fix: generate default netmap.conf, if required

builder/vmware/common/driver_workstation9.go

@@ -6,15 +6,52 @@ package common
 import (
 	"errors"
 	"fmt"
+	"html/template"
 	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
+	"sort"
 	"strings"
 
 	"github.com/hashicorp/packer-plugin-sdk/multistep"
 )
 
+// Template for the network mapper configuration file, 'netmap.conf'.
+// This file is used to map network devices to their respective network names.
+// This template is used to generate the file if if the default file does not
+// exist on the system.
+const netmapTemplate = `
+# This file is automatically generated.
+# Hand-editing this file is not recommended.
+network0.name = "Bridged"
+network0.device = "vmnet0"
+network1.name = "HostOnly"
+network1.device = "vmnet1"
+{{- range . }}
+{{- if gt .Index 1 }}
+{{- if lt .Index 8 }}
+network{{ .Index }}.name = "VMNet{{ .Index }}"
+network{{ .Index }}.device = "vmnet{{ .Index }}"
+{{- else if eq .Index 8 }}
+network8.name = "NAT"
+network8.device = "vmnet8"
+{{- else }}
+network{{ .Index }}.name = "VMNet{{ .Index }}"
+network{{ .Index }}.device = "vmnet{{ .Index }}"
+{{- end }}
+{{- end }}
+{{- end }}
+`
+
+// NetmapConfig is a struct that represents a network mapper configuration.
+type NetmapConfig struct {
+	Index  int
+	Name   string
+	Device string
+}
+
 // Workstation9Driver is a driver that can run VMware Workstation 9
 type Workstation9Driver struct {
 	VmwareDriver
@@ -173,33 +210,34 @@ func (d *Workstation9Driver) Verify() error {
 	}
 
 	d.VmwareDriver.NetworkMapper = func() (NetworkNameMapper, error) {
-		pathNetmap := workstationNetmapConfPath()
+		// Check if the network mapper configuration file exists.
+		mapper, err := checkNetmapConfExists()
+
+		if err == nil {
+			return mapper, nil
+		}
 
-		// Check that the file for the networkmapper configuration exists. If there's no
-		// error, then the file exists and we can proceed to read the configuration out of it.
-		if _, err := os.Stat(pathNetmap); err == nil {
-			log.Printf("Located networkmapper configuration file: %s", pathNetmap)
-			return ReadNetmapConfig(pathNetmap)
+		// For non-Windows, if neither the default nor alternate configuration
+		// paths exist, return an error.
+		if err != nil && runtime.GOOS != "windows" {
+			return nil, err
 		}
 
-		// If we weren't able to find the networkmapper configuration file, then fall back
-		// to the networking file which might also be in the configuration directory.
-		libpath, _ := workstationVMwareRoot()
-		pathNetworking := filepath.Join(libpath, "networking")
-		if _, err := os.Stat(pathNetworking); err != nil {
-			return nil, fmt.Errorf("error determining network mappings from files in path: %s", libpath)
+		if !errors.Is(err, os.ErrNotExist) {
+			return nil, err
 		}
 
-		// We were able to successfully stat the file.. So, now we can open a handle to it.
-		log.Printf("Located networking configuration file: %s", pathNetworking)
-		fd, err := os.Open(pathNetworking)
+		// For Windows, safely generate the network mapper configuration file
+		// in the default path.
+		pathNetmap, err := generateNetmapConfig()
 		if err != nil {
+			log.Fatalf("error generating the absent network configuration file: %v", err)
 			return nil, err
 		}
-		defer fd.Close()
 
