[GRASS-dev] Re: [GRASS GIS] #783: r.watershed fails on wingrass

[GRASS GIS]

#783: r.watershed fails on wingrass
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  Reporter:  hamish        |       Owner:  grass-dev at lists.osgeo.org
      Type:  defect        |      Status:  new                      
  Priority:  major         |   Milestone:  6.4.0                    
 Component:  Raster        |     Version:  6.4.0 RCs                
Resolution:                |    Keywords:  r.watershed, wingrass    
  Platform:  MSWindows XP  |         Cpu:  x86-32                   
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Comment (by glynn):

 Replying to [comment:12 hamish]:

 > > and without Administrator privileges you may be unable to
 > > install GRASS in a directory which doesn't contain spaces.
 >
 > Can you install to your Windows home dir or desktop anyway?

 You ought to be able to create files in that directory, although the
 administrator could have added an ACL which prohibits execution (although
 I'm not all that sure what "execute" permission really means on Windows).

 If you're a member of the "Power Users" group, you can also create files
 in the "Program Files" (etc) directory.

 But both of those have spaces in the name; Microsoft may have even done
 this intentionally to force developers to handle spaces in pathnames. The
 only standard directory which doesn't have spaces in the name is the
 "Windows" directory, and we shouldn't be putting anything there even if we
 could.

 > note that MSys devs do not seem interested in accepting patches which
 allow it to work in directories containing spaces, so it may be a long
 wait until this is more than an academic issue.

 Where does MSys' come into this?

 We're talking about one binary executable invoking another via system() or
 G_system() (which uses cmd.exe on Windows). MSys doesn't have any effect
 upon this even if it's installed.

 > > In short, I could not find a way to make it work with quotes on
 > > windows (BTW, neither osgeo4w nor mingw-w64 with XP 64bit).
 >
 > the easiest and least invasive solution seems to me to just replace
 system("") with G_spawn($0, **list).

 I can't guarantee that G_spawn() works correctly on Windows; I suspect
 that it still needs more testing (with usable feedback) than it has
 received so far.

 I note that Microsoft's documentation for the _spawn* functions says that
 the caller is supposed to quote arguments (which isn't happening at
 present), but I don't think that applies to the executable name.

 In any case, G_spawn() only offers a _spawnl() interface, while
 r.watershed would need a _spawnv() interface, as the argument list can
 vary at run-time. Using G_vspawn_ex() might be a solution.

 In any case, I don't doubt that it is possible to make it work using
 system(); it just needs someone who cares enough about getting 6.4 working
 on Windows to spend more time on it.

 One of the first Google hits for "windows command syntax" suggests that
 two "levels" of quotes are required:
 {{{
 CMD /k ""c:\batch files\test.cmd" "Parameter 1 with space" "Parameter2
 with space""
 }}}

 Brief testing from the command line confirms this. I suggest trying this
 with both system() and G_system(); if the two don't match, then G_system()
 needs to add the outermost quotes itself.

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/783#comment:13>
GRASS GIS <http://grass.osgeo.org>