sanitizer: avoid divide-by-zero instances

Merges pull request #1094, with some minor changes. mpv expects IEEE,
and IEEE allows divisions by 0 for floats, so these shouldn't actually
be a problem, but do it anyway for the sake of clang.

Signed-off-by: wm4 <wm4@nowhere>

player/lua.c

@@ -892,7 +892,7 @@ static int script_get_screen_size(lua_State *L)
     struct MPContext *mpctx = get_mpctx(L);
     struct mp_osd_res vo_res = osd_get_vo_res(mpctx->osd, OSDTYPE_EXTERNAL);
     double aspect = 1.0 * vo_res.w / MPMAX(vo_res.h, 1) /
-                    vo_res.display_par;
+                    (vo_res.display_par ? vo_res.display_par : 1);
     lua_pushnumber(L, vo_res.w);
     lua_pushnumber(L, vo_res.h);
     lua_pushnumber(L, aspect);
@@ -978,10 +978,10 @@ static int script_input_set_section_mouse_area(lua_State *L)
     osd_object_get_scale_factor(mpctx->osd, OSDTYPE_EXTERNAL, &sw, &sh);
 
     char *section = (char *)luaL_checkstring(L, 1);
-    int x0 = luaL_checkinteger(L, 2) / sw;
-    int y0 = luaL_checkinteger(L, 3) / sh;
-    int x1 = luaL_checkinteger(L, 4) / sw;
-    int y1 = luaL_checkinteger(L, 5) / sh;
+    int x0 = sw ? luaL_checkinteger(L, 2) / sw : 0;
+    int y0 = sh ? luaL_checkinteger(L, 3) / sh : 0;
+    int x1 = sw ? luaL_checkinteger(L, 4) / sw : 0;
+    int y1 = sh ? luaL_checkinteger(L, 5) / sh : 0;
     mp_input_set_section_mouse_area(mpctx->input, section, x0, y0, x1, y1);
     return 0;
 }

sub/osd.c

@@ -428,9 +428,11 @@ void osd_object_get_scale_factor(struct osd_state *osd, int obj,
     int nw, nh;
     osd_object_get_resolution(osd, obj, &nw, &nh);
     pthread_mutex_lock(&osd->lock);
-    *sw = nw / (double)osd->objs[obj]->vo_res.w;
-    *sh = nh / (double)osd->objs[obj]->vo_res.h;
+    int vow = osd->objs[obj]->vo_res.w;
+    int voh = osd->objs[obj]->vo_res.h;
     pthread_mutex_unlock(&osd->lock);
+    *sw = vow ? nw / (double)vow : 0;
+    *sh = voh ? nh / (double)voh : 0;
 }
 
 // Turn *x and *y, which are given in OSD coordinates, to video coordinates.

video/out/gl_video.c

@@ -573,7 +573,7 @@ static void update_uniforms(struct gl_video *p, GLuint program)
     }
 
     loc = gl->GetUniformLocation(program, "transform");
-    if (loc >= 0) {
+    if (loc >= 0 && p->vp_w > 0 && p->vp_h > 0) {
         float matrix[3][3];
         matrix_ortho2d(matrix, 0, p->vp_w, p->vp_h, 0);
         gl->UniformMatrix3fv(loc, 1, GL_FALSE, &matrix[0][0]);