Fix #2861 (changes in mobi metadata reset the language to NEUTRAL)

src/calibre/ebooks/mobi/langcodes.py

@@ -5,6 +5,9 @@ __docformat__ = 'restructuredtext en'
 
 from struct import pack
 
+lang_codes = {
+        }
+
 main_language = {
          0 : "NEUTRAL",
          54 : "AFRIKAANS",
@@ -326,3 +329,21 @@ def iana2mobi(icode):
             mcode = langdict[subtag]
             break
     return pack('>HBB', 0, mcode[1], mcode[0])
+
+def mobi2iana(langcode, sublangcode):
+    prefix = suffix = None
+    for code, d in IANA_MOBI.items():
+        for subcode, t in d.items():
+            cc, cl = t
+            if cc == langcode:
+                prefix = code
+            if cl == sublangcode:
+                suffix = subcode.lower() if subcode else None
+                break
+        if prefix is not None:
+            break
+    if prefix is None:
+        return 'und'
+    if suffix is None:
+        return prefix
+    return prefix + '-' + suffix

src/calibre/ebooks/mobi/reader.py

@@ -27,7 +27,7 @@ from calibre.ebooks import DRMError
 from calibre.ebooks.chardet import ENCODING_PATS
 from calibre.ebooks.mobi import MobiError
 from calibre.ebooks.mobi.huffcdic import HuffReader
-from calibre.ebooks.mobi.langcodes import main_language, sub_language
+from calibre.ebooks.mobi.langcodes import main_language, sub_language, mobi2iana
 from calibre.ebooks.compression.palmdoc import decompress_doc
 from calibre.ebooks.metadata import MetaInformation
 from calibre.ebooks.metadata.opf2 import OPFCreator, OPF
@@ -163,7 +163,11 @@ class BookHeader(object):
             if self.exth_flag & 0x40:
                 self.exth = EXTHHeader(raw[16 + self.length:], self.codec, self.title)
                 self.exth.mi.uid = self.unique_id
-                self.exth.mi.language = self.language
+                try:
+                    self.exth.mi.language = mobi2iana(langid, sublangid)
+                except:
+                    import traceback
+                    traceback.print_exc()
 
 
 class MetadataHeader(BookHeader):