secrules/FindFile.py initial version

secrules/FindFile.py

+from vms import descrip, rmsdef, dvidef, devdef
+from vms.rtl import lib
+import ctypes
+
+
+VMSLIBRTL = "/SYS$COMMON/SYSLIB/LIBRTL.EXE"
+LIBRTL = ctypes.CDLL(VMSLIBRTL)
+vms_find_file = getattr(LIBRTL,"LIB$FIND_FILE")
+vms_find_file_end = getattr(LIBRTL,"LIB$FIND_FILE_END")
+vms_trim_filespec = getattr(LIBRTL,"LIB$TRIM_FILESPEC")
+
+LIB_M_FIL_LONG_NAMES = 4
+NAML_C_MAXRSS = 4095
+
+class FindFile(object):
+    def __init__(self, filespec, default_filespec=None,
+                 flags=LIB_M_FIL_LONG_NAMES):
+        self.filespec = ctypes.create_string_buffer(filespec)
+        self.default_filespec = None if default_filespec is None else \
+          descrip.bydesc(ctypes.create_string_buffer(default_filespec))
+        self.resultant_filespec = \
+             ctypes.create_string_buffer(NAML_C_MAXRSS + 1)
+        self.context = ctypes.c_uint32()
+        self.nullArg = ctypes.c_voidp()
+        self.flags = ctypes.c_uint(flags)
+        self.new_filespec = ctypes.create_string_buffer(NAML_C_MAXRSS + 1)
+        self.resultant_length = ctypes.c_uint16()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        s = vms_find_file_end(ctypes.byref(self.context))
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        s = vms_find_file(descrip.bydesc(self.filespec),
+                          descrip.bydesc(self.resultant_filespec),
+                          ctypes.byref(self.context),
+                          self.default_filespec, 
+                          self.nullArg, self.nullArg, ctypes.byref(self.flags))
+        if not (s & 1):
+            raise StopIteration \
+               if s in (rmsdef.RMS__NMF, rmsdef.RMS__FNF ) \
+               else VMSError(s)
+
+        s = vms_trim_filespec(descrip.bydesc(self.resultant_filespec),
+                              descrip.bydesc(self.new_filespec),
+                              self.nullArg,
+                              ctypes.byref(self.resultant_length))
+        res = self.new_filespec[:self.resultant_length.value]
+        # Check if the device is file oriented, lib$find_file return a file if
+        # a device like NLA0: is used
+        if (lib.getdvi(dvidef.DVI__DEVCHAR, device_name=res)[1] &
+             devdef.DEV_M_FOD) == 0:
+            raise StopIteration
+        return res
+     
+    def next(self):
+        return self.__next__()
+
+def file_exists(fn):
+    try:
+        with FindFile(fn) as ifn:
+            ifn.__next__()
+        return True
+    except (VMSError, StopIteration), e:
+        return False
+
+if __name__ == '__main__':
+    import sys
+    with FindFile(sys.argv[1]) as ifn:
+        for fn in ifn:
+            print fn