fix: generate default netmap.conf, if required

Generates the `netmap.conf` in the default location if the file does not exist in the default path or the alternate path.

There have been reported issues (GH, Discuss, blogs) of fresh installations of Workstation 17 (and 16) not generating the default file which will cause a build to fail on a newly configured system.

Ref: #65

Signed-off-by: Ryan Johnson <ryan@tenthirtyam.org>

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 +210,12 @@ func (d *Workstation9Driver) Verify() error {
 	}
 
 	d.VmwareDriver.NetworkMapper = func() (NetworkNameMapper, error) {
-		pathNetmap := workstationNetmapConfPath()
-
-		// 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)
-		}
-
-		// 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)
-		}
-
-		// 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)
-		if err != nil {
-			return nil, err
+		// Check if the network mapper configuration file exists.
+		mapper, err := checkNetmapConfExists() // Capture both the mapper and the error
+		if err != nil {                        // Check the error instead of the mapper being nil
+			return nil, fmt.Errorf("error reading network mapper configuration: %v", err)
 		}
-		defer fd.Close()
-
-		// Then we pass the handle to the networking configuration parser.
-		return ReadNetworkingConfig(fd)
+		return mapper, nil
 	}
 	return nil
 }
@@ -215,3 +231,112 @@ 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.
+	if _, err := os.Stat(pathNetmap); os.IsNotExist(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)
+		if _, err := os.Stat(pathNetworking); err == nil {
+			// 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()
+
+			// Then we pass the handle to the networking configuration parser.
+			return ReadNetworkingConfig(fd)
+		} else if runtime.GOOS == "windows" {
+			// Neither the default nor alternate exists.
+			// Generate the network mapper configuration file in the default path.
+			log.Printf("Generating a network mapper configuration file in the default path: %s", pathNetmap)
+			pathNetmap, err := generateNetmapConfig()
+			if err != nil {
+				log.Fatalf("error generating the absent network configuration file: %v", err)
+				return nil, err
+			}
+			// If the file exists, attempt to read the newly generated
+			// network mapper configuration file.
+			return ReadNetmapConfig(pathNetmap)
+		} else {
+			// For non-Windows, if neither the default nor alternate
+			// configuration paths exist, return an error.
+			return nil, fmt.Errorf("error determining network mappings from files in path: %s", libpath)
+		}
+	} else if err != nil {
+		// There was an error other than the file not existing.
+		return nil, err
+	}
+
+	// If the default network mapper configuration file exists, read the configuration.
+	log.Printf("Located the network mapper configuration file: %s", pathNetmap)
+	return ReadNetmapConfig(pathNetmap)
+}
+
+// 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")
+	}
+}