pkg/osutil: introduce TempFile helper

Introduce TempFile helper and use it in several packages.

3 files changed, 25 insertions, 16 deletions

diff --git a/pkg/csource/build.go b/pkg/csource/build.go
index c0fc86078..cd67aa4f3 100644
--- a/pkg/csource/build.go
+++ b/pkg/csource/build.go
@@ -19,21 +19,19 @@ import (
 // Build builds a C/C++ program from source src and returns name of the resulting binary.
 // lang can be "c" or "c++".
 func Build(target *prog.Target, lang, src string) (string, error) {
-	// We call the binary syz-executor because it sometimes shows in bug titles,
-	// and we don't want 2 different bugs for when a crash is triggered during fuzzing and during repro.
-	bin, err := ioutil.TempFile("", "syz-executor")
-	if err != nil {
-		return "", fmt.Errorf("failed to create temp file: %v", err)
-	}
-	bin.Close()
 	sysTarget := targets.List[target.OS][target.Arch]
 	compiler := sysTarget.CCompilerPrefix + "gcc"
 	if _, err := exec.LookPath(compiler); err != nil {
 		return "", ErrNoCompiler
 	}
+	// We call the binary syz-executor because it sometimes shows in bug titles,
+	// and we don't want 2 different bugs for when a crash is triggered during fuzzing and during repro.
+	bin, err := osutil.TempFile("syz-executor")
+	if err != nil {
+		return "", err
+	}
 	flags := []string{
-		"-x", lang, "-Wall", "-Werror", "-O1", "-g", "-o", bin.Name(),
-		src, "-pthread",
+		"-x", lang, "-Wall", "-Werror", "-O1", "-g", "-o", bin, src, "-pthread",
 	}
 	flags = append(flags, sysTarget.CrossCFlags...)
 	if sysTarget.PtrSize == 4 {
@@ -46,12 +44,12 @@ func Build(target *prog.Target, lang, src string) (string, error) {
 		out, err = osutil.Command(compiler, flags...).CombinedOutput()
 	}
 	if err != nil {
-		os.Remove(bin.Name())
+		os.Remove(bin)
 		data, _ := ioutil.ReadFile(src)
 		return "", fmt.Errorf("failed to build program:\n%s\n%s\ncompiler invocation: %v %v",
 			data, out, compiler, flags)
 	}
-	return bin.Name(), nil
+	return bin, nil
 }
 
 var ErrNoCompiler = errors.New("no target compiler")
diff --git a/pkg/db/db_test.go b/pkg/db/db_test.go
index 538544c60..38456eb17 100644
--- a/pkg/db/db_test.go
+++ b/pkg/db/db_test.go
@@ -5,11 +5,12 @@ package db
 
 import (
 	"fmt"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"reflect"
 	"testing"
+
+	"github.com/google/syzkaller/pkg/osutil"
 )
 
 func TestBasic(t *testing.T) {
@@ -118,10 +119,9 @@ func TestLarge(t *testing.T) {
 }
 
 func tempFile(t *testing.T) string {
-	f, err := ioutil.TempFile("", "syzkaller.test.db")
+	fn, err := osutil.TempFile("syzkaller.test.db")
 	if err != nil {
-		t.Fatalf("failed to create temp file: %v", err)
+		t.Fatal(err)
 	}
-	f.Close()
-	return f.Name()
+	return fn
 }
diff --git a/pkg/osutil/osutil.go b/pkg/osutil/osutil.go
index 6f06fb4a4..a1d65e835 100644
--- a/pkg/osutil/osutil.go
+++ b/pkg/osutil/osutil.go
@@ -141,6 +141,17 @@ func WriteExecFile(filename string, data []byte) error {
 	return ioutil.WriteFile(filename, data, DefaultExecPerm)
 }
 
+// TempFile creates a unique temp filename.
+// Note: the file already exists when the function returns.
+func TempFile(prefix string) (string, error) {
+	f, err := ioutil.TempFile("", prefix)
+	if err != nil {
+		return "", fmt.Errorf("failed to create temp file: %v", err)
+	}
+	f.Close()
+	return f.Name(), nil
+}
+
 // Return all files in a directory.
 func ListDir(dir string) ([]string, error) {
 	f, err := os.Open(dir)