1 files changed, 287 insertions, 78 deletions

diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index fe15b28041..12a4279dd7 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -1,3 +1,6 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
 #include <assert.h>
 #include <inttypes.h>
 #include <stdbool.h>
@@ -9,6 +12,7 @@
 #include "nvim/api/private/handle.h"
 #include "nvim/msgpack_rpc/helpers.h"
 #include "nvim/ascii.h"
+#include "nvim/assert.h"
 #include "nvim/vim.h"
 #include "nvim/buffer.h"
 #include "nvim/window.h"
@@ -21,6 +25,8 @@
 #include "nvim/option_defs.h"
 #include "nvim/version.h"
 #include "nvim/lib/kvec.h"
+#include "nvim/getchar.h"
+#include "nvim/ui.h"
 
 /// Helper structure for vim_to_object
 typedef struct {
@@ -30,9 +36,74 @@ typedef struct {
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/private/helpers.c.generated.h"
 # include "api/private/funcs_metadata.generated.h"
+# include "api/private/ui_events_metadata.generated.h"
 #endif
 
+/// Start block that may cause VimL exceptions while evaluating another code
+///
+/// Used when caller is supposed to be operating when other VimL code is being
+/// processed and that “other VimL code” must not be affected.
+///
+/// @param[out]  tstate  Location where try state should be saved.
+void try_enter(TryState *const tstate)
+{
+  // TODO(ZyX-I): Check whether try_enter()/try_leave() may use
+  //              enter_cleanup()/leave_cleanup(). Or
+  //              save_dbg_stuff()/restore_dbg_stuff().
+  *tstate = (TryState) {
+    .current_exception = current_exception,
+    .msg_list = (const struct msglist *const *)msg_list,
+    .private_msg_list = NULL,
+    .trylevel = trylevel,
+    .got_int = got_int,
+    .need_rethrow = need_rethrow,
+    .did_emsg = did_emsg,
+  };
+  msg_list = &tstate->private_msg_list;
+  current_exception = NULL;
+  trylevel = 1;
+  got_int = false;
+  need_rethrow = false;
+  did_emsg = false;
+}
+
+/// End try block, set the error message if any and restore previous state
+///
+/// @warning Return is consistent with most functions (false on error), not with
+///          try_end (true on error).
+///
+/// @param[in]  tstate  Previous state to restore.
+/// @param[out]  err  Location where error should be saved.
+///
+/// @return false if error occurred, true otherwise.
+bool try_leave(const TryState *const tstate, Error *const err)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  const bool ret = !try_end(err);
+  assert(trylevel == 0);
+  assert(!need_rethrow);
+  assert(!got_int);
+  assert(!did_emsg);
+  assert(msg_list == &tstate->private_msg_list);
+  assert(*msg_list == NULL);
+  assert(current_exception == NULL);
+  msg_list = (struct msglist **)tstate->msg_list;
+  current_exception = tstate->current_exception;
+  trylevel = tstate->trylevel;
+  got_int = tstate->got_int;
+  need_rethrow = tstate->need_rethrow;
+  did_emsg = tstate->did_emsg;
+  return ret;
+}
+
 /// Start block that may cause vimscript exceptions
+///
+/// Each try_start() call should be mirrored by try_end() call.
+///
+/// To be used as a replacement of `:try … catch … endtry` in C code, in cases
+/// when error flag could not already be set. If there may be pending error
+/// state at the time try_start() is executed which needs to be preserved,
+/// try_enter()/try_leave() pair should be used instead.
 void try_start(void)
 {
   ++trylevel;
@@ -45,7 +116,9 @@ void try_start(void)
 /// @return true if an error occurred
 bool try_end(Error *err)
 {
-  --trylevel;
+  // Note: all globals manipulated here should be saved/restored in
+  // try_enter/try_leave.
+  trylevel--;
 
   // Without this it stops processing all subsequent VimL commands and
   // generates strange error messages if I e.g. try calling Test() in a
@@ -53,12 +126,12 @@ bool try_end(Error *err)
   did_emsg = false;
 
   if (got_int) {
-    if (did_throw) {
+    if (current_exception) {
       // If we got an interrupt, discard the current exception
       discard_current_exception();
     }
 
