eval/typval_encode: Make partial conversions not recursive

Is known to crash in the current state.

Ref #5825.

4 files changed, 207 insertions, 98 deletions

diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index b004cfc7a1..0d1d88055f 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -357,11 +357,12 @@ void set_option_to(void *to, int type, String name, Object value, Error *err)
 #define TYPVAL_ENCODE_CONV_EXT_STRING(str, len, type) \
     TYPVAL_ENCODE_CONV_NIL()
 
-#define TYPVAL_ENCODE_CONV_FUNC(fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(fun, is_partial, pt) \
     TYPVAL_ENCODE_CONV_NIL()
 
-#define TYPVAL_ENCODE_CONV_PARTIAL(partial) \
-    TYPVAL_ENCODE_CONV_NIL()
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(len)
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(len)
+#define TYPVAL_ENCODE_CONV_FUNC_END()
 
 #define TYPVAL_ENCODE_CONV_EMPTY_LIST() \
     kv_push(edata->stack, ARRAY_OBJ(((Array) { .capacity = 0, .size = 0 })))
@@ -484,8 +485,10 @@ TYPVAL_ENCODE_DEFINE_CONV_FUNCTIONS(static, object, EncodedData *const, edata)
 #undef TYPVAL_ENCODE_CONV_EXT_STRING
 #undef TYPVAL_ENCODE_CONV_NUMBER
 #undef TYPVAL_ENCODE_CONV_FLOAT
-#undef TYPVAL_ENCODE_CONV_FUNC
-#undef TYPVAL_ENCODE_CONV_PARTIAL
+#undef TYPVAL_ENCODE_CONV_FUNC_START
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF
+#undef TYPVAL_ENCODE_CONV_FUNC_END
 #undef TYPVAL_ENCODE_CONV_EMPTY_LIST
 #undef TYPVAL_ENCODE_CONV_LIST_START
 #undef TYPVAL_ENCODE_CONV_EMPTY_DICT
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index ea42a58cdd..dbc279685a 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -19070,22 +19070,24 @@ void free_tv(typval_T *varp)
 
 #define TYPVAL_ENCODE_CONV_EXT_STRING(ignored1, ignored2, ignored3)
 
-#define TYPVAL_ENCODE_CONV_FUNC(fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(fun, is_partial, pt) \
     do { \
-      func_unref(fun); \
-      if (fun != empty_string) { \
-        xfree(fun); \
+      if (is_partial) { \
+        partial_unref(pt); \
+        tv->vval.v_partial = NULL; \
+      } else { \
+        func_unref(fun); \
+        if (fun != empty_string) { \
+          xfree(fun); \
+        } \
+        tv->vval.v_string = NULL; \
       } \
-      tv->vval.v_string = NULL; \
       tv->v_lock = VAR_UNLOCKED; \
     } while (0)
 
-#define TYPVAL_ENCODE_CONV_PARTIAL(pt) \
-    do { \
-      partial_unref(pt); \
-      pt = NULL; \
-      tv->v_lock = VAR_UNLOCKED; \
-    } while (0)
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(len)
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(len)
+#define TYPVAL_ENCODE_CONV_FUNC_END()
 
