ipn,tailfs: tie TailFS share configuration to user profile

Previously, the configuration of which folders to share persisted across
profile changes. Now, it is tied to the user's profile.

Updates tailscale/corp#16827

Signed-off-by: Percy Wegmann <percy@tailscale.com>

ipn/prefs.go

@@ -14,6 +14,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"runtime"
+	"slices"
 	"strings"
 
 	"tailscale.com/atomicfile"
@@ -21,6 +22,7 @@ import (
 	"tailscale.com/net/netaddr"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
+	"tailscale.com/tailfs"
 	"tailscale.com/types/opt"
 	"tailscale.com/types/persist"
 	"tailscale.com/types/preftype"
@@ -222,6 +224,10 @@ type Prefs struct {
 	// Linux-only.
 	NetfilterKind string
 
+	// TailFSShares are the configured TailFSShares, stored in increasing order
+	// by name.
+	TailFSShares []*tailfs.Share
+
 	// The Persist field is named 'Config' in the file for backward
 	// compatibility with earlier versions.
 	// TODO(apenwarr): We should move this out of here, it's not a pref.
@@ -293,6 +299,7 @@ type MaskedPrefs struct {
 	AppConnectorSet           bool                `json:",omitempty"`
 	PostureCheckingSet        bool                `json:",omitempty"`
 	NetfilterKindSet          bool                `json:",omitempty"`
+	TailFSSharesSet           bool                `json:",omitempty"`
 }
 
 type AutoUpdatePrefsMask struct {
@@ -556,6 +563,7 @@ func (p *Prefs) Equals(p2 *Prefs) bool {
 		p.AutoUpdate.Equals(p2.AutoUpdate) &&
 		p.AppConnector == p2.AppConnector &&
 		p.PostureChecking == p2.PostureChecking &&
+		slices.EqualFunc(p.TailFSShares, p2.TailFSShares, tailfs.SharesEqual) &&
 		p.NetfilterKind == p2.NetfilterKind
 }