attempting to fix VM reboot bug(2)

tsvm_core/src/net/torvald/tsvm/UnsafePtr.kt

@@ -29,8 +29,10 @@ internal object UnsafeHelper {
         return UnsafePtr(ptr, size, caller)
     }
 
-    fun memcpy(src: UnsafePtr, fromIndex: Long, dest: UnsafePtr, toIndex: Long, copyLength: Long) =
+    fun memcpy(src: UnsafePtr, fromIndex: Long, dest: UnsafePtr, toIndex: Long, copyLength: Long) {
+        if (src.destroyed || dest.destroyed) return
         unsafe.copyMemory(src.ptr + fromIndex, dest.ptr + toIndex, copyLength)
+    }
     fun memcpy(srcAddress: Long, destAddress: Long, copyLength: Long) =
         unsafe.copyMemory(srcAddress, destAddress, copyLength)
     fun memcpyRaw(srcObj: Any?, srcPos: Long, destObj: Any?, destPos: Long, len: Long) =
@@ -84,81 +86,96 @@ internal class UnsafePtr(pointer: Long, allocSize: Long, private val caller: Any
         }
     }
 
-    private inline fun checkNullPtr(index: Long) { // ignore what IDEA says and do inline this
+    /**
-        //// commenting out because of the suspected (or minor?) performance impact.
+     * Returns true when the operation should proceed; false when the pointer is destroyed
-        //// You may break the glass and use this tool when some fucking incomprehensible bugs ("vittujen vitun bugit")
+     * (so the caller short-circuits to a safe no-op / zero return).
-        //// appear (e.g. getting garbage values when it fucking shouldn't)
+     *
-
+     * Why no exception: a JS worker thread that survives killVMenv (because it wasn't
-//        if (destroyed) { throw DanglingPointerException("The pointer is already destroyed ($this)") }
+     * tracked in vm.contexts, e.g. raw java.lang.Thread spawned by JS code) will keep
-//        if (index !in 0 until size) throw AddressOverflowException("Index: $index; alloc size: $size; pointer: ${this}\n${Thread.currentThread().stackTrace.joinToString("\n", limit=10) { "    $it" }}")
+     * poking peripheral memory for one or more iterations after dispose(). Letting it
+     * actually call unsafe.putByte on freed memory corrupts the malloc heap and crashes
+     * the JVM with `free_list_checksum_botch`. Returning quietly turns the race into a
+     * harmless no-op until the thread drains.
+     */
+    private inline fun aliveAt(index: Long): Boolean {
+        if (destroyed) return false
+        if (index < 0 || index >= size) return false
+        return true
     }
 
     operator fun get(index: Long): Byte {
-        checkNullPtr(index)
+        if (!aliveAt(index)) return 0
         return UnsafeHelper.unsafe.getByte(ptr + index)
     }
 
     operator fun set(index: Long, value: Byte) {
-        checkNullPtr(index)
+        if (!aliveAt(index)) return
         UnsafeHelper.unsafe.putByte(ptr + index, value)
     }
 
 
     fun getFloatFree(index: Long): Float {
-        checkNullPtr(index)
+        if (!aliveAt(index + 3)) return 0f
         return UnsafeHelper.unsafe.getFloat(ptr + index)
     }
     fun getFloat(unit: Long): Float {
-        checkNullPtr(unit * 4L)
+        val idx = unit * 4L
-        return UnsafeHelper.unsafe.getFloat(ptr + (unit * 4L))
+        if (!aliveAt(idx + 3)) return 0f
+        return UnsafeHelper.unsafe.getFloat(ptr + idx)
     }
 
     fun getIntFree(index: Long): Int {
-        checkNullPtr(index)
+        if (!aliveAt(index + 3)) return 0
         return UnsafeHelper.unsafe.getInt(ptr + index)
     }
     fun getInt(unit: Long): Int {
-        checkNullPtr(unit * 4L)
+        val idx = unit * 4L
-        return UnsafeHelper.unsafe.getInt(ptr + (unit * 4L))
+        if (!aliveAt(idx + 3)) return 0
+        return UnsafeHelper.unsafe.getInt(ptr + idx)
     }
 
     fun getShortFree(index: Long): Short {
-        checkNullPtr(index)
+        if (!aliveAt(index + 1)) return 0
         return UnsafeHelper.unsafe.getShort(ptr + index)
     }
     fun getShort(unit: Long): Short {
-        checkNullPtr(unit * 2L)
+        val idx = unit * 2L
-        return UnsafeHelper.unsafe.getShort(ptr + (unit * 2L))
+        if (!aliveAt(idx + 1)) return 0
+        return UnsafeHelper.unsafe.getShort(ptr + idx)
     }
 
     fun setFloatFree(index: Long, value: Float) {
-        checkNullPtr(index)
+        if (!aliveAt(index + 3)) return
         UnsafeHelper.unsafe.putFloat(ptr + index, value)
     }
     fun setFloat(unit: Long, value: Float) {
-        checkNullPtr(unit * 4L)
+        val idx = unit * 4L
-        UnsafeHelper.unsafe.putFloat(ptr + (unit * 4L), value)
+        if (!aliveAt(idx + 3)) return
+        UnsafeHelper.unsafe.putFloat(ptr + idx, value)
     }
 
