/*
* c_runtime.c -- C-acceleration runtime for tarantool-protobuf.
*
* Phase 1 (bd-mq7): descriptor -> plan compiler. Walks a finalized
* Lua descriptor table and produces an opaque `pb_plan` userdata.
* Encode/decode entry points arrive with bd-3b/3c/etc.; this file
* only carries the plan compilation surface and enough introspection
* to make a smoke test possible.
*
* Conventions follow docs/specs/c_accel_strategy.md.
*/
/* strdup is POSIX, not C99; declare we want the POSIX surface from
* <string.h> before any system header pulls it in. */
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 200809L
#endif
#include <module.h>
#include <lauxlib.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#define PB_PLAN_MT "pb.plan"
#define PB_ABI_VERSION "1"
/* ---------------------------------------------------------------- *
* Kind / wire-type taxonomy. *
* *
* Mirrors runtime/pb/wire.lua's TYPE_INFO. The numbering is *
* internal — only the C runtime needs to agree with itself. *
* ---------------------------------------------------------------- */
enum {
PB_KIND_NONE = 0,
PB_KIND_INT32,
PB_KIND_INT64,
PB_KIND_UINT32,
PB_KIND_UINT64,
PB_KIND_SINT32,
PB_KIND_SINT64,
PB_KIND_FIXED32,
PB_KIND_FIXED64,
PB_KIND_SFIXED32,
PB_KIND_SFIXED64,
PB_KIND_FLOAT,
PB_KIND_DOUBLE,
PB_KIND_BOOL,
PB_KIND_STRING,
PB_KIND_BYTES,
PB_KIND_ENUM,
PB_KIND_MESSAGE,
PB_KIND_MAP,
};
/* Wire types per proto3 spec. */
enum {
PB_WIRE_VARINT = 0,
PB_WIRE_I64 = 1,
PB_WIRE_LEN = 2,
PB_WIRE_I32 = 5,
};
struct kind_info {
const char *proto_type;
uint8_t kind;
uint8_t wire_type;
};
/* Lookup table keyed by proto3 field type string. Linear scan is fine —
* a finalized descriptor calls this once per field at plan-compile time,
* not per encode/decode. */
static const struct kind_info kind_table[] = {
{"int32", PB_KIND_INT32, PB_WIRE_VARINT},
{"int64", PB_KIND_INT64, PB_WIRE_VARINT},
{"uint32", PB_KIND_UINT32, PB_WIRE_VARINT},
{"uint64", PB_KIND_UINT64, PB_WIRE_VARINT},
{"sint32", PB_KIND_SINT32, PB_WIRE_VARINT},
{"sint64", PB_KIND_SINT64, PB_WIRE_VARINT},
{"bool", PB_KIND_BOOL, PB_WIRE_VARINT},
{"fixed32", PB_KIND_FIXED32, PB_WIRE_I32},
{"sfixed32", PB_KIND_SFIXED32, PB_WIRE_I32},
{"float", PB_KIND_FLOAT, PB_WIRE_I32},
{"fixed64", PB_KIND_FIXED64, PB_WIRE_I64},
{"sfixed64", PB_KIND_SFIXED64, PB_WIRE_I64},
{"double", PB_KIND_DOUBLE, PB_WIRE_I64},
{"string", PB_KIND_STRING, PB_WIRE_LEN},
{"bytes", PB_KIND_BYTES, PB_WIRE_LEN},
};
static const struct kind_info *
lookup_kind(const char *proto_type)
{
if (proto_type == NULL)
return NULL;
for (size_t i = 0; i < sizeof(kind_table) / sizeof(kind_table[0]); i++) {
if (strcmp(kind_table[i].proto_type, proto_type) == 0)
return &kind_table[i];
}
return NULL;
}
/* ---------------------------------------------------------------- *
* Plan struct layout. *
* *
* Spec: docs/specs/c_accel_strategy.md § The plan userdata. *
* Simplifications from the spec for mq7: *
* - oneofs[] populated but member dispatch lives in 3i *
* - extension_range_* populated but dispatch lives in 3i *
* - sub_plan_idx points into `sub_plans_ref` table (1-based) *
* - Field name strings live in a Lua table keyed by 1..n; *
* lookup via `lua_rawgeti(L, names, i+1)` per spec. *
* ---------------------------------------------------------------- */
typedef struct pb_plan_field {
uint32_t field_number;
uint8_t wire_type;
uint8_t kind;
uint8_t packed;
uint8_t repeated;
uint8_t optional;
uint8_t tag_len;
uint8_t tag_bytes[5];
int sub_plan_idx; /* 1-based into sub_plans table; 0 if none */
uint8_t map_key_kind;
uint8_t map_value_kind;
int map_value_sub_plan_idx; /* 1-based; 0 if value is scalar */
int oneof_idx; /* 0-based into plan->oneofs; -1 if none */
int enum_ref; /* LUA_REGISTRYINDEX ref for enum desc; LUA_NOREF if none */
} pb_plan_field;
typedef struct pb_plan_oneof {
char *name; /* malloc'd */
int n_members;
int *member_indices; /* indices into plan->fields */
} pb_plan_oneof;
typedef struct pb_plan {
char *name; /* malloc'd descriptor name */
int n_fields;
pb_plan_field *fields;
int n_oneofs;
pb_plan_oneof *oneofs;
int extension_range_start;
int extension_range_end;
uint8_t has_override;
int override_encode_ref; /* LUA_NOREF if absent */
int override_decode_ref;
int field_names_ref; /* table { [1]=name1, ... } */
int sub_plans_ref; /* table { [1]=plan_userdata, ... } */
} pb_plan;
/* ---------------------------------------------------------------- *
* Tag encoding. *
* *
* Pre-encodes the (field_number << 3) | wire_type varint so the *
* hot encode path emits a fixed memcpy instead of recomputing. *
* Up to 5 bytes for any legal field number (2^29 - 1 max). *
* ---------------------------------------------------------------- */
static void
encode_tag(uint32_t field_number, uint8_t wire_type,
uint8_t *out, uint8_t *out_len)
{
uint64_t v = ((uint64_t)field_number << 3) | wire_type;
uint8_t i = 0;
while (v >= 0x80) {
out[i++] = (uint8_t)(v | 0x80);
v >>= 7;
}
out[i++] = (uint8_t)v;
*out_len = i;
}
/* ---------------------------------------------------------------- *
* Plan lifecycle: alloc / free. *
* ---------------------------------------------------------------- */
static void
plan_free(lua_State *L, pb_plan *p)
{
if (p->name != NULL)
free(p->name);
if (p->fields != NULL) {
for (int i = 0; i < p->n_fields; i++) {
if (p->fields[i].enum_ref != LUA_NOREF)
luaL_unref(L, LUA_REGISTRYINDEX, p->fields[i].enum_ref);
}
free(p->fields);
}
if (p->oneofs != NULL) {
for (int i = 0; i < p->n_oneofs; i++) {
free(p->oneofs[i].name);
free(p->oneofs[i].member_indices);
}
free(p->oneofs);
}
if (p->override_encode_ref != LUA_NOREF)
luaL_unref(L, LUA_REGISTRYINDEX, p->override_encode_ref);
if (p->override_decode_ref != LUA_NOREF)
luaL_unref(L, LUA_REGISTRYINDEX, p->override_decode_ref);
if (p->field_names_ref != LUA_NOREF)
luaL_unref(L, LUA_REGISTRYINDEX, p->field_names_ref);
if (p->sub_plans_ref != LUA_NOREF)
luaL_unref(L, LUA_REGISTRYINDEX, p->sub_plans_ref);
memset(p, 0, sizeof(*p));
p->override_encode_ref = LUA_NOREF;
p->override_decode_ref = LUA_NOREF;
p->field_names_ref = LUA_NOREF;
p->sub_plans_ref = LUA_NOREF;
}
static int
plan_gc(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
plan_free(L, p);
return 0;
}
static int
plan_tostring(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
lua_pushfstring(L, "pb.plan: %s (n_fields=%d)",
p->name != NULL ? p->name : "(unnamed)",
p->n_fields);
return 1;
}
/* ---------------------------------------------------------------- *
* Field compilation. *
* *
