ExtSST serialization pacth to fix corruption when there are a large number of strings in the SST record.

It seems that only 128 buckets can be serialized. This patch addresses this excel oddity.


git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/branches/REL_2_BRANCH@353372 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/ExtSSTInfoSubRecord.java

@@ -73,6 +73,7 @@ import org.apache.poi.util.LittleEndian;
 public class ExtSSTInfoSubRecord
     extends Record
 {
+   public static final int INFO_SIZE = 8;
     public final static short sid =
         0xFFF;                                             // only here for conformance, doesn't really have an sid
     private int               field_1_stream_pos;          // stream pointer to the SST record

src/java/org/apache/poi/hssf/record/ExtSSTRecord.java

@@ -76,6 +76,9 @@ public class ExtSSTRecord
     extends Record
 {
     public static final int DEFAULT_BUCKET_SIZE = 8;
+    //Cant seem to find this documented but from the biffviewer it is clear that
+    //Excel only records the indexes for the first 128 buckets.
+    public static final int MAX_BUCKETS = 128;
     public final static short sid = 0xff;
     private short             field_1_strings_per_bucket = DEFAULT_BUCKET_SIZE;
     private ArrayList         field_2_sst_info;
@@ -202,11 +205,28 @@ public class ExtSSTRecord
         return pos;
     }
 
+    /** Returns the size of this record */
     public int getRecordSize()
     {
         return 6 + 8*getNumInfoRecords();
     }
 
+    public static final int getNumberOfInfoRecsForStrings(int numStrings) {
+      int infoRecs = (numStrings / DEFAULT_BUCKET_SIZE);
+      if ((numStrings % DEFAULT_BUCKET_SIZE) != 0)
+        infoRecs ++;
+      //Excel seems to max out after 128 info records.
+      //This isnt really documented anywhere...
+      if (infoRecs > MAX_BUCKETS)
+        infoRecs = MAX_BUCKETS;
+      return infoRecs;
+    }
+
+    /** Given a number of strings (in the sst), returns the size of the extsst record*/
+    public static final int getRecordSizeForStrings(int numStrings) {
+      return 4 + 2 + (getNumberOfInfoRecsForStrings(numStrings) * 8);
+    }
+
     public short getSid()
     {
         return sid;

src/java/org/apache/poi/hssf/record/SSTRecord.java

@@ -586,10 +586,7 @@ public class SSTRecord
      */
     public int calcExtSSTRecordSize()
     {
-        int infoRecs = (field_3_strings.size() / SSTSerializer.DEFAULT_BUCKET_SIZE);
+      return ExtSSTRecord.getRecordSizeForStrings(field_3_strings.size());
-        if ((field_3_strings.size() % SSTSerializer.DEFAULT_BUCKET_SIZE) != 0)
-          infoRecs ++;
-        return 4 + 2 + (infoRecs * 8);
     }
 }
 

src/java/org/apache/poi/hssf/record/SSTSerializer.java

@@ -82,8 +82,6 @@ class SSTSerializer
     /** Offsets relative the start of the current SST or continue record */
     int[] bucketRelativeOffsets;
     int startOfSST, startOfRecord;
-    /** The default bucket size (this is used for ExternSST) */
-    final static int DEFAULT_BUCKET_SIZE = 8;
 
     public SSTSerializer( List recordLengths, BinaryTree strings, int numStrings, int numUniqueStrings )
     {
@@ -93,9 +91,7 @@ class SSTSerializer
         this.numUniqueStrings = numUniqueStrings;
         this.sstRecordHeader = new SSTRecordHeader( numStrings, numUniqueStrings );
 
-        int infoRecs = (strings.size() / SSTSerializer.DEFAULT_BUCKET_SIZE);
+        int infoRecs = ExtSSTRecord.getNumberOfInfoRecsForStrings(strings.size());
-        if ((strings.size() % SSTSerializer.DEFAULT_BUCKET_SIZE) != 0)
-          infoRecs ++;
         this.bucketAbsoluteOffsets = new int[infoRecs];
         this.bucketRelativeOffsets = new int[infoRecs];
     }
@@ -157,10 +153,14 @@ class SSTSerializer
 
         for ( int k = 0; k < strings.size(); k++ )
         {
-            if (k % DEFAULT_BUCKET_SIZE == 0)
+            if (k % ExtSSTRecord.DEFAULT_BUCKET_SIZE == 0)
             {
-                bucketAbsoluteOffsets[k / DEFAULT_BUCKET_SIZE] = pos;
+              int index = k/ExtSSTRecord.DEFAULT_BUCKET_SIZE;
-                bucketRelativeOffsets[k / DEFAULT_BUCKET_SIZE] = pos;
+              if (index < ExtSSTRecord.MAX_BUCKETS) {
+                //Excel only indexes the first 128 buckets.
+                bucketAbsoluteOffsets[index] = pos;
+                bucketRelativeOffsets[index] = pos;
+              }
             }
             System.arraycopy( getUnicodeString( k ).serialize(), 0, data, pos + offset, getUnicodeString( k ).getRecordSize() );
             pos += getUnicodeString( k ).getRecordSize();
@@ -210,10 +210,15 @@ class SSTSerializer
             {
                 UnicodeString unistr = getUnicodeString( stringIndex );
 
-                if (stringIndex % DEFAULT_BUCKET_SIZE == 0)
+                if (stringIndex % ExtSSTRecord.DEFAULT_BUCKET_SIZE == 0)
                 {
-                    bucketAbsoluteOffsets[stringIndex / DEFAULT_BUCKET_SIZE] = offset + totalWritten + recordProcessor.getRecordOffset() - startOfSST;
+                  int index = stringIndex / ExtSSTRecord.DEFAULT_BUCKET_SIZE;
-                    bucketRelativeOffsets[stringIndex / DEFAULT_BUCKET_SIZE] = offset + totalWritten + recordProcessor.getRecordOffset() - startOfRecord;
+                  if (index < ExtSSTRecord.MAX_BUCKETS) {
+                    bucketAbsoluteOffsets[index] = offset + totalWritten +
+                        recordProcessor.getRecordOffset() - startOfSST;
+                    bucketRelativeOffsets[index] = offset + totalWritten +
+                        recordProcessor.getRecordOffset() - startOfRecord;
+                  }
                 }
 
                 if ( unistr.getRecordSize() <= recordProcessor.getAvailable() )