 #define TYPVAL_ENCODE_CONV_EMPTY_LIST() \
     do { \
@@ -19162,8 +19164,10 @@ TYPVAL_ENCODE_DEFINE_CONV_FUNCTIONS(static, nothing, void *, ignored)
 #undef TYPVAL_ENCODE_CONV_STRING
 #undef TYPVAL_ENCODE_CONV_STR_STRING
 #undef TYPVAL_ENCODE_CONV_EXT_STRING
-#undef TYPVAL_ENCODE_CONV_FUNC
-#undef TYPVAL_ENCODE_CONV_PARTIAL
+#undef TYPVAL_ENCODE_CONV_FUNC_START
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF
+#undef TYPVAL_ENCODE_CONV_FUNC_END
 #undef TYPVAL_ENCODE_CONV_EMPTY_LIST
 #undef TYPVAL_ENCODE_CONV_EMPTY_DICT
 #undef TYPVAL_ENCODE_CONV_LIST_START
diff --git a/src/nvim/eval/encode.c b/src/nvim/eval/encode.c
index 5af4893975..7e59998bf0 100644
--- a/src/nvim/eval/encode.c
+++ b/src/nvim/eval/encode.c
@@ -108,9 +108,12 @@ static int conv_error(const char *const msg, const MPConvStack *const mpstack,
 {
   garray_T msg_ga;
   ga_init(&msg_ga, (int)sizeof(char), 80);
-  char *const key_msg = _("key %s");
-  char *const key_pair_msg = _("key %s at index %i from special map");
-  char *const idx_msg = _("index %i");
+  const char *const key_msg = _("key %s");
+  const char *const key_pair_msg = _("key %s at index %i from special map");
+  const char *const idx_msg = _("index %i");
+  const char *const partial_arg_msg = _("partial");
+  const char *const partial_arg_i_msg = _("argument %i");
+  const char *const partial_self_msg = _("partial self dictionary");
   for (size_t i = 0; i < kv_size(*mpstack); i++) {
     if (i != 0) {
       ga_concat(&msg_ga, ", ");
@@ -154,6 +157,29 @@ static int conv_error(const char *const msg, const MPConvStack *const mpstack,
         }
         break;
       }
+      case kMPConvPartial: {
+        switch (v.data.p.stage) {
+          case kMPConvPartialArgs: {
+            assert(false);
+            break;
+          }
+          case kMPConvPartialSelf: {
+            ga_concat(&msg_ga, partial_arg_msg);
+            break;
+          }
+          case kMPConvPartialEnd: {
+            ga_concat(&msg_ga, partial_self_msg);
+            break;
+          }
+        }
+        break;
+      }
+      case kMPConvPartialList: {
+        const int idx = (int)(v.data.a.arg - v.data.a.argv) - 1;
+        vim_snprintf((char *)IObuff, IOSIZE, partial_arg_i_msg, idx);
+        ga_concat(&msg_ga, IObuff);
+        break;
+      }
     }
   }
   EMSG3(msg, objname, (kv_size(*mpstack) == 0
@@ -308,67 +334,29 @@ int encode_read_from_list(ListReaderState *const state, char *const buf,
       } \
     } while (0)
 
-#define TYPVAL_ENCODE_CONV_FUNC(fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(fun, is_partial, pt) \
     do { \
       ga_concat(gap, "function("); \
       TYPVAL_ENCODE_CONV_STRING(fun, STRLEN(fun)); \
-      ga_append(gap, ')'); \
     } while (0)
 
-#define TYPVAL_ENCODE_CONV_PARTIAL(pt) \
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(len) \
     do { \
-        int i; \
-        ga_concat(gap, "function("); \
-        if (pt->pt_name != NULL) { \
-          size_t len; \
-          char_u *p; \
-          len = 3; \
-          len += STRLEN(pt->pt_name); \
-          for (p = pt->pt_name; *p != NUL; mb_ptr_adv(p)) { \
-            if (*p == '\'') { \
-              len++; \
-            } \
-          } \
-          char_u *r, *s; \
-          s = r = xmalloc(len); \
-          if (r != NULL) { \
-            *r++ = '\''; \
-            for (p = pt->pt_name; *p != NUL; ) { \
-              if (*p == '\'') { \
-                *r++ = '\''; \
-              } \
-            MB_COPY_CHAR(p, r); \
-            } \
-            *r++ = '\''; \
-            *r++ = NUL; \
-          } \
-          ga_concat(gap, s); \
-          xfree(s); \
-        } \
-        if (pt->pt_argc > 0) { \
-          ga_concat(gap, ", ["); \
-          for (i = 0; i < pt->pt_argc; i++) { \
-            if (i > 0) { \
-              ga_concat(gap, ", "); \
-            } \
-            char *tofree = encode_tv2string(&pt->pt_argv[i], NULL); \
-            ga_concat(gap, tofree); \
-            xfree(tofree); \
-          } \
-          ga_append(gap, ']'); \
-        } \
-        if (pt->pt_dict != NULL) { \
-          typval_T dtv; \
-          ga_concat(gap, ", "); \
-          dtv.v_type = VAR_DICT; \
-          dtv.vval.v_dict = pt->pt_dict; \
-          char *tofree = encode_tv2string(&dtv, NULL); \
-          ga_concat(gap, tofree); \
-          xfree(tofree); \
-        } \
-        ga_append(gap, ')'); \
+      if (len != 0) { \
+        ga_concat(gap, ", "); \
+      } \
+    } while (0)
+
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(len) \
+    do { \
+      if ((ptrdiff_t)len != -1) { \
+        ga_concat(gap, ", "); \
+      } \
     } while (0)
 