* Reads one descriptor-field table (at the top of the stack) and *
* fills the corresponding pb_plan_field. Recurses into sub-message *
* plans by calling compile_plan_impl. *
* *
* Stack expectations on entry: *
* -1: field-descriptor table (e.g. {name="foo", id=1, kind=...})*
* sub_plans_stack_idx: the sub-plans table being filled *
* *
* Stack on exit: same (we pop everything we push). *
* ---------------------------------------------------------------- */
static int compile_plan_impl(lua_State *L, int desc_idx);
/* Append a sub-plan userdata (at -1) to the sub-plans table at
* sub_plans_idx; return its 1-based index. Pops the userdata. */
static int
push_sub_plan(lua_State *L, int sub_plans_idx)
{
int n = (int)lua_objlen(L, sub_plans_idx);
lua_rawseti(L, sub_plans_idx, n + 1);
return n + 1;
}
/* Resolve a sub-message descriptor (at stack idx `sub_desc_idx`) into a
* 1-based index into the sub-plans table. Stack-neutral: pushes/pops the
* intermediate desc copy and plan userdata internally. */
static int
resolve_sub_plan(lua_State *L, int sub_desc_idx, int sub_plans_idx)
{
int saved_top = lua_gettop(L);
/* compile_plan_impl is idempotent — if desc.c_plan exists it just
* leaves the cached userdata on top. */
lua_pushvalue(L, sub_desc_idx);
int dup_idx = lua_gettop(L);
compile_plan_impl(L, dup_idx);
if (!lua_isuserdata(L, -1))
luaL_error(L, "compile_plan_impl did not return a userdata");
int idx = push_sub_plan(L, sub_plans_idx); /* pops plan userdata */
lua_settop(L, saved_top); /* drop sub_desc copy */
return idx;
}
/* Compile one field. `f_desc_idx` is the absolute stack index of the
* field descriptor table. `field` points at the pb_plan_field slot to
* fill. `field_names_idx`, `sub_plans_idx` are absolute indices of the
* field-names and sub-plans tables being populated. `field_idx_1based`
* is the 1-based position used for the field-names lookup table. */
static void
compile_field(lua_State *L, int f_desc_idx, pb_plan_field *field,
int field_names_idx, int sub_plans_idx, int field_idx_1based)
{
memset(field, 0, sizeof(*field));
field->enum_ref = LUA_NOREF;
field->oneof_idx = -1;
/* field number */
lua_getfield(L, f_desc_idx, "id");
if (!lua_isnumber(L, -1))
luaL_error(L, "field descriptor missing 'id'");
field->field_number = (uint32_t)lua_tointeger(L, -1);
lua_pop(L, 1);
/* name (interned in field_names_ref under field_idx_1based) */
lua_getfield(L, f_desc_idx, "name");
if (!lua_isstring(L, -1))
luaL_error(L, "field descriptor missing 'name'");
lua_pushvalue(L, -1); /* dup */
lua_rawseti(L, field_names_idx, field_idx_1based);
lua_pop(L, 1);
/* repeated / packed / optional */
lua_getfield(L, f_desc_idx, "repeated");
field->repeated = lua_toboolean(L, -1) ? 1 : 0;
lua_pop(L, 1);
lua_getfield(L, f_desc_idx, "packed");
field->packed = lua_toboolean(L, -1) ? 1 : 0;
lua_pop(L, 1);
lua_getfield(L, f_desc_idx, "optional");
field->optional = lua_toboolean(L, -1) ? 1 : 0;
lua_pop(L, 1);
/* kind dispatch on desc.kind */
lua_getfield(L, f_desc_idx, "kind");
const char *kind_str = lua_tostring(L, -1);
if (kind_str == NULL)
luaL_error(L, "field descriptor missing 'kind'");
uint8_t element_wire_type;
if (strcmp(kind_str, "scalar") == 0) {
lua_pop(L, 1); /* pop kind */
lua_getfield(L, f_desc_idx, "proto_type");
const char *pt = lua_tostring(L, -1);
const struct kind_info *ki = lookup_kind(pt);
if (ki == NULL)
luaL_error(L, "unknown scalar proto_type: %s",
pt != NULL ? pt : "(nil)");
field->kind = ki->kind;
element_wire_type = ki->wire_type;
lua_pop(L, 1);
} else if (strcmp(kind_str, "enum") == 0) {
lua_pop(L, 1);
field->kind = PB_KIND_ENUM;
element_wire_type = PB_WIRE_VARINT;
lua_getfield(L, f_desc_idx, "enum");
if (lua_istable(L, -1)) {
field->enum_ref = luaL_ref(L, LUA_REGISTRYINDEX);
} else {
lua_pop(L, 1);
}
} else if (strcmp(kind_str, "message") == 0) {
lua_pop(L, 1);
field->kind = PB_KIND_MESSAGE;
element_wire_type = PB_WIRE_LEN;
lua_getfield(L, f_desc_idx, "message");
if (!lua_istable(L, -1))
luaL_error(L, "message field '%s' missing 'message' descriptor",
"?");
int sub_desc = lua_gettop(L);
field->sub_plan_idx = resolve_sub_plan(L, sub_desc, sub_plans_idx);
lua_pop(L, 1); /* sub-desc table */
} else if (strcmp(kind_str, "map") == 0) {
lua_pop(L, 1);
field->kind = PB_KIND_MAP;
element_wire_type = PB_WIRE_LEN;
/* key */
lua_getfield(L, f_desc_idx, "key");
if (!lua_istable(L, -1))
luaL_error(L, "map field missing 'key' descriptor");
lua_getfield(L, -1, "proto_type");
const struct kind_info *ki = lookup_kind(lua_tostring(L, -1));
if (ki == NULL)
luaL_error(L, "map key has unknown proto_type");
field->map_key_kind = ki->kind;
lua_pop(L, 2); /* proto_type + key */
/* value */
lua_getfield(L, f_desc_idx, "value");
if (!lua_istable(L, -1))
luaL_error(L, "map field missing 'value' descriptor");
lua_getfield(L, -1, "kind");
const char *vk = lua_tostring(L, -1);
lua_pop(L, 1);
if (vk != NULL && strcmp(vk, "scalar") == 0) {
lua_getfield(L, -1, "proto_type");
const struct kind_info *vki = lookup_kind(lua_tostring(L, -1));
if (vki == NULL)
luaL_error(L, "map value has unknown scalar proto_type");
field->map_value_kind = vki->kind;
lua_pop(L, 1);
} else if (vk != NULL && strcmp(vk, "message") == 0) {
field->map_value_kind = PB_KIND_MESSAGE;
lua_getfield(L, -1, "message");
if (lua_istable(L, -1)) {
int sub_desc = lua_gettop(L);
field->map_value_sub_plan_idx =
resolve_sub_plan(L, sub_desc, sub_plans_idx);
}
lua_pop(L, 1);
} else if (vk != NULL && strcmp(vk, "enum") == 0) {
field->map_value_kind = PB_KIND_ENUM;
} else {
luaL_error(L, "map value has unknown kind: %s",
vk != NULL ? vk : "(nil)");
}
lua_pop(L, 1); /* value table */
} else {
luaL_error(L, "unknown field kind: %s", kind_str);
return; /* unreachable */
}
/* Wire type: repeated+packed → LEN regardless of element type;
* repeated unpacked → element type per tag; singular → element. */
if (field->repeated && field->packed) {
field->wire_type = PB_WIRE_LEN;
} else {
field->wire_type = element_wire_type;
}
encode_tag(field->field_number, field->wire_type,
field->tag_bytes, &field->tag_len);
}
/* ---------------------------------------------------------------- *
* Oneof compilation. *
* *
* desc.oneofs is the hash table {[name]=members}. We walk it and *
* build pb_plan_oneof[]. For each member field, set its oneof_idx *
* to point back at the plan's oneof entry. *
* ---------------------------------------------------------------- */
static int
find_field_by_name(pb_plan *p, lua_State *L, int field_names_idx,
const char *name)
{
for (int i = 0; i < p->n_fields; i++) {
