Add feature checking support to go-criu

This adds the feature checking interface with the same semantics as the
feature checking through libcriu.

Signed-off-by: Adrian Reber <[email protected]>

Author: adrianreber

Makefile

@@ -2,6 +2,11 @@ SHELL = /bin/bash
 GO ?= go
 CC ?= gcc
 COVERAGE_PATH ?= $(shell pwd)/.coverage
+CRIU_FEATURE_MEM_TRACK = $(shell if criu check --feature mem_dirty_track > /dev/null; then echo 1; else echo 0; fi)
+CRIU_FEATURE_LAZY_PAGES = $(shell if criu check --feature uffd-noncoop > /dev/null; then echo 1; else echo 0; fi)
+CRIU_FEATURE_PIDFD_STORE = $(shell if criu check --feature pidfd_store > /dev/null; then echo 1; else echo 0; fi)
+
+export CRIU_FEATURE_MEM_TRACK CRIU_FEATURE_LAZY_PAGES CRIU_FEATURE_PIDFD_STORE
 
 all: build test phaul-test
 

features.go

@@ -0,0 +1,45 @@
+package criu
+
+import (
+	"fmt"
+
+	"github.com/checkpoint-restore/go-criu/v5/rpc"
+)
+
+// Feature checking in go-criu is based on the libcriu feature checking function.
+
+// Feature checking allows the user to check if CRIU supports
+// certain features. There are CRIU features which do not depend
+// on the version of CRIU but on kernel features or architecture.
+//
+// One example is memory tracking. Memory tracking can be disabled
+// in the kernel or there are architectures which do not support
+// it (aarch64 for example). By using the feature check a libcriu
+// user can easily query CRIU if a certain feature is available.
+//
+// The features which should be checked can be marked in the
+// structure 'struct criu_feature_check'. Each structure member
+// that is set to true will result in CRIU checking for the
+// availability of that feature in the current combination of
+// CRIU/kernel/architecture.
+//
+// Available features will be set to true when the function
+// returns successfully. Missing features will be set to false.
+
+func (c *Criu) FeatureCheck(features *rpc.CriuFeatures) (*rpc.CriuFeatures, error) {
+	resp, err := c.doSwrkWithResp(
+		rpc.CriuReqType_FEATURE_CHECK,
+		nil,
+		nil,
+		features,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.GetType() != rpc.CriuReqType_FEATURE_CHECK {
+		return nil, fmt.Errorf("Unexpected CRIU RPC response")
+	}
+
+	return features, nil
+}

main.go

@@ -87,19 +87,19 @@ func (c *Criu) sendAndRecv(reqB []byte) ([]byte, int, error) {
 }
 
 func (c *Criu) doSwrk(reqType rpc.CriuReqType, opts *rpc.CriuOpts, nfy Notify) error {
-	resp, err := c.doSwrkWithResp(reqType, opts, nfy)
+	resp, err := c.doSwrkWithResp(reqType, opts, nfy, nil)
 	if err != nil {
 		return err
 	}
 	respType := resp.GetType()
 	if respType != reqType {
-		return errors.New("unexpected responce")
+		return errors.New("unexpected CRIU RPC response")
 	}
 
 	return nil
 }
 
-func (c *Criu) doSwrkWithResp(reqType rpc.CriuReqType, opts *rpc.CriuOpts, nfy Notify) (*rpc.CriuResp, error) {
+func (c *Criu) doSwrkWithResp(reqType rpc.CriuReqType, opts *rpc.CriuOpts, nfy Notify, features *rpc.CriuFeatures) (*rpc.CriuResp, error) {
 	var resp *rpc.CriuResp
 
 	req := rpc.CriuReq{
@@ -111,6 +111,10 @@ func (c *Criu) doSwrkWithResp(reqType rpc.CriuReqType, opts *rpc.CriuOpts, nfy N
 		opts.NotifyScripts = proto.Bool(true)
 	}
 
