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Posted to reviews@impala.apache.org by "Jim Apple (Code Review)" <ge...@cloudera.org> on 2019/07/05 00:27:53 UTC

[Impala-ASF-CR] IMPALA-5031: out-of-range enum values are undefined behavior

Jim Apple has uploaded this change for review. ( http://gerrit.cloudera.org:8080/13805


Change subject: IMPALA-5031: out-of-range enum values are undefined behavior
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IMPALA-5031: out-of-range enum values are undefined behavior

This patch fixes an out-of-range enum value in the end-to-end tests.

The [expr] section of the C++14 standard indicates that out-of-range
enum values are undefined behavior: "If during the evaluation of an
expression, the result is not mathematically defined or not in the
range of representable values for its type, the behavior is
undefined."

The [decl.enum] section explains what values are "in the range of
representable values for its type": "[F]or an enumeration where emin
is the smallest enumerator and emax is the largest, the values of the
enumeration are the values in the range bmin to bmax, defined as
follows: Let K be 1 for a two's complement representation and 0 for a
one's complement or sign-magnitude representation. bmax is the
smallest value greater than or equal to max(|emin| - K, |emax|) and
equal to 2M-1, where M is a non-negative integer. bmin is zero if emin
is non-negative and -(bmax+K) otherwise."

The Parquet PageType enum has emin = 0 and emax = 3, so bmin = 0 and
bmax = 3. The out-of-range value in the tests is 4294967249, and is
therefore undefined behavior. The interesting part of the backtrace
is:

parquet/parquet-column-readers.cc:1269:24: runtime error: load of
  value 4294967249, which is not a valid value for type
  'PageType::type'
    #0 BaseScalarColumnReader::InitDictionary()
       parquet/parquet-column-readers.cc:1269:24
    #1 BaseScalarColumnReader::InitDictionaries(
       vector<BaseScalarColumnReader*>)
       parquet/parquet-column-readers.cc:1381:53
    #2 HdfsParquetScanner::NextRowGroup()
       parquet/hdfs-parquet-scanner.cc:678:14
    #3 HdfsParquetScanner::GetNextInternal(RowBatch*)
       parquet/hdfs-parquet-scanner.cc:437:45
    #4 HdfsParquetScanner::ProcessSplit()
       parquet/hdfs-parquet-scanner.cc:353:21
    #5 HdfsScanNode::ProcessSplit(vector<FilterContext> const&,
       MemPool*, io::ScanRange*, long*) exec/hdfs-scan-node.cc:514:21
    #6 HdfsScanNode::ScannerThread(bool, long)
       hdfs-scan-node.cc:415:7
    #7 HdfsScanNode::ThreadTokenAvailableCb(ThreadResourcePool*)
       ::$_0::operator()() const hdfs-scan-node.cc:337:13

Change-Id: I2d126a8f3e5910d23088a3f916c4cf31aac28d95
---
M be/src/exec/parquet/parquet-column-readers.cc
1 file changed, 4 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/05/13805/1
-- 
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I2d126a8f3e5910d23088a3f916c4cf31aac28d95
Gerrit-Change-Number: 13805
Gerrit-PatchSet: 1
Gerrit-Owner: Jim Apple <jb...@apache.org>