Crash when reverting a file with SVG fonts

[jazzynico]

Reproduced on Windows XP, Inkscape trunk rev. 13823 and 0.91.x rev. 13690.
Not reproduced with 0.48.5.

Steps:
1. Open the attached file (twice, due to Bug #1406540).
2. Open the SVG font editor (Text>SVG Font Editor).
3. Click on the font name in the Global settings tab.
4. Draw an object (let's say a simple square).
5. Use File>Revert
-> Crash

GDB trace (well, on Windows...):
Program received signal SIGSEGV, Segmentation fault.
0x68614dad in g_utf8_get_char () from d:\dev\inkscape-0.91.x-13690\inkscape\libglib-2.0-0.dll
(gdb) bt
#0 0x68614dad in g_utf8_get_char () from d:\dev\inkscape-0.91.x-13690\inkscape\libglib-2.0-0.dll
#1 0x0051e95d in size_of_substring(char const*, char*) ()
#2 0x00000000 in ?? ()

Inkscape also crashes if you first draw the object and revert, and then use the SVG font editor, but with a different trace (segfault in __dynamic_cast ()).

[jazzynico (jazzynico)]

Also reproduced on Crunchbang Waldorf,trunk rev. 13829.

[su_v (suv-lp)]

Crash based on original steps (use SVG font editor first (select an entry), then draw object and revert) not reproduced on OS X 10.7.5 with Inkscape 0.91+devel r13829.

Crash based on second steps (first draw the object and revert, and then use the SVG font editor) not reproduced on OS X 10.7.5 with Inkscape 0.91+devel r13829.

[jazzynico (jazzynico)]

Sometimes an additional step is needed to reproduce the crash:
6. Resize the Inkscape application window.

[su_v (suv-lp)]

On 2015-01-03 08:23 (+0100), jazzynico wrote:
> Sometimes an additional step is needed to reproduce the crash:
> 6. Resize the Inkscape application window.

Confirmed: crash on window resize after the revert is reproducible on OS X too.

[su_v (suv-lp)]

Reproduced at least once with a stable 0.48.x build too (backtrace of a crash after toggling maximized window state on and off with Inkscape 0.48.4 attached).

I haven't found the actual trigger - it seems too random to reproduce. The same applies for tests with archived builds: results are not consistent, but the crash reproduced at least once with the oldest trunk build I have available on this computer (r10795).

[jazzynico (jazzynico)]

Crash reproduced again on Windows 7, lp:inkscape/0.92.x rev. 15074.

[jazzynico (jazzynico)]

Lowering importance. The crash only occurs in very specific circumstances and doesn't lead to loss of data.