internal/pkg: caller-supplied reporting name for exec

This does not have a reasonable way of inferring the underlying name. For zero value it falls back to base of executable pathname.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/exec.go

@@ -4,7 +4,9 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"os"
+	"path"
 	"slices"
 	"strconv"
 	"syscall"
@@ -55,6 +57,8 @@ const (
 // Methods of execArtifact does not modify any struct field or underlying arrays
 // referred to by slices.
 type execArtifact struct {
+	// Caller-supplied user-facing reporting name.
+	name string
 	// Caller-supplied inner mount points.
 	paths []ExecPath
 
@@ -73,6 +77,8 @@ type execArtifact struct {
 	timeout time.Duration
 }
 
+var _ fmt.Stringer = new(execArtifact)
+
 // execNetArtifact is like execArtifact but implements [KnownChecksum] and has
 // its resulting container keep the host net namespace.
 type execNetArtifact struct {
@@ -119,24 +125,32 @@ func (a *execNetArtifact) Cure(f *FContext) error {
 // process and all processes originating from it is terminated. A zero or
 // negative timeout value is equivalent tp [ExecTimeoutDefault], a timeout value
 // greater than [ExecTimeoutMax] is equivalent to [ExecTimeoutMax].
+//
+// The user-facing name is not accessible from the container and does not
+// affect curing outcome. Because of this, it is omitted from parameter data
+// for computing identifier.
 func NewExec(
+	name string,
 	checksum *Checksum,
 	timeout time.Duration,
 
 	dir *check.Absolute,
 	env []string,
-	path *check.Absolute,
+	pathname *check.Absolute,
 	args []string,
 
 	paths ...ExecPath,
 ) Artifact {
+	if name == "" {
+		name = "exec-" + path.Base(pathname.String())
+	}
 	if timeout <= 0 {
 		timeout = ExecTimeoutDefault
 	}
 	if timeout > ExecTimeoutMax {
 		timeout = ExecTimeoutMax
 	}
-	a := execArtifact{paths, dir, env, path, args, timeout}
+	a := execArtifact{name, paths, dir, env, pathname, args, timeout}
 	if checksum == nil {
 		return &a
 	}
@@ -192,6 +206,9 @@ func (a *execArtifact) Dependencies() []Artifact {
 	return slices.Concat(artifacts...)
 }
 
+// String returns the caller-supplied reporting name.
+func (a *execArtifact) String() string { return a.name }
+
 // Cure cures the [Artifact] in the container described by the caller.
 func (a *execArtifact) Cure(f *FContext) (err error) {
 	return a.cure(f, false)