-    api_set_error(err, Exception, _("Keyboard interrupt"));
+    api_set_error(err, kErrorTypeException, "Keyboard interrupt");
     got_int = false;
   } else if (msg_list != NULL && *msg_list != NULL) {
     int should_free;
@@ -66,19 +139,18 @@ bool try_end(Error *err)
                                              ET_ERROR,
                                              NULL,
                                              &should_free);
-    xstrlcpy(err->msg, msg, sizeof(err->msg));
-    err->set = true;
+    api_set_error(err, kErrorTypeException, "%s", msg);
     free_global_msglist();
 
     if (should_free) {
       xfree(msg);
     }
-  } else if (did_throw) {
-    api_set_error(err, Exception, "%s", current_exception->value);
+  } else if (current_exception) {
+    api_set_error(err, kErrorTypeException, "%s", current_exception->value);
     discard_current_exception();
   }
 
-  return err->set;
+  return ERROR_SET(err);
 }
 
 /// Recursively expands a vimscript value in a dict
@@ -91,8 +163,8 @@ Object dict_get_value(dict_T *dict, String key, Error *err)
   dictitem_T *const di = tv_dict_find(dict, key.data, (ptrdiff_t)key.size);
 
   if (di == NULL) {
-    api_set_error(err, Validation, _("Key not found"));
-    return (Object) OBJECT_INIT;
+    api_set_error(err, kErrorTypeValidation, "Key '%s' not found", key.data);
+    return (Object)OBJECT_INIT;
   }
 
   return vim_to_object(&di->di_tv);
@@ -115,17 +187,18 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del,
   Object rv = OBJECT_INIT;
 
   if (dict->dv_lock) {
-    api_set_error(err, Exception, _("Dictionary is locked"));
+    api_set_error(err, kErrorTypeException, "Dictionary is locked");
     return rv;
   }
 
   if (key.size == 0) {
-    api_set_error(err, Validation, _("Empty variable names aren't allowed"));
+    api_set_error(err, kErrorTypeValidation,
+                  "Empty variable names aren't allowed");
     return rv;
   }
 
   if (key.size > INT_MAX) {
-    api_set_error(err, Validation, _("Key length is too high"));
+    api_set_error(err, kErrorTypeValidation, "Key length is too high");
     return rv;
   }
 
@@ -133,13 +206,13 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del,
 
   if (di != NULL) {
     if (di->di_flags & DI_FLAGS_RO) {
-      api_set_error(err, Exception, _("Key is read-only: %s"), key.data);
+      api_set_error(err, kErrorTypeException, "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);
+      api_set_error(err, kErrorTypeException, "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);
+      api_set_error(err, kErrorTypeException, "Key is locked: %s", key.data);
       return rv;
     }
   }
@@ -148,7 +221,8 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del,
     // Delete the key
     if (di == NULL) {
       // Doesn't exist, fail
-      api_set_error(err, Validation, _("Key \"%s\" doesn't exist"), key.data);
+      api_set_error(err, kErrorTypeValidation, "Key does not exist: %s",
+                    key.data);
     } else {
       // Return the old value
       if (retval) {
@@ -200,7 +274,7 @@ Object get_option_from(void *from, int type, String name, Error *err)
   Object rv = OBJECT_INIT;
 
   if (name.size == 0) {
-    api_set_error(err, Validation, _("Empty option name"));
+    api_set_error(err, kErrorTypeValidation, "Empty option name");
     return rv;
   }
 
@@ -212,8 +286,8 @@ Object get_option_from(void *from, int type, String name, Error *err)
 
   if (!flags) {
     api_set_error(err,
-                  Validation,
-                  _("Invalid option name \"%s\""),
+                  kErrorTypeValidation,
+                  "Invalid option name \"%s\"",
                   name.data);
     return rv;
   }
@@ -231,14 +305,14 @@ Object get_option_from(void *from, int type, String name, Error *err)
       rv.data.string.size = strlen(stringval);
     } else {
       api_set_error(err,
-                    Exception,
-                    _("Unable to get value for option \"%s\""),
+                    kErrorTypeException,
+                    "Unable to get value for option \"%s\"",
                     name.data);
     }
   } else {
     api_set_error(err,
-                  Exception,
-                  _("Unknown type for option \"%s\""),
+                  kErrorTypeException,
+                  "Unknown type for option \"%s\"",
                   name.data);
   }
 
