prog: don't require preallocated buffer for exec encoding

If we send exec encoding to the fuzzer, it's not necessary to serialize
exec encoding into existing buffer (currnetly we serialize directly into shmem).
So simplify code by serializing into a new slice.

2 files changed, 7 insertions, 9 deletions

diff --git a/pkg/csource/csource.go b/pkg/csource/csource.go
index 96237e64b..3d019a59c 100644
--- a/pkg/csource/csource.go
+++ b/pkg/csource/csource.go
@@ -239,12 +239,11 @@ func (ctx *context) generateSyscallDefines() string {
 }
 
 func (ctx *context) generateProgCalls(p *prog.Prog, trace bool) ([]string, []uint64, error) {
-	exec := make([]byte, prog.ExecBufferSize)
-	progSize, err := p.SerializeForExec(exec)
+	exec, err := p.SerializeForExec()
 	if err != nil {
 		return nil, nil, fmt.Errorf("failed to serialize program: %w", err)
 	}
-	decoded, err := ctx.target.DeserializeExec(exec[:progSize], nil)
+	decoded, err := ctx.target.DeserializeExec(exec, nil)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/pkg/ipc/ipc.go b/pkg/ipc/ipc.go
index 536b494e7..ea2e22569 100644
--- a/pkg/ipc/ipc.go
+++ b/pkg/ipc/ipc.go
@@ -185,7 +185,6 @@ func MakeEnv(config *Config, pid int) (*Env, error) {
 			}
 		}()
 	} else {
-		inmem = make([]byte, prog.ExecBufferSize)
 		outmem = make([]byte, outputSize)
 	}
 	env := &Env{
@@ -254,15 +253,15 @@ func (env *Env) Close() error {
 // hanged: program hanged and was killed
 // err0: failed to start the process or bug in executor itself.
 func (env *Env) Exec(opts *ExecOpts, p *prog.Prog) (output []byte, info *ProgInfo, hanged bool, err0 error) {
-	// Copy-in serialized program.
-	progSize, err := p.SerializeForExec(env.in)
+	progData, err := p.SerializeForExec()
 	if err != nil {
 		err0 = err
 		return
 	}
-	var progData []byte
-	if !env.config.UseShmem {
-		progData = env.in[:progSize]
+	// Copy-in serialized program.
+	if env.config.UseShmem {
+		copy(env.in, progData)
+		progData = nil
 	}
 	// Zero out the first two words (ncmd and nsig), so that we don't have garbage there
 	// if executor crashes before writing non-garbage there.