pkg/repro: fix invalid options minimization

Repro can generate Sandbox="namespace"/UseTmpDir=false.
This combination is broken for two reasons:
 - on second and subsequent executions of the program,
   it fails to create syz-tmp dir
 - with Procs>1, it fails right away, because all procs
   try to create syz-tmp dir

Don't generate such combination.

1 files changed, 8 insertions, 0 deletions

diff --git a/pkg/csource/csource.go b/pkg/csource/csource.go
index e351a2e1d..163a9b065 100644
--- a/pkg/csource/csource.go
+++ b/pkg/csource/csource.go
@@ -51,11 +51,19 @@ type Options struct {
 // Invalid combinations must not be passed to Write.
 func (opts Options) Check() error {
 	if !opts.Threaded && opts.Collide {
+		// Collide requires threaded.
 		return errors.New("Collide without Threaded")
 	}
 	if !opts.Repeat && opts.Procs > 1 {
+		// This does not affect generated code.
 		return errors.New("Procs>1 without Repeat")
 	}
+	if opts.Sandbox == "namespace" && !opts.UseTmpDir {
+		// This is borken and never worked.
+		// This tries to create syz-tmp dir in cwd,
+		// which will fail if procs>1 and on second run of the program.
+		return errors.New("Sandbox=namespace without UseTmpDir")
+	}
 	return nil
 }