Fix libimobiledevice failing to load library on unsupported linux builds

Also some pep8 cleanup

src/calibre/devices/idevice/libimobiledevice.py

@@ -20,12 +20,13 @@ from ctypes import (
     c_char, c_char_p, c_int, c_long, c_ubyte, c_uint, c_ulonglong, c_void_p,
     POINTER, string_at, Structure)
 
-from calibre.constants import DEBUG, islinux, isosx, iswindows
+from calibre.constants import DEBUG, isosx, iswindows
 from calibre.devices.idevice.parse_xml import XmlPropertyListParser
 from calibre.devices.usbms.driver import debug_print
 
 
 class libiMobileDeviceException(Exception):
+
     def __init__(self, value):
         self.value = value
 
@@ -34,6 +35,7 @@ class libiMobileDeviceException(Exception):
 
 
 class libiMobileDeviceIOException(Exception):
+
     def __init__(self, value):
         self.value = value
 
@@ -42,6 +44,7 @@ class libiMobileDeviceIOException(Exception):
 
 
 class AFC_CLIENT_T(Structure):
+
     '''
     http://www.libimobiledevice.org/docs/html/structafc__client__private.html
     '''
@@ -74,6 +77,7 @@ class AFC_CLIENT_T(Structure):
 
 
 class HOUSE_ARREST_CLIENT_T(Structure):
+
     '''
     http://www.libimobiledevice.org/docs/html/structhouse__arrest__client__private.html
     '''
@@ -94,6 +98,7 @@ class HOUSE_ARREST_CLIENT_T(Structure):
 
 
 class IDEVICE_T(Structure):
+
     '''
     http://www.libimobiledevice.org/docs/html/structidevice__private.html
     '''
@@ -104,6 +109,7 @@ class IDEVICE_T(Structure):
 
 
 class INSTPROXY_CLIENT_T(Structure):
+
     '''
     http://www.libimobiledevice.org/docs/html/structinstproxy__client__private.html
     '''
@@ -129,6 +135,7 @@ class INSTPROXY_CLIENT_T(Structure):
 
 
 class LOCKDOWND_CLIENT_T(Structure):
+
     '''
     http://www.libimobiledevice.org/docs/html/structlockdownd__client__private.html
     '''
@@ -152,6 +159,7 @@ class LOCKDOWND_CLIENT_T(Structure):
 
 
 class LOCKDOWND_SERVICE_DESCRIPTOR(Structure):
+
     '''
     from libimobiledevice/include/libimobiledevice/lockdown.h
     '''
@@ -162,6 +170,7 @@ class LOCKDOWND_SERVICE_DESCRIPTOR(Structure):
 
 
 class libiMobileDevice():
+
     '''
     Wrapper for libiMobileDevice
     '''
@@ -438,10 +447,10 @@ class libiMobileDevice():
         return self._afc_read_directory(path, get_stats=get_stats)
 
     def load_library(self):
-        if islinux:
-            env = "linux"
-            self.lib = cdll.LoadLibrary('libimobiledevice.so.5')
-            self.plist_lib = cdll.LoadLibrary('libplist.so.3')
+        if iswindows:
+            env = "Windows"
+            self.lib = cdll.LoadLibrary('libimobiledevice.dll')
+            self.plist_lib = cdll.LoadLibrary('libplist.dll')
         elif isosx:
             env = "OS X"
 
@@ -458,11 +467,13 @@ class libiMobileDevice():
                 self.plist_lib = cdll.LoadLibrary(os.path.join(getattr(sys, 'frameworks_dir'), path))
             else:
                 self.plist_lib = cdll.LoadLibrary(path)
-        elif iswindows:
-            env = "Windows"
-            self.lib = cdll.LoadLibrary('libimobiledevice.dll')
-            self.plist_lib = cdll.LoadLibrary('libplist.dll')
-
+        else:
+            env = "linux"
+            try:
+                self.lib = cdll.LoadLibrary('libimobiledevice.so.5')
+            except EnvironmentError:
+                self.lib = cdll.LoadLibrary('libimobiledevice.so')
+            self.plist_lib = cdll.LoadLibrary('libplist.so.3')
         self._log_location(env)
         self._log(" libimobiledevice loaded from '{0}'".format(self.lib._name))
         self._log(" libplist loaded from '{0}'".format(self.plist_lib._name))
@@ -506,7 +517,7 @@ class libiMobileDevice():
                 self._instproxy_client_options_free()
                 self._instproxy_client_free()
 
-                if not app_name in self.installed_apps:
+                if app_name not in self.installed_apps:
                     self._log(" {0} not installed on this iDevice".format(repr(app_name)))
                     self.disconnect_idevice()
                 else:
@@ -1719,7 +1730,6 @@ class libiMobileDevice():
         return device_name
 
     def _lockdown_get_value(self, requested_items=[]):
-
         '''
         Retrieves a preferences plist using an optional domain and/or key name.
 
@@ -1937,4 +1947,3 @@ class libiMobileDevice():
 
     def __null(self, *args, **kwargs):
         pass
-