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

[Andrew Bell]

I've already fixed this, but I can't locate the PR right now. I'll write
again when I find it.

On Tue, Jan 18, 2022 at 9:48 AM Jim Klassen <klassen.js at gmail.com> wrote:

> 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
> GNU gdb (Debian 10.1-1.7) 10.1.90.20210103-git
> Copyright (C) 2021 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <
> http://gnu.org/licenses/gpl.html>
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> For help, type "help".
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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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-- 
Andrew Bell
andrew.bell.ia at gmail.com
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