[pdal] seg-fault when compressing zero points with lazperf

[Jim Klassen]

It appears there is a seg-fault in pdal when compressing a file with zero points with lazperf.  Using laszip correctly creates an empty laz file.  With at least one point into the source file both laszip and lazperf work as expected.

My guess is LazPerfVlrCompressorImpl::compress() is never getting called, so m_compressor is null, but that condition isn't being checked in LazPerfVlrCompressorImpl::done() before calling m_compress->done().  I'm not sure how much of LazPerfVlrCompressorImpl::done() should be skipped if m_compressor is null (there were no points to process).


liblaszip: 3.4.1-6-gc7b67ca
laz-perf: 3.0.0-1-g03ed832
pdal: ac8068c7d


$ cat lasperf.fail.txt
X,Y,Z

$ pdal info lasperf.fail.txt
{
   "file_size": 7,
   "filename": "lasperf.fail.txt",
   "now": "2022-01-18T08:19:08-0600",
   "pdal_version": "2.3.0 (git-version: ac8068)",
   "reader": "readers.text",
   "stats":
   {
     "statistic":
     [
       {
         "average": 0,
         "count": 0,
         "maximum": -1.797693135e+308,
         "minimum": 1.797693135e+308,
         "name": "X",
         "position": 0,
         "stddev": 0,
         "variance": 0
       },
       {
         "average": 0,
         "count": 0,
         "maximum": -1.797693135e+308,
         "minimum": 1.797693135e+308,
         "name": "Y",
         "position": 1,
         "stddev": 0,
         "variance": 0
       },
       {
         "average": 0,
         "count": 0,
         "maximum": -1.797693135e+308,
         "minimum": 1.797693135e+308,
         "name": "Z",
         "position": 2,
         "stddev": 0,
         "variance": 0
       }
     ]
   }
}
$ pdal translate lasperf.fail.txt lasperf.fail.laz --writers.las.compression=laszip
$ pdal translate lasperf.fail.txt lasperf.fail.laz --writers.las.compression=lazperf
Segmentation fault
$ gdb --args pdal translate lasperf.fail.txt lasperf.fail.laz --writers.las.compression=lazperf
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Reading symbols from pdal...
(No debugging symbols found in pdal)
(gdb) run
Starting program: /apps/PointClouds/pdal/2.3.0-ac8068c7d-laszip/bin/pdal translate lasperf.fail.txt lasperf.fail.laz --writers.las.compression=lazperf
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7e0c4d9 in pdal::LazPerfVlrCompressorImpl::done (this=0x4c2ea0)
     at /apps/PointClouds/pdal/src/pdal/pdal/compression/LazPerfVlrCompression.cpp:101
101            m_compressor->done();
(gdb) print m_compressor
$1 = std::shared_ptr<lazperf::las_compressor> (empty) = {get() = 0x0}
(gdb) quit
A debugging session is active.

     Inferior 1 [process 283225] will be killed.

Quit anyway? (y or n) y
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