@@ -255,7 +329,7 @@ Object get_option_from(void *from, int type, String name, Error *err)
 void set_option_to(void *to, int type, String name, Object value, Error *err)
 {
   if (name.size == 0) {
-    api_set_error(err, Validation, _("Empty option name"));
+    api_set_error(err, kErrorTypeValidation, "Empty option name");
     return;
   }
 
@@ -263,8 +337,8 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
 
   if (flags == 0) {
     api_set_error(err,
-                  Validation,
-                  _("Invalid option name \"%s\""),
+                  kErrorTypeValidation,
+                  "Invalid option name \"%s\"",
                   name.data);
     return;
   }
@@ -272,15 +346,15 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
   if (value.type == kObjectTypeNil) {
     if (type == SREQ_GLOBAL) {
       api_set_error(err,
-                    Exception,
-                    _("Unable to unset option \"%s\""),
+                    kErrorTypeException,
+                    "Unable to unset option \"%s\"",
                     name.data);
       return;
     } else if (!(flags & SOPT_GLOBAL)) {
       api_set_error(err,
-                    Exception,
-                    _("Cannot unset option \"%s\" "
-                      "because it doesn't have a global value"),
+                    kErrorTypeException,
+                    "Cannot unset option \"%s\" "
+                    "because it doesn't have a global value",
                     name.data);
       return;
     } else {
@@ -294,8 +368,8 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
   if (flags & SOPT_BOOL) {
     if (value.type != kObjectTypeBoolean) {
       api_set_error(err,
-                    Validation,
-                    _("Option \"%s\" requires a boolean value"),
+                    kErrorTypeValidation,
+                    "Option \"%s\" requires a boolean value",
                     name.data);
       return;
     }
@@ -305,16 +379,16 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
   } else if (flags & SOPT_NUM) {
     if (value.type != kObjectTypeInteger) {
       api_set_error(err,
-                    Validation,
-                    _("Option \"%s\" requires an integer value"),
+                    kErrorTypeValidation,
+                    "Option \"%s\" requires an integer value",
                     name.data);
       return;
     }
 
     if (value.data.integer > INT_MAX || value.data.integer < INT_MIN) {
       api_set_error(err,
-                    Validation,
-                    _("Value for option \"%s\" is outside range"),
+                    kErrorTypeValidation,
+                    "Value for option \"%s\" is outside range",
                     name.data);
       return;
     }
@@ -324,8 +398,8 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
   } else {
     if (value.type != kObjectTypeString) {
       api_set_error(err,
-                    Validation,
-                    _("Option \"%s\" requires a string value"),
+                    kErrorTypeValidation,
+                    "Option \"%s\" requires a string value",
                     name.data);
       return;
     }
@@ -349,7 +423,7 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
 #define TYPVAL_ENCODE_CONV_UNSIGNED_NUMBER TYPVAL_ENCODE_CONV_NUMBER
 
 #define TYPVAL_ENCODE_CONV_FLOAT(tv, flt) \
-    kv_push(edata->stack, FLOATING_OBJ((Float)(flt)))
+    kv_push(edata->stack, FLOAT_OBJ((Float)(flt)))
 
 #define TYPVAL_ENCODE_CONV_STRING(tv, str, len) \
     do { \
@@ -492,7 +566,7 @@ static inline void typval_encode_dict_end(EncodedData *const edata)
     typval_encode_dict_end(edata)
 
 #define TYPVAL_ENCODE_CONV_RECURSE(val, conv_type) \
-    TYPVAL_ENCODE_CONV_NIL()
+    TYPVAL_ENCODE_CONV_NIL(val)
 
 #define TYPVAL_ENCODE_SCOPE static
 #define TYPVAL_ENCODE_NAME object
@@ -558,13 +632,13 @@ buf_T *find_buffer_by_handle(Buffer buffer, Error *err)
   buf_T *rv = handle_get_buffer(buffer);
 
   if (!rv) {
-    api_set_error(err, Validation, _("Invalid buffer id"));
+    api_set_error(err, kErrorTypeValidation, "Invalid buffer id");
   }
 
   return rv;
 }
 
-win_T * find_window_by_handle(Window window, Error *err)
+win_T *find_window_by_handle(Window window, Error *err)
 {
   if (window == 0) {
     return curwin;
@@ -573,13 +647,13 @@ win_T * find_window_by_handle(Window window, Error *err)
   win_T *rv = handle_get_window(window);
 