lua_rawgeti(L, field_names_idx, i + 1);
const char *fn = lua_tostring(L, -1);
int match = (fn != NULL && strcmp(fn, name) == 0);
lua_pop(L, 1);
if (match) return i;
}
return -1;
}
static void
compile_oneofs(lua_State *L, pb_plan *p, int desc_idx, int field_names_idx)
{
lua_getfield(L, desc_idx, "oneofs");
if (!lua_istable(L, -1)) {
lua_pop(L, 1);
return;
}
/* First pass: count. */
int count = 0;
lua_pushnil(L);
while (lua_next(L, -2) != 0) {
count++;
lua_pop(L, 1);
}
if (count == 0) {
lua_pop(L, 1);
return;
}
p->oneofs = (pb_plan_oneof *)calloc(count, sizeof(pb_plan_oneof));
p->n_oneofs = count;
int idx = 0;
lua_pushnil(L);
while (lua_next(L, -2) != 0) {
/* key at -2 (oneof name), value at -1 (members array) */
const char *oname = lua_tostring(L, -2);
p->oneofs[idx].name = strdup(oname != NULL ? oname : "");
int n_members = (int)lua_objlen(L, -1);
p->oneofs[idx].n_members = n_members;
p->oneofs[idx].member_indices = (int *)calloc(n_members, sizeof(int));
for (int j = 0; j < n_members; j++) {
lua_rawgeti(L, -1, j + 1);
const char *mname = lua_tostring(L, -1);
int fi = find_field_by_name(p, L, field_names_idx,
mname != NULL ? mname : "");
lua_pop(L, 1);
p->oneofs[idx].member_indices[j] = fi;
if (fi >= 0)
p->fields[fi].oneof_idx = idx;
}
lua_pop(L, 1); /* value */
idx++;
}
lua_pop(L, 1); /* oneofs table */
}
/* ---------------------------------------------------------------- *
* Main compile entry. *
* *
* Idempotent. If desc.c_plan exists and is a pb.plan userdata, *
* returns it. Otherwise allocates a new one, stashes it on *
* desc.c_plan BEFORE recursing into sub-plans (breaks cycles for *
* self-referencing messages like Person.friends → Person), then *
* walks fields and oneofs. *
* ---------------------------------------------------------------- */
/* Lua 5.1 lacks lua_absindex; LuaJIT's compatibility layer too. */
static inline int
abs_idx(lua_State *L, int idx)
{
if (idx < 0 && idx > LUA_REGISTRYINDEX)
return lua_gettop(L) + idx + 1;
return idx;
}
static int
compile_plan_impl(lua_State *L, int desc_idx)
{
desc_idx = abs_idx(L, desc_idx);
/* Idempotency check. */
lua_getfield(L, desc_idx, "c_plan");
if (lua_isuserdata(L, -1)) {
/* Already compiled; leave on top of stack and pop the original
* desc-table push pattern wasn't done — caller still owns. */
return 1;
}
lua_pop(L, 1);
/* Allocate the plan userdata and stash it immediately. */
pb_plan *p = (pb_plan *)lua_newuserdata(L, sizeof(pb_plan));
memset(p, 0, sizeof(*p));
p->override_encode_ref = LUA_NOREF;
p->override_decode_ref = LUA_NOREF;
p->field_names_ref = LUA_NOREF;
p->sub_plans_ref = LUA_NOREF;
luaL_getmetatable(L, PB_PLAN_MT);
lua_setmetatable(L, -2);
int plan_idx = lua_gettop(L);
/* Stash on desc.c_plan first to break sub-message cycles. */
lua_pushvalue(L, plan_idx);
lua_setfield(L, desc_idx, "c_plan");
/* desc.name */
lua_getfield(L, desc_idx, "name");
const char *dname = lua_tostring(L, -1);
p->name = strdup(dname != NULL ? dname : "");
lua_pop(L, 1);
/* WKT override pointers — desc.encode / desc.decode. */
lua_getfield(L, desc_idx, "encode");
if (lua_isfunction(L, -1)) {
p->has_override = 1;
p->override_encode_ref = luaL_ref(L, LUA_REGISTRYINDEX);
} else {
lua_pop(L, 1);
}
lua_getfield(L, desc_idx, "decode");
if (lua_isfunction(L, -1)) {
p->has_override = 1;
p->override_decode_ref = luaL_ref(L, LUA_REGISTRYINDEX);
} else {
lua_pop(L, 1);
}
/* Extension ranges (proto2). desc.extension_ranges = {{start, end}, ...} */
lua_getfield(L, desc_idx, "extension_ranges");
if (lua_istable(L, -1) && lua_objlen(L, -1) >= 1) {
lua_rawgeti(L, -1, 1);
if (lua_istable(L, -1)) {
lua_rawgeti(L, -1, 1);
p->extension_range_start = (int)lua_tointeger(L, -1);
lua_pop(L, 1);
lua_rawgeti(L, -1, 2);
p->extension_range_end = (int)lua_tointeger(L, -1);
lua_pop(L, 1);
}
lua_pop(L, 1);
}
lua_pop(L, 1);
/* If this descriptor has an override, we skip field-walk entirely —
* the override owns encode/decode and the field array is unused. */
if (p->has_override) {
return 1;
}
/* Create the field-names and sub-plans tables. */
lua_newtable(L);
int field_names_idx = lua_gettop(L);
lua_newtable(L);
int sub_plans_idx = lua_gettop(L);
/* Walk desc.fields. */
lua_getfield(L, desc_idx, "fields");
if (!lua_istable(L, -1))
luaL_error(L, "descriptor '%s' has no 'fields'",
p->name != NULL ? p->name : "?");
int n_fields = (int)lua_objlen(L, -1);
int fields_table_idx = lua_gettop(L);
p->n_fields = n_fields;
p->fields = (pb_plan_field *)calloc(
n_fields > 0 ? n_fields : 1, sizeof(pb_plan_field));
for (int i = 0; i < n_fields; i++) {
lua_rawgeti(L, fields_table_idx, i + 1);
int f_desc_idx = lua_gettop(L);
compile_field(L, f_desc_idx, &p->fields[i],
field_names_idx, sub_plans_idx, i + 1);
lua_pop(L, 1);
}
lua_pop(L, 1); /* fields table */
/* Compile oneofs after fields so oneof_idx back-pointers can be set. */
compile_oneofs(L, p, desc_idx, field_names_idx);
/* Stash the field-names + sub-plans tables in the registry. */
lua_pushvalue(L, sub_plans_idx);
p->sub_plans_ref = luaL_ref(L, LUA_REGISTRYINDEX);
lua_pop(L, 1); /* sub_plans_idx (now unreferenced from stack) */
lua_pushvalue(L, field_names_idx);
p->field_names_ref = luaL_ref(L, LUA_REGISTRYINDEX);
lua_pop(L, 1);
/* Stack now has just the plan userdata on top. */
return 1;
}
static int
compile_plan_lua(lua_State *L)
{
luaL_checktype(L, 1, LUA_TTABLE);
lua_settop(L, 1);
return compile_plan_impl(L, 1);
}
/* ---------------------------------------------------------------- *
* Introspection (for the smoke test and future debugging). *
* *
* These are intentionally lean — enough to let a Lua test assert *
* the plan-build produced sensible values without a C-side test *
* harness. *
* ---------------------------------------------------------------- */
static int
plan_n_fields(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
lua_pushinteger(L, p->n_fields);
return 1;
}
static int
plan_name(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
lua_pushstring(L, p->name != NULL ? p->name : "");
return 1;
}
static int
plan_field_info(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
int i = luaL_checkint(L, 2);
if (i < 1 || i > p->n_fields)
return luaL_error(L, "field index %d out of range [1, %d]",
i, p->n_fields);
pb_plan_field *f = &p->fields[i - 1];
lua_createtable(L, 0, 9);
lua_pushinteger(L, f->field_number);
lua_setfield(L, -2, "field_number");
lua_pushinteger(L, f->wire_type);
lua_setfield(L, -2, "wire_type");
lua_pushinteger(L, f->kind);
lua_setfield(L, -2, "kind");
lua_pushboolean(L, f->repeated);
