[GRASS-dev] [GRASS GIS] #2438: Vect_get_line_type cannot handle line out of range

[GRASS GIS]

#2438: Vect_get_line_type cannot handle line out of range
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  Reporter:  artegion     |       Owner:  grass-dev@…              
      Type:  defect       |      Status:  reopened                 
  Priority:  normal       |   Milestone:  6.4.5                    
 Component:  LibVector    |     Version:  unspecified              
Resolution:               |    Keywords:                           
  Platform:  Unspecified  |         Cpu:  Unspecified              
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Changes (by artegion):

  * status:  closed => reopened
  * resolution:  invalid =>


Comment:

 Replying to [comment:1 mmetz]:
 > Replying to [ticket:2438 artegion]:
 > > calling Vect_get_line_type with line out of range (i.e. line=0)
 > > Vect_line_alive returns -1 but Vect_get_line_type ignores it (not -1
 is False just like not 1) -> access violation reading ....
 >
 > This is a programmer's error. 'Vect_get_line_type()' assumes that the
 programmer first tested if the provided line id is indeed valid. You did
 call 'Vect_line_alive()' first, you can only proceed if the line is alive.
 Fix your code.

 For sure calling 'Vect_get_line_type()' with a wrong line id is a
 programmer error but 'Vect_get_line_type()' already call
 'Vect_line_alive()'.


 {{{
   258 int Vect_get_line_type(const struct Map_info *Map, int line)
   259 {
   260     check_level(Map);
   261
   262     if (!Vect_line_alive(Map, line))
   263         return 0;
   264
   265     return (Map->plus.Line[line]->type);
   266 }
 }}}

 Testing  if (!Vect_line_alive(Map, line)) is wrong because Vect_line_alive
 returns[[BR]]

 1 feature alive[[BR]]

 0 feature is dead[[BR]]

 -1 on error[[BR]]


 a small change ( if (Vect_line_alive(Map, line!=1)) may improve code
 robustness.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/2438#comment:2>
GRASS GIS <http://grass.osgeo.org>