   if (!rv) {
-    api_set_error(err, Validation, _("Invalid window id"));
+    api_set_error(err, kErrorTypeValidation, "Invalid window id");
   }
 
   return rv;
 }
 
-tabpage_T * find_tab_by_handle(Tabpage tabpage, Error *err)
+tabpage_T *find_tab_by_handle(Tabpage tabpage, Error *err)
 {
   if (tabpage == 0) {
     return curtab;
@@ -588,12 +662,28 @@ tabpage_T * find_tab_by_handle(Tabpage tabpage, Error *err)
   tabpage_T *rv = handle_get_tabpage(tabpage);
 
   if (!rv) {
-    api_set_error(err, Validation, _("Invalid tabpage id"));
+    api_set_error(err, kErrorTypeValidation, "Invalid tabpage id");
   }
 
   return rv;
 }
 
+/// Allocates a String consisting of a single char. Does not support multibyte
+/// characters. The resulting string is also NUL-terminated, to facilitate
+/// interoperating with code using C strings.
+///
+/// @param char the char to convert
+/// @return the resulting String, if the input char was NUL, an
+///         empty String is returned
+String cchar_to_string(char c)
+{
+  char buf[] = { c, NUL };
+  return (String) {
+    .data = xmemdupz(buf, 1),
+    .size = (c != NUL) ? 1 : 0
+  };
+}
+
 /// Copies a C string into a String (binary safe string, characters + length).
 /// The resulting string is also NUL-terminated, to facilitate interoperating
 /// with code using C strings.
@@ -614,6 +704,23 @@ String cstr_to_string(const char *str)
     };
 }
 
+/// Copies buffer to an allocated String.
+/// The resulting string is also NUL-terminated, to facilitate interoperating
+/// with code using C strings.
+///
+/// @param buf the buffer to copy
+/// @param size length of the buffer
+/// @return the resulting String, if the input string was NULL, an
+///         empty String is returned
+String cbuf_to_string(const char *buf, size_t size)
+  FUNC_ATTR_NONNULL_ALL
+{
+  return (String) {
+    .data = xmemdupz(buf, size),
+    .size = size
+  };
+}
+
 /// Creates a String using the given C string. Unlike
 /// cstr_to_string this function DOES NOT copy the C string.
 ///
@@ -654,12 +761,8 @@ bool object_to_vim(Object obj, typval_T *tv, Error *err)
     case kObjectTypeWindow:
     case kObjectTypeTabpage:
     case kObjectTypeInteger:
-      if (obj.data.integer > VARNUMBER_MAX
-          || obj.data.integer < VARNUMBER_MIN) {
-        api_set_error(err, Validation, _("Integer value outside range"));
-        return false;
-      }
-
+      STATIC_ASSERT(sizeof(obj.data.integer) <= sizeof(varnumber_T),
+                    "Integer size must be <= VimL number size");
       tv->v_type = VAR_NUMBER;
       tv->vval.v_number = (varnumber_T)obj.data.integer;
       break;
@@ -680,22 +783,20 @@ bool object_to_vim(Object obj, typval_T *tv, Error *err)
       break;
 
     case kObjectTypeArray: {
-      list_T *const list = tv_list_alloc();
+      list_T *const list = tv_list_alloc((ptrdiff_t)obj.data.array.size);
 
       for (uint32_t i = 0; i < obj.data.array.size; i++) {
         Object item = obj.data.array.items[i];
-        listitem_T *li = tv_list_item_alloc();
+        typval_T li_tv;
 
-        if (!object_to_vim(item, &li->li_tv, err)) {
-          // cleanup
-          tv_list_item_free(li);
+        if (!object_to_vim(item, &li_tv, err)) {
           tv_list_free(list);
           return false;
         }
 
-        tv_list_append(list, li);
+        tv_list_append_owned_tv(list, li_tv);
       }
-      list->lv_refcount++;
+      tv_list_ref(list);
 
       tv->v_type = VAR_LIST;
       tv->vval.v_list = list;
@@ -710,8 +811,8 @@ bool object_to_vim(Object obj, typval_T *tv, Error *err)
         String key = item.key;
 
         if (key.size == 0) {
-          api_set_error(err, Validation,
-                        _("Empty dictionary keys aren't allowed"));
+          api_set_error(err, kErrorTypeValidation,
+                        "Empty dictionary keys aren't allowed");
           // cleanup
           tv_dict_free(dict);
           return false;
@@ -798,6 +899,17 @@ void api_free_dictionary(Dictionary value)
   xfree(value.items);
 }
 