lua_setfield(L, -2, "repeated");
lua_pushboolean(L, f->packed);
lua_setfield(L, -2, "packed");
lua_pushboolean(L, f->optional);
lua_setfield(L, -2, "optional");
lua_pushinteger(L, f->sub_plan_idx);
lua_setfield(L, -2, "sub_plan_idx");
lua_pushinteger(L, f->oneof_idx);
lua_setfield(L, -2, "oneof_idx");
lua_pushlstring(L, (const char *)f->tag_bytes, f->tag_len);
lua_setfield(L, -2, "tag_bytes");
/* Field name from cached table. */
lua_rawgeti(L, LUA_REGISTRYINDEX, p->field_names_ref);
lua_rawgeti(L, -1, i);
lua_remove(L, -2);
lua_setfield(L, -2, "name");
/* Map kinds, if any. */
if (f->kind == PB_KIND_MAP) {
lua_pushinteger(L, f->map_key_kind);
lua_setfield(L, -2, "map_key_kind");
lua_pushinteger(L, f->map_value_kind);
lua_setfield(L, -2, "map_value_kind");
lua_pushinteger(L, f->map_value_sub_plan_idx);
lua_setfield(L, -2, "map_value_sub_plan_idx");
}
return 1;
}
static int
plan_n_oneofs(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
lua_pushinteger(L, p->n_oneofs);
return 1;
}
static int
plan_oneof_info(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
int i = luaL_checkint(L, 2);
if (i < 1 || i > p->n_oneofs)
return luaL_error(L, "oneof index %d out of range [1, %d]",
i, p->n_oneofs);
pb_plan_oneof *o = &p->oneofs[i - 1];
lua_createtable(L, 0, 2);
lua_pushstring(L, o->name != NULL ? o->name : "");
lua_setfield(L, -2, "name");
lua_createtable(L, o->n_members, 0);
for (int j = 0; j < o->n_members; j++) {
lua_pushinteger(L, o->member_indices[j]);
lua_rawseti(L, -2, j + 1);
}
lua_setfield(L, -2, "member_indices");
return 1;
}
static int
plan_has_override(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
lua_pushboolean(L, p->has_override);
return 1;
}
static int
plan_sub_plan(lua_State *L)
{
pb_plan *p = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
int i = luaL_checkint(L, 2);
if (p->sub_plans_ref == LUA_NOREF || i < 1) {
lua_pushnil(L);
return 1;
}
lua_rawgeti(L, LUA_REGISTRYINDEX, p->sub_plans_ref);
lua_rawgeti(L, -1, i);
lua_remove(L, -2);
return 1;
}
/* ---------------------------------------------------------------- *
* Encode (bd-y1n / ra6 3b, bd-hwe / ra6 3d). *
* *
* Singular scalars (3b) and singular sub-messages (3d). Repeated/ *
* packed and map fields are silently skipped — 3e / 3h land them. *
* *
* Buffer strategy: a 4KB stack-backed scratch buffer that promotes *
* to a Lua userdata (GC'd automatically) on overflow. Using *
* `lua_newuserdata` for heap growth means a luaL_error mid-encode *
* doesn't leak — the userdata is still on the stack at the unwind *
* point and gets collected normally. *
* *
* Recursion shape: encode_body is called once per message; sub- *
* message fields recurse by allocating a fresh enc_buf on the C *
* stack and re-entering encode_body with the sub-plan. The parent's *
* heap_idx is force-established before recursing so it survives *
* the lua_settop cleanup at sub-encode exit (see *
* encode_submessage_field for the contract). *
* ---------------------------------------------------------------- */
#define ENC_STACK_BUF 4096
typedef struct enc_buf {
uint8_t stack[ENC_STACK_BUF];
uint8_t *heap; /* pointer into Lua userdata when grown; NULL while on stack */
int heap_idx; /* stack slot of the userdata; 0 if not yet on heap */
size_t cap;
size_t used;
} enc_buf;
static inline uint8_t *
ebuf_base(enc_buf *b)
{
return b->heap != NULL ? b->heap : b->stack;
}
static void
ebuf_init(enc_buf *b)
{
b->heap = NULL;
b->heap_idx = 0;
b->cap = ENC_STACK_BUF;
b->used = 0;
}
static void
ebuf_grow(lua_State *L, enc_buf *b, size_t needed)
{
size_t new_cap = b->cap * 2;
while (new_cap - b->used < needed)
new_cap *= 2;
uint8_t *new_buf = (uint8_t *)lua_newuserdata(L, new_cap);
memcpy(new_buf, ebuf_base(b), b->used);
if (b->heap_idx == 0) {
b->heap_idx = lua_gettop(L);
} else {
lua_replace(L, b->heap_idx);
}
b->heap = new_buf;
b->cap = new_cap;
}
static inline void
ebuf_reserve(lua_State *L, enc_buf *b, size_t needed)
{
if (b->cap - b->used < needed)
ebuf_grow(L, b, needed);
}
static inline void
ebuf_put_byte(enc_buf *b, uint8_t v)
{
ebuf_base(b)[b->used++] = v;
}
static inline void
ebuf_put_bytes(enc_buf *b, const uint8_t *src, size_t n)
{
memcpy(ebuf_base(b) + b->used, src, n);
b->used += n;
}
static inline void
ebuf_put_varint(enc_buf *b, uint64_t v)
{
uint8_t *p = ebuf_base(b) + b->used;
while (v >= 0x80) {
*p++ = (uint8_t)(v | 0x80);
v >>= 7;
}
*p++ = (uint8_t)v;
b->used = (size_t)(p - ebuf_base(b));
}
static inline void
ebuf_put_fixed32(enc_buf *b, uint32_t v)
{
uint8_t *p = ebuf_base(b) + b->used;
p[0] = (uint8_t)v;
p[1] = (uint8_t)(v >> 8);
p[2] = (uint8_t)(v >> 16);
p[3] = (uint8_t)(v >> 24);
b->used += 4;
}
static inline void
ebuf_put_fixed64(enc_buf *b, uint64_t v)
{
uint8_t *p = ebuf_base(b) + b->used;
p[0] = (uint8_t)v;
p[1] = (uint8_t)(v >> 8);
p[2] = (uint8_t)(v >> 16);
p[3] = (uint8_t)(v >> 24);
p[4] = (uint8_t)(v >> 32);
p[5] = (uint8_t)(v >> 40);
p[6] = (uint8_t)(v >> 48);
p[7] = (uint8_t)(v >> 56);
b->used += 8;
}
static inline void
ebuf_put_tag(enc_buf *b, const pb_plan_field *f)
{
memcpy(ebuf_base(b) + b->used, f->tag_bytes, f->tag_len);
b->used += f->tag_len;
}
/* Read a Lua value as uint64. Mirrors wire.lua's to_uint64: negative
* Lua numbers are sign-extended through int64 (proto3 wire spec for
* int32 fields). int64/uint64 cdata flow through luaL_touint64. */
static uint64_t
to_uint64_at(lua_State *L, int idx)
{
if (lua_type(L, idx) == LUA_TNUMBER) {
double d = lua_tonumber(L, idx);
if (d < 0)
return (uint64_t)(int64_t)d;
return (uint64_t)d;
}
return luaL_touint64(L, idx);
}
static int32_t
to_int32_at(lua_State *L, int idx)
{
if (lua_type(L, idx) == LUA_TNUMBER)
return (int32_t)lua_tointeger(L, idx);
return (int32_t)luaL_toint64(L, idx);
}
static int64_t
to_int64_at(lua_State *L, int idx)
{
if (lua_type(L, idx) == LUA_TNUMBER)
return (int64_t)lua_tonumber(L, idx);
return luaL_toint64(L, idx);
}
static inline uint32_t
zigzag32(int32_t n)
{
return ((uint32_t)n << 1) ^ (uint32_t)(n >> 31);
}
static inline uint64_t
zigzag64(int64_t n)
{
return ((uint64_t)n << 1) ^ (uint64_t)(n >> 63);
}
static inline uint32_t
f32_to_u32(float f)
{
union { float f; uint32_t u; } pun;
pun.f = f;
return pun.u;
}
static inline uint64_t
f64_to_u64(double d)
{
union { double d; uint64_t u; } pun;
pun.d = d;
return pun.u;
}
/* Resolve an enum field's Lua value to its int32 ordinal. Accepts
* numbers (returned directly), cdata int64 (downcast), or strings
* (looked up in field->enum_ref's by_name table). Mirrors the
* `if type(v) == 'string' then nv = M.Status[v]` branch in mode=full. */
