[trac875] Utility to search for file in several dirs

src/lib/python/isc/util/Makefile.am

@@ -1,5 +1,5 @@
 SUBDIRS = . tests
 
-python_PYTHON = __init__.py process.py socketserver_mixin.py
+python_PYTHON = __init__.py process.py socketserver_mixin.py file.py
 
 pythondir = $(pyexecdir)/isc/util

src/lib/python/isc/util/file.py

@@ -0,0 +1,29 @@
+# Copyright (C) 2011  Internet Systems Consortium.
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM
+# DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
+# INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
+# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
+# FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
+# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+"""Various functions for working with files and directories."""
+
+from os.path import exists, join
+
+def path_search(filename, paths):
+    """
+    Searches list of paths to find filename in one of them. The found one will
+    be returned or IOError will be returned if it isn't found.
+    """
+    for p in paths:
+        f = join(p, filename)
+        if exists(f):
+            return f
+    raise IOError("'" + filename + "' not found")

src/lib/python/isc/util/tests/Makefile.am

@@ -1,5 +1,5 @@
 PYCOVERAGE_RUN = @PYCOVERAGE_RUN@
-PYTESTS = process_test.py socketserver_mixin_test.py
+PYTESTS = process_test.py socketserver_mixin_test.py file_test.py
 EXTRA_DIST = $(PYTESTS)
 
 # test using command-line arguments, so use check-local target instead of TESTS

src/lib/python/isc/util/tests/file_test.py

@@ -0,0 +1,32 @@
+# Copyright (C) 2011  Internet Systems Consortium.
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM
+# DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
+# INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
+# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
+# FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
+# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+import isc.util.file
+import unittest
+
+class FileTest(unittest.TestCase):
+    def test_search_path_find(self):
+        """Test it returns the first occurence of the file"""
+        self.assertEqual('./file_test.py',
+                         isc.util.file.path_search('file_test.py',
+                                                  ['/no/such/directory/', '.',
+                                                  '../tests/']))
+
+    def test_search_path_notfound(self):
+        """Test it throws an exception when the file can't be found"""
+        self.assertRaises(IOError, isc.util.file.path_search, 'no file', ['/no/such/directory'])
+
+if __name__ == "__main__":
+    unittest.main()