api: Make sure dict_set_var doesn’t edit read-only values

Fixes #6147

src/nvim/api/private/helpers.c

@@ -131,6 +131,19 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del,
 
   dictitem_T *di = dict_find(dict, (char_u *)key.data, (int)key.size);
 
+  if (di != NULL) {
+    if (di->di_flags & DI_FLAGS_RO) {
+      api_set_error(err, Exception, _("Key is read-only: %s"), key.data);
+      return rv;
+    } else if (di->di_flags & DI_FLAGS_FIX) {
+      api_set_error(err, Exception, _("Key is fixed: %s"), key.data);
+      return rv;
+    } else if (di->di_flags & DI_FLAGS_LOCK) {
+      api_set_error(err, Exception, _("Key is locked: %s"), key.data);
+      return rv;
+    }
+  }
+
   if (del) {
     // Delete the key
     if (di == NULL) {

test/functional/api/buffer_spec.lua

@@ -6,6 +6,8 @@ local funcs = helpers.funcs
 local request = helpers.request
 local neq = helpers.neq
 local NIL = helpers.NIL
+local meth_pcall = helpers.meth_pcall
+local command = helpers.command
 
 describe('api/buf', function()
   before_each(clear)
@@ -251,6 +253,15 @@ describe('api/buf', function()
       eq(1, funcs.exists('b:lua'))
       curbufmeths.del_var('lua')
       eq(0, funcs.exists('b:lua'))
+      eq({false, 'Key "lua" doesn\'t exist'}, meth_pcall(curbufmeths.del_var, 'lua'))
+      curbufmeths.set_var('lua', 1)
+      command('lockvar b:lua')
+      eq({false, 'Key is locked: lua'}, meth_pcall(curbufmeths.del_var, 'lua'))
+      eq({false, 'Key is locked: lua'}, meth_pcall(curbufmeths.set_var, 'lua', 1))
+      eq({false, 'Key is read-only: changedtick'},
+         meth_pcall(curbufmeths.del_var, 'changedtick'))
+      eq({false, 'Key is read-only: changedtick'},
+         meth_pcall(curbufmeths.set_var, 'changedtick', 1))
     end)
   end)
 

test/functional/api/tabpage_spec.lua

@@ -6,6 +6,8 @@ local curtabmeths = helpers.curtabmeths
 local funcs = helpers.funcs
 local request = helpers.request
 local NIL = helpers.NIL
+local meth_pcall = helpers.meth_pcall
+local command = helpers.command
 
 describe('api/tabpage', function()
   before_each(clear)
@@ -32,6 +34,11 @@ describe('api/tabpage', function()
       eq(1, funcs.exists('t:lua'))
       curtabmeths.del_var('lua')
       eq(0, funcs.exists('t:lua'))
+      eq({false, 'Key "lua" doesn\'t exist'}, meth_pcall(curtabmeths.del_var, 'lua'))
+      curtabmeths.set_var('lua', 1)
+      command('lockvar t:lua')
+      eq({false, 'Key is locked: lua'}, meth_pcall(curtabmeths.del_var, 'lua'))
+      eq({false, 'Key is locked: lua'}, meth_pcall(curtabmeths.set_var, 'lua', 1))
     end)
 
     it('tabpage_set_var returns the old value', function()

test/functional/api/vim_spec.lua

@@ -7,6 +7,8 @@ local os_name = helpers.os_name
 local meths = helpers.meths
 local funcs = helpers.funcs
 local request = helpers.request
+local meth_pcall = helpers.meth_pcall
+local command = helpers.command
 
 describe('api', function()
   before_each(clear)
@@ -117,6 +119,11 @@ describe('api', function()
       eq(1, funcs.exists('g:lua'))
       meths.del_var('lua')
       eq(0, funcs.exists('g:lua'))
+      eq({false, 'Key "lua" doesn\'t exist'}, meth_pcall(meths.del_var, 'lua'))
+      meths.set_var('lua', 1)
+      command('lockvar lua')
+      eq({false, 'Key is locked: lua'}, meth_pcall(meths.del_var, 'lua'))
+      eq({false, 'Key is locked: lua'}, meth_pcall(meths.set_var, 'lua', 1))
     end)
 
     it('vim_set_var returns the old value', function()

test/functional/api/window_spec.lua

@@ -8,6 +8,8 @@ local curwinmeths = helpers.curwinmeths
 local funcs = helpers.funcs
 local request = helpers.request
 local NIL = helpers.NIL
+local meth_pcall = helpers.meth_pcall
+local command = helpers.command
 
