refactor: internal package

internal/engine/exec.go

@@ -0,0 +1,54 @@
+package engine
+
+import (
+	"context"
+	"io"
+	"os/exec"
+	"strings"
+	"time"
+
+	"github.com/nalgeon/codapi/internal/execy"
+	"github.com/nalgeon/codapi/internal/logx"
+)
+
+// A Program is an executable program.
+type Program struct {
+	timeout time.Duration
+	nOutput int64
+}
+
+// NewProgram creates a new program.
+func NewProgram(timeoutSec int, nOutput int64) *Program {
+	return &Program{
+		timeout: time.Duration(timeoutSec) * time.Second,
+		nOutput: nOutput,
+	}
+}
+
+// Run starts the program and waits for it to complete (or timeout).
+func (p *Program) Run(id, name string, arg ...string) (stdout string, stderr string, err error) {
+	return p.RunStdin(nil, id, name, arg...)
+}
+
+// RunStdin starts the program with data from stdin
+// and waits for it to complete (or timeout).
+func (p *Program) RunStdin(stdin io.Reader, id, name string, arg ...string) (stdout string, stderr string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), p.timeout)
+	defer cancel()
+
+	var cmdout, cmderr strings.Builder
+	cmd := exec.CommandContext(ctx, name, arg...)
+	cmd.Cancel = func() error {
+		err := cmd.Process.Kill()
+		logx.Debug("%s: execution timeout, killed process=%d, err=%v", id, cmd.Process.Pid, err)
+		return err
+	}
+
+	cmd.Stdin = stdin
+	cmd.Stdout = LimitWriter(&cmdout, p.nOutput)
+	cmd.Stderr = LimitWriter(&cmderr, p.nOutput)
+	err = execy.Run(cmd)
+	stdout = cmdout.String()
+	stderr = cmderr.String()
+	return
+}