pkg/host: move machine info functionality from syz-fuzzer

It's better to keep functionality in packages rather than in main.
It makes it reusable and better organized.
Move machine info functionality to pkg/host and do some cosmetic refactoring.

pkg/host/machine_info.go

@@ -0,0 +1,34 @@
+// Copyright 2020 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 host
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"strings"
+)
+
+func CollectMachineInfo() ([]byte, error) {
+	buf := new(bytes.Buffer)
+	for _, pair := range machineInfoFuncs {
+		fmt.Fprintf(buf, "[%s]\n", pair.name)
+		err := pair.fn(buf)
+		if err != nil {
+			if !os.IsNotExist(err) {
+				return nil, err
+			}
+			fmt.Fprintf(buf, "%v\n", err)
+		}
+		fmt.Fprintf(buf, "%v\n\n", strings.Repeat("-", 80))
+	}
+	return buf.Bytes(), nil
+}
+
+var machineInfoFuncs []machineInfoFunc
+
+type machineInfoFunc struct {
+	name string
+	fn   func(*bytes.Buffer) error
+}

pkg/host/machine_info_linux.go

@@ -1,7 +1,7 @@
 // Copyright 2020 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 main
+package host
 
 import (
 	"bufio"
@@ -10,41 +10,14 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"runtime"
 	"strings"
 )
 
-func CollectMachineInfo() ([]byte, error) {
-	if runtime.GOOS != "linux" {
-		return nil, nil
-	}
-
-	type machineInfoFunc struct {
-		name string
-		fn   func(*bytes.Buffer) error
-	}
-
-	allMachineInfo := []machineInfoFunc{
+func init() {
+	machineInfoFuncs = []machineInfoFunc{
 		{"CPU Info", readCPUInfo},
 		{"KVM", readKVMInfo},
 	}
-
-	buffer := new(bytes.Buffer)
-
-	for _, pair := range allMachineInfo {
-		fmt.Fprintf(buffer, "[%s]\n", pair.name)
-		err := pair.fn(buffer)
-		if err != nil {
-			if os.IsNotExist(err) {
-				buffer.WriteString(err.Error() + "\n")
-			} else {
-				return nil, err
-			}
-		}
-		fmt.Fprintf(buffer, "-----------------------------------\n\n")
-	}
-
-	return buffer.Bytes(), nil
 }
 
 func readCPUInfo(buffer *bytes.Buffer) error {
@@ -143,7 +116,7 @@ func readKVMInfo(buffer *bytes.Buffer) error {
 			fmt.Fprintf(buffer, "\t%s: ", keyName)
 			buffer.Write(data)
 		}
-		buffer.WriteString("\n")
+		buffer.WriteByte('\n')
 	}
 	return nil
 }

pkg/host/machine_info_test.go

@@ -1,16 +1,20 @@
 // Copyright 2020 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 main
+package host
 
 import (
 	"bufio"
 	"bytes"
+	"runtime"
 	"strings"
 	"testing"
 )
 
 func TestMachineInfoLinux(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip()
+	}
 	result, err := CollectMachineInfo()
 	if err != nil {
 		t.Fatal(err)
@@ -116,7 +120,7 @@ D:	d
 	scanner := bufio.NewScanner(strings.NewReader(input))
 	buffer := new(bytes.Buffer)
 	scanCPUInfo(buffer, scanner)
-	result := bufio.NewScanner(strings.NewReader(buffer.String()))
+	result := bufio.NewScanner(buffer)
 
 	idx := 0
 	for result.Scan() {

syz-fuzzer/fuzzer.go

@@ -181,7 +181,7 @@ func main() {
 		runtime.MemProfileRate = 0
 	}
 
-	machineInfo, err := CollectMachineInfo()
+	machineInfo, err := host.CollectMachineInfo()
 	if err != nil {
 		log.Fatalf("failed to collect machine information: %v", err)
 	}