static int32_t
enum_value_at(lua_State *L, pb_plan_field *f, int idx)
{
int t = lua_type(L, idx);
if (t == LUA_TSTRING) {
const char *s = lua_tostring(L, idx);
if (f->enum_ref == LUA_NOREF)
luaL_error(L, "enum field '%s' has no enum descriptor", s);
lua_rawgeti(L, LUA_REGISTRYINDEX, f->enum_ref);
lua_getfield(L, -1, "by_name");
if (!lua_istable(L, -1)) {
luaL_error(L, "enum descriptor missing by_name");
}
lua_pushvalue(L, idx);
lua_rawget(L, -2);
if (lua_isnil(L, -1)) {
luaL_error(L, "unknown enum value '%s'", s);
}
int32_t v = (int32_t)lua_tointeger(L, -1);
lua_pop(L, 3); /* value + by_name + desc */
return v;
}
return (int32_t)to_int64_at(L, idx);
}
/* Encode one scalar/enum/string field. Returns 1 if bytes were
* written, 0 if the value collapsed to its proto3 default and was
* suppressed. Zero-suppression is skipped for proto3-optional AND
* when `force_emit` is non-zero (used by repeated-unpacked, where
* every element must reach the wire regardless of value). */
static int
encode_one_field(lua_State *L, enc_buf *b, pb_plan_field *f, int val_idx,
int force_emit)
{
int suppress = !force_emit && !f->optional;
switch (f->kind) {
case PB_KIND_INT32:
case PB_KIND_INT64:
case PB_KIND_UINT32:
case PB_KIND_UINT64: {
uint64_t u = to_uint64_at(L, val_idx);
if (suppress && u == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 10);
ebuf_put_tag(b, f);
ebuf_put_varint(b, u);
return 1;
}
case PB_KIND_SINT32: {
int32_t s = to_int32_at(L, val_idx);
if (suppress && s == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 5);
ebuf_put_tag(b, f);
ebuf_put_varint(b, zigzag32(s));
return 1;
}
case PB_KIND_SINT64: {
int64_t s = to_int64_at(L, val_idx);
if (suppress && s == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 10);
ebuf_put_tag(b, f);
ebuf_put_varint(b, zigzag64(s));
return 1;
}
case PB_KIND_BOOL: {
int truthy = lua_toboolean(L, val_idx);
if (suppress && !truthy) return 0;
ebuf_reserve(L, b, f->tag_len + 1);
ebuf_put_tag(b, f);
ebuf_put_byte(b, truthy ? 1 : 0);
return 1;
}
case PB_KIND_FIXED32:
case PB_KIND_SFIXED32: {
uint64_t u = to_uint64_at(L, val_idx);
uint32_t u32 = (uint32_t)u;
if (suppress && u32 == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 4);
ebuf_put_tag(b, f);
ebuf_put_fixed32(b, u32);
return 1;
}
case PB_KIND_FIXED64:
case PB_KIND_SFIXED64: {
uint64_t u = to_uint64_at(L, val_idx);
if (suppress && u == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 8);
ebuf_put_tag(b, f);
ebuf_put_fixed64(b, u);
return 1;
}
case PB_KIND_FLOAT: {
double d = lua_tonumber(L, val_idx);
uint32_t u = f32_to_u32((float)d);
/* +0.0 -> u==0 (skip); -0.0 -> u==0x80000000 (emit). Matches the
* Lua-side `(v ~= 0 or 1/v == -math.huge)` guard. */
if (suppress && u == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 4);
ebuf_put_tag(b, f);
ebuf_put_fixed32(b, u);
return 1;
}
case PB_KIND_DOUBLE: {
double d = lua_tonumber(L, val_idx);
uint64_t u = f64_to_u64(d);
if (suppress && u == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 8);
ebuf_put_tag(b, f);
ebuf_put_fixed64(b, u);
return 1;
}
case PB_KIND_ENUM: {
int32_t e = enum_value_at(L, f, val_idx);
if (suppress && e == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 10);
ebuf_put_tag(b, f);
/* enum is wire-equivalent to int32: sign-extend to uint64 then varint. */
ebuf_put_varint(b, (uint64_t)(int64_t)e);
return 1;
}
case PB_KIND_STRING:
case PB_KIND_BYTES: {
if (lua_type(L, val_idx) != LUA_TSTRING)
luaL_error(L, "string/bytes field requires a string value");
size_t len;
const char *s = lua_tolstring(L, val_idx, &len);
if (suppress && len == 0) return 0;
ebuf_reserve(L, b, f->tag_len + 10 + len);
ebuf_put_tag(b, f);
ebuf_put_varint(b, (uint64_t)len);
if (len > 0)
ebuf_put_bytes(b, (const uint8_t *)s, len);
return 1;
}
default:
/* Map is 3h scope; message singular goes through
* encode_submessage_field; repeated dispatches at the
* field-walk level. */
return 0;
}
}
/* Encode one element of a packed scalar/enum/bool field into `b` —
* raw value bytes only, no tag. Mirrors encode_one_field's per-kind
* value emission with suppression always off. Length-delimited kinds
* (STRING/BYTES/MESSAGE) are not packable per spec — caller must
* dispatch them elsewhere. */
static void
encode_packed_element_at(lua_State *L, enc_buf *b, pb_plan_field *f,
int val_idx)
{
switch (f->kind) {
case PB_KIND_INT32:
case PB_KIND_INT64:
case PB_KIND_UINT32:
case PB_KIND_UINT64: {
uint64_t u = to_uint64_at(L, val_idx);
ebuf_reserve(L, b, 10);
ebuf_put_varint(b, u);
return;
}
case PB_KIND_SINT32: {
int32_t s = to_int32_at(L, val_idx);
ebuf_reserve(L, b, 5);
ebuf_put_varint(b, zigzag32(s));
return;
}
case PB_KIND_SINT64: {
int64_t s = to_int64_at(L, val_idx);
ebuf_reserve(L, b, 10);
ebuf_put_varint(b, zigzag64(s));
return;
}
case PB_KIND_BOOL: {
int truthy = lua_toboolean(L, val_idx);
ebuf_reserve(L, b, 1);
ebuf_put_byte(b, truthy ? 1 : 0);
return;
}
case PB_KIND_FIXED32:
case PB_KIND_SFIXED32: {
uint64_t u = to_uint64_at(L, val_idx);
ebuf_reserve(L, b, 4);
ebuf_put_fixed32(b, (uint32_t)u);
return;
}
case PB_KIND_FIXED64:
case PB_KIND_SFIXED64: {
uint64_t u = to_uint64_at(L, val_idx);
ebuf_reserve(L, b, 8);
ebuf_put_fixed64(b, u);
return;
}
case PB_KIND_FLOAT: {
double d = lua_tonumber(L, val_idx);
ebuf_reserve(L, b, 4);
ebuf_put_fixed32(b, f32_to_u32((float)d));
return;
}
case PB_KIND_DOUBLE: {
double d = lua_tonumber(L, val_idx);
ebuf_reserve(L, b, 8);
ebuf_put_fixed64(b, f64_to_u64(d));
return;
}
case PB_KIND_ENUM: {
int32_t e = enum_value_at(L, f, val_idx);
ebuf_reserve(L, b, 10);
ebuf_put_varint(b, (uint64_t)(int64_t)e);
return;
}
default:
luaL_error(L, "kind %d not packable", (int)f->kind);
}
}
/* Forward decls for the recursive encode pair. */
static void encode_body(lua_State *L, enc_buf *b, pb_plan *plan, int msg_idx);
static void encode_submessage_field(lua_State *L, enc_buf *b, pb_plan *plan,
pb_plan_field *f, int val_idx);
/* Encode a repeated field's elements into `b`. Dispatches on element
* kind and the `packed` plan flag:
* - packed scalar/enum/bool → single tag(LEN) + varint(len) + tight
* payload built in a stack-backed sub-buffer
* - unpacked scalar/enum/bool → per-element tag(elem_wire) + value
* - string/bytes → per-element tag(LEN) + varint(len) + bytes
* (string/bytes are never packable per spec)
* - message → per-element tag(LEN) + len-prefix + nested body via
* encode_submessage_field
*
* Empty arrays produce nothing — proto3 wire spec treats an absent
* repeated field and an empty one identically.