-		// Then we pass the handle to the networking configuration parser.
-		return ReadNetworkingConfig(fd)
+		// If the file exists, attempt to read the newly generated network
+		// mapper configuration file.
+		return ReadNetmapConfig(pathNetmap)
 	}
 	return nil
 }
@@ -215,3 +253,107 @@ func (d *Workstation9Driver) ToolsInstall() error {
 func (d *Workstation9Driver) GetVmwareDriver() VmwareDriver {
 	return d.VmwareDriver
 }
+
+// checkNetmapConfExists checks if the network mapper configuration file exists.
+// If not, if attempts to generate the file using generateNetmapConfig.
+func checkNetmapConfExists() (NetworkNameMapper, error) {
+	pathNetmap := workstationNetmapConfPath()
+
+	// Check if the default network mapper configuration file exists.
+	_, err := os.Stat(pathNetmap)
+
+	if err == nil {
+		// If the default network mapper configuration file exists, read the configuration.
+		log.Printf("Located the network mapper configuration file: %s", pathNetmap)
+		return ReadNetmapConfig(pathNetmap)
+	}
+
+	if !os.IsNotExist(err) {
+		return nil, fmt.Errorf("error determining network mappings from files %w", err)
+	}
+
+	log.Printf("A network mapper configuration file does not exist in the default path: %s", pathNetmap)
+
+	// The file does not exist, check the alternate configuration path.
+	libpath, _ := workstationVMwareRoot()
+	pathNetworking := filepath.Join(libpath, "networking")
+	log.Printf("Checking alternate path for network mapper configuration file: %s", pathNetworking)
+	_, err = os.Stat(pathNetworking)
+
+	// If there is an error, wrap return it.
+	// The caller can check if it is a ErrNotExist and act accordingly.
+	if err != nil {
+		return nil, fmt.Errorf("error determining network mappings from files %w", err)
+	}
+
+	// Alternate networking configuration path exists. Using this path.
+	log.Printf("Located the network mapper configuration file: %s", pathNetworking)
+	fd, err := os.Open(pathNetworking)
+	if err != nil {
+		return nil, err
+	}
+
+	defer fd.Close()
+
+	// Pass the handle to the networking configuration parser.
+	return ReadNetworkingConfig(fd)
+}
+
+// generateNetmapConfig creates the network mapper configuration file in the
+// default path using the netmapTemplate and returns the path of the created
+// file.
+func generateNetmapConfig() (string, error) {
+	var paths []string
+	if os.Getenv("ProgramData") != "" {
+		paths = append(paths, filepath.Join(os.Getenv("ProgramData"), "VMware"))
+	}
+
+	networks := []NetmapConfig{
+		{0, "Bridged", "vmnet0"},
+		{1, "HostOnly", "vmnet1"},
+		{8, "NAT", "vmnet8"},
+	}
+	for i := 2; i <= 19; i++ {
+		if i != 8 {
+			networks = append(networks, NetmapConfig{i, fmt.Sprintf("VMNet%d", i), fmt.Sprintf("vmnet%d", i)})
+		}
+	}
+
+	sort.Slice(networks, func(i, j int) bool {
+		return networks[i].Index < networks[j].Index
+	})
+
+	t, err := template.New("netmap").Parse(netmapTemplate)
+	if err != nil {
+		return "", err
+	}
+
+	var sb strings.Builder
+	if err := t.Execute(&sb, networks); err != nil {
+		return "", err
+	}
+	netmapContent := []byte(sb.String())
+
+	var pathNetmap string
+	for _, basePath := range paths {
+		path := filepath.Join(basePath, "netmap.conf")
+		if err := os.MkdirAll(basePath, 0755); err != nil {
+			continue // Skip to the next path on error.
+		}
+		if err := os.WriteFile(path, netmapContent, 0644); err != nil {
+			continue // Skip to the next path on error.
+		}
+
+		// If the file exists, set pathNetmap and break the loop.
+		if _, err := os.Stat(path); err == nil {
+			pathNetmap = path
+			break // Exit the loop since the file was successfully created.
+		}
+	}
+
+	if pathNetmap != "" {
+		return pathNetmap, nil
+	} else {
+		return "", fmt.Errorf("no valid path found for generating the network mapper configuration file")
+	}
+}