fix(autocmd): api functions accepting garbage after event name

"VimEnter foo" was accepted as a valid event name for "VimEnter".
Events delimited with commas, eg. "VimEnter,BufRead", were also
accepted, even though only the first event was actually parsed.

(cherry picked from commit 1397016259)

src/nvim/api/autocmd.c

@@ -33,13 +33,11 @@
 // Copy string or array of strings into an empty array.
 // Get the event number, unless it is an error. Then goto `goto_name`.
 #define GET_ONE_EVENT(event_nr, event_str, goto_name) \
-  char *__next_ev; \
   event_T event_nr = \
-    event_name2nr(event_str.data.string.data, &__next_ev); \
+    event_name2nr_str(event_str.data.string); \
-  if (event_nr >= NUM_EVENTS) { \
+  VALIDATE_S((event_nr < NUM_EVENTS), "event", event_str.data.string.data, { \
-    api_set_error(err, kErrorTypeValidation, "unexpected event"); \
     goto goto_name; \
-  }
+  });
 
 // ID for associating autocmds created via nvim_create_autocmd
 // Used to delete autocmds from nvim_del_autocmd

src/nvim/autocmd.c

@@ -675,9 +675,9 @@ bool is_aucmd_win(win_T *win)
   return false;
 }
 
-// Return the event number for event name "start".
+/// Return the event number for event name "start".
-// Return NUM_EVENTS if the event name was not found.
+/// Return NUM_EVENTS if the event name was not found.
-// Return a pointer to the next event name in "end".
+/// Return a pointer to the next event name in "end".
 event_T event_name2nr(const char *start, char **end)
 {
   const char *p;
@@ -701,6 +701,18 @@ event_T event_name2nr(const char *start, char **end)
   return event_names[i].event;
 }
 
+/// Return the event number for event name "str".
+/// Return NUM_EVENTS if the event name was not found.
+event_T event_name2nr_str(String str)
+{
+  for (int i = 0; event_names[i].name != NULL; i++) {
+    if (str.size == event_names[i].len && STRNICMP(str.data, event_names[i].name, str.size) == 0) {
+      return event_names[i].event;
+    }
+  }
+  return NUM_EVENTS;
+}
+
 /// Return the name for event
 ///
 /// @param[in]  event  Event to return name for.

test/functional/api/autocmd_spec.lua

@@ -43,6 +43,11 @@ describe('autocmd api', function()
         group = 0,
         command = 'ls',
       }))
+
+      eq("Invalid 'event': 'foo'", pcall_err(meths.create_autocmd, 'foo', { command = '' }))
+      eq("Invalid 'event': 'VimEnter '", pcall_err(meths.create_autocmd, 'VimEnter ', { command = '' }))
+      eq("Invalid 'event': 'VimEnter foo'", pcall_err(meths.create_autocmd, 'VimEnter foo', { command = '' }))
+      eq("Invalid 'event': 'BufAdd,BufDelete'", pcall_err(meths.create_autocmd, 'BufAdd,BufDelete', { command = '' }))
     end)
 
     it('doesnt leak when you use ++once', function()