nwatalk: cache AFP fallback entry ids in xattrs

The AFP smoke endpoints can now read mars_nwe-owned entry ids from the versioned org.mars-nwe.afp.entry-id xattr, but a newly discovered file still had to fall back to the temporary stat-derived id on every request until a real CNID allocator exists.

Preserve the existing WebSDK/NWAFP response semantics while making that fallback sticky: when Get Entry ID, Get File Information, or Scan File Information has no mars_nwe xattr and no Netatalk/libatalk AppleDouble/CNID id, derive the existing compatibility id and cache it through nwatalk_set_entry_id().  The first request still logs fallback so diagnostics remain honest about the id origin; subsequent requests should read the xattr directly and avoid re-entering the stat fallback path.

Keep the write narrowly scoped to mars_nwe's private AFP metadata namespace.  The payload is versioned, big-endian, and stored through the nwxattr helper, so Linux persists it as user.org.mars-nwe.afp.entry-id while source-level code continues to use the Netatalk-style org.mars-nwe.afp.entry-id name.  This does not implement CNID allocation, parent-id lookup, entry-id-only resolution, FinderInfo mutation beyond the existing smoke path, or resource-fork semantics.

Tests:

- git diff --check

- cmake --build build-xattr-off --target nwconn with ENABLE_NETATALK_LIBATALK=OFF

- cmake --build build-xattr-on --target nwconn with ENABLE_NETATALK_LIBATALK=ON against Netatalk 4.4.3 headers plus local link stubs

src/nwatalk.c

@@ -156,6 +156,36 @@ int nwatalk_set_finder_info(const char *path, const uint8 *finder_info,
 #endif
 }
 
+
+int nwatalk_set_entry_id(const char *path, uint32 entry_id)
+{
+#if XATTR_SUPPORT
+  MARS_NWE_AFP_ENTRY_ID_XATTR_DATA d;
+
+  if (!path || !*path) return(-0x9c);
+  entry_id &= 0x7fffffffU;
+  if (!entry_id) return(-0x9c);
+
+  memset(&d, 0, sizeof(d));
+  d.version = MARS_NWE_AFP_ENTRY_ID_VERSION;
+  U32_TO_BE32(entry_id, d.entry_id);
+
+  if (mars_nwe_setxattr(path, MARS_NWE_AFP_ENTRY_ID_XATTR,
+                        &d, sizeof(d), 0)) {
+    int err = errno;
+    XDPRINTF((5,0,"AFP entry-id xattr write ignored for %s entry=0x%08x errno=%d",
+              path, entry_id, err));
+    return(-0x8c);
+  }
+
+  return(0);
+#else
+  (void)path;
+  (void)entry_id;
+  return(-0xbf);
+#endif
+}
+
 int nwatalk_get_resource_fork_size(const char *path, uint32 *resource_size)
 {
 #if NETATALK_SUPPORT

src/nwconn.c

@@ -507,6 +507,34 @@ static uint32 afp_fallback_entry_id(int volume, const struct stat *stb)
 }
 
 
+
+static uint32 afp_get_or_create_entry_id(const char *unixname, int volume,
+                                         const struct stat *stb,
+                                         int *fallback_out)
+/*
+ * Return a persistent mars_nwe AFP entry id when available.  If neither the
+ * mars_nwe xattr nor Netatalk/libatalk metadata contains an id yet, derive the
+ * existing stat-backed compatibility id and cache that id in mars_nwe's private
+ * AFP xattr namespace.  The first caller still records fallback diagnostics so
+ * the log remains honest about the id origin; follow-up requests should read the
+ * xattr directly and no longer need the temporary stat derivation path.
+ */
+{
+  uint32 entry_id = 0;
+  int result;
+
+  result = nwatalk_get_entry_id(unixname, &entry_id);
+  if (!result && entry_id) {
+    if (fallback_out) *fallback_out = 0;
+    return(entry_id);
+  }
+
+  entry_id = afp_fallback_entry_id(volume, stb);
+  if (fallback_out) *fallback_out = 1;
+  (void)nwatalk_set_entry_id(unixname, entry_id);
+  return(entry_id);
+}
+
 static int afp_get_entry_id_from_name(uint8 *afp_req, int afp_len,
                                       uint8 *response)
 {
@@ -561,15 +589,13 @@ static int afp_get_entry_id_from_name(uint8 *afp_req, int afp_len,
     return(-0x9c); /* Invalid Path */
   }
 
