Attachment 705178 Details for Bug 915321 – Fix for compressed object cache

[patch] Fix for compressed object cache

compressed-object.patch (text/plain), 2.38 KB, created by Jay Berkenbilt on 2013-03-04 21:31:22 UTC

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Creator: Jay Berkenbilt

Created: 2013-03-04 21:31:22 UTC

Size: 2.38 KB

patch

obsolete

>diff -urN ../qpdf-4.0.1.orig/ChangeLog ./ChangeLog
>--- ../qpdf-4.0.1.orig/ChangeLog	2013-01-17 14:51:04.000000000 +0000
>+++ ./ChangeLog	2013-03-04 21:15:53.952108469 +0000
>@@ -1,3 +1,13 @@
>+2013-02-23  Jay Berkenbilt  <ejb@ql.org>
>+
>+	* Bug fix: properly handle overridden compressed objects.  When
>+	caching objects from an object stream, only cache objects that,
>+	based on the xref table, would actually be resolved into this
>+	stream.  Prior to this fix, if an object stream A contained an
>+	object B that was overridden by an appended section of the file,
>+	qpdf would cache the old value of B if any non-overridden member
>+	of A was accessed before B.  This commit fixes that bug.
>+
> 2013-01-17  Jay Berkenbilt  <ejb@ql.org>
> 
> 	* 4.0.1: release
>diff -urN ../qpdf-4.0.1.orig/libqpdf/QPDF.cc ./libqpdf/QPDF.cc
>--- ../qpdf-4.0.1.orig/libqpdf/QPDF.cc	2013-01-17 14:51:04.000000000 +0000
>+++ ./libqpdf/QPDF.cc	2013-03-04 21:15:53.952108469 +0000
>@@ -1538,20 +1538,31 @@
> 	offsets[num] = offset + first;
>     }
> 
>+    // To avoid having to read the object stream multiple times, store
>+    // all objects that would be found here in the cache.  Remember
>+    // that some objects stored here might have been overridden by new
>+    // objects appended to the file, so it is necessary to recheck the
>+    // xref table and only cache what would actually be resolved here.
>     for (std::map<int, int>::iterator iter = offsets.begin();
> 	 iter != offsets.end(); ++iter)
>     {
> 	int obj = (*iter).first;
>-	int offset = (*iter).second;
>-	input->seek(offset, SEEK_SET);
>-	QPDFObjectHandle oh = readObject(input, "", obj, 0, true);
>-
>-	// Store in cache
> 	ObjGen og(obj, 0);
>-
>-	this->obj_cache[og] =
>-	    ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh),
>-		     end_before_space, end_after_space);
>+        QPDFXRefEntry const& entry = this->xref_table[og];
>+        if ((entry.getType() == 2) &&
>+            (entry.getObjStreamNumber() == obj_stream_number))
>+        {
>+            int offset = (*iter).second;
>+            input->seek(offset, SEEK_SET);
>+            QPDFObjectHandle oh = readObject(input, "", obj, 0, true);
>+            this->obj_cache[og] =
>+                ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh),
>+                         end_before_space, end_after_space);
>+        }
>+        else
>+        {
>+            //QTC::TC("qpdf", "QPDF not caching overridden objstm object");
>+        }
>     }
> }
>

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Attachments on bug 915321: 702363 | 705177 | 705178 | 705534