vm: overhaul

VM infrastructure currently has several problems:
 - Config struct is complete mess with a superset of params for all VM types
 - verification of Config is mess spread across several places
 - there is no place where VM code could do global initialization
   like creating GCE connection, uploading GCE image to GCS,
   matching adb devices with consoles, etc
 - it hard to add private VM implementations
   such impl would need to add code to config package
   which would lead to constant merge conflicts
 - interface for VM implementation is mixed with interface for VM users
   this does not allow to provide best interface for both of them
 - there is no way to add common code for all VM implementations

This change solves these problems by:
 - splitting VM interface for users (vm package) and VM interface
   for VM implementations (vmimpl pacakge), this in turn allows
   to add common code
 - adding Pool concept that allows to do global initialization
   and config checking at the right time
 - decoupling manager config from VM-specific config
   each VM type now defines own config

Note: manager configs need to be changed after this change:
VM-specific parts are moved to own "vm" subobject.

Note: this change also drops "local" VM type.
Its story was long unclear and there is now syz-stress which solves the same problem.

3 files changed, 42 insertions, 7 deletions

diff --git a/pkg/config/config.go b/pkg/config/config.go
index 461ebdabc..03d4b283e 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -11,7 +11,7 @@ import (
 	"strings"
 )
 
-func Load(filename string, cfg interface{}) error {
+func LoadFile(filename string, cfg interface{}) error {
 	if filename == "" {
 		return fmt.Errorf("no config file specified")
 	}
@@ -19,10 +19,10 @@ func Load(filename string, cfg interface{}) error {
 	if err != nil {
 		return fmt.Errorf("failed to read config file: %v", err)
 	}
-	return load(data, cfg)
+	return LoadData(data, cfg)
 }
 
-func load(data []byte, cfg interface{}) error {
+func LoadData(data []byte, cfg interface{}) error {
 	if err := checkUnknownFields(data, reflect.ValueOf(cfg).Type()); err != nil {
 		return err
 	}
diff --git a/pkg/config/config_test.go b/pkg/config/config_test.go
index e36dd9ee9..79836f39e 100644
--- a/pkg/config/config_test.go
+++ b/pkg/config/config_test.go
@@ -161,7 +161,7 @@ func TestLoad(t *testing.T) {
 	for i, test := range tests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {
 			var cfg Config
-			err := load([]byte(test.input), &cfg)
+			err := LoadData([]byte(test.input), &cfg)
 			errStr := ""
 			if err != nil {
 				errStr = err.Error()
@@ -178,15 +178,15 @@ func TestLoad(t *testing.T) {
 
 func TestLoadBadType(t *testing.T) {
 	want := "config type is not pointer to struct"
-	if err := load([]byte("{}"), 1); err == nil || err.Error() != want {
+	if err := LoadData([]byte("{}"), 1); err == nil || err.Error() != want {
 		t.Fatalf("got '%v', want '%v'", err, want)
 	}
 	i := 0
-	if err := load([]byte("{}"), &i); err == nil || err.Error() != want {
+	if err := LoadData([]byte("{}"), &i); err == nil || err.Error() != want {
 		t.Fatalf("got '%v', want '%v'", err, want)
 	}
 	s := struct{}{}
-	if err := load([]byte("{}"), s); err == nil || err.Error() != want {
+	if err := LoadData([]byte("{}"), s); err == nil || err.Error() != want {
 		t.Fatalf("got '%v', want '%v'", err, want)
 	}
 }
diff --git a/pkg/osutil/osutil.go b/pkg/osutil/osutil.go
index 0bd4cdfac..3f42dbc12 100644
--- a/pkg/osutil/osutil.go
+++ b/pkg/osutil/osutil.go
@@ -6,7 +6,11 @@ package osutil
 import (
 	"bytes"
 	"fmt"
+	"io"
+	"os"
 	"os/exec"
+	"path/filepath"
+	"syscall"
 	"time"
 )
 
@@ -34,3 +38,34 @@ func RunCmd(timeout time.Duration, dir, bin string, args ...string) ([]byte, err
 	}
 	return output.Bytes(), nil
 }
+
+func LongPipe() (io.ReadCloser, io.WriteCloser, error) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to create pipe: %v", err)
+	}
+	for sz := 128 << 10; sz <= 2<<20; sz *= 2 {
+		syscall.Syscall(syscall.SYS_FCNTL, w.Fd(), syscall.F_SETPIPE_SZ, uintptr(sz))
+	}
+	return r, w, err
+}
+
+var wd string
+
+func init() {
+	var err error
+	wd, err = os.Getwd()
+	if err != nil {
+		panic(fmt.Sprintf("failed to get wd: %v", err))
+	}
+}
+
+func Abs(path string) string {
+	if wd1, err := os.Getwd(); err == nil && wd1 != wd {
+		panic("don't mess with wd in a concurrent program")
+	}
+	if path == "" || filepath.IsAbs(path) {
+		return path
+	}
+	return filepath.Join(wd, path)
+}