Monorepo for Aesthetic.Computer
aesthetic.computer
feat: SDL3 crash recovery via sigsetjmp — no fork needed
Replace fork-based probe with signal handler + sigsetjmp/siglongjmp.
If Mesa DRI crashes during dlopen or SDL_Init, the SIGSEGV/SIGBUS
handler catches it, restores signal handlers, cleans up, and falls
back to DRM dumb buffers. No fork, no child process, no PID 1 issues.
Works as init (PID 1) and under systemd alike.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
+50
-41
+50
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fedac/native/src/drm-display.c
+50
-41
fedac/native/src/drm-display.c
···
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return 1;
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}
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// Probe SDL3 in a child process — catches segfaults from broken DRI/GBM/Mesa
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static int sdl_probe_safe(void) {
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pid_t pid = fork();
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if (pid < 0) return 0;
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if (pid == 0) {
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// Child: try full init. Crash = signal caught by parent.
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setenv("SDL_VIDEO_DRIVER", "kmsdrm", 0);
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setenv("LIBGL_DRIVERS_PATH", "/lib64/dri", 0);
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setenv("GBM_DRIVERS_PATH", "/lib64/dri", 0);
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setenv("MESA_LOADER_DRIVER_OVERRIDE", "iris", 0);
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void *lib = dlopen("libSDL3.so.0", RTLD_LAZY);
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if (!lib) _exit(2);
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pfn_SDL_Init fn_init = (pfn_SDL_Init)dlsym(lib, "SDL_Init");
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pfn_SDL_Quit fn_quit = (pfn_SDL_Quit)dlsym(lib, "SDL_Quit");
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if (!fn_init) _exit(3);
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int ok = fn_init(0x20) ? 0 : 1; // SDL_INIT_VIDEO = 0x20
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if (!ok && fn_quit) fn_quit();
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dlclose(lib);
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_exit(ok);
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}
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int status = 0;
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waitpid(pid, &status, 0);
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if (WIFSIGNALED(status)) {
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ac_log("[sdl3] Probe crashed (signal %d) — falling back to DRM\n", WTERMSIG(status));
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return 0;
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}
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if (WIFEXITED(status) && WEXITSTATUS(status) == 0) return 1;
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ac_log("[sdl3] Probe failed (exit %d) — falling back to DRM\n",
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WIFEXITED(status) ? WEXITSTATUS(status) : -1);
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return 0;
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// Signal-based crash recovery for SDL3 init (no fork needed)
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#include <setjmp.h>
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static sigjmp_buf sdl_crash_jmp;
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static volatile int sdl_crash_sig = 0;
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+
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static void sdl_crash_handler(int sig) {
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sdl_crash_sig = sig;
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siglongjmp(sdl_crash_jmp, 1);
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}
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static ACDisplay *sdl_init(void) {
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// Skip SDL when running as PID 1 (bare metal init) — the DRI/Mesa
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// probe can corrupt GPU state even in a child process, and fork()
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// from PID 1 has kernel implications. Use DRM dumb buffers instead.
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// SDL works fine when running under a proper init system (systemd, etc.)
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if (getpid() == 1) {
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ac_log("[sdl3] Skipping SDL3 (PID 1 — using DRM dumb buffers)\n");
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// Set Mesa env vars before any dlopen
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setenv("LIBGL_DRIVERS_PATH", "/lib64/dri", 0);
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setenv("GBM_DRIVERS_PATH", "/lib64/dri", 0);
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setenv("MESA_LOADER_DRIVER_OVERRIDE", "iris", 0);
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if (getpid() == 1) setenv("SDL_VIDEO_DRIVER", "kmsdrm", 0);
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+
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// Install crash handler — catches SIGSEGV/SIGBUS from Mesa DRI loading
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struct sigaction sa = {0}, old_segv = {0}, old_bus = {0}, old_abrt = {0};
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sa.sa_handler = sdl_crash_handler;
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sa.sa_flags = 0;
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sigemptyset(&sa.sa_mask);
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sigaction(SIGSEGV, &sa, &old_segv);
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sigaction(SIGBUS, &sa, &old_bus);
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sigaction(SIGABRT, &sa, &old_abrt);
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+
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if (sigsetjmp(sdl_crash_jmp, 1) != 0) {
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// Crashed during SDL init — restore handlers and fall back
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sigaction(SIGSEGV, &old_segv, NULL);
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sigaction(SIGBUS, &old_bus, NULL);
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sigaction(SIGABRT, &old_abrt, NULL);
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ac_log("[sdl3] Crashed (signal %d) during init — falling back to DRM\n", sdl_crash_sig);
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if (sdl_lib_handle) { dlclose(sdl_lib_handle); sdl_lib_handle = NULL; }
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memset(&sdl, 0, sizeof(sdl));
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return NULL;
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}
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// Probe in child process first (catches DRI segfaults)
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if (!sdl_probe_safe()) return NULL;
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// Load SDL3 via dlopen
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if (!sdl_load()) return NULL;
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setenv("SDL_VIDEO_DRIVER", "kmsdrm", 0);
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// Try loading SDL3 (dlopen may trigger Mesa DRI load → potential crash)
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if (!sdl_load()) {
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sigaction(SIGSEGV, &old_segv, NULL);
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sigaction(SIGBUS, &old_bus, NULL);
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sigaction(SIGABRT, &old_abrt, NULL);
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return NULL;
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}
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if (!sdl.Init(0x20)) { // SDL_INIT_VIDEO
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ac_log("[sdl3] SDL_Init failed: %s\n", sdl.GetError ? sdl.GetError() : "?");
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sigaction(SIGSEGV, &old_segv, NULL);
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sigaction(SIGBUS, &old_bus, NULL);
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sigaction(SIGABRT, &old_abrt, NULL);
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return NULL;
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}
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// Past the danger zone — restore handlers now
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sigaction(SIGSEGV, &old_segv, NULL);
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sigaction(SIGBUS, &old_bus, NULL);
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sigaction(SIGABRT, &old_abrt, NULL);
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unsigned int primary = sdl.GetPrimaryDisplay();
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if (!primary) {
···
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d->sdl_tex_h = 0;
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snprintf(d->sdl_renderer_name, sizeof(d->sdl_renderer_name), "%s",
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ren_name ? ren_name : "unknown");
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// Restore signal handlers — SDL init survived
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sigaction(SIGSEGV, &old_segv, NULL);
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sigaction(SIGBUS, &old_bus, NULL);
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sigaction(SIGABRT, &old_abrt, NULL);
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ac_log("[sdl3] Ready (%dx%d)\n", d->width, d->height);
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return d;