vfs: Add VFS --links command line switch

This will be used to enable links support for the various mount engines
in a follow up commit.

vfs/help.go

@@ -258,6 +258,7 @@ read of the modification time takes a transaction.
     --no-modtime      Don't read/write the modification time (can speed things up).
     --no-seek         Don't allow seeking in files.
     --read-only       Only allow read-only access.
+    --links           Translate symlinks to/from regular files with a '.rclonelink' extension.
 
 Sometimes rclone is delivered reads or writes out of order. Rather
 than seeking rclone will wait a short time for the in sequence read or

vfs/vfs.go

@@ -227,6 +227,11 @@ func New(f fs.Fs, opt *vfscommon.Options) *VFS {
 		fs.Logf(f, "--vfs-cache-mode writes or full is recommended for this remote as it can't stream")
 	}
 
+	// Warn if we handle symlinks
+	if vfs.Opt.Links {
+		fs.Logf(f, "Symlinks support enabled")
+	}
+
 	vfs.SetCacheMode(vfs.Opt.CacheMode)
 
 	// Pin the Fs into the cache so that when we use cache.NewFs

vfs/vfscommon/options.go

@@ -13,6 +13,7 @@ type Options struct {
 	NoSeek             bool          // don't allow seeking if set
 	NoChecksum         bool          // don't check checksums if set
 	ReadOnly           bool          // if set VFS is read only
+	Links              bool          // if set VFS handle symlinks
 	NoModTime          bool          // don't read mod times for files
 	DirCacheTime       time.Duration // how long to consider directory listing cache valid
 	PollInterval       time.Duration
@@ -45,6 +46,7 @@ var DefaultOpt = Options{
 	DirCacheTime:       5 * 60 * time.Second,
 	PollInterval:       time.Minute,
 	ReadOnly:           false,
+	Links:              false,
 	Umask:              0,
 	UID:                ^uint32(0), // these values instruct WinFSP-FUSE to use the current user
 	GID:                ^uint32(0), // overridden for non windows in mount_unix.go

vfs/vfsflags/vfsflags.go

@@ -2,6 +2,7 @@
 package vfsflags
 
 import (
+	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/config/flags"
 	"github.com/rclone/rclone/fs/rc"
 	"github.com/rclone/rclone/vfs/vfscommon"
@@ -24,6 +25,7 @@ func AddFlags(flagSet *pflag.FlagSet) {
 	flags.DurationVarP(flagSet, &Opt.DirCacheTime, "dir-cache-time", "", Opt.DirCacheTime, "Time to cache directory entries for")
 	flags.DurationVarP(flagSet, &Opt.PollInterval, "poll-interval", "", Opt.PollInterval, "Time to wait between polling for changes, must be smaller than dir-cache-time and only on supported remotes (set 0 to disable)")
 	flags.BoolVarP(flagSet, &Opt.ReadOnly, "read-only", "", Opt.ReadOnly, "Only allow read-only access")
+	flags.BoolVarP(flagSet, &Opt.Links, "links", "l", Opt.Links, "Translate symlinks to/from regular files with a '"+fs.LinkSuffix+"' extension")
 	flags.FVarP(flagSet, &Opt.CacheMode, "vfs-cache-mode", "", "Cache mode off|minimal|writes|full")
 	flags.DurationVarP(flagSet, &Opt.CachePollInterval, "vfs-cache-poll-interval", "", Opt.CachePollInterval, "Interval to poll the cache for stale objects")
 	flags.DurationVarP(flagSet, &Opt.CacheMaxAge, "vfs-cache-max-age", "", Opt.CacheMaxAge, "Max age of objects in the cache")