nasmon/internal/shares/external.go

package shares

import (
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// Other services on the host publish their own shares through
// drop-in files. nasmon includes the SMB drop-ins into the smb.conf it
// generates and keeps smbd / nfs-server running while any of them define a
// share, even when nasmon itself has none.
const (
	DefaultSMBIncludeDir = "/etc/samba/smb.conf.d"
	DefaultExportsDir    = "/etc/exports.d"
)

// ExternalShare is a share defined outside nasmon (read-only in the UI).
type ExternalShare struct {
	Kind    string // smb | nfs
	Source  string // drop-in file name without extension
	Name    string // SMB share name (empty for NFS)
	Path    string
	Clients string // NFS clients with options, as written in the file
}

// IncludeFiles lists the *.conf drop-ins in dir, sorted. A missing dir yields nil.
func IncludeFiles(dir string) []string {
	if dir == "" {
		return nil
	}
	m, _ := filepath.Glob(filepath.Join(dir, "*.conf"))
	sort.Strings(m)
	return m
}

func sourceName(file string) string {
	return strings.TrimSuffix(filepath.Base(file), filepath.Ext(file))
}

// ParseSMBDropIn returns the shares ([section] other than [global], [homes],
// [printers]) defined in a Samba config fragment.
func ParseSMBDropIn(text, source string) []ExternalShare {
	var out []ExternalShare
	var cur *ExternalShare
	for _, raw := range strings.Split(text, "\n") {
		line := strings.TrimSpace(raw)
		if line == "" || line[0] == '#' || line[0] == ';' {
			continue
		}
		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
			name := strings.TrimSpace(line[1 : len(line)-1])
			switch strings.ToLower(name) {
			case "global", "homes", "printers":
				cur = nil
			default:
				out = append(out, ExternalShare{Kind: "smb", Source: source, Name: name})
				cur = &out[len(out)-1]
			}
			continue
		}
		if cur == nil {
			continue
		}
		if k, v, ok := strings.Cut(line, "="); ok && strings.EqualFold(strings.TrimSpace(k), "path") {
			cur.Path = strings.TrimSpace(v)
		}
	}
	return out
}

// ParseExportsFile returns the exports in an exports(5) file.
func ParseExportsFile(text, source string) []ExternalShare {
	var out []ExternalShare
	for _, raw := range strings.Split(text, "\n") {
		line := strings.TrimSpace(raw)
		if line == "" || line[0] == '#' {
			continue
		}
		var path, rest string
		if line[0] == '"' {
			if end := strings.Index(line[1:], `"`); end >= 0 {
				path, rest = line[1:end+1], line[end+2:]
			}
		} else {
			path, rest, _ = strings.Cut(line, " ")
		}
		if path == "" {
			continue
		}
		out = append(out, ExternalShare{Kind: "nfs", Source: source, Path: path, Clients: strings.TrimSpace(rest)})
	}
	return out
}

// External reads the SMB drop-ins and the exports.d files of other services.
func (m *Manager) External() []ExternalShare {
	var out []ExternalShare
	for _, f := range IncludeFiles(m.IncludeDir) {
		if b, err := os.ReadFile(f); err == nil {
			out = append(out, ParseSMBDropIn(string(b), sourceName(f))...)
		}
	}
	if m.ExportsDir != "" {
		files, _ := filepath.Glob(filepath.Join(m.ExportsDir, "*.exports"))
		sort.Strings(files)
		for _, f := range files {
			if filepath.Clean(f) == filepath.Clean(m.Exports) {
				continue
			}
			if b, err := os.ReadFile(f); err == nil {
				out = append(out, ParseExportsFile(string(b), sourceName(f))...)
			}
		}
	}
	return out
}

func countKind(ext []ExternalShare, kind string) int {
	n := 0
	for _, e := range ext {
		if e.Kind == kind {
			n++
		}
	}
	return n
}