+#define TYPVAL_ENCODE_CONV_FUNC_END() \
+    ga_append(gap, ')')
+
 #define TYPVAL_ENCODE_CONV_EMPTY_LIST() \
     ga_concat(gap, "[]")
 
@@ -709,18 +697,12 @@ static inline int convert_to_json_string(garray_T *const gap,
       return FAIL; \
     } while (0)
 
-#undef TYPVAL_ENCODE_CONV_FUNC
-#define TYPVAL_ENCODE_CONV_FUNC(fun) \
+#undef TYPVAL_ENCODE_CONV_FUNC_START
+#define TYPVAL_ENCODE_CONV_FUNC_START(fun, is_partial, pt) \
     return conv_error(_("E474: Error while dumping %s, %s: " \
                         "attempt to dump function reference"), \
                       mpstack, objname)
 
-#undef TYPVAL_ENCODE_CONV_PARTIAL
-#define TYPVAL_ENCODE_CONV_PARTIAL(pt) \
-    return conv_error(_("E474: Error while dumping %s, %s: " \
-                        "attempt to dump partial"), \
-                      mpstack, objname)
-
 /// Check whether given key can be used in json_encode()
 ///
 /// @param[in]  tv  Key to check.
@@ -777,8 +759,10 @@ TYPVAL_ENCODE_DEFINE_CONV_FUNCTIONS(static, json, garray_T *const, gap)
 #undef TYPVAL_ENCODE_CONV_EXT_STRING
 #undef TYPVAL_ENCODE_CONV_NUMBER
 #undef TYPVAL_ENCODE_CONV_FLOAT
-#undef TYPVAL_ENCODE_CONV_FUNC
-#undef TYPVAL_ENCODE_CONV_PARTIAL
+#undef TYPVAL_ENCODE_CONV_FUNC_START
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF
+#undef TYPVAL_ENCODE_CONV_FUNC_END
 #undef TYPVAL_ENCODE_CONV_EMPTY_LIST
 #undef TYPVAL_ENCODE_CONV_LIST_START
 #undef TYPVAL_ENCODE_CONV_EMPTY_DICT
@@ -902,15 +886,14 @@ char *encode_tv2json(typval_T *tv, size_t *len)
 #define TYPVAL_ENCODE_CONV_FLOAT(flt) \
     msgpack_pack_double(packer, (double) (flt))
 
-#define TYPVAL_ENCODE_CONV_FUNC(fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(fun, is_partial, pt) \
     return conv_error(_("E5004: Error while dumping %s, %s: " \
                         "attempt to dump function reference"), \
                       mpstack, objname)
 
-#define TYPVAL_ENCODE_CONV_PARTIAL(partial) \
-    return conv_error(_("E5004: Error while dumping %s, %s: " \
-                        "attempt to dump partial"), \
-                      mpstack, objname)
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(len)
+#define TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(len)
+#define TYPVAL_ENCODE_CONV_FUNC_END()
 