+	if features != nil {
+		req.Features = features
+	}
+
 	if c.swrkCmd == nil {
 		err := c.Prepare()
 		if err != nil {
@@ -209,7 +213,7 @@ func (c *Criu) StartPageServer(opts *rpc.CriuOpts) error {
 
 // StartPageServerChld starts the page server and returns PID and port
 func (c *Criu) StartPageServerChld(opts *rpc.CriuOpts) (int, int, error) {
-	resp, err := c.doSwrkWithResp(rpc.CriuReqType_PAGE_SERVER_CHLD, opts, nil)
+	resp, err := c.doSwrkWithResp(rpc.CriuReqType_PAGE_SERVER_CHLD, opts, nil, nil)
 	if err != nil {
 		return 0, 0, err
 	}
@@ -220,7 +224,7 @@ func (c *Criu) StartPageServerChld(opts *rpc.CriuOpts) (int, int, error) {
 // GetCriuVersion executes the VERSION RPC call and returns the version
 // as an integer. Major * 10000 + Minor * 100 + SubLevel
 func (c *Criu) GetCriuVersion() (int, error) {
-	resp, err := c.doSwrkWithResp(rpc.CriuReqType_VERSION, nil, nil)
+	resp, err := c.doSwrkWithResp(rpc.CriuReqType_VERSION, nil, nil, nil)
 	if err != nil {
 		return 0, err
 	}

test/main.go

@@ -58,6 +58,69 @@ func doDump(c *criu.Criu, pidS string, imgDir string, pre bool, prevImg string)
 	return nil
 }
 
+func featureCheck(c *criu.Criu) error {
+	features := &rpc.CriuFeatures{}
+	featuresToCompare := &rpc.CriuFeatures{}
+	env := os.Getenv("CRIU_FEATURE_MEM_TRACK")
+	if env != "" {
+		val, err := strconv.Atoi(env)
+		if err != nil {
+			return err
+		}
+		features.MemTrack = proto.Bool(val != 0)
+		featuresToCompare.MemTrack = proto.Bool(val != 0)
+	}
+	env = os.Getenv("CRIU_FEATURE_LAZY_PAGES")
+	if env != "" {
+		val, err := strconv.Atoi(env)
+		if err != nil {
+			return err
+		}
+		features.LazyPages = proto.Bool(val != 0)
+		featuresToCompare.LazyPages = proto.Bool(val != 0)
+	}
+	env = os.Getenv("CRIU_FEATURE_PIDFD_STORE")
+	if env != "" {
+		val, err := strconv.Atoi(env)
+		if err != nil {
+			return err
+		}
+		features.PidfdStore = proto.Bool(val != 0)
+		featuresToCompare.PidfdStore = proto.Bool(val != 0)
+	}
+
+	features, err := c.FeatureCheck(features)
+	if err != nil {
+		return err
+	}
+
+	if *features.MemTrack != *featuresToCompare.MemTrack {
+		return fmt.Errorf(
+			"Unexpected MemTrack FeatureCheck result %v:%v",
+			*features.MemTrack,
+			*featuresToCompare.MemTrack,
+		)
+	}
+
+	if *features.LazyPages != *featuresToCompare.LazyPages {
+		return fmt.Errorf(
+			"Unexpected LazyPages FeatureCheck result %v:%v",
+			*features.LazyPages,
+			*featuresToCompare.LazyPages,
+		)
+	}
+
+	if *features.PidfdStore != *featuresToCompare.PidfdStore {
+		return fmt.Errorf(
+			"Unexpected PidfdStore FeatureCheck result %v:%v",
+			*features.PidfdStore,
+			*featuresToCompare.PidfdStore,
+		)
+	}
+
+	return nil
+}
+
 // Usage: test $act $pid $images_dir
 func main() {
 	c := criu.MakeCriu()
@@ -76,6 +139,11 @@ func main() {
 	if !result {
 		log.Fatalln("CRIU version to old")
 	}
+
+	if err = featureCheck(c); err != nil {
+		log.Fatalln(err)
+	}
+
 	act := os.Args[1]
 	switch act {
 	case "dump":