config: split and refactor

Introduce generic config.Load function that can be
reused across multiple programs (syz-manager, syz-gce, etc).
Move the generic config functionality to pkg/config package.
The idea is to move all helper (non-main) packages to pkg/ dir,
because we have more and more of them and they pollute the top dir.
Move the syz-manager config parts into syz-manager/config package.

2 files changed, 126 insertions, 0 deletions

diff --git a/pkg/config/config.go b/pkg/config/config.go
new file mode 100644
index 000000000..feb031c71
--- /dev/null
+++ b/pkg/config/config.go
@@ -0,0 +1,61 @@
+// Copyright 2017 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"reflect"
+	"strings"
+)
+
+func Load(filename string, cfg interface{}) error {
+	if filename == "" {
+		return fmt.Errorf("no config file specified")
+	}
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return fmt.Errorf("failed to read config file: %v", err)
+	}
+	return load(data, cfg)
+}
+
+func load(data []byte, cfg interface{}) error {
+	if err := checkUnknownFields(data, reflect.ValueOf(cfg).Type()); err != nil {
+		return err
+	}
+	if err := json.Unmarshal(data, cfg); err != nil {
+		return fmt.Errorf("failed to parse config file: %v", err)
+	}
+	return nil
+}
+
+func checkUnknownFields(data []byte, typ reflect.Type) error {
+	if typ.Kind() != reflect.Ptr {
+		return fmt.Errorf("config type is not pointer to struct")
+	}
+	typ = typ.Elem()
+	if typ.Kind() != reflect.Struct {
+		return fmt.Errorf("config type is not pointer to struct")
+	}
+	fields := make(map[string]bool)
+	for i := 0; i < typ.NumField(); i++ {
+		field := typ.Field(i)
+		if field.Tag.Get("json") == "-" {
+			continue
+		}
+		fields[strings.ToLower(field.Name)] = true
+	}
+	f := make(map[string]interface{})
+	if err := json.Unmarshal(data, &f); err != nil {
+		return fmt.Errorf("failed to parse config file: %v", err)
+	}
+	for k := range f {
+		if !fields[strings.ToLower(k)] {
+			return fmt.Errorf("unknown field '%v' in config", k)
+		}
+	}
+	return nil
+}
diff --git a/pkg/config/config_test.go b/pkg/config/config_test.go
new file mode 100644
index 000000000..73ad3502c
--- /dev/null
+++ b/pkg/config/config_test.go
@@ -0,0 +1,65 @@
+// Copyright 2016 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package config
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+func TestUnknown(t *testing.T) {
+	type Config struct {
+		Foo int
+		Bar string
+		Baz string `json:"-"`
+	}
+	tests := []struct {
+		input  string
+		output Config
+		err    string
+	}{
+		{
+			`{"foo": 42}`,
+			Config{
+				Foo: 42,
+			},
+			"",
+		},
+		{
+			`{"BAR": "Baz", "foo": 42}`,
+			Config{
+				Foo: 42,
+				Bar: "Baz",
+			},
+			"",
+		},
+		{
+			`{"foobar": 42}`,
+			Config{},
+			"unknown field 'foobar' in config",
+		},
+		{
+			`{"foo": 1, "baz": "baz", "bar": "bar"}`,
+			Config{},
+			"unknown field 'baz' in config",
+		},
+	}
+	for i, test := range tests {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			var cfg Config
+			err := load([]byte(test.input), &cfg)
+			errStr := ""
+			if err != nil {
+				errStr = err.Error()
+			}
+			if test.err != errStr {
+				t.Fatalf("bad err: want '%v', got '%v'", test.err, errStr)
+			}
+			if !reflect.DeepEqual(test.output, cfg) {
+				t.Fatalf("bad output: want '%#v', got '%#v'", test.output, cfg)
+			}
+		})
+	}
+}