            raise
+    return _unique_file(
+        path, filename_pat=(lambda count: "%s-%04d.conf" % (filename, count)),
+        count=1, mode=mode)
 
 
 def safely_remove(path):