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Backport D2's Dont_start_sound_objects to D1

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Descent 2 has a hack, present as far back as I can trace, that
suppresses starting sounds during level load.  The original reason was
not recorded, but this hack has the useful side effect that it avoids
using uninitialized data when set_sound_sources tries to use a Viewer
that has not been reset for the objects of the new level.

Descent 1 lacks this hack, so an invalid Viewer is used, which may
trigger a valptridx trap if the undefined data has an invalid segment
number, and could cause memory corruption in builds which do not
validate the segment index.  The valptridx trap:

```
terminate called after throwing an instance of 'valptridx<dcx::segment>::index_range_exception'
  what():  similar/main/digiobj.cpp:389: invalid index used in array subscript: base=(nil) size=9000 index=65021
```

The backtrace leading to the trap:
```
d1x::digi_link_sound_common (viewer=..., so=..., pos=..., forever=<optimized out>, max_volume=<optimized out>, max_distance=..., soundnum=42, segnum=...) at similar/main/digiobj.cpp:389
0x00005555555a4e2d in d1x::digi_link_sound_to_pos2 (vcobjptr=..., max_distance=..., max_volume=32768, forever=1, pos=..., sidenum=4, segnum=..., org_soundnum=121) at similar/main/digiobj.cpp:483
d1x::digi_link_sound_to_pos (soundnum=soundnum@entry=121, segnum=..., sidenum=sidenum@entry=4, pos=..., forever=forever@entry=1, max_volume=32768) at similar/main/digiobj.cpp:490
0x00005555555c140d in d1x::set_sound_sources (vcsegptridx=..., vcvertptr=...) at similar/main/gameseq.cpp:817
d1x::LoadLevel (level_num=<optimized out>, page_in_textures=1) at similar/main/gameseq.cpp:1022
0x00005555555c2654 in d1x::StartNewLevelSub (level_num=-1, page_in_textures=<optimized out>) at similar/main/gameseq.cpp:1865
```

Backport this hack into Descent 1.  Ultimately, the hack should go away
and data should be loaded in an order that does not access undefined
memory.

Reported-by: Spacecpp <https://github.com/dxx-rebirth/dxx-rebirth/issues/463>
This commit is contained in:
Kp 2019-10-26 23:13:14 +00:00
parent 2cf0085b1d
commit d2640462cb
3 changed files with 2 additions and 12 deletions
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3
common/main/digi.h
View file

@ -138,9 +138,8 @@ extern void digi_start_sound_queued( short soundnum, fix volume );
extern int digi_volume;
#if defined(DXX_BUILD_DESCENT_I)
extern int digi_sample_rate;
#elif defined(DXX_BUILD_DESCENT_II)
extern int Dont_start_sound_objects;
#endif
extern int Dont_start_sound_objects;
extern int SoundQ_channel;
void digi_select_system();

6
similar/main/digiobj.cpp
View file

@ -333,10 +333,8 @@ static void digi_unpause_looping_sound()
digi_play_sample_looping_sub();
}
#if defined(DXX_BUILD_DESCENT_II)
//hack to not start object when loading level
int Dont_start_sound_objects = 0;
#endif
static void digi_start_sound_object(sound_object &s)
{
@ -346,10 +344,8 @@ static void digi_start_sound_object(sound_object &s)
if ( s.volume <= 0 )
return;
#if defined(DXX_BUILD_DESCENT_II)
if ( Dont_start_sound_objects )
return;
#endif
// only use up to half the sound channels for "permanent" sounts
if ((s.flags & SOF_PERMANENT) && (N_active_sound_objects >= max(1, digi_max_channels / 4)))
@ -378,13 +374,11 @@ static void digi_link_sound_common(const object_base &viewer, sound_object &so,
so.max_distance = max_distance;
so.volume = 0;
so.pan = 0;
#if defined(DXX_BUILD_DESCENT_II)
if (Dont_start_sound_objects) { //started at level start
so.flags |= SOF_PERMANENT;
so.channel = -1;
}
else
#endif
{
digi_get_sound_loc(viewer.orient, viewer.pos, segnum.absolute_sibling(viewer.segnum),
pos, segnum, so.max_volume,

5
similar/main/gameseq.cpp
View file

@ -760,8 +760,8 @@ static void set_sound_sources(fvcsegptridx &vcsegptridx, fvcvertptr &vcvertptr)
#if defined(DXX_BUILD_DESCENT_II)
auto &Walls = LevelUniqueWallSubsystemState.Walls;
auto &vcwallptr = Walls.vcptr;
Dont_start_sound_objects = 1;
#endif
Dont_start_sound_objects = 1;
const auto get_eclip_for_tmap = [](const d_level_unique_tmap_info_state::TmapInfo_array &TmapInfo, const unique_side &side) {
if (const auto tm2 = side.tmap_num2)
@ -819,10 +819,7 @@ static void set_sound_sources(fvcsegptridx &vcsegptridx, fvcvertptr &vcvertptr)
}
}
}
#if defined(DXX_BUILD_DESCENT_II)
Dont_start_sound_objects = 0;
#endif
}
constexpr fix flash_dist=fl2f(.9);