Fix scan for central directory end signature in ODF in Spotlight importer

Once this was fixed it seems to work nicely. Add keywords in
File:Properties and they show up in Finder's Properties, and Spotlight
finds text from the document contents.

(cherry picked from commit b8da61acb2bb887a7335a5db82b8b5ae1e0fab69)
(cherry picked from commit 95e6a0885e65cc57b11719cc0658be9d8b78fba9)

Change-Id: I9adc65d1821d0920ce3a39d05697557c4303ff68
Reviewed-on: https://gerrit.libreoffice.org/2266
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Reviewed-by: Fridrich Strba <fridrich@documentfoundation.org>
Tested-by: Fridrich Strba <fridrich@documentfoundation.org>

1 files changed, 22 insertions, 5 deletions

diff --git a/extensions/source/macosx/spotlight/OOoSpotlightImporter.m b/extensions/source/macosx/spotlight/OOoSpotlightImporter.m
index 964b627d5ca2..3a72d5337051 100644
--- a/extensions/source/macosx/spotlight/OOoSpotlightImporter.m
+++ b/extensions/source/macosx/spotlight/OOoSpotlightImporter.m
@@ -208,21 +208,38 @@ static bool areHeadersConsistent(const LocalFileHeader *header, const CentralDir
 
 static bool findCentralDirectoryEnd(NSFileHandle *file)
 {
+    // Assume the cdir end is in the last 1024 bytes
+    // Scan backward from end of file for the end signature
+
     [file seekToEndOfFile];
     unsigned long long fileLength = [file offsetInFile];
-    [file seekToFileOffset: 0];
 
-    while ([file offsetInFile] < fileLength)
+    if (fileLength < 10)
+        return false;
+
+    [file seekToFileOffset: (fileLength - 4)];
+
+    unsigned long long limit;
+    if (fileLength > 1024)
+        limit = fileLength - 1024;
+    else
+        limit = 0;
+
+    unsigned long long offset;
+    while ((offset = [file offsetInFile]) > limit)
     {
-        unsigned long long offset = [file offsetInFile];
         unsigned signature = readInt(file);
         if (signature == CDIR_END_SIG)
         {
-            [file seekToFileOffset: (offset - 4)];
+            // Seek back over the CDIR_END_SIG
+            [file seekToFileOffset: offset];
             return true;
         }
         else
-            [file seekToFileOffset: (offset - 3)];
+        {
+            // Seek one byte back
+            [file seekToFileOffset: (offset - 1)];
+        }
     }
     return false;
 }