-  result = nwatalk_get_entry_id(unixname, &entry_id);
-  if (result < 0 || !entry_id)
-    entry_id = afp_fallback_entry_id(volume, &stbuff);
+  entry_id = afp_get_or_create_entry_id(unixname, volume, &stbuff, &result);
 
   U32_TO_BE32(entry_id, response);
   XDPRINTF((3,0, "AFP Get Entry ID From Name: vol=%d entry=0x%08x path='%s' reply_entry=0x%08x%s",
             (int)volume_number, request_entry_id,
             visable_data(afp_req + 7, path_len), entry_id,
-            (result < 0) ? " fallback" : ""));
+            result ? " fallback" : ""));
   return(4);
 }
 
@@ -612,9 +638,7 @@ static int afp_get_entry_id_from_netware_handle(uint8 *afp_req, int afp_len,
   volume = afp_volume_from_unixname((char *)unixname);
   if (volume < 0) volume = 0;
 
-  result = nwatalk_get_entry_id((char *)unixname, &entry_id);
-  if (result < 0 || !entry_id)
-    entry_id = afp_fallback_entry_id(volume, &stbuff);
+  entry_id = afp_get_or_create_entry_id((char *)unixname, volume, &stbuff, &result);
 
   response[0] = (uint8)volume;
   U32_TO_BE32(entry_id, response + 1);
@@ -622,7 +646,7 @@ static int afp_get_entry_id_from_netware_handle(uint8 *afp_req, int afp_len,
 
   XDPRINTF((3,0, "AFP Get Entry ID From NetWare Handle: handle=%u volume=%d unix='%s' entry=0x%08x%s",
             fhandle, volume, unixname, entry_id,
-            (result < 0) ? " fallback" : ""));
+            result ? " fallback" : ""));
   return(6);
 }
 
@@ -844,14 +868,12 @@ static int afp_get_entry_id_from_path_name(uint8 *afp_req, int afp_len,
     return(-0x9c); /* Invalid Path */
   }
 
-  result = nwatalk_get_entry_id(unixname, &entry_id);
-  if (result < 0 || !entry_id)
-    entry_id = afp_fallback_entry_id(volume, &stbuff);
+  entry_id = afp_get_or_create_entry_id(unixname, volume, &stbuff, &result);
 
   U32_TO_BE32(entry_id, response);
   XDPRINTF((3,0, "AFP Get Entry ID From Path Name: dh=%d path='%s' entry=0x%08x%s",
             (int)dir_handle, visable_data(afp_req + 3, path_len), entry_id,
-            (result < 0) ? " fallback" : ""));
+            result ? " fallback" : ""));
   return(4);
 }
 
@@ -956,16 +978,11 @@ static int afp_fill_file_info_response(const char *unixname,
   uint32 parent_id = 0;
   uint32 resource_size = 0;
   uint8 finder_info[NWATALK_FINDER_INFO_LEN];
-  int result;
 
   if (stat(unixname, &stbuff))
     return(-0x9c); /* Invalid Path */
 
-  result = nwatalk_get_entry_id(unixname, &entry_id);
-  if (result < 0 || !entry_id) {
-    entry_id = afp_fallback_entry_id(volume, &stbuff);
-    if (fallback_out) *fallback_out = 1;
-  } else if (fallback_out) *fallback_out = 0;
+  entry_id = afp_get_or_create_entry_id(unixname, volume, &stbuff, fallback_out);
 
   memset(response, 0, 120);
   U32_TO_BE32(entry_id, response + 0);
@@ -1280,7 +1297,6 @@ static int afp_scan_file_information(uint8 *afp_req, int afp_len,
     struct stat stbuff;
     int child_fallback = 0;
     uint32 child_entry_id = 0;
-    int child_result;
 
     if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
       continue;
@@ -1289,11 +1305,8 @@ static int afp_scan_file_information(uint8 *afp_req, int afp_len,
     if (stat(childname, &stbuff))
       continue;
 
-    child_result = nwatalk_get_entry_id(childname, &child_entry_id);
-    if (child_result < 0 || !child_entry_id) {
-      child_entry_id = afp_fallback_entry_id(volume, &stbuff);
-      child_fallback = 1;
-    }
+    child_entry_id = afp_get_or_create_entry_id(childname, volume, &stbuff,
+                                                &child_fallback);
 
     if (last_seen_id && !seen) {
       if (child_entry_id == last_seen_id)