msgpack-rpc: Accept method names in requests

scripts/msgpack-gen.lua

@@ -91,6 +91,7 @@ output:write([[
 #include <assert.h>
 #include <msgpack.h>
 
+#include "nvim/map.h"
 #include "nvim/log.h"
 #include "nvim/os/msgpack_rpc.h"
 #include "nvim/os/msgpack_rpc_helpers.h"
@@ -241,12 +242,49 @@ for i = 1, #api.functions do
 end
 output:write('\n};\n\n')
 
+-- Generate a function that initializes method names with handler functions
 output:write([[
+static Map(cstr_t, uint64_t) *rpc_method_ids = NULL;
+
+void msgpack_rpc_init(void)
+{
+  rpc_method_ids = map_new(cstr_t, uint64_t)();
+
+]])
+
+-- Msgpack strings must be copied to a 0-terminated temporary buffer before
+-- searching in the map, so we keep track of the maximum method name length in
+-- order to create the smallest possible buffer for xstrlcpy
+local max_fname_len = 0
+for i = 1, #api.functions do
+  local fn = api.functions[i]
+  output:write('  map_put(cstr_t, uint64_t)(rpc_method_ids, "'
+               ..fn.name..'", '..i..');\n')
+  if #fn.name > max_fname_len then
+    max_fname_len = #fn.name
+  end
+end
+
+output:write('\n}\n\n')
+
+output:write([[
+#define min(X, Y) (X < Y ? X : Y)
+
 Object msgpack_rpc_dispatch(uint64_t channel_id,
-                            uint64_t method_id,
                             msgpack_object *req,
                             Error *error)
 {
+  msgpack_object method = req->via.array.ptr[2];
+  uint64_t method_id = method.via.u64;
+
+  if (method.type == MSGPACK_OBJECT_RAW) {
+    char method_name[]]..(max_fname_len + 1)..[[];
+    xstrlcpy(method_name, method.via.raw.ptr, min(method.via.raw.size, ]] ..(max_fname_len)..[[) + 1);
+    method_id = map_get(cstr_t, uint64_t)(rpc_method_ids, method_name);
+    if (!method_id) {
+      method_id = UINT64_MAX;
+    }
+  }
 ]])
 output:write('\n  // method_id=0 is specially handled')
 output:write('\n  assert(method_id > 0);')

src/nvim/os/msgpack_rpc.c

@@ -39,15 +39,14 @@ WBuffer *msgpack_rpc_call(uint64_t channel_id,
     return serialize_response(response_id, err, NIL, sbuffer);
   }
 
-  uint64_t method_id = req->via.array.ptr[2].via.u64;
-
-  if (method_id == 0) {
+  if (req->via.array.ptr[2].type == MSGPACK_OBJECT_POSITIVE_INTEGER
+     && req->via.array.ptr[2].via.u64 == 0) {
     return serialize_metadata(response_id, channel_id, sbuffer);
   }
 
   // dispatch the call
   Error error = { .set = false };
-  Object rv = msgpack_rpc_dispatch(channel_id, method_id, req, &error);
+  Object rv = msgpack_rpc_dispatch(channel_id, req, &error);
   // send the response
   msgpack_packer response;
   msgpack_packer_init(&response, sbuffer, msgpack_sbuffer_write);
@@ -235,8 +234,9 @@ static char *msgpack_rpc_validate(uint64_t *response_id, msgpack_object *req)
     return "Message type must be 0";
   }
 
-  if (req->via.array.ptr[2].type != MSGPACK_OBJECT_POSITIVE_INTEGER) {
-    return "Method id must be a positive integer";
+  if (req->via.array.ptr[2].type != MSGPACK_OBJECT_POSITIVE_INTEGER
+      && req->via.array.ptr[2].type != MSGPACK_OBJECT_RAW) {
+    return "Method must be a positive integer or a string";
   }
 
   if (req->via.array.ptr[3].type != MSGPACK_OBJECT_ARRAY) {

src/nvim/os/msgpack_rpc.h

@@ -21,6 +21,11 @@ typedef Object (*rpc_method_handler_fn)(uint64_t channel_id,
                                         msgpack_object *req,
                                         Error *error);
 
+
+/// Initializes the msgpack-rpc method table
+void msgpack_rpc_init(void);
+
+
 /// Dispatches to the actual API function after basic payload validation by
 /// `msgpack_rpc_call`. It is responsible for validating/converting arguments
 /// to C types, and converting the return value back to msgpack types.
@@ -33,11 +38,11 @@ typedef Object (*rpc_method_handler_fn)(uint64_t channel_id,
 /// @param error Pointer to error structure
 /// @return Some object
 Object msgpack_rpc_dispatch(uint64_t channel_id,
-                            uint64_t method_id,
                             msgpack_object *req,
                             Error *error)
   FUNC_ATTR_NONNULL_ARG(2) FUNC_ATTR_NONNULL_ARG(3);
 
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/msgpack_rpc.h.generated.h"
 #endif

src/nvim/os_unix.c

@@ -54,6 +54,7 @@
 #include "nvim/os/shell.h"
 #include "nvim/os/signal.h"
 #include "nvim/os/job.h"
+#include "nvim/os/msgpack_rpc.h"
 
 #if defined(HAVE_SYS_IOCTL_H)
 # include <sys/ioctl.h>
@@ -164,6 +165,7 @@ void mch_init(void)
   mac_conv_init();
 #endif
 
+  msgpack_rpc_init();
   event_init();
 }