remove rsync support

rsync was executed as an external command, which means we have no insight
into or control over what it actually does.
From a security perspective, this is far from ideal.

To be clear, there's nothing inherently wrong with rsync itself. However,
if we were to support it properly within SFTPGo, we would need to implement
the low-level protocol internally rather than relying on launching an external
process. This would ensure it works seamlessly with any storage backend,
just as SFTP does, for example.
We recommend using one of the many alternatives that rely on the SFTP
protocol, such as rclone

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

Author: drakkan

internal/common/common_test.go

@@ -1412,19 +1412,6 @@ func TestUserPerms(t *testing.T) {
 	u.Permissions["/"] = []string{dataprovider.PermDeleteDirs, dataprovider.PermRenameFiles, dataprovider.PermRenameDirs}
 	assert.False(t, u.HasPermsDeleteAll("/"))
 	assert.True(t, u.HasPermsRenameAll("/"))
-
-	toCheck := []string{dataprovider.PermDownload, dataprovider.PermUpload, dataprovider.PermCreateDirs, dataprovider.PermListItems,
-		dataprovider.PermOverwrite, dataprovider.PermDelete}
-	u.Permissions = make(map[string][]string)
-	u.Permissions["/"] = []string{dataprovider.PermListItems}
-	u.Permissions["/example-dir/bar"] = []string{dataprovider.PermListItems}
-	u.Permissions["/example-dir"] = toCheck
-	assert.True(t, u.HasPerms(toCheck, "/example-dir"))
-	assert.False(t, u.HasRecursivePerms(toCheck, "/example-dir"))
-	delete(u.Permissions, "/example-dir/bar")
-	assert.True(t, u.HasRecursivePerms(toCheck, "/example-dir"))
-	u.Permissions["/example-dirbar"] = []string{dataprovider.PermListItems}
-	assert.True(t, u.HasRecursivePerms(toCheck, "/example-dir"))
 }
 
 func TestGetTLSVersion(t *testing.T) {

internal/dataprovider/user.go

@@ -876,27 +876,6 @@ func (u *User) HasAnyPerm(permissions []string, path string) bool {
 	return false
 }
 
-// HasRecursivePerms returns true if the user has all the specified permissions
-// in the given folder and in every subfolder that has explicit permissions
-// defined.
-func (u *User) HasRecursivePerms(permissions []string, virtualPath string) bool {
-	if !u.HasPerms(permissions, virtualPath) {
-		return false
-	}
-	for dir, perms := range u.Permissions {
-		if len(dir) > len(virtualPath) {
-			if strings.HasPrefix(dir, virtualPath+"/") {
-				for _, permission := range permissions {
-					if !slices.Contains(perms, permission) {
-						return false
-					}
-				}
-			}
-		}
-	}
-	return true
-}
-
 // HasPerms returns true if the user has all the given permissions
 func (u *User) HasPerms(permissions []string, path string) bool {
 	perms := u.GetPermissionsForPath(path)