sys/syz-extract: refactor main

main is too long and complex. Move more logic into helper functions.

Update #538

sys/syz-extract/extract.go

@@ -74,56 +74,25 @@ func main() {
 		failf("-build and -builddir is an invalid combination")
 	}
 
-	osStr, archArray, files, err := archFileList(*flagOS, *flagArch, flag.Args())
+	OS, archArray, files, err := archFileList(*flagOS, *flagArch, flag.Args())
 	if err != nil {
 		failf("%v", err)
 	}
 
-	extractor := extractors[osStr]
+	extractor := extractors[OS]
 	if extractor == nil {
-		failf("unknown os: %v", osStr)
+		failf("unknown os: %v", OS)
 	}
 	if err := extractor.prepare(*flagSourceDir, *flagBuild, archArray); err != nil {
 		failf("%v", err)
 	}
 
+	arches, err := createArches(OS, archArray, files)
+	if err != nil {
+		failf("%v", err)
+	}
 	jobC := make(chan interface{}, len(archArray)*len(files))
-
-	var arches []*Arch
-	for _, archStr := range archArray {
-		buildDir := ""
-		if *flagBuild {
-			dir, err := ioutil.TempDir("", "syzkaller-kernel-build")
-			if err != nil {
-				failf("failed to create temp dir: %v", err)
-			}
-			buildDir = dir
-		} else if *flagBuildDir != "" {
-			buildDir = *flagBuildDir
-		} else {
-			buildDir = *flagSourceDir
-		}
-
-		target := targets.Get(osStr, archStr)
-		if target == nil {
-			failf("unknown arch: %v", archStr)
-		}
-
-		arch := &Arch{
-			target:    target,
-			sourceDir: *flagSourceDir,
-			buildDir:  buildDir,
-			build:     *flagBuild,
-			done:      make(chan bool),
-		}
-		for _, f := range files {
-			arch.files = append(arch.files, &File{
-				arch: arch,
-				name: f,
-				done: make(chan bool),
-			})
-		}
-		arches = append(arches, arch)
+	for _, arch := range arches {
 		jobC <- arch
 	}
 
@@ -171,28 +140,8 @@ func main() {
 	}
 
 	if !failed {
-		supported := make(map[string]bool)
-		unsupported := make(map[string]string)
-		for _, arch := range arches {
-			for _, f := range arch.files {
-				for name := range f.consts {
-					supported[name] = true
-				}
-				for name := range f.undeclared {
-					unsupported[name] = f.name
-				}
-			}
-		}
-		for name, file := range unsupported {
-			if supported[name] {
-				continue
-			}
-			failed = true
-			fmt.Printf("%v: %v is unsupported on all arches (typo?)\n",
-				file, name)
-		}
+		failed = checkUnsupportedCalls(arches)
 	}
-
 	for _, arch := range arches {
 		if arch.build {
 			os.RemoveAll(arch.buildDir)
@@ -203,6 +152,71 @@ func main() {
 	}
 }
 
+func createArches(OS string, archArray, files []string) ([]*Arch, error) {
+	var arches []*Arch
+	for _, archStr := range archArray {
+		buildDir := ""
+		if *flagBuild {
+			dir, err := ioutil.TempDir("", "syzkaller-kernel-build")
+			if err != nil {
+				return nil, fmt.Errorf("failed to create temp dir: %v", err)
+			}
+			buildDir = dir
+		} else if *flagBuildDir != "" {
+			buildDir = *flagBuildDir
+		} else {
+			buildDir = *flagSourceDir
+		}
+
+		target := targets.Get(OS, archStr)
+		if target == nil {
+			return nil, fmt.Errorf("unknown arch: %v", archStr)
+		}
+
+		arch := &Arch{
+			target:    target,
+			sourceDir: *flagSourceDir,
+			buildDir:  buildDir,
+			build:     *flagBuild,
+			done:      make(chan bool),
+		}
+		for _, f := range files {
+			arch.files = append(arch.files, &File{
+				arch: arch,
+				name: f,
+				done: make(chan bool),
+			})
+		}
+		arches = append(arches, arch)
+	}
+	return arches, nil
+}
+
+func checkUnsupportedCalls(arches []*Arch) bool {
+	supported := make(map[string]bool)
+	unsupported := make(map[string]string)
+	for _, arch := range arches {
+		for _, f := range arch.files {
+			for name := range f.consts {
+				supported[name] = true
+			}
+			for name := range f.undeclared {
+				unsupported[name] = f.name
+			}
+		}
+	}
+	failed := false
+	for name, file := range unsupported {
+		if supported[name] {
+			continue
+		}
+		failed = true
+		fmt.Printf("%v: %v is unsupported on all arches (typo?)\n",
+			file, name)
+	}
+	return failed
+}
+
 func archFileList(os, arch string, files []string) (string, []string, []string, error) {
 	android := false
 	if os == "android" {