     fun setIntFree(index: Long, value: Int) {
-        checkNullPtr(index)
+        if (!aliveAt(index + 3)) return
         UnsafeHelper.unsafe.putInt(ptr + index, value)
     }
     fun setInt(unit: Long, value: Int) {
-        checkNullPtr(unit * 4L)
+        val idx = unit * 4L
-        UnsafeHelper.unsafe.putInt(ptr + (unit * 4L), value)
+        if (!aliveAt(idx + 3)) return
+        UnsafeHelper.unsafe.putInt(ptr + idx, value)
     }
 
     fun setShortFree(index: Long, value: Short) {
-        checkNullPtr(index)
+        if (!aliveAt(index + 1)) return
         UnsafeHelper.unsafe.putShort(ptr + index, value)
     }
     fun setShortUnit(unit: Long, value: Short) {
-        checkNullPtr(unit * 2L)
+        val idx = unit * 2L
-        UnsafeHelper.unsafe.putShort(ptr + (unit * 2L), value)
+        if (!aliveAt(idx + 1)) return
+        UnsafeHelper.unsafe.putShort(ptr + idx, value)
     }
 
     fun fillWith(byte: Byte) {
+        if (destroyed) return
         UnsafeHelper.unsafe.setMemory(ptr, size, byte)
     }
 

tsvm_core/src/net/torvald/tsvm/VM.kt

@@ -333,6 +333,29 @@ class VM(
             try { it.join(500L) } catch (_: InterruptedException) { Thread.currentThread().interrupt() }
         }
         contexts.clear()
+
+        // Some JS code (e.g. TVDOS) spawns workers that aren't routed through Parallel.attachProgram,
+        // so they never land in `contexts`. We can still find them by walking the JVM thread set and
+        // matching the per-VM suffix that VMRunnerFactory uses for thread names ("…!<vmId>").
+        val suffix = "!${id.text}"
+        val all = arrayOfNulls<Thread>(Thread.activeCount() * 2)
+        val n = Thread.enumerate(all)
+        for (i in 0 until n) {
+            val t = all[i] ?: continue
+            if (t === Thread.currentThread()) continue
+            val name = t.name
+            if (name.endsWith(suffix) || name == "VmRunner:${id.text}") {
+                t.interrupt()
+            }
+        }
+        for (i in 0 until n) {
+            val t = all[i] ?: continue
+            if (t === Thread.currentThread()) continue
+            val name = t.name
+            if (name.endsWith(suffix) || name == "VmRunner:${id.text}") {
+                try { t.join(500L) } catch (_: InterruptedException) { Thread.currentThread().interrupt() }
+            }
+        }
     }
 
     /**

tsvm_core/src/net/torvald/tsvm/peripheral/CLCDDisplay.kt

@@ -45,6 +45,7 @@ class CLCDDisplay(assetsRoot: String, vm: VM) : GraphicsAdapter(assetsRoot, vm,
         shader: ShaderProgram?,
         uiFBO: FrameBuffer?
     ) {
+        if (disposed) return
         batch.shader = null
         batch.inUse {
             batch.color = Color.WHITE

tsvm_core/src/net/torvald/tsvm/peripheral/CharacterLCDdisplay.kt

@@ -40,6 +40,7 @@ class CharacterLCDdisplay(assetsRoot: String, vm: VM) : GraphicsAdapter(assetsRo
         shader: ShaderProgram?,
         uiFBO: FrameBuffer?
     ) {
+        if (disposed) return
         batch.shader = null
         batch.inUse {
             batch.color = Color.WHITE

tsvm_core/src/net/torvald/tsvm/peripheral/GraphicsAdapter.kt

@@ -942,7 +942,11 @@ open class GraphicsAdapter(private val assetsRoot: String, val vm: VM, val confi
         try { this.dispose() } catch (_: GdxRuntimeException) {} catch (_: IllegalArgumentException) {}
     }
 
+    @Volatile var disposed = false; private set
+
     override fun dispose() {
+        if (disposed) return
+        disposed = true
         //testTex.dispose()
 //        paletteShader.tryDispose()
 //        textShader.tryDispose()
@@ -986,6 +990,11 @@ open class GraphicsAdapter(private val assetsRoot: String, val vm: VM, val confi
     private val isRefSize = (WIDTH == 560 && HEIGHT == 448)
 
     open fun render(delta: Float, uiBatch: SpriteBatch, xoff: Float, yoff: Float, flipY: Boolean = false, shader: ShaderProgram? = null, uiFBO: FrameBuffer? = null) {
+        // Bail out if the adapter has already been torn down. Otherwise touching
+        // any of the disposed Pixmaps / Textures / native buffers below would
+        // raise a GdxRuntimeException or SIGSEGV.
+        if (disposed) return
+
         uiFBO?.end()