+void api_clear_error(Error *value)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (!ERROR_SET(value)) {
+    return;
+  }
+  xfree(value->msg);
+  value->msg = NULL;
+  value->type = kErrorTypeNone;
+}
+
 Dictionary api_metadata(void)
 {
   static Dictionary metadata = ARRAY_DICT_INIT;
@@ -805,6 +917,7 @@ Dictionary api_metadata(void)
   if (!metadata.size) {
     PUT(metadata, "version", DICTIONARY_OBJ(version_dict()));
     init_function_metadata(&metadata);
+    init_ui_event_metadata(&metadata);
     init_error_type_metadata(&metadata);
     init_type_metadata(&metadata);
   }
@@ -828,6 +941,28 @@ static void init_function_metadata(Dictionary *metadata)
   PUT(*metadata, "functions", functions);
 }
 
+static void init_ui_event_metadata(Dictionary *metadata)
+{
+  msgpack_unpacked unpacked;
+  msgpack_unpacked_init(&unpacked);
+  if (msgpack_unpack_next(&unpacked,
+                          (const char *)ui_events_metadata,
+                          sizeof(ui_events_metadata),
+                          NULL) != MSGPACK_UNPACK_SUCCESS) {
+    abort();
+  }
+  Object ui_events;
+  msgpack_rpc_to_object(&unpacked.data, &ui_events);
+  msgpack_unpacked_destroy(&unpacked);
+  PUT(*metadata, "ui_events", ui_events);
+  Array ui_options = ARRAY_DICT_INIT;
+  ADD(ui_options, STRING_OBJ(cstr_to_string("rgb")));
+  for (UIExtension i = 0; i < kUIExtCount; i++) {
+    ADD(ui_options, STRING_OBJ(cstr_to_string(ui_ext_names[i])));
+  }
+  PUT(*metadata, "ui_options", ARRAY_OBJ(ui_options));
+}
+
 static void init_error_type_metadata(Dictionary *metadata)
 {
   Dictionary types = ARRAY_DICT_INIT;
@@ -849,15 +984,18 @@ static void init_type_metadata(Dictionary *metadata)
   Dictionary types = ARRAY_DICT_INIT;
 
   Dictionary buffer_metadata = ARRAY_DICT_INIT;
-  PUT(buffer_metadata, "id", INTEGER_OBJ(kObjectTypeBuffer));
+  PUT(buffer_metadata, "id",
+      INTEGER_OBJ(kObjectTypeBuffer - EXT_OBJECT_TYPE_SHIFT));
   PUT(buffer_metadata, "prefix", STRING_OBJ(cstr_to_string("nvim_buf_")));
 
   Dictionary window_metadata = ARRAY_DICT_INIT;
-  PUT(window_metadata, "id", INTEGER_OBJ(kObjectTypeWindow));
+  PUT(window_metadata, "id",
+      INTEGER_OBJ(kObjectTypeWindow - EXT_OBJECT_TYPE_SHIFT));
   PUT(window_metadata, "prefix", STRING_OBJ(cstr_to_string("nvim_win_")));
 
   Dictionary tabpage_metadata = ARRAY_DICT_INIT;
-  PUT(tabpage_metadata, "id", INTEGER_OBJ(kObjectTypeTabpage));
+  PUT(tabpage_metadata, "id",
+      INTEGER_OBJ(kObjectTypeTabpage - EXT_OBJECT_TYPE_SHIFT));
   PUT(tabpage_metadata, "prefix", STRING_OBJ(cstr_to_string("nvim_tabpage_")));
 
   PUT(types, "Buffer", DICTIONARY_OBJ(buffer_metadata));
@@ -867,6 +1005,24 @@ static void init_type_metadata(Dictionary *metadata)
   PUT(*metadata, "types", DICTIONARY_OBJ(types));
 }
 