*
* Sub-buffer cleanup follows encode_submessage_field's contract: the
* parent's heap is force-established before allocating the sub-buffer
* so the parent's heap_idx sits below saved_top and survives the final
* lua_settop. */
static void
encode_repeated_field(lua_State *L, enc_buf *b, pb_plan *plan,
pb_plan_field *f, int val_idx)
{
val_idx = abs_idx(L, val_idx);
int n = (int)lua_objlen(L, val_idx);
if (n == 0)
return;
if (f->kind == PB_KIND_MESSAGE) {
for (int i = 1; i <= n; i++) {
lua_rawgeti(L, val_idx, i);
int elem = lua_gettop(L);
encode_submessage_field(L, b, plan, f, elem);
lua_pop(L, 1);
}
return;
}
if (f->packed) {
if (b->heap_idx == 0)
ebuf_grow(L, b, 1);
int saved_top = lua_gettop(L);
enc_buf sub;
ebuf_init(&sub);
for (int i = 1; i <= n; i++) {
lua_rawgeti(L, val_idx, i);
encode_packed_element_at(L, &sub, f, lua_gettop(L));
lua_pop(L, 1);
}
ebuf_reserve(L, b, f->tag_len + 10 + sub.used);
ebuf_put_tag(b, f);
ebuf_put_varint(b, (uint64_t)sub.used);
if (sub.used > 0)
ebuf_put_bytes(b, ebuf_base(&sub), sub.used);
lua_settop(L, saved_top);
return;
}
/* Unpacked: per-element tag + value. string/bytes flow through
* encode_one_field too — its STRING/BYTES branch already emits
* `tag + varint(len) + bytes`, which is exactly the unpacked
* length-delimited element shape. */
for (int i = 1; i <= n; i++) {
lua_rawgeti(L, val_idx, i);
encode_one_field(L, b, f, lua_gettop(L), /* force_emit */ 1);
lua_pop(L, 1);
}
}
/* Encode one singular sub-message field into the parent buffer `b`.
* Lifecycle / stack-management contract:
* - Parent's heap is force-established (one 8KB grow) BEFORE recursing
* so b->heap_idx is below the saved_top. This way the final
* ebuf_reserve on the parent can only either re-use b->heap_idx via
* lua_replace (no new stack slot) or — if no further grow is
* needed — leave the stack alone. Either way, lua_settop(L,
* saved_top) at the end is safe.
* - sub-buf is a fresh stack-backed enc_buf; its potential heap
* userdata is on the Lua stack above saved_top and is dropped by
* the lua_settop. */
static void
encode_submessage_field(lua_State *L, enc_buf *b, pb_plan *plan,
pb_plan_field *f, int val_idx)
{
if (lua_type(L, val_idx) != LUA_TTABLE)
luaL_error(L, "message field requires a table value");
if (plan->sub_plans_ref == LUA_NOREF)
luaL_error(L, "plan '%s' has no sub-plans table",
plan->name != NULL ? plan->name : "?");
/* Force parent's heap to exist before the sub-encode allocates. */
if (b->heap_idx == 0)
ebuf_grow(L, b, 1);
val_idx = abs_idx(L, val_idx);
int saved_top = lua_gettop(L);
lua_rawgeti(L, LUA_REGISTRYINDEX, plan->sub_plans_ref);
lua_rawgeti(L, -1, f->sub_plan_idx);
pb_plan *subplan = (pb_plan *)lua_touserdata(L, -1);
if (subplan == NULL)
luaL_error(L, "sub-plan at index %d is not a userdata",
f->sub_plan_idx);
enc_buf sub;
ebuf_init(&sub);
encode_body(L, &sub, subplan, val_idx);
/* Write tag + length-varint + body into parent. Parent regrowth
* here goes through lua_replace at b->heap_idx (safely below
* saved_top) — no stack-frame disruption. */
ebuf_reserve(L, b, f->tag_len + 10 + sub.used);
ebuf_put_tag(b, f);
ebuf_put_varint(b, (uint64_t)sub.used);
if (sub.used > 0)
ebuf_put_bytes(b, ebuf_base(&sub), sub.used);
lua_settop(L, saved_top);
}
static void
encode_body(lua_State *L, enc_buf *b, pb_plan *plan, int msg_idx)
{
msg_idx = abs_idx(L, msg_idx);
if (plan->has_override) {
luaL_error(L,
"C encode on plan with override is unsupported (bd-rmf)");
}
if (plan->field_names_ref == LUA_NOREF || plan->n_fields == 0)
return;
lua_rawgeti(L, LUA_REGISTRYINDEX, plan->field_names_ref);
int names_idx = lua_gettop(L);
for (int i = 0; i < plan->n_fields; i++) {
pb_plan_field *f = &plan->fields[i];
/* Map dispatches in 3h. */
if (f->kind == PB_KIND_MAP) continue;
lua_rawgeti(L, names_idx, i + 1); /* push field name */
lua_rawget(L, msg_idx); /* push msg[name] */
int val_idx = lua_gettop(L);
if (lua_isnil(L, val_idx)) {
lua_pop(L, 1);
continue;
}
if (f->repeated) {
if (lua_type(L, val_idx) != LUA_TTABLE)
luaL_error(L,
"repeated field requires a table value");
encode_repeated_field(L, b, plan, f, val_idx);
} else if (f->kind == PB_KIND_MESSAGE) {
encode_submessage_field(L, b, plan, f, val_idx);
} else {
encode_one_field(L, b, f, val_idx, /* force_emit */ 0);
}
lua_pop(L, 1);
}
lua_pop(L, 1); /* names table */
}
static int
encode_lua(lua_State *L)
{
pb_plan *plan = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
luaL_checktype(L, 2, LUA_TTABLE);
if (plan->has_override) {
return luaL_error(L,
"C encode on plan with override is unsupported (bd-rmf)");
}
enc_buf b;
ebuf_init(&b);
encode_body(L, &b, plan, 2);
lua_pushlstring(L, (const char *)ebuf_base(&b), b.used);
return 1;
}
/* ---------------------------------------------------------------- *
* Decode (bd-mz6 / ra6 3c, bd-hwe / ra6 3d). *
* *
* Singular scalars (3c) and singular sub-messages (3d). Repeated *
* and map fields are skipped by wire type — 3e / 3h will land *
* them. Unknown tags are skipped silently too; bd-wyp will add *
* round-trip capture. *
* *
* Result-table shape must match mode=full pure-Lua decode. That *
* pins per-kind value types: int64/uint64/sint64/fixed64/sfixed64 *
* push Tarantool int64_t/uint64_t cdata via luaL_pushint64 / *
* luaL_pushuint64; everything else pushes a Lua number, boolean, *
* or string. See runtime/pb/wire.lua decoder comments. *
* *
* Nested-message decode bounds the byte range by temporarily *
* shrinking c->len to the sub-message's end offset; the wire-prim *
* helpers (dec_varint / dec_fixed*) already bounds-check against *
* c->len, so this keeps a malformed inner payload from over- *
* reading into the outer message's bytes. *
* ---------------------------------------------------------------- */
typedef struct dec_ctx {
lua_State *L;
const uint8_t *buf;
size_t len;
size_t pos;
} dec_ctx;
static uint64_t
dec_varint(dec_ctx *c)
{
uint64_t v = 0;
int shift = 0;
for (int i = 0; i < 10; i++) {
if (c->pos >= c->len)
luaL_error(c->L, "truncated varint at offset %d",
(int)c->pos);
uint8_t b = c->buf[c->pos++];
v |= ((uint64_t)(b & 0x7f)) << shift;
if ((b & 0x80) == 0)
return v;
shift += 7;
}
luaL_error(c->L, "varint exceeds 10 bytes at offset %d",
(int)c->pos);
return 0;
}
static uint32_t
dec_fixed32(dec_ctx *c)
