Suppress EOF errors when seeking empty result sets. (Velocidex#3593)

api/tables/table.go

@@ -147,7 +147,7 @@ func getTable(
 
 	// Seek to the row we need.
 	err = rs_reader.SeekToRow(int64(in.StartRow))
-	if err == io.EOF {
+	if errors.Is(err, io.EOF) {
 		return result, nil
 	}
 
@@ -207,7 +207,7 @@ func getStackTable(
 
 	// Seek to the row we need.
 	err = rs_reader.SeekToRow(int64(in.StartRow))
-	if err == io.EOF {
+	if errors.Is(err, io.EOF) {
 		return result, nil
 	}
 

artifacts/definitions/Server/Utils/CreateMSI.yaml

@@ -2,6 +2,13 @@ name: Server.Utils.CreateMSI
 description: |
   Build an MSI ready for deployment in the current org.
 
+  This artifact depends on the following tools:
+
+  * <velo-tool-viewer name="VelociraptorWindowsMSI" />
+  * <velo-tool-viewer name="VelociraptorWindows_x86MSI" />
+
+  You can replace those with suitable MSI builds.
+
 type: SERVER
 
 parameters:

artifacts/definitions/Windows/Memory/Acquisition.yaml

@@ -12,13 +12,18 @@ tools:
     github_asset_regex: winpmem_mini_x64.+exe
     serve_locally: true
 
-precondition: SELECT OS From info() where OS = 'windows' AND Architecture = "amd64"
+precondition: |
+  SELECT OS FROM info()
+  WHERE OS = 'windows'
+    AND Architecture = "amd64"
 
 sources:
   - query: |
+      LET Tempfile <= tempfile(extension=".raw")
+
       SELECT * FROM foreach(
           row={
-            SELECT OSPath, tempfile(extension=".raw", remove_last=TRUE) AS Tempfile
+            SELECT OSPath
             FROM Artifact.Generic.Utils.FetchBinary(ToolName="WinPmem64")
           },
           query={

result_sets/api.go

@@ -45,6 +45,7 @@ type TimedResultSetWriter interface {
 }
 
 type ResultSetReader interface {
+	// Returns EOF if the row does not exist in the result set.
 	SeekToRow(start int64) error
 	Rows(ctx context.Context) <-chan *ordereddict.Dict
 

services/hunt_dispatcher/flows.go

@@ -2,6 +2,8 @@ package hunt_dispatcher
 
 import (
 	"context"
+	"errors"
+	"io"
 	"time"
 
 	api_proto "www.velocidex.com/golang/velociraptor/api/proto"
@@ -133,6 +135,13 @@ func (self *HuntDispatcher) GetFlows(
 
 	// Seek to the row we need.
 	err = rs_reader.SeekToRow(int64(start))
+	if errors.Is(err, io.EOF) {
+		close(output_chan)
+		rs_reader.Close()
+
+		return output_chan, 0, nil
+	}
+
 	if err != nil {
 		close(output_chan)
 		rs_reader.Close()

services/hunt_dispatcher/storage.go

@@ -2,7 +2,9 @@ package hunt_dispatcher
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"io"
 	"os"
 	"sync"
 	"sync/atomic"
@@ -249,6 +251,10 @@ func (self *HuntStorageManagerImpl) ListHunts(
 	defer rs_reader.Close()
 
 	err = rs_reader.SeekToRow(offset)
+	if errors.Is(err, io.EOF) {
+		return nil, 0, nil
+	}
+
 	if err != nil {
 		return nil, 0, err
 	}

services/launcher/storage.go

@@ -3,6 +3,7 @@ package launcher
 import (
 	"context"
 	"fmt"
+	"io"
 	"os"
 
 	"github.com/Velocidex/ordereddict"
@@ -101,30 +102,37 @@ func (self *FlowStorageManager) ListFlows(
 		// Try to rebuild the index
 		err = self.buildFlowIndexFromLegacy(ctx, config_obj, client_id)
 		if err != nil {
-			return nil, 0, err
+			return nil, 0, fmt.Errorf("buildFlowIndexFromLegacy %w", err)
 		}
 
 		rs_reader, err = result_sets.NewResultSetReaderWithOptions(
 			ctx, config_obj, file_store_factory,
 			client_path_manager.FlowIndex(), options)
+		if err != nil {
+			return nil, 0, fmt.Errorf("NewResultSetReaderWithOptions %w", err)
+		}
 	}
 
 	if err != nil {
 		return nil, 0, err
 	}
 
+	result := []*services.FlowSummary{}
 	err = rs_reader.SeekToRow(offset)
+	if errors.Is(err, io.EOF) {
+		return result, 0, nil
+	}
+
 	if err != nil {
-		return nil, 0, err
+		return nil, 0, fmt.Errorf("SeekToRow %v %w", offset, err)
 	}
 
 	// Highly optimized reader for speed.
 	json_chan, err := rs_reader.JSON(ctx)
 	if err != nil {
-		return nil, 0, err
+		return nil, 0, fmt.Errorf("JSON %w", err)
 	}
 
-	result := []*services.FlowSummary{}
 	for serialized := range json_chan {
 		summary := &services.FlowSummary{}
 		err = json.Unmarshal(serialized, summary)

services/vfs_service/directory.go

@@ -3,6 +3,7 @@ package vfs_service
 import (
 	"context"
 	"errors"
+	"io"
 
 	"github.com/Velocidex/ordereddict"
 	"google.golang.org/protobuf/proto"
@@ -102,6 +103,10 @@ func renderDBVFS(
 	defer reader.Close()
 
 	err = reader.SeekToRow(int64(result.StartIdx))
+	if errors.Is(err, io.EOF) {
+		return nil, nil
+	}
+
 	if err != nil {
 		return nil, err
 	}

vql/server/flows/results.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 
 	"github.com/Velocidex/ordereddict"
 	"www.velocidex.com/golang/velociraptor/acls"
@@ -181,6 +182,10 @@ func (self SourcePlugin) Call(
 
 		if arg.StartRow > 0 {
 			err = result_set_reader.SeekToRow(arg.StartRow)
+			if errors.Is(err, io.EOF) {
+				return
+			}
+
 			if err != nil {
 				scope.Log("source: %v", err)
 				return