feat(eval): writefile() treats RPC string as "blob"

related: fb6aeaba2d

runtime/doc/news.txt

@@ -255,8 +255,8 @@ LUA
   terminal supports it.
 • |vim.net.request()| can specify custom headers by passing `opts.headers`.
 • |vim.net.request()| can now accept  `method` param overload for multiple HTTP methods.
-• |writefile()| treats Lua strings as "blob", so it can be used to write
-  binary data.
+• |writefile()| treats Lua and RPC strings as |Blob|, so it can be used to
+  write binary data.
 • |vim.fs.dir()| with `opts.err=true`, reports errors. An inaccessible root
   dir yields a single (name, nil, err) item.
 • |vim.fs.find()| returns a list of errors as its second return value.

src/nvim/api/vimscript.c

@@ -197,7 +197,8 @@ Object nvim_eval(String expr, Arena *arena, Error *err)
 /// @param self `self` dict, or NULL for non-dict functions
 /// @param[out] err Error details, if any
 /// @return Result of the function call
-static Object _call_function(String fn, Array args, dict_T *self, Arena *arena, Error *err)
+static Object _call_function(uint64_t channel_id, String fn, Array args, dict_T *self, Arena *arena,
+                             Error *err)
 {
   static int recursive = 0;  // recursion depth
   Object rv = OBJECT_INIT;
@@ -233,9 +234,11 @@ static Object _call_function(String fn, Array args, dict_T *self, Arena *arena,
   funcexe.fe_selfdict = self;
 
   TRY_WRAP(err, {
+    const sctx_T save_current_sctx = api_set_sctx(channel_id);
     // call_func() retval is deceptive, ignore it.  Instead TRY_WRAP sets `msg_list` to capture
     // abort-causing non-exception errors.
     (void)call_func(fn.data, (int)fn.size, &rettv, (int)args.size, vim_args, &funcexe);
+    current_sctx = save_current_sctx;
   });
 
   if (!ERROR_SET(err)) {
@@ -260,10 +263,10 @@ static Object _call_function(String fn, Array args, dict_T *self, Arena *arena,
 /// @param args     Function arguments packed in an Array
 /// @param[out] err Error details, if any
 /// @return Result of the function call
-Object nvim_call_function(String fn, Array args, Arena *arena, Error *err)
+Object nvim_call_function(uint64_t channel_id, String fn, Array args, Arena *arena, Error *err)
   FUNC_API_SINCE(1)
 {
-  return _call_function(fn, args, NULL, arena, err);
+  return _call_function(channel_id, fn, args, NULL, arena, err);
 }
 
 /// Calls a Vimscript |Dictionary-function| with the given arguments.
@@ -275,7 +278,8 @@ Object nvim_call_function(String fn, Array args, Arena *arena, Error *err)
 /// @param args Function arguments packed in an Array
 /// @param[out] err Error details, if any
 /// @return Result of the function call
-Object nvim_call_dict_function(Object dict, String fn, Array args, Arena *arena, Error *err)
+Object nvim_call_dict_function(uint64_t channel_id, Object dict, String fn, Array args,
+                               Arena *arena, Error *err)
   FUNC_API_SINCE(4)
 {
   Object rv = OBJECT_INIT;
@@ -337,7 +341,7 @@ Object nvim_call_dict_function(Object dict, String fn, Array args, Arena *arena,
     goto end;
   });
 
-  rv = _call_function(fn, args, self_dict, arena, err);
+  rv = _call_function(channel_id, fn, args, self_dict, arena, err);
 end:
   if (mustfree) {
     tv_clear(&rettv);

src/nvim/eval/fs.c

@@ -1794,8 +1794,10 @@ void f_writefile(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
       }
     });
   } else if (argvars[0].v_type != VAR_BLOB
-             // Always treat Lua strings as "blob" data.
-             && !(argvars[0].v_type == VAR_STRING && script_is_lua(current_sctx.sc_sid))) {
+             // Always treat Lua/RPC strings as "blob" data.
+             && !(argvars[0].v_type == VAR_STRING
+                  && (script_is_lua(current_sctx.sc_sid)
+                      || current_sctx.sc_sid == SID_API_CLIENT))) {
     semsg(_(e_invarg2), _("writefile() first argument must be a List or a Blob"));
     return;
   }

test/functional/vimscript/writefile_spec.lua

@@ -107,11 +107,18 @@ describe('writefile()', function()
     eq('a\0', read_file(fname))
   end)
 
-  it('writes Lua (binary) strings to a file', function()
+  it('writes Lua (binary) strings', function()
     eq(0, exec_lua([[return vim.fn.writefile('foo\0bar', ..., 'b')]], fname))
     eq('foo\0bar', read_file(fname))
   end)
 
+  it('writes RPC-API (binary) String', function()
+    eq(0, api.nvim_call_function('writefile', { 'foobar', fname }))
+    eq('foobar', read_file(fname))
+    eq(0, api.nvim_call_function('writefile', { 'foo\0bar', fname }))
+    eq('foo\0bar', read_file(fname))
+  end)
+
   it('shows correct file name when supplied numbers', function()
     api.nvim_set_current_dir(dname)
     eq(