{
if (c->len - c->pos < 4)
luaL_error(c->L, "truncated fixed32 at offset %d",
(int)c->pos);
uint32_t v = (uint32_t)c->buf[c->pos]
| ((uint32_t)c->buf[c->pos + 1] << 8)
| ((uint32_t)c->buf[c->pos + 2] << 16)
| ((uint32_t)c->buf[c->pos + 3] << 24);
c->pos += 4;
return v;
}
static uint64_t
dec_fixed64(dec_ctx *c)
{
if (c->len - c->pos < 8)
luaL_error(c->L, "truncated fixed64 at offset %d",
(int)c->pos);
uint64_t v = 0;
for (int i = 0; i < 8; i++)
v |= ((uint64_t)c->buf[c->pos + i]) << (i * 8);
c->pos += 8;
return v;
}
static void
dec_skip(dec_ctx *c, uint8_t wt)
{
switch (wt) {
case PB_WIRE_VARINT:
(void)dec_varint(c);
break;
case PB_WIRE_I32:
(void)dec_fixed32(c);
break;
case PB_WIRE_I64:
(void)dec_fixed64(c);
break;
case PB_WIRE_LEN: {
uint64_t plen = dec_varint(c);
if (c->len - c->pos < plen)
luaL_error(c->L, "truncated length-delimited payload");
c->pos += (size_t)plen;
break;
}
default:
luaL_error(c->L, "unsupported wire type %d for skip", (int)wt);
}
}
static inline int32_t
zigzag32_dec(uint32_t u)
{
return (int32_t)((u >> 1) ^ (~(u & 1) + 1));
}
static inline int64_t
zigzag64_dec(uint64_t u)
{
return (int64_t)((u >> 1) ^ (~(u & 1) + 1));
}
/* Decode a single value for field `f` and push it onto the Lua stack. */
static void
dec_push_one(dec_ctx *c, pb_plan_field *f)
{
switch (f->kind) {
case PB_KIND_INT32: {
uint64_t u = dec_varint(c);
int32_t v = (int32_t)(uint32_t)u;
lua_pushinteger(c->L, v);
return;
}
case PB_KIND_INT64: {
uint64_t u = dec_varint(c);
luaL_pushint64(c->L, (int64_t)u);
return;
}
case PB_KIND_UINT32: {
uint64_t u = dec_varint(c);
uint32_t v = (uint32_t)u;
lua_pushnumber(c->L, (double)v);
return;
}
case PB_KIND_UINT64: {
uint64_t u = dec_varint(c);
luaL_pushuint64(c->L, u);
return;
}
case PB_KIND_SINT32: {
uint64_t u = dec_varint(c);
int32_t v = zigzag32_dec((uint32_t)u);
lua_pushinteger(c->L, v);
return;
}
case PB_KIND_SINT64: {
uint64_t u = dec_varint(c);
luaL_pushint64(c->L, zigzag64_dec(u));
return;
}
case PB_KIND_BOOL: {
uint64_t u = dec_varint(c);
lua_pushboolean(c->L, u != 0);
return;
}
case PB_KIND_ENUM: {
uint64_t u = dec_varint(c);
int32_t v = (int32_t)(uint32_t)u;
lua_pushinteger(c->L, v);
return;
}
case PB_KIND_FIXED32: {
uint32_t u = dec_fixed32(c);
lua_pushnumber(c->L, (double)u);
return;
}
case PB_KIND_SFIXED32: {
uint32_t u = dec_fixed32(c);
lua_pushinteger(c->L, (int32_t)u);
return;
}
case PB_KIND_FLOAT: {
uint32_t u = dec_fixed32(c);
union { uint32_t u; float f; } pun;
pun.u = u;
lua_pushnumber(c->L, (double)pun.f);
return;
}
case PB_KIND_FIXED64: {
uint64_t u = dec_fixed64(c);
luaL_pushuint64(c->L, u);
return;
}
case PB_KIND_SFIXED64: {
uint64_t u = dec_fixed64(c);
luaL_pushint64(c->L, (int64_t)u);
return;
}
case PB_KIND_DOUBLE: {
uint64_t u = dec_fixed64(c);
union { uint64_t u; double d; } pun;
pun.u = u;
lua_pushnumber(c->L, pun.d);
return;
}
case PB_KIND_STRING:
case PB_KIND_BYTES: {
uint64_t plen = dec_varint(c);
if (c->len - c->pos < plen)
luaL_error(c->L, "truncated string/bytes payload");
lua_pushlstring(c->L, (const char *)(c->buf + c->pos),
(size_t)plen);
c->pos += (size_t)plen;
return;
}
default:
luaL_error(c->L, "dec_push_one: unsupported kind %d",
(int)f->kind);
}
}
/* Forward decl for the recursive decode. */
static void decode_body(dec_ctx *c, pb_plan *plan, int result_idx);
static void decode_submessage_field(dec_ctx *c, pb_plan_field *f,
int sub_plans_idx);
/* Decode one singular sub-message field. On entry, `c->pos` points at
* the length-varint byte; on exit, `c->pos == c->pos + plen`. Pushes
* the decoded sub-table onto the Lua stack. */
static void
decode_submessage_field(dec_ctx *c, pb_plan_field *f, int sub_plans_idx)
{
lua_State *L = c->L;
uint64_t plen = dec_varint(c);
if (c->len - c->pos < plen)
luaL_error(L, "truncated nested message at offset %d",
(int)c->pos);
lua_rawgeti(L, sub_plans_idx, f->sub_plan_idx);
pb_plan *subplan = (pb_plan *)lua_touserdata(L, -1);
if (subplan == NULL)
luaL_error(L, "sub-plan at index %d is not a userdata",
f->sub_plan_idx);
lua_pop(L, 1);
lua_createtable(L, 0, subplan->n_fields);
int sub_result_idx = lua_gettop(L);
/* Temporarily shrink c->len so the inner decode loop terminates at
* the sub-message boundary and so inner wire-prim reads cannot
* spill past it. */
size_t saved_len = c->len;
c->len = c->pos + (size_t)plen;
decode_body(c, subplan, sub_result_idx);
if (c->pos != c->len)
luaL_error(L,
"nested message body underflow at offset %d (expected %d)",
(int)c->pos, (int)c->len);
c->len = saved_len;
}
/* Return 1 if the field's element wire type is varint/i32/i64 — i.e.
* the field is eligible for packed encoding. Length-delimited kinds
* (STRING/BYTES/MESSAGE) and MAP are never packable. Used on decode
* to detect a wt==LEN payload for a repeated scalar field as a packed
* blob even when the schema declares packed=false (proto3 readers MUST
* accept both). */
static inline int
field_is_packable(const pb_plan_field *f)
{
switch (f->kind) {
case PB_KIND_STRING:
case PB_KIND_BYTES:
case PB_KIND_MESSAGE:
case PB_KIND_MAP:
case PB_KIND_NONE:
return 0;
default:
return 1;
}
}
static void
decode_body(dec_ctx *c, pb_plan *plan, int result_idx)
{
lua_State *L = c->L;
if (plan->has_override) {
luaL_error(L,
"C decode on plan with override is unsupported (bd-rmf)");
}
result_idx = abs_idx(L, result_idx);
/* Pin field-names + sub-plans so the loop can rawgeti by index. */
int names_idx, sub_plans_idx;
if (plan->field_names_ref != LUA_NOREF) {
lua_rawgeti(L, LUA_REGISTRYINDEX, plan->field_names_ref);
} else {
lua_pushnil(L);
}
names_idx = lua_gettop(L);
if (plan->sub_plans_ref != LUA_NOREF) {
lua_rawgeti(L, LUA_REGISTRYINDEX, plan->sub_plans_ref);
} else {
lua_pushnil(L);
}
sub_plans_idx = lua_gettop(L);
/* Per-field stack-slot cache for repeated fields. On first hit for
* a given field, we lua_createtable + store into result[name] and
* dup-push the table onto the stack; subsequent hits reuse the
* cached absolute stack index and lua_rawseti the new element
* directly. Avoids the per-element lua_getfield(result, name) round
* trip that the c-accel spike measured at 2x slower at 100KB.
*
* list_count[i] tracks length without calling lua_objlen per append
* — a Lua-side O(log n) probe that adds up fast on the 1000-element
* acceptance path.
