test: add strace function

Signed-off-by: Alessio Greggi <[email protected]>

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/coreos/go-iptables v0.6.1-0.20220901214115-d2b8608923d1
 	github.com/fsnotify/fsnotify v1.6.0
 	github.com/spf13/cobra v1.5.0
+	golang.org/x/sync v0.8.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -19,7 +20,6 @@ require (
 	github.com/spf13/cast v1.5.0 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect
 	github.com/subosito/gotenv v1.4.2 // indirect
-	golang.org/x/sync v0.8.0 // indirect
 	golang.org/x/sys v0.4.0 // indirect
 	golang.org/x/text v0.5.0 // indirect
 	golang.org/x/tools v0.1.12 // indirect

tests/strace.txtar

@@ -0,0 +1,7 @@
+# this testscript test the 'create' command
+
+# if go is not installed, then skip
+[!exec:go] skip
+
+strace fwdctl list -h
+stdout 'Usage:'

utils.go

@@ -1,6 +1,14 @@
 package main
 
 import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
 	"github.com/alegrey91/fwdctl/pkg/iptables"
 	goiptables "github.com/coreos/go-iptables/iptables"
 	"github.com/rogpeppe/go-internal/testscript"
@@ -39,11 +47,82 @@ func fwdExists(ts *testscript.TestScript, neg bool, args []string) {
 	}
 }
 
+func strace(ts *testscript.TestScript, neg bool, args []string) {
+	if len(args) < 1 {
+		ts.Fatalf("syntax: strace needs at least one argument")
+	}
+
+	outputDir := "syscalls"
+	if err := os.MkdirAll(outputDir, 0755); err != nil {
+		ts.Fatalf("failed to create output directory: %v", err)
+	}
+
+	// Prepare the strace output file
+	timestamp := time.Now().Format("20060102-150405")
+	outputFile := filepath.Join(outputDir, fmt.Sprintf("strace-%s.log", timestamp))
+
+	// Prepare the command to execute with strace, filtering only system calls
+	straceArgs := []string{"-f", "-e", "trace=all"}
+	straceArgs = append(straceArgs, args...)
+	strace := exec.Command("strace", straceArgs...)
+
+	var stdoutBuf bytes.Buffer
+	strace.Stdout = &stdoutBuf
+	var stderrBuf bytes.Buffer
+	strace.Stderr = &stderrBuf
+
+	// Run the command
+	if err := strace.Run(); err != nil {
+		if !neg {
+			ts.Fatalf("command failed: %v", err)
+		}
+	} else {
+		if neg {
+			ts.Fatalf("command succeeded when it should have failed")
+		}
+	}
+
+	fmt.Fprintf(ts.Stdout(), "%s", stdoutBuf.String())
+
+	syscalls := processStraceOutput(stderrBuf.String())
+	if err := os.WriteFile(outputFile, []byte(syscalls), 0644); err != nil {
+		ts.Logf("strace output saved to %s", outputFile)
+	}
+}
+
+func processStraceOutput(output string) string {
+	lines := strings.Split(output, "\n")
+
+	// Use a map to store unique system call names
+	syscalls := make(map[string]struct{})
+
+	// Iterate over each line and extract the system call name
+	for _, line := range lines {
+		// Extract the system call name before the first '('
+		if idx := strings.Index(line, "("); idx != -1 {
+			syscall := strings.TrimSpace(line[:idx])
+			if syscall != "" {
+				syscalls[syscall] = struct{}{}
+			}
+		}
+	}
+
+	// Convert the map keys to a slice to get unique system call names
+	var syscallList []string
+	for syscall := range syscalls {
+		syscallList = append(syscallList, syscall)
+	}
+
+	// Join the unique system call names into a single string, one per line
+	return strings.Join(syscallList, "\n")
+}
+
 func customCommands() map[string]func(ts *testscript.TestScript, neg bool, args []string) {
 	return map[string]func(ts *testscript.TestScript, neg bool, args []string){
 
 		// fwd_exists check that the given forward exists
 		// invoke as "fwd_exists iface proto dest_port src_addr src_port"
 		"fwd_exists": fwdExists,
+		"strace":     strace,
 	}
 }