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Any attempt to read Cairo.Context.FontMatrix on OSX Lion throws a SEGV like the following:
0 mono 0x000b6ea9 mono + 745129
1 mono 0x00006e0e mono + 24078
2 libsystem_c.dylib 0x949e259b _sigtramp + 43
3 ??? 0xffffffff 0x0 + 4294967295
4 mono 0x000b4e32 mono + 736818
5 mono 0x000b7ac4 mono + 748228
6 mono 0x000b8e18 mono + 753176
7 mono 0x00107a02 mono + 1075714
8 ??? 0x0035e2c1 0x0 + 3531457
9 ??? 0x003d9a18 0x0 + 4037144
10 ??? 0x0a20deb0 0x0 + 169926320
Debug info from gdb:
/tmp/mono-gdb-commands.ulVxAb:1: Error in sourced command file:
unable to debug self
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
I dont know the mono codebase very well, but from my brief poking at it, my ignorant suspicion is that cairo_font_get_matrix expects to have a pointer to a block of memory to put the resulting matrix as iust second parameter, but the binding is just passing an unitialized object reference. My guess is that this results in it trying to write the matrix to wherever in memory a .NET "null" maps to (address 0?)
The call is correct, since the parameter is passed with the "out" modifier, which passes a pointer to the stack variable "Matrix m".
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