pkg/kernel: accept kernel config as byte slice

We usually have the config in memory,
so saving it to disk is an unnecessary step.
Accept byte slice directly.

Update #501

3 files changed, 9 insertions, 12 deletions

diff --git a/pkg/kernel/kernel.go b/pkg/kernel/kernel.go
index 3cd689d70..a51da8db3 100644
--- a/pkg/kernel/kernel.go
+++ b/pkg/kernel/kernel.go
@@ -24,9 +24,9 @@ import (
 	"github.com/google/syzkaller/pkg/osutil"
 )
 
-func Build(dir, compiler, config string) error {
+func Build(dir, compiler string, config []byte) error {
 	configFile := filepath.Join(dir, ".config")
-	if err := osutil.CopyFile(config, configFile); err != nil {
+	if err := osutil.WriteFile(configFile, config); err != nil {
 		return fmt.Errorf("failed to write config file: %v", err)
 	}
 	if err := osutil.SandboxChown(configFile); err != nil {
@@ -89,6 +89,7 @@ func CreateImage(kernelDir, userspaceDir, cmdlineFile, sysctlFile, image, sshkey
 	if _, err = osutil.Run(time.Hour, cmd); err != nil {
 		return fmt.Errorf("image build failed: %v", err)
 	}
+	// Note: we use CopyFile instead of Rename because src and dst can be on different filesystems.
 	if err := osutil.CopyFile(filepath.Join(tempDir, "disk.raw"), image); err != nil {
 		return err
 	}
diff --git a/syz-ci/jobs.go b/syz-ci/jobs.go
index e4518f897..bda2df703 100644
--- a/syz-ci/jobs.go
+++ b/syz-ci/jobs.go
@@ -247,18 +247,13 @@ func (jp *JobProcessor) buildImage(job *Job) error {
 	}
 
 	log.Logf(0, "job: building kernel...")
-	configFile := filepath.Join(dir, "kernel.config")
-	if err := osutil.WriteFile(configFile, req.KernelConfig); err != nil {
-		return fmt.Errorf("failed to write temp file: %v", err)
-	}
-	if err := kernel.Build(kernelDir, mgr.mgrcfg.Compiler, configFile); err != nil {
+	if err := kernel.Build(kernelDir, mgr.mgrcfg.Compiler, req.KernelConfig); err != nil {
 		return fmt.Errorf("kernel build failed: %v", err)
 	}
-	kernelConfig, err := ioutil.ReadFile(filepath.Join(kernelDir, ".config"))
+	resp.Build.KernelConfig, err = ioutil.ReadFile(filepath.Join(kernelDir, ".config"))
 	if err != nil {
 		return fmt.Errorf("failed to read config file: %v", err)
 	}
-	resp.Build.KernelConfig = kernelConfig
 
 	log.Logf(0, "job: creating image...")
 	image := filepath.Join(imageDir, "image")
diff --git a/syz-ci/manager.go b/syz-ci/manager.go
index fda534940..00ef66af8 100644
--- a/syz-ci/manager.go
+++ b/syz-ci/manager.go
@@ -261,15 +261,15 @@ func (mgr *Manager) build() error {
 	if err := osutil.MkdirAll(tmpDir); err != nil {
 		return fmt.Errorf("failed to create tmp dir: %v", err)
 	}
-	kernelConfig := filepath.Join(tmpDir, "kernel.config")
-	if err := osutil.CopyFile(mgr.mgrcfg.KernelConfig, kernelConfig); err != nil {
+	kernelConfigData, err := ioutil.ReadFile(mgr.mgrcfg.KernelConfig)
+	if err != nil {
 		return err
 	}
 	if err := config.SaveFile(filepath.Join(tmpDir, "tag"), info); err != nil {
 		return fmt.Errorf("failed to write tag file: %v", err)
 	}
 
-	if err := kernel.Build(mgr.kernelDir, mgr.mgrcfg.Compiler, kernelConfig); err != nil {
+	if err := kernel.Build(mgr.kernelDir, mgr.mgrcfg.Compiler, kernelConfigData); err != nil {
 		rep := &report.Report{
 			Title:  fmt.Sprintf("%v build error", mgr.mgrcfg.RepoAlias),
 			Output: []byte(err.Error()),
@@ -279,6 +279,7 @@ func (mgr *Manager) build() error {
 		}
 		return fmt.Errorf("kernel build failed: %v", err)
 	}
+	kernelConfig := filepath.Join(tmpDir, "kernel.config")
 	if err := osutil.CopyFile(filepath.Join(mgr.kernelDir, ".config"), kernelConfig); err != nil {
 		return err
 	}