Initial implementation of stepping back on Windows

src/ctrl/ctrl_core.c

@@ -1056,6 +1056,21 @@ ctrl_stored_hash_from_process_vaddr_range(CTRL_MachineID machine_id, CTRL_Handle
   return result;
 }
 
+internal CTRL_Handle
+ctrl_thread_snapshot(CTRL_MachineID machine_id, CTRL_Handle thread)
+{
+  DEMON_Handle handle = ctrl_demon_handle_from_ctrl(thread);
+  DEMON_Handle snapshot_handle = demon_snapshot_thread(handle);
+  return ctrl_handle_from_demon(snapshot_handle);
+}
+
+internal void
+ctrl_snapshot_release(CTRL_MachineID machine_id, CTRL_Handle process)
+{
+  DEMON_Handle handle = ctrl_demon_handle_from_ctrl(process);
+  demon_snapshot_release(handle);
+}
+
 //- rjf: register reading/writing
 
 internal void *

src/ctrl/ctrl_core.h

@@ -564,6 +564,8 @@ internal String8 ctrl_query_cached_data_from_process_vaddr_range(Arena *arena, C
 internal String8 ctrl_query_cached_zero_terminated_data_from_process_vaddr_limit(Arena *arena, CTRL_MachineID machine_id, CTRL_Handle process, U64 vaddr, U64 limit, U64 endt_us);
 internal B32 ctrl_process_write_data(CTRL_MachineID machine_id, CTRL_Handle process, U64 vaddr, String8 data);
 internal U128 ctrl_stored_hash_from_process_vaddr_range(CTRL_MachineID machine_id, CTRL_Handle process, Rng1U64 range, B32 zero_terminated);
+internal CTRL_Handle ctrl_process_snapshot(CTRL_MachineID machine_id, CTRL_Handle thread);
+internal void ctrl_snapshot_release(CTRL_MachineID machine_id, CTRL_Handle snapshot);
 
 //- rjf: register reading/writing
 internal void *ctrl_reg_block_from_thread(CTRL_MachineID machine_id, CTRL_Handle thread);

src/demon/demon_common.h

@@ -15,6 +15,7 @@ typedef enum DEMON_EntityKind
   DEMON_EntityKind_Process,
   DEMON_EntityKind_Thread,
   DEMON_EntityKind_Module,
+  DEMON_EntityKind_Snapshot,
 
   DEMON_EntityKind_COUNT
 }

src/demon/demon_core.c

@@ -396,6 +396,35 @@ demon_detach_process(DEMON_Handle process){
   return(result);
 }
 
+internal DEMON_Handle
+demon_snapshot_thread(DEMON_Handle thread)
+{
+  DEMON_Handle result = 0;
+  if (demon_access_begin()){
+    DEMON_Entity *entity = demon_ent_ptr_from_handle(thread);
+    if (entity != 0 &&
+        entity->kind == DEMON_EntityKind_Thread){
+      result = demon_os_create_snapshot(entity);
+    }
+    demon_access_end();
+  }
+
+  return(result);
+}
+
+internal void
+demon_snapshot_release(DEMON_Handle snapshot)
+{
+  if (demon_access_begin()){
+    DEMON_Entity *entity = demon_ent_ptr_from_handle(snapshot);
+    if (entity != 0 &&
+        entity->kind == DEMON_EntityKind_Snapshot){
+      demon_os_snapshot_release(entity);
+    }
+    demon_access_end();
+  }
+}
+
 ////////////////////////////////
 //~ rjf: Entity Functions
 
@@ -646,7 +675,7 @@ demon_read_memory(DEMON_Handle process, void *dst, U64 src_address, U64 size){
   if (demon_access_begin()){
     DEMON_Entity *entity = demon_ent_ptr_from_handle(process);
     if (entity != 0 &&
-        entity->kind == DEMON_EntityKind_Process){
+        (entity->kind == DEMON_EntityKind_Process || entity->kind == DEMON_EntityKind_Snapshot)){
       bytes_read = demon_os_read_memory(entity, dst, src_address, size);
     }
     demon_access_end();

src/demon/demon_core.h

@@ -240,6 +240,8 @@ internal U32 demon_launch_process(OS_LaunchOptions *options);
 internal B32 demon_attach_process(U32 pid);
 internal B32 demon_kill_process(DEMON_Handle process, U32 exit_code);
 internal B32 demon_detach_process(DEMON_Handle process);
+internal DEMON_Handle demon_snapshot_thread(DEMON_Handle process);
+internal void demon_snapshot_release(DEMON_Handle snapshot);
 
