Source: imgui Version: 1.79+ds-1 Severity: serious Hi,
I tried to build an application that uses imgui, but it crashes
with a "Floating point exception".
Then I tried to build the examples included in the libimgui-dev package
and noticed that they crash as well in the same function.
Steps to reproduce:
$ mkdir /tmp/imgui
$ cp
/usr/share/doc/libimgui-dev/examples/{example_null/main.cpp,imgui_impl_opengl3.*}
/tmp/imgui/
$ cd /tmp/imgui
$ g++ main.cpp imgui_impl_opengl3.cpp $(pkg-config imgui glew stb --cflags
--libs)
$ ./a.out
Floating point exception
$ gdb ./a.out
(gdb) run
Starting program: /tmp/imgui/a.out
Program received signal SIGFPE, Arithmetic exception.
0x00007ffff7e2773f in stbrp__skyline_find_best_pos (height=64, width=64,
c=0x55555560fbb0) at stb_rect_pack.c:350
350 stb_rect_pack.c: No such file or directory.
(gdb) bt
#0 0x00007ffff7e2773f in stbrp__skyline_find_best_pos (height=64, width=64,
c=0x55555560fbb0) at stb_rect_pack.c:350
#1 stbrp__skyline_pack_rectangle (height=64, width=65, context=0x55555560fbb0)
at stb_rect_pack.c:447
#2 stbrp_pack_rects (context=0x55555560fbb0, rects=0x55555560fde0,
num_rects=2) at stb_rect_pack.c:563
#3 0x0000555555596563 in ImFontAtlasBuildPackCustomRects(ImFontAtlas*, void*)
()
#4 0x00005555555999e8 in ImFontAtlasBuildWithStbTruetype(ImFontAtlas*) ()
#5 0x000055555559a53f in ImFontAtlas::GetTexDataAsAlpha8(unsigned char**,
int*, int*, int*) ()
#6 0x000055555559a5f5 in ImFontAtlas::GetTexDataAsRGBA32(unsigned char**,
int*, int*, int*) ()
#7 0x0000555555557e15 in main ()
(gdb) p *c
$1 = {
width = 511,
height = 32767,
align = 0,
init_mode = 0,
heuristic = 0,
num_nodes = 21845,
active_head = 0x211,
free_head = 0x7ffff7ab1be0 <main_arena+96>,
extra = {{
x = 7136,
y = 63403,
next = 0x0
}, {
x = 0,
y = 0,
next = 0x41077b4210bb410f
}}
}
stb_rect_pack.h from libstb-dev (0.0~git20200713.b42009b-1) contains the
function stbrp__skyline_find_best_pos:
static stbrp__findresult stbrp__skyline_find_best_pos(stbrp_context *c, int
width, int height)
{
...
width -= width % c->align;
As seen above in gdb, c->align is 0, so this line will cause a division by zero,
which triggers the exception.
I'm not sure if the problem is really in imgui which does not initialize the
stb context properly, or if it's a problem in libstb.
Kind regards,
Reiner
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