[postgis-users] Postgis on Solaris - gdb details

[strk at refractions.net]

On Wed, Feb 09, 2005 at 07:07:53PM -0800, Ionut Iordache wrote:
> Hello,
> 
> I found a more specific reason why my installation crashes:
> 
> Following is an excerpt from running gdb against the backend and
> breaking at a point close to where it crashes after executing " select
> X(geom) from gtest;":
> 
> ----------------------------------------------------------------------
> Breakpoint 2, LWGEOM_x_point (fcinfo=0xffbed600) at lwgeom_ogc.c:528
> 528             if ( point == NULL ) PG_RETURN_NULL();
> (gdb) print point
> $1 = (LWPOINT *) 0x37f188
> (gdb) print point->point
> $2 = (POINTARRAY *) 0x37f248
> (gdb) print point->point->dims
> $3 = 0 '\0'
> (gdb) print point->point->npoints
> $4 = 1
> (gdb) n
> 531             p = (POINT2D *)getPoint(point->point, 0);
> (gdb) print p
> Cannot access memory at address 0xfffffff0
> (gdb) n
> 533             PG_RETURN_FLOAT8(p->x);
> (gdb) n
> 
> Program received signal SIGSEGV, Segmentation fault.
> LWGEOM_x_point (fcinfo=0xffbed600) at lwgeom_ogc.c:533
> 533             PG_RETURN_FLOAT8(p->x);
> (gdb) 
> ------------------------------------------------------------------
> 
> My understanding is that the POINTARRAY structure passed to the "getPoint"
> function is somehow invalid... One obvious thing that I noticed (and I
> might be way off track here, it's my first time reading through this
> code...) is that the dimension is always 0, where this is noted in
> the source files:
> 
> /size of point represeneted in the POINTARRAY
> // 16 for 2d, 24 for 3d, 32 for 4d
> int
> pointArray_ptsize(const POINTARRAY *pa)
> {
>         return sizeof(double)*TYPE_NDIMS(pa->dims);
> }
> 
> I also tested with LINESTRING and pointArray_ptsize will always return
> 0 here...
> 

POINTARRAY.dims is used as a bitfield for hasZ and hasM flags. 0==2d.
Can you print value of pa->serialized_pointlist ?
Return from getPoint should be an offset from there
(+16*pointN for a 2d ptarray, same address X)
--strk;


> 
> Any help is greatly appreciated!
> 
> 
> Tuesday, February 8, 2005, 2:40:23 PM, you wrote:
> 
> II> Hello,
> 
> II> I've been having problems for a while with Postgis on Solaris 8
> II> (sparc). I have tried various combinations of Postgresql 8.0.1, 7.4.6
> II> with Postgis versions 0.9.1 and up.
> II> The problem is that after the packages compile relatively without
> II> hassle, I can't use any postgis spatial function without crashing the
> II> database.
> II> For example, I create an empty database, add the lwpostgis.sql
> II> extension, create a spatial table with point geometry, insert one row
> II> into the table... up to this point everything is fine... when I run
> II> "select astext(geom) ..." the point shows up correctly, but when I
> II> execute "select X(geom) ..." the backend crashes:
> 
> 
> II> server closed the connection unexpectedly
> II>          This probably means the server terminated abnormally
> II>          before or while processing the request.
> II> The connection to the server was lost. Attempting reset: Failed
> 
> 
> II> I compiled with LDFLAGS="-lstdc++ -lgcc" and gcc  3.4.1.
> II> My gcc installation is configured as follows:
> II> Reading specs from
> II> /a/perry/data/pkgs3/local/bin/../lib/gcc/sparc-sun-solaris2.8/3.4.1/specs
> II> Configured with: ../configure --with-as=/usr/ccs/bin/as
> II> --with-ld=/usr/ccs/bin/ld --disable-nls
> II> Thread model: posix
> II> gcc version 3.4.1
> 
> II> The compiler uses Sun's linker and I was wondering if this is part of
> II> the problem... When I try to compile with GNU's ld, I get a
> II> "option -dn and -P are incompatible" linker error.
> 
> II> The logs are not showing anything interesting, even with the highest
> II> debug option set...
> II> I also tried to debug the backend, but I get this error in gdb:
> II>   Reading symbols from /usr/local/lib/libstdc++.so.6...Error
> II> while reading shared library symbols:
> II>   Dwarf Error: Cannot handle DW_FORM_strp in DWARF reader.
> 
> 
> 
> II> So, is anyone else using lwgeom Postgis on Solaris 8? Did you compile
> II> gcc from scratch, or used the binaries from sunfreeware.com ?
> II> Any ideas of what might go wrong with my installation?
> 
> 
> II> Many thanks,
> II> -----------------------------------------------
> II> Dorel Ionut Iordache - <ionut at eps.berkeley.edu>
> II> UC Berkeley - Earth & Planetary Science Dept.
> 
> II> _______________________________________________
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> II> postgis-users at postgis.refractions.net
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> 
> 
> 
> -- 
> Best regards,
> -----------------------------------------------
> Dorel Ionut Iordache - <ionut at eps.berkeley.edu>
> UC Berkeley - Earth & Planetary Science Dept.
> 
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