cmd/gendb: minor style changes

- Use `if err := ...; err != nil` when feasible.

- Remove references to the deprecated io/ioutil package.

Change-Id: I94dacacd5d982531b658d629e0dd691f15405098
Reviewed-on: https://go-review.googlesource.com/c/vulndb/+/352889
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>

cmd/gendb/main.go

diff --git a/cmd/gendb/main.go b/cmd/gendb/main.go
index 8bd7267..86ffde4 100644
--- a/cmd/gendb/main.go
+++ b/cmd/gendb/main.go
@@ -8,7 +8,6 @@
 	"encoding/json"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -31,11 +30,11 @@
 
 func matchesCurrent(path string, new []osv.Entry) bool {
 	var current []osv.Entry
-	content, err := ioutil.ReadFile(path + ".json")
+	content, err := os.ReadFile(path + ".json")
 	if err != nil {
 		return false
 	}
-	if err = json.Unmarshal(content, &current); err != nil {
+	if err := json.Unmarshal(content, &current); err != nil {
 		return false
 	}
 	return reflect.DeepEqual(current, new)
@@ -46,7 +45,7 @@
 	jsonDir := flag.String("out", "out", "Directory to write JSON database to")
 	flag.Parse()
 
-	yamlFiles, err := ioutil.ReadDir(*yamlDir)
+	yamlFiles, err := os.ReadDir(*yamlDir)
 	if err != nil {
 		failf("can't read %q: %s", *yamlDir, err)
 	}
@@ -56,13 +55,12 @@
 		if !strings.HasSuffix(f.Name(), ".yaml") {
 			continue
 		}
-		content, err := ioutil.ReadFile(filepath.Join(*yamlDir, f.Name()))
+		content, err := os.ReadFile(filepath.Join(*yamlDir, f.Name()))
 		if err != nil {
 			failf("can't read %q: %s", f.Name(), err)
 		}
 		var vuln report.Report
-		err = yaml.UnmarshalStrict(content, &vuln)
-		if err != nil {
+		if err := yaml.UnmarshalStrict(content, &vuln); err != nil {
 			failf("unable to unmarshal %q: %s", f.Name(), err)
 		}
 		if lints := vuln.Lint(); len(lints) > 0 {
@@ -91,12 +89,10 @@
 		if err != nil {
 			failf("failed to marshal json: %s", err)
 		}
-		err = os.MkdirAll(filepath.Dir(outPath), 0700)
-		if err != nil {
+		if err := os.MkdirAll(filepath.Dir(outPath), 0700); err != nil {
 			failf("failed to create directory %q: %s", filepath.Dir(outPath), err)
 		}
-		err = ioutil.WriteFile(outPath+".json", content, 0644)
-		if err != nil {
+		if err := os.WriteFile(outPath+".json", content, 0644); err != nil {
 			failf("failed to write %q: %s", outPath+".json", err)
 		}
 		for _, v := range vulns {
@@ -110,8 +106,7 @@
 	if err != nil {
 		failf("failed to marshal index json: %s", err)
 	}
-	err = ioutil.WriteFile(filepath.Join(*jsonDir, "index.json"), indexJSON, 0644)
-	if err != nil {
+	if err := os.WriteFile(filepath.Join(*jsonDir, "index.json"), indexJSON, 0644); err != nil {
 		failf("failed to write index: %s", err)
 	}
 }