+String copy_string(String str)
+{
+  if (str.data != NULL) {
+    return (String){ .data = xmemdupz(str.data, str.size), .size = str.size };
+  } else {
+    return (String)STRING_INIT;
+  }
+}
+
+Array copy_array(Array array)
+{
+  Array rv = ARRAY_DICT_INIT;
+  for (size_t i = 0; i < array.size; i++) {
+    ADD(rv, copy_object(array.items[i]));
+  }
+  return rv;
+}
+
 /// Creates a deep clone of an object
 Object copy_object(Object obj)
 {
@@ -878,15 +1034,10 @@ Object copy_object(Object obj)
       return obj;
 
     case kObjectTypeString:
-      return STRING_OBJ(cstr_to_string(obj.data.string.data));
+      return STRING_OBJ(copy_string(obj.data.string));
 
-    case kObjectTypeArray: {
-      Array rv = ARRAY_DICT_INIT;
-      for (size_t i = 0; i < obj.data.array.size; i++) {
-        ADD(rv, copy_object(obj.data.array.items[i]));
-      }
-      return ARRAY_OBJ(rv);
-    }
+    case kObjectTypeArray:
+      return ARRAY_OBJ(copy_array(obj.data.array));
 
     case kObjectTypeDictionary: {
       Dictionary rv = ARRAY_DICT_INIT;
@@ -911,7 +1062,7 @@ static void set_option_value_for(char *key,
 {
   win_T *save_curwin = NULL;
   tabpage_T *save_curtab = NULL;
-  bufref_T save_curbuf =  { NULL, 0 };
+  bufref_T save_curbuf =  { NULL, 0, 0 };
 
   try_start();
   switch (opt_type)
@@ -924,8 +1075,8 @@ static void set_option_value_for(char *key,
           return;
         }
         api_set_error(err,
-                      Exception,
-                      _("Problem while switching windows"));
+                      kErrorTypeException,
+                      "Problem while switching windows");
         return;
       }
       set_option_value_err(key, numval, stringval, opt_flags, err);
@@ -941,7 +1092,7 @@ static void set_option_value_for(char *key,
       break;
   }
 
-  if (err->set) {
+  if (ERROR_SET(err)) {
     return;
   }
 
@@ -962,6 +1113,64 @@ static void set_option_value_err(char *key,
       return;
     }
 
-    api_set_error(err, Exception, "%s", errmsg);
+    api_set_error(err, kErrorTypeException, "%s", errmsg);
+  }
+}
+
+void api_set_error(Error *err, ErrorType errType, const char *format, ...)
+  FUNC_ATTR_NONNULL_ALL
+{
+  assert(kErrorTypeNone != errType);
+  va_list args1;
+  va_list args2;
+  va_start(args1, format);
+  va_copy(args2, args1);
+  int len = vsnprintf(NULL, 0, format, args1);
+  va_end(args1);
+  assert(len >= 0);
+  // Limit error message to 1 MB.
+  size_t bufsize = MIN((size_t)len + 1, 1024 * 1024);
+  err->msg = xmalloc(bufsize);
+  vsnprintf(err->msg, bufsize, format, args2);
+  va_end(args2);
+
+  err->type = errType;
+}
+
+/// Get an array containing dictionaries describing mappings
+/// based on mode and buffer id
+///
+/// @param  mode  The abbreviation for the mode
+/// @param  buf  The buffer to get the mapping array. NULL for global
+/// @returns An array of maparg() like dictionaries describing mappings
+ArrayOf(Dictionary) keymap_array(String mode, buf_T *buf)
+{
+  Array mappings = ARRAY_DICT_INIT;
+  dict_T *const dict = tv_dict_alloc();
+
+  // Convert the string mode to the integer mode
+  // that is stored within each mapblock
+  char_u *p = (char_u *)mode.data;
+  int int_mode = get_map_mode(&p, 0);
+
+  // Determine the desired buffer value
+  long buffer_value = (buf == NULL) ? 0 : buf->handle;
+
+  for (int i = 0; i < MAX_MAPHASH; i++) {
+    for (const mapblock_T *current_maphash = get_maphash(i, buf);
+         current_maphash;
+         current_maphash = current_maphash->m_next) {
+      // Check for correct mode
+      if (int_mode & current_maphash->m_mode) {
+        mapblock_fill_dict(dict, current_maphash, buffer_value, false);
+        ADD(mappings, vim_to_object(
+            (typval_T[]) { { .v_type = VAR_DICT, .vval.v_dict = dict } }));
+
+        tv_dict_clear(dict);
+      }
+    }
   }
+  tv_dict_free(dict);
+
+  return mappings;
 }