 #define TYPVAL_ENCODE_CONV_EMPTY_LIST() \
     msgpack_pack_array(packer, 0)
@@ -967,8 +950,10 @@ TYPVAL_ENCODE_DEFINE_CONV_FUNCTIONS(, msgpack, msgpack_packer *const, packer)
 #undef TYPVAL_ENCODE_CONV_EXT_STRING
 #undef TYPVAL_ENCODE_CONV_NUMBER
 #undef TYPVAL_ENCODE_CONV_FLOAT
-#undef TYPVAL_ENCODE_CONV_FUNC
-#undef TYPVAL_ENCODE_CONV_PARTIAL
+#undef TYPVAL_ENCODE_CONV_FUNC_START
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS
+#undef TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF
+#undef TYPVAL_ENCODE_CONV_FUNC_END
 #undef TYPVAL_ENCODE_CONV_EMPTY_LIST
 #undef TYPVAL_ENCODE_CONV_LIST_START
 #undef TYPVAL_ENCODE_CONV_EMPTY_DICT
diff --git a/src/nvim/eval/typval_encode.h b/src/nvim/eval/typval_encode.h
index b79158b30c..149dd22ff7 100644
--- a/src/nvim/eval/typval_encode.h
+++ b/src/nvim/eval/typval_encode.h
@@ -69,10 +69,30 @@
 ///
 /// @param  fun  Function name.
 
-/// @def TYPVAL_ENCODE_CONV_PARTIAL
-/// @brief Macros used to convert a partial
+/// @def TYPVAL_ENCODE_CONV_FUNC_START
+/// @brief Macros used when starting to convert a funcref or a partial
 ///
-/// @param  pt Partial name.
+/// @param  fun  Function name.
+/// @param  is_partial  True if converted function is a partial.
+/// @param  pt  Pointer to partial or NULL.
+
+/// @def TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS
+/// @brief Macros used before starting to convert partial arguments
+///
+/// @param  len  Number of arguments. Zero for absent arguments or when
+///              converting a funcref.
+
+/// @def TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF
+/// @brief Macros used before starting to convert self dictionary
+///
+/// @param  len  Number of arguments. May be zero for empty dictionary or -1 for
+///              missing self dictionary, also when converting function
+///              reference.
+
+/// @def TYPVAL_ENCODE_CONV_FUNC_END
+/// @brief Macros used after converting a funcref or a partial
+///
+/// Accepts no arguments, but still must be a function-like macros.
 
 /// @def TYPVAL_ENCODE_CONV_EMPTY_LIST
 /// @brief Macros used to convert an empty list
@@ -151,11 +171,20 @@
 
 /// Type of the stack entry
 typedef enum {
-  kMPConvDict,   ///< Convert dict_T *dictionary.
-  kMPConvList,   ///< Convert list_T *list.
+  kMPConvDict,  ///< Convert dict_T *dictionary.
+  kMPConvList,  ///< Convert list_T *list.
   kMPConvPairs,  ///< Convert mapping represented as a list_T* of pairs.
+  kMPConvPartial,  ///< Convert partial_T* partial.
+  kMPConvPartialList,  ///< Convert argc/argv pair coming from a partial.
 } MPConvStackValType;
 
+/// Stage at which partial is being converted
+typedef enum {
+  kMPConvPartialArgs,  ///< About to convert arguments.
+  kMPConvPartialSelf,  ///< About to convert self dictionary.
+  kMPConvPartialEnd,  ///< Already converted everything.
+} MPConvPartialStage;
+
 /// Structure representing current VimL to messagepack conversion state
 typedef struct {
   MPConvStackValType type;  ///< Type of the stack entry.
@@ -170,6 +199,15 @@ typedef struct {
       list_T *list;    ///< Currently converted list.
       listitem_T *li;  ///< Currently converted list item.
     } l;  ///< State of list or generic mapping conversion.
+    struct {
+      MPConvPartialStage stage;  ///< Stage at which partial is being converted.
+      partial_T *pt;  ///< Currently converted partial.
+    } p;  ///< State of partial conversion.
+    struct {
+      typval_T *arg;    ///< Currently converted argument.
+      typval_T *argv;    ///< Start of the argument list.
+      size_t todo;  ///< Number of items left to process.
+    } a;  ///< State of list or generic mapping conversion.
   } data;  ///< Data to convert.
 } MPConvStackVal;
 
