Allow symlinked directories to be registered.

We already allow symlinks in the parents of the registered directory, so we
might as well allow the symlinked directory itself to be registered.

Also centralized the logic for checking that a path is indeed a directory.
This allows us to get rid of another Lstat call.

handlers.go

@@ -123,18 +123,6 @@ func checkVerificationCode(path string, verifier *verificationRegistry, timeout
 
 /**********************************************************************/
 
-func checkValidRegistrationPath(path string) error {
-    info, err := os.Lstat(path) // distinguish between directories and symlinks to one.
-    if err != nil {
-        return fmt.Errorf("failed to stat; %w", err)
-    } else if info.Mode() & fs.ModeSymlink != 0 {
-        return errors.New("path cannot be a symbolic link to a directory")
-    } else if !info.IsDir() {
-        return errors.New("path should be a directory")
-    }
-    return nil
-}
-
 func newRegisterStartHandler(verifier *verificationRegistry) func(http.ResponseWriter, *http.Request) {
     return func(w http.ResponseWriter, r *http.Request) {
         if r.Body == nil {
@@ -155,7 +143,7 @@ func newRegisterStartHandler(verifier *verificationRegistry) func(http.ResponseW
             return
         }
 
-        err = checkValidRegistrationPath(regpath)
+        err = verifyDirectory(regpath)
         if err != nil {
             dumpErrorResponse(w, http.StatusBadRequest, err.Error())
             return
@@ -195,7 +183,7 @@ func newRegisterFinishHandler(db *sql.DB, verifier *verificationRegistry, tokeni
             return
         }
 
-        err = checkValidRegistrationPath(regpath)
+        err = verifyDirectory(regpath)
         if err != nil {
             dumpHttpErrorResponse(w, err)
             return

handlers_test.go

@@ -237,7 +237,7 @@ func TestRegisterHandlers(t *testing.T) {
         }
     })
 
-    t.Run("register start failure", func(t *testing.T) {
+    t.Run("register start symlink", func(t *testing.T) {
         handler := http.HandlerFunc(newRegisterStartHandler(verifier))
 
         tmp, err := os.MkdirTemp("", "")
@@ -254,8 +254,8 @@ func TestRegisterHandlers(t *testing.T) {
         req := createJsonRequest("POST", "/register/start", map[string]interface{}{ "path": to_add2 }, t)
         rr := httptest.NewRecorder()
         handler.ServeHTTP(rr, req)
-        if rr.Code != http.StatusBadRequest {
-            t.Fatalf("registration of a symlink should have failed")
+        if rr.Code != http.StatusAccepted {
+            t.Fatalf("should have succeeded")
         }
     })
 

list.go

@@ -7,26 +7,8 @@ import (
     "path/filepath"
     "strings"
     "errors"
-    "net/http"
 )
 
-func verifyDirectory(dir string) error {
-    info, err := os.Stat(dir)
-    if errors.Is(err, os.ErrNotExist) {
-        return newHttpError(http.StatusNotFound, fmt.Errorf("path %q does not exist", dir))
-    }
-
-    if err != nil {
-        return fmt.Errorf("failed to check %q; %w", dir, err)
-    }
-
-    if !info.IsDir() {
-        return newHttpError(http.StatusBadRequest, fmt.Errorf("%q is not a directory", dir))
-    }
-
-    return nil
-}
-
 func listFiles(dir string, recursive bool) ([]string, error) {
     err := verifyDirectory(dir)
     if err != nil {

utils.go

@@ -1,5 +1,12 @@
 package main
 
+import (
+    "fmt"
+    "os"
+    "net/http"
+    "errors"
+)
+
 type httpError struct {
     Status int
     Reason error
@@ -16,3 +23,20 @@ func (r *httpError) Unwrap() error {
 func newHttpError(status int, reason error) *httpError {
     return &httpError{ Status: status, Reason: reason }
 }
+
+func verifyDirectory(dir string) error {
+    info, err := os.Stat(dir)
+    if errors.Is(err, os.ErrNotExist) {
+        return newHttpError(http.StatusNotFound, fmt.Errorf("path %q does not exist", dir))
+    }
+
+    if err != nil {
+        return fmt.Errorf("failed to check %q; %w", dir, err)
+    }
+
+    if !info.IsDir() {
+        return newHttpError(http.StatusBadRequest, fmt.Errorf("%q is not a directory", dir))
+    }
+
+    return nil
+}