[GRASS-dev] [GRASS GIS] #3061: "Export vector data as multi-features" leads to crash

[GRASS GIS]

#3061: "Export vector data as multi-features" leads to crash
---------------------+--------------------------------------
  Reporter:  neo     |      Owner:  grass-dev@…
      Type:  defect  |     Status:  new
  Priority:  normal  |  Milestone:  7.0.5
 Component:  Vector  |    Version:  unspecified
Resolution:          |   Keywords:  v.out.ogr, multifeatures
       CPU:  x86-64  |   Platform:  MSWindows 7
---------------------+--------------------------------------

Comment (by mmetz):

 Replying to [comment:3 neteler]:
 > In the first place I have some doubts that you can automatically fix
 these severe topological errors in the map (with the digitizer, yes). See
 attached screenshot.
 >
 > Anyway, I checked with the debugger:
 >
 > {{{
 > gdb v.out.ogr
 > (gdb) r -s -m input=tempB output=~/tmp format=ESRI_Shapefile
 > Exporting 3999 areas (may take some time)...
 >    0%
 > Program received signal SIGSEGV, Segmentation fault.
 > 0x00007ffff79538f7 in Vect_get_area_points (Map=0x7fffffffcce0,
 area=-1979, BPoints=0xb76460) at area.c:54
 > 54        G_debug(3, "  n_lines = %d", Area->n_lines);
 > (gdb)
 >
 >
 > (gdb) bt full
 > #0  0x00007ffff79538f7 in Vect_get_area_points (Map=0x7fffffffcce0,
 area=-1979, BPoints=0xb76460) at area.c:54
 >         Plus = 0x7fffffffccf0
 >         Area = 0x7bc00000879
 > #1  0x000000000040445a in create_polygon (In=0x7fffffffcce0, area=-1979,
 Points=0xb76460) at export_areas.c:294
 > }}}

 Area ID is negative: more than one centroid in this area. With negative
 area ID, Vect_get_area_points() will fail with segfault. The fix is to add
 a check to v.out.ogr for such cases. That avoids the segfault.

 The main problem, however, is that cleaning did not succeed. Apparently, a
 last step with v.clean tool=rmdac is needed. After each run of v.clean,
 the output messages should be read carefully in order to decide if the
 output vector is sufficiently clean.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3061#comment:4>
GRASS GIS <https://grass.osgeo.org>