pkg/build: share parameters sanitization between builds and cleans

When refactoring the Clean() function to share more code with Image(),
there is logic I forgot to replicate, like setting a default number of
CPUs to build/clean with. I imagine that not setting the default tracer
could end up being a subtle issue in the future too.

To avoid missing these cases in the future, refactor the parameters
sanitization into a helper function called by both.

1 files changed, 11 insertions, 6 deletions

diff --git a/pkg/build/build.go b/pkg/build/build.go
index b84adb20b..c9a5b038f 100644
--- a/pkg/build/build.go
+++ b/pkg/build/build.go
@@ -49,6 +49,15 @@ type ImageDetails struct {
 	CompilerID string
 }
 
+func sanitize(params *Params) {
+	if params.Tracer == nil {
+		params.Tracer = &debugtracer.NullTracer{}
+	}
+	if params.BuildCPUs == 0 {
+		params.BuildCPUs = runtime.NumCPU()
+	}
+}
+
 // Image creates a disk image for the specified OS/ARCH/VM.
 // Kernel is taken from KernelDir, userspace system is taken from UserspaceDir.
 // If CmdlineFile is not empty, contents of the file are appended to the kernel command line.
@@ -71,12 +80,7 @@ type ImageDetails struct {
 // the version of the compiler/toolchain that was used to build the kernel.
 // The CompilerID field is not guaranteed to be non-empty.
 func Image(params Params) (details ImageDetails, err error) {
-	if params.Tracer == nil {
-		params.Tracer = &debugtracer.NullTracer{}
-	}
-	if params.BuildCPUs == 0 {
-		params.BuildCPUs = runtime.NumCPU()
-	}
+	sanitize(&params)
 	var builder builder
 	builder, err = getBuilder(params.TargetOS, params.TargetArch, params.VMType)
 	if err != nil {
@@ -114,6 +118,7 @@ func Image(params Params) (details ImageDetails, err error) {
 }
 
 func Clean(params Params) error {
+	sanitize(&params)
 	builder, err := getBuilder(params.TargetOS, params.TargetArch, params.VMType)
 	if err != nil {
 		return err