*
* VLA size guarded against n_fields == 0 (UB for zero-length VLA).
* Both arrays live on the C stack; n_fields is bounded by message
* shape — for any realistic schema this is well under 1KB. */
int vla_n = plan->n_fields > 0 ? plan->n_fields : 1;
int list_stack_idx[vla_n];
int list_count[vla_n];
memset(list_stack_idx, 0, sizeof(list_stack_idx));
memset(list_count, 0, sizeof(list_count));
while (c->pos < c->len) {
uint64_t tag = dec_varint(c);
uint32_t field_number = (uint32_t)(tag >> 3);
uint8_t wt = (uint8_t)(tag & 0x07);
/* Linear scan over plan->fields. n_fields is typically small;
* tag-keyed dispatch table is a future optimization. */
pb_plan_field *f = NULL;
int f_idx = -1;
for (int i = 0; i < plan->n_fields; i++) {
if (plan->fields[i].field_number == field_number) {
f = &plan->fields[i];
f_idx = i;
break;
}
}
/* Unknown tag, or map (3h territory). */
if (f == NULL || f->kind == PB_KIND_MAP) {
dec_skip(c, wt);
continue;
}
/* ------------------------------------------------------ *
* Repeated dispatch *
* ------------------------------------------------------ */
if (f->repeated) {
/* Lazy-create the list table on first hit. */
int list_idx = list_stack_idx[f_idx];
if (list_idx == 0) {
lua_createtable(L, 0, 0);
/* Stack: ..., new_list. Dup, write name → list
* into result, leave list on top as our cache. */
lua_pushvalue(L, -1);
lua_rawgeti(L, names_idx, f_idx + 1);
lua_insert(L, -2); /* name, list_copy */
lua_rawset(L, result_idx); /* result[name] = list */
list_idx = lua_gettop(L);
list_stack_idx[f_idx] = list_idx;
list_count[f_idx] = 0;
}
/* Repeated message: per-element length-delimited body. */
if (f->kind == PB_KIND_MESSAGE) {
if (wt != PB_WIRE_LEN)
luaL_error(L,
"repeated message field %d expected wire 2, got %d",
(int)field_number, (int)wt);
decode_submessage_field(c, f, sub_plans_idx);
/* Stack top is the decoded sub-table. */
list_count[f_idx]++;
lua_rawseti(L, list_idx, list_count[f_idx]);
continue;
}
/* Packed payload: a single LEN-prefixed blob carrying
* N elements end-to-end. Proto3 readers must accept a
* packed payload for any packable scalar regardless of
* the schema's packed flag — that's why this check is
* `field_is_packable`, not `f->packed`. */
if (wt == PB_WIRE_LEN && field_is_packable(f)) {
uint64_t plen = dec_varint(c);
if (c->len - c->pos < plen)
luaL_error(L,
"truncated packed payload for field %d",
(int)field_number);
size_t saved_len = c->len;
c->len = c->pos + (size_t)plen;
while (c->pos < c->len) {
dec_push_one(c, f);
list_count[f_idx]++;
lua_rawseti(L, list_idx, list_count[f_idx]);
}
if (c->pos != c->len)
luaL_error(L,
"packed payload underflow for field %d",
(int)field_number);
c->len = saved_len;
continue;
}
/* Unpacked single element. */
dec_push_one(c, f);
list_count[f_idx]++;
lua_rawseti(L, list_idx, list_count[f_idx]);
continue;
}
/* ------------------------------------------------------ *
* Singular dispatch *
* ------------------------------------------------------ */
if (f->kind == PB_KIND_MESSAGE) {
decode_submessage_field(c, f, sub_plans_idx);
/* stack: ..., names, sub_plans, [lists...], sub_result */
lua_rawgeti(L, names_idx, f_idx + 1);
lua_insert(L, -2); /* name, sub_result */
lua_rawset(L, result_idx); /* result[name] = sub_result */
continue;
}
dec_push_one(c, f); /* stack: ..., names, sub_plans, [lists...], value */
lua_rawgeti(L, names_idx, f_idx + 1);
lua_insert(L, -2); /* name, value */
lua_rawset(L, result_idx); /* result[name] = value */
}
/* Pop everything we pushed: per-field list tables (one per repeated
* field that appeared), then sub_plans and names. Walk list_stack_idx
* to count list-table pushes — equals lua_gettop(L) - sub_plans_idx. */
int top = lua_gettop(L);
int to_pop = top - names_idx + 1;
lua_pop(L, to_pop);
}
static int
decode_lua(lua_State *L)
{
pb_plan *plan = (pb_plan *)luaL_checkudata(L, 1, PB_PLAN_MT);
size_t buf_len;
const char *buf = luaL_checklstring(L, 2, &buf_len);
if (plan->has_override) {
return luaL_error(L,
"C decode on plan with override is unsupported (bd-rmf)");
}
lua_createtable(L, 0, plan->n_fields);
int result_idx = lua_gettop(L);
dec_ctx c;
c.L = L;
c.buf = (const uint8_t *)buf;
c.len = buf_len;
c.pos = 0;
decode_body(&c, plan, result_idx);
return 1;
}
/* ---------------------------------------------------------------- *
* Module entry. *
* ---------------------------------------------------------------- */
static const struct luaL_Reg c_runtime_methods[] = {
{"compile_plan", compile_plan_lua},
{"plan_n_fields", plan_n_fields},
{"plan_name", plan_name},
{"plan_field_info", plan_field_info},
{"plan_n_oneofs", plan_n_oneofs},
{"plan_oneof_info", plan_oneof_info},
{"plan_has_override", plan_has_override},
{"plan_sub_plan", plan_sub_plan},
{"encode", encode_lua},
{"decode", decode_lua},
{NULL, NULL},
};
static const struct luaL_Reg plan_mt_methods[] = {
{"__gc", plan_gc},
{"__tostring", plan_tostring},
{NULL, NULL},
};
LUA_API int
luaopen_pb_c_runtime(lua_State *L)
{
/* Register the plan metatable. */
luaL_newmetatable(L, PB_PLAN_MT);
luaL_register(L, NULL, plan_mt_methods);
lua_pop(L, 1);
/* Build the module table. */
lua_newtable(L);
luaL_register(L, NULL, c_runtime_methods);
lua_pushliteral(L, PB_ABI_VERSION);
lua_setfield(L, -2, "_abi_version");
/* Kind constants — exported so Lua tests can compare without
* duplicating the enum. */
lua_createtable(L, 0, 19);
lua_pushinteger(L, PB_KIND_NONE); lua_setfield(L, -2, "NONE");
lua_pushinteger(L, PB_KIND_INT32); lua_setfield(L, -2, "INT32");
lua_pushinteger(L, PB_KIND_INT64); lua_setfield(L, -2, "INT64");
lua_pushinteger(L, PB_KIND_UINT32); lua_setfield(L, -2, "UINT32");
lua_pushinteger(L, PB_KIND_UINT64); lua_setfield(L, -2, "UINT64");
lua_pushinteger(L, PB_KIND_SINT32); lua_setfield(L, -2, "SINT32");
lua_pushinteger(L, PB_KIND_SINT64); lua_setfield(L, -2, "SINT64");
lua_pushinteger(L, PB_KIND_FIXED32); lua_setfield(L, -2, "FIXED32");
lua_pushinteger(L, PB_KIND_FIXED64); lua_setfield(L, -2, "FIXED64");
lua_pushinteger(L, PB_KIND_SFIXED32); lua_setfield(L, -2, "SFIXED32");
lua_pushinteger(L, PB_KIND_SFIXED64); lua_setfield(L, -2, "SFIXED64");
lua_pushinteger(L, PB_KIND_FLOAT); lua_setfield(L, -2, "FLOAT");
lua_pushinteger(L, PB_KIND_DOUBLE); lua_setfield(L, -2, "DOUBLE");
lua_pushinteger(L, PB_KIND_BOOL); lua_setfield(L, -2, "BOOL");
lua_pushinteger(L, PB_KIND_STRING); lua_setfield(L, -2, "STRING");
lua_pushinteger(L, PB_KIND_BYTES); lua_setