BIND 10 trac2850_3, updated. bb8a03934fabf266b6ade7b0bdf07d429dbdec43 [2850] Update comment about when the segment had been cleared

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       via  dd7ce4249bbc5e81c3e085ab143e4cb54efdfc44 (commit)
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- Log -----------------------------------------------------------------
commit bb8a03934fabf266b6ade7b0bdf07d429dbdec43
Author: Mukund Sivaraman <muks at isc.org>
Date:   Wed May 15 19:51:41 2013 +0530

    [2850] Update comment about when the segment had been cleared

commit dd7ce4249bbc5e81c3e085ab143e4cb54efdfc44
Author: JINMEI Tatuya <jinmei at isc.org>
Date:   Wed May 15 19:49:47 2013 +0530

    [2850] Add a comment about unsafe code

-----------------------------------------------------------------------

Summary of changes:
 .../datasrc/memory/zone_table_segment_mapped.cc    |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

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diff --git a/src/lib/datasrc/memory/zone_table_segment_mapped.cc b/src/lib/datasrc/memory/zone_table_segment_mapped.cc
index 186e580..efadab7 100644
--- a/src/lib/datasrc/memory/zone_table_segment_mapped.cc
+++ b/src/lib/datasrc/memory/zone_table_segment_mapped.cc
@@ -122,6 +122,18 @@ ZoneTableSegmentMapped::processHeader(MemorySegmentMapped& segment,
             }
         }
         try {
+             // FIXME: in theory this code is not safe:
+             // - ZoneTable::create could throw MemorySegmentGrown, leaking
+             //   ptr
+             // - even on successful return from ZoneTable::create(), ptr
+             //   could be reallocated due to its internal implementation detail
+             // So, to make it 100% safe we should protect both ptr and
+             // zone table in something similar to SegmentObjectHolder, get
+             // their addresses via the holder's get() method, and expect
+             // MemorySegmentGrown and handle it.  However, in this specific
+             // context the segment should have sufficient capacity in practice
+             // and the above cases are extremely unlikely to happen.  So
+             // we go for simpler code for now.
             ZoneTableHeader* new_header = new(ptr)
                 ZoneTableHeader(ZoneTable::create(segment, rrclass_));
             segment.setNamedAddress(ZONE_TABLE_HEADER_NAME, new_header);
@@ -369,8 +381,8 @@ bool
 ZoneTableSegmentMapped::isWritable() const {
     if (!isUsable()) {
         // If reset() was never performed for this segment, or if the
-        // most recent reset() had failed, then the segment is not
-        // writable.
+        // most recent reset() had failed, or if the segment had been
+        // cleared, then the segment is not writable.
         return (false);
     }