 ////////////////////////////////
 //~ rjf: Entity Functions

src/demon/demon_os.h

@@ -54,6 +54,9 @@ internal B32 demon_os_attach_process(U32 pid);
 internal B32 demon_os_kill_process(DEMON_Entity *process, U32 exit_code);
 internal B32 demon_os_detach_process(DEMON_Entity *process);
 
+internal DEMON_Handle demon_os_create_snapshot(DEMON_Entity *thread);
+internal void         demon_os_snapshot_release(DEMON_Entity *entity);
+
 ////////////////////////////////
 //~ rjf: @demon_os_hooks Entity Functions
 

src/demon/linux/demon_os_linux.c

@@ -1757,6 +1757,20 @@ demon_os_detach_process(DEMON_Entity *process){
   return(0);
 }
 
+internal DEMON_Handle
+demon_os_create_snapshot(DEMON_Entity *thread)
+{
+  NotImplemented;
+  return(0);
+}
+
+internal void
+demon_os_snapshot_release(DEMON_Entity *entity)
+{
+  NotImplemented;
+  return(0);
+}
+
 ////////////////////////////////
 //~ rjf: @demon_os_hooks Entity Functions
 

src/demon/win32/demon_os_win32.c

@@ -1426,6 +1426,56 @@ demon_os_detach_process(DEMON_Entity *process){
   return(result);
 }
 
+internal DEMON_Handle
+demon_os_create_snapshot(DEMON_Entity *thread)
+{
+  DEMON_Entity *process = thread->parent;
+  DEMON_W32_Ext *ext = demon_w32_ext(process);
+  OS_Handle result = os_handle_zero();
+  HANDLE proc_all = OpenProcess(PROCESS_ALL_ACCESS, 0, GetProcessId(ext->proc.handle));
+  if (!proc_all) {
+    return 0;
+  }
+
+  HPSS snapshot = 0;
+  DWORD success = PssCaptureSnapshot(
+    proc_all,
+    PSS_CAPTURE_VA_CLONE,
+    0,
+    &snapshot
+  );
+
+  CloseHandle(proc_all);
+  if (success != ERROR_SUCCESS)
+  {
+    return 0;
+  }
+
+  PSS_VA_CLONE_INFORMATION info = {0};
+  success = PssQuerySnapshot(snapshot, PSS_QUERY_VA_CLONE_INFORMATION, &info, sizeof(info));
+  if (success != ERROR_SUCCESS)
+  {
+    PssFreeSnapshot(GetCurrentProcess(), snapshot);
+    return 0;
+  }
+
+  DEMON_W32_Ext *snapshot_ext = demon_w32_ext_alloc();
+  snapshot_ext->snapshot.handle = info.VaCloneHandle;
+  snapshot_ext->snapshot.snapshot_handle = snapshot;
+
+  DEMON_Entity *entity = demon_ent_new(thread, DEMON_EntityKind_Snapshot, GetProcessId(info.VaCloneHandle));
+  entity->ext = snapshot_ext;
+  return demon_ent_handle_from_ptr(entity);
+}
+
+internal void
+demon_os_snapshot_release(DEMON_Entity *entity)
+{
+  DEMON_W32_Ext *ext = demon_w32_ext(entity);
+  PssFreeSnapshot(GetCurrentProcess(), ext->snapshot.snapshot_handle);
+  demon_ent_release_root_and_children(entity);
+}
+
 ////////////////////////////////
 //~ rjf: @demon_os_hooks Entity Functions
 

src/demon/win32/demon_os_win32.h

@@ -44,6 +44,10 @@ union DEMON_W32_Ext
     B32 is_main;
     B32 name_is_unicode;
   } module;
+  struct {
+    HANDLE handle;
+    HPSS snapshot_handle;
+  } snapshot;
 };
 
 //- helpers