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fix(linux): guard XRandR NULL returns to avoid a SEGV during display setup #5644

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fix(linux): guard XRandR NULL returns to avoid a SEGV during display setup #5644

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14 changes: 13 additions & 1 deletion src/platform/linux/x11grab.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -513,6 +513,10 @@ namespace platf {
}

screen_res_t screenr {x11::rr::GetScreenResources(xdisplay.get(), xwindow)};
if (!screenr) {
BOOST_LOG(error) << "Could not query X screen resources"sv;
return -1;
}
int output = screenr->noutput;

output_info_t result;
Expand All @@ -531,8 +535,12 @@ namespace platf {
}
}

crtc_info_t crt_info;
if (result_found && result->crtc) {
crtc_info_t crt_info {x11::rr::GetCrtcInfo(xdisplay.get(), screenr.get(), result->crtc)};
crt_info = crtc_info_t {x11::rr::GetCrtcInfo(xdisplay.get(), screenr.get(), result->crtc)};
}

if (crt_info) {

@ReenigneArcher ReenigneArcher Sep 29, 2026

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[P1] A transient null XRRGetCrtcInfo result for a successfully matched, selected monitor now takes the existing whole-desktop branch and returns success. Both X11 capture paths then use xattr.width/height from the root window, so a stream configured for one monitor can show every monitor for the lifetime of that capture object. Please fail initialization for this lookup error (as the screen-resources guard does) so the existing display reset/retry path can recover without changing the captured area.

BOOST_LOG(info)
<< "Streaming display: "sv << result->name << " with res "sv << crt_info->width << 'x' << crt_info->height << " offset by "sv << crt_info->x << 'x' << crt_info->y;

Expand Down Expand Up @@ -942,6 +950,10 @@ namespace platf {

auto xwindow = DefaultRootWindow(xdisplay.get());
screen_res_t screenr {x11::rr::GetScreenResources(xdisplay.get(), xwindow)};
if (!screenr) {
BOOST_LOG(error) << "Could not query X screen resources"sv;
return {};

@ReenigneArcher ReenigneArcher Sep 29, 2026

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[P2] If XRRGetScreenResources is transiently null during startup, returning an empty list makes verify_x11() false. platf::init() performs that backend probe once and leaves sources[source::X11] unset, so a later healthy RandR state cannot be retried by a stream; Sunshine needs a restart to use X11. Please retry the transient discovery failure or provide a path to re-probe X11 availability.

}
int output = screenr->noutput;

std::vector<std::string> names;
Expand Down