 -- check if str is visible at the beginning of some line
 local function is_visible(str)
@@ -137,6 +139,11 @@ describe('api/win', function()
       eq(1, funcs.exists('w:lua'))
       curwinmeths.del_var('lua')
       eq(0, funcs.exists('w:lua'))
+      eq({false, 'Key "lua" doesn\'t exist'}, meth_pcall(curwinmeths.del_var, 'lua'))
+      curwinmeths.set_var('lua', 1)
+      command('lockvar w:lua')
+      eq({false, 'Key is locked: lua'}, meth_pcall(curwinmeths.del_var, 'lua'))
+      eq({false, 'Key is locked: lua'}, meth_pcall(curwinmeths.set_var, 'lua', 1))
     end)
 
     it('window_set_var returns the old value', function()

test/functional/eval/changedtick_spec.lua

@@ -1,16 +1,17 @@
 local helpers = require('test.functional.helpers')(after_each)
 
-local curbufmeths = helpers.curbufmeths
-local clear = helpers.clear
 local eq = helpers.eq
 local neq = helpers.neq
 local eval = helpers.eval
 local feed = helpers.feed
+local clear = helpers.clear
 local funcs = helpers.funcs
 local meths = helpers.meths
 local command = helpers.command
 local exc_exec = helpers.exc_exec
 local redir_exec = helpers.redir_exec
+local meth_pcall = helpers.meth_pcall
+local curbufmeths = helpers.curbufmeths
 
 before_each(clear)
 
@@ -66,9 +67,8 @@ describe('b:changedtick', function()
        redir_exec('let b:.changedtick = ' .. ctn))
     eq('\nE46: Cannot change read-only variable "d.changedtick"',
        redir_exec('let d.changedtick = ' .. ctn))
-    -- FIXME
-    -- eq({fales, ''},
-       -- {pcall(curbufmeths.set_var, 'changedtick', ctn)})
+    eq({false, 'Key is read-only: changedtick'},
+       meth_pcall(curbufmeths.set_var, 'changedtick', ctn))
 
     eq('\nE795: Cannot delete variable b:changedtick',
        redir_exec('unlet b:changedtick'))
@@ -78,9 +78,8 @@ describe('b:changedtick', function()
        redir_exec('unlet b:["changedtick"]'))
     eq('\nE46: Cannot change read-only variable "d.changedtick"',
        redir_exec('unlet d.changedtick'))
-    -- FIXME
-    -- eq({},
-       -- {pcall(curbufmeths.del_var, 'changedtick')})
+    eq({false, 'Key is read-only: changedtick'},
+       meth_pcall(curbufmeths.del_var, 'changedtick'))
     eq(ct, changedtick())
 
     eq('\nE46: Cannot change read-only variable "b:["changedtick"]"',

test/functional/helpers.lua

@@ -534,6 +534,14 @@ local function skip_fragile(pending_fn, cond)
   return false
 end
 
+local function meth_pcall(...)
+  local ret = {pcall(...)}
+  if type(ret[2]) == 'string' then
+    ret[2] = ret[2]:gsub('^[^:]+:%d+: ', '')
+  end
+  return ret
+end
+
 local funcs = create_callindex(nvim_call)
 local meths = create_callindex(nvim)
 local uimeths = create_callindex(ui)
@@ -604,6 +612,7 @@ local M = {
   skip_fragile = skip_fragile,
   set_shell_powershell = set_shell_powershell,
   tmpname = tmpname,
+  meth_pcall = meth_pcall,
   NIL = mpack.NIL,
 }