@@ -250,11 +288,26 @@ static int name##_convert_one_value(firstargtype firstargname, \
       break; \
     } \
     case VAR_FUNC: { \
-      TYPVAL_ENCODE_CONV_FUNC(tv->vval.v_string); \
+      TYPVAL_ENCODE_CONV_FUNC_START(tv->vval.v_string, false, NULL); \
+      TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(0); \
+      TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(-1); \
+      TYPVAL_ENCODE_CONV_FUNC_END(); \
       break; \
     } \
     case VAR_PARTIAL: { \
-      TYPVAL_ENCODE_CONV_PARTIAL(tv->vval.v_partial); \
+      partial_T *const pt = tv->vval.v_partial; \
+      (void)pt; \
+      TYPVAL_ENCODE_CONV_FUNC_START(pt->pt_name, true, pt); \
+      _mp_push(*mpstack, ((MPConvStackVal) { \
+        .type = kMPConvPartial, \
+        .tv = tv, \
+        .data = { \
+          .p = { \
+            .stage = kMPConvPartialArgs, \
+            .pt = tv->vval.v_partial, \
+          }, \
+        }, \
+      })); \
       break; \
     } \
     case VAR_LIST: { \
@@ -562,6 +615,70 @@ scope int encode_vim_to_##name(firstargtype firstargname, typval_T *const tv, \
         cur_mpsv->data.l.li = cur_mpsv->data.l.li->li_next; \
         break; \
       } \
+      case kMPConvPartial: { \
+        partial_T *const pt = cur_mpsv->data.p.pt; \
+        switch (cur_mpsv->data.p.stage) { \
+          case kMPConvPartialArgs: { \
+            TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(pt->pt_argc); \
+            cur_mpsv->data.p.stage = kMPConvPartialSelf; \
+            if (pt->pt_argc > 0) { \
+              TYPVAL_ENCODE_CONV_LIST_START(pt->pt_argc); \
+              _mp_push(mpstack, ((MPConvStackVal) { \
+                .type = kMPConvPartialList, \
+                .tv = tv, \
+                .data = { \
+                  .a = { \
+                    .arg = pt->pt_argv, \
+                    .argv = pt->pt_argv, \
+                    .todo = (size_t)pt->pt_argc, \
+                  }, \
+                }, \
+              })); \
+            } \
+            break; \
+          } \
+          case kMPConvPartialSelf: { \
+            cur_mpsv->data.p.stage = kMPConvPartialEnd; \
+            dict_T *const dict = pt->pt_dict; \
+            if (dict != NULL) { \
+              TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(dict->dv_hashtab.ht_used); \
+              TYPVAL_ENCODE_CONV_DICT_START(dict->dv_hashtab.ht_used); \
+              _mp_push(mpstack, ((MPConvStackVal) { \
+                .type = kMPConvDict, \
+                .tv = tv, \
+                .data = { \
+                  .d = { \
+                    .dict = dict, \
+                    .hi = dict->dv_hashtab.ht_array, \
+                    .todo = dict->dv_hashtab.ht_used, \
+                  }, \
+                }, \
+              })); \
+            } else { \
+              TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(-1); \
+            } \
+            break; \
+          } \
+          case kMPConvPartialEnd: { \
+            TYPVAL_ENCODE_CONV_FUNC_END(); \
+            (void) _mp_pop(mpstack); \
+            break; \
+          } \
+        } \
+        continue; \
+      } \
+      case kMPConvPartialList: { \
+        if (!cur_mpsv->data.a.todo) { \
+          (void) _mp_pop(mpstack); \
+          TYPVAL_ENCODE_CONV_LIST_END(); \
+          continue; \
+        } else if (cur_mpsv->data.a.argv != cur_mpsv->data.a.arg) { \
+          TYPVAL_ENCODE_CONV_LIST_BETWEEN_ITEMS(); \
+        } \
+        cur_tv = cur_mpsv->data.a.arg++; \
+        cur_mpsv->data.a.todo--; \
+        break; \
+      } \
     } \
     assert(cur_tv != NULL); \
     if (name##_convert_one_value(firstargname, &mpstack, cur_tv, copyID, \