all: try to query compiler id even when a build fails

Currently syzkaller leaves an empty CompilerID, when it has failed to
build a kernel. However, in almost all cases this is possible to do.

Query compiler information irregardless of whether the build process
is successful.

2 files changed, 23 insertions, 22 deletions

diff --git a/pkg/build/build.go b/pkg/build/build.go
index c1b0302e9..0add9451b 100644
--- a/pkg/build/build.go
+++ b/pkg/build/build.go
@@ -76,6 +76,14 @@ func Image(params Params) (details ImageDetails, err error) {
 		}
 	}
 	details, err = builder.build(params)
+	if details.CompilerID == "" {
+		// Fill in the compiler info even if the build failed.
+		var idErr error
+		details.CompilerID, idErr = compilerIdentity(params.Compiler)
+		if err == nil {
+			err = idErr
+		} // Try to preserve the build error otherwise.
+	}
 	if err != nil {
 		err = extractRootCause(err, params.TargetOS, params.KernelDir)
 		return
@@ -85,12 +93,6 @@ func Image(params Params) (details ImageDetails, err error) {
 			return details, fmt.Errorf("failed to chmod 0600 %v: %v", key, err)
 		}
 	}
-	if details.CompilerID == "" {
-		details.CompilerID, err = compilerIdentity(params.Compiler)
-		if err != nil {
-			return
-		}
-	}
 	return
 }
 
diff --git a/pkg/build/linux.go b/pkg/build/linux.go
index 85575e621..3947463de 100644
--- a/pkg/build/linux.go
+++ b/pkg/build/linux.go
@@ -26,12 +26,17 @@ import (
 type linux struct{}
 
 func (linux linux) build(params Params) (ImageDetails, error) {
-	if err := linux.buildKernel(params); err != nil {
-		return ImageDetails{}, err
+	details := ImageDetails{}
+	err := linux.buildKernel(params)
+	// Even if the build fails, autogenerated files would still be present (unless the build is really broken).
+	if err != nil {
+		details.CompilerID, _ = queryLinuxCompiler(params.KernelDir)
+		return details, err
 	}
-	compilerID, err := queryLinuxCompiler(params.KernelDir)
+
+	details.CompilerID, err = queryLinuxCompiler(params.KernelDir)
 	if err != nil {
-		return ImageDetails{}, err
+		return details, err
 	}
 
 	kernelPath := filepath.Join(params.KernelDir, filepath.FromSlash(kernelBin(params.TargetArch)))
@@ -39,28 +44,22 @@ func (linux linux) build(params Params) (ImageDetails, error) {
 		// The old way of assembling the image from userspace dir.
 		// It should be removed once all syzbot instances are switched.
 		if err := linux.createImage(params, kernelPath); err != nil {
-			return ImageDetails{}, err
+			return details, err
 		}
 	} else if params.VMType == "qemu" {
 		// If UserspaceDir is a file (image) and we use qemu, we just copy image and kernel to the output dir
 		// assuming that qemu will use injected kernel boot. In this mode we also assume password/key-less ssh.
 		if err := osutil.CopyFile(kernelPath, filepath.Join(params.OutputDir, "kernel")); err != nil {
-			return ImageDetails{}, err
+			return details, err
 		}
 		if err := osutil.CopyFile(params.UserspaceDir, filepath.Join(params.OutputDir, "image")); err != nil {
-			return ImageDetails{}, err
+			return details, err
 		}
 	} else if err := embedLinuxKernel(params, kernelPath); err != nil {
-		return ImageDetails{}, err
-	}
-	signature, err := elfBinarySignature(filepath.Join(params.OutputDir, "obj", "vmlinux"))
-	if err != nil {
-		return ImageDetails{}, err
+		return details, err
 	}
-	return ImageDetails{
-		Signature:  signature,
-		CompilerID: compilerID,
-	}, nil
+	details.Signature, err = elfBinarySignature(filepath.Join(params.OutputDir, "obj", "vmlinux"))
+	return details, err
 }
 
 func (linux linux) buildKernel(params Params) error {