CHM Input: Fix a regression that broke processing of some CHM files

Fixes #1831511 [Can't open chm file](https://bugs.launchpad.net/calibre/+bug/1831511)

Bug was introduced due to adding of unicode_literals.
Also fix CHM input on python3

setup/extensions.json

@@ -84,7 +84,7 @@
         "windows_libraries": "ChmLib",
         "inc_dirs": "!chmlib_inc_dirs",
         "lib_dirs": "!chmlib_lib_dirs",
-        "defines": "SWIG_COBJECT_TYPES"
+        "defines": "SWIG_COBJECT_TYPES SWIG_PYTHON_STRICT_BYTE_CHAR"
     },
     {
         "name": "lzx",

src/calibre/ebooks/chm/reader.py

@@ -5,7 +5,7 @@ __license__ = 'GPL v3'
 __copyright__  = '2008, Kovid Goyal <kovid at kovidgoyal.net>,' \
                  ' and Alex Bramley <a.bramley at gmail.com>.'
 
-import os, re, codecs
+import os, re
 
 from calibre import guess_type as guess_mimetype
 from calibre.ebooks.BeautifulSoup import BeautifulSoup, NavigableString
@@ -15,7 +15,7 @@ from calibre.utils.chm.chm import CHMFile
 from calibre.constants import plugins
 from calibre.ebooks.metadata.toc import TOC
 from calibre.ebooks.chardet import xml_to_unicode
-from polyglot.builtins import unicode_type, getcwd
+from polyglot.builtins import unicode_type, getcwd, as_unicode
 
 
 chmlib, chmlib_err = plugins['chmlib']
@@ -56,12 +56,17 @@ class CHMReader(CHMFile):
             raise CHMError("Unable to open CHM file '%s'"%(input,))
         self.log = log
         self.input_encoding = input_encoding
+        self.chm_encoding = self.get_encoding() or 'cp1252'
         self._sourcechm = input
         self._contents = None
         self._playorder = 0
         self._metadata = False
         self._extracted = False
         self.re_encoded_files = set()
+        if self.home:
+            self.home = as_unicode(self.home, self.chm_encoding)
+        if self.topics:
+            self.topics = as_unicode(self.topics, self.chm_encoding)
 
         # location of '.hhc' file, which is the CHM TOC.
         if self.topics is None:
@@ -91,6 +96,11 @@ class CHMReader(CHMFile):
         # print toc
         return toc
 
+    def ResolveObject(self, path):
+        if not isinstance(path, bytes):
+            path = path.encode(self.chm_encoding)
+        return CHMFile.ResolveObject(self, path)
+
     def GetFile(self, path):
         # have to have abs paths for ResolveObject, but Contents() deliberately
         # makes them relative. So we don't have to worry, re-add the leading /.
@@ -107,12 +117,7 @@ class CHMReader(CHMFile):
 
     def ExtractFiles(self, output_dir=getcwd(), debug_dump=False):
         html_files = set()
-        try:
-            x = self.get_encoding()
-            codecs.lookup(x)
-            enc = x
-        except:
-            enc = 'cp1252'
+        enc = self.chm_encoding
         for path in self.Contents():
             fpath = path
             if not isinstance(path, unicode_type):
@@ -275,11 +280,12 @@ class CHMReader(CHMFile):
         paths = []
 
         def get_paths(chm, ui, ctx):
+            path = as_unicode(ui.path, self.chm_encoding)
             # skip directories
             # note this path refers to the internal CHM structure
-            if ui.path[-1] != '/':
+            if path[-1] != '/':
                 # and make paths relative
-                paths.append(ui.path.lstrip('/'))
+                paths.append(path.lstrip('/'))
         chmlib.chm_enumerate(self.file, chmlib.CHM_ENUMERATE_NORMAL, get_paths, None)
         self._contents = paths
         return self._contents

src/calibre/utils/chm/chm.py

@@ -30,7 +30,7 @@ import codecs
 import struct
 import sys
 
-from calibre.constants import plugins
+from calibre.constants import plugins, filesystem_encoding
 from polyglot.builtins import long_type
 
 chmlib, chmlib_err = plugins['chmlib']
@@ -226,7 +226,10 @@ class CHMFile:
         if self.filename is not None:
             self.CloseCHM()
 
-        self.file = chmlib.chm_open(archiveName)
+        path = archiveName
+        if not isinstance(path, bytes):
+            path = path.encode(filesystem_encoding)
+        self.file = chmlib.chm_open(path)
         if self.file is None:
             return 0
 
@@ -382,11 +385,8 @@ class CHMFile:
         The UnitInfo is used to retrieve the document contents
         '''
         if self.file:
-            # path = os.path.abspath(document)
-            path = document
-            return chmlib.chm_resolve_object(self.file, path)
-        else:
-            return (1, None)
+            return chmlib.chm_resolve_object(self.file, document)
+        return 1, None
 
     def RetrieveObject(self, ui, start=-1, length=-1):
         '''Retrieves the contents of a document.
@@ -442,7 +442,7 @@ class CHMFile:
         if ans:
             try:
                 codecs.lookup(ans)
-            except:
+            except Exception:
                 ans = None
         return ans
 

src/calibre/utils/chm/swig_chm.c

@@ -3827,18 +3827,18 @@ int dummy_enumerator (struct chmFile *h,
     if (arglist) {
       result = PyEval_CallObject(my_callback, arglist);
       Py_DECREF(arglist);
-      Py_DECREF(result);
 
       Py_DECREF(py_h);
       Py_DECREF(py_ui);
 
       if (result == NULL) {
-        return 0; /* Pass error back */
-      } else {
-        return 1;
+          PyErr_Print();
+          return 0; /* Pass error back */
       }
-    } else
-      return 0;
+      Py_DECREF(result);
+      return 1;
+      }
+    return 0;
  }
 
 

src/calibre/utils/chm/swig_chm.i

@@ -60,20 +60,20 @@ int dummy_enumerator (struct chmFile *h,
     /* Time to call the callback */
     arglist = Py_BuildValue("(OOO)", py_h, py_ui, py_c);
     if (arglist) {
-      result = PyEval_CallObject(my_callback, arglist);
-      Py_DECREF(arglist);
-      Py_DECREF(result);
-      
-      Py_DECREF(py_h);
-      Py_DECREF(py_ui);
-      
-      if (result == NULL) {
-        return 0; /* Pass error back */
-      } else {
+        result = PyEval_CallObject(my_callback, arglist);
+        Py_DECREF(arglist);
+        
+        Py_DECREF(py_h);
+        Py_DECREF(py_ui);
+        
+        if (result == NULL) {
+            PyErr_Print();
+            return 0; /* Pass error back */
+        }
+        Py_DECREF(result);
         return 1;
-      }
-    } else
-      return 0;
+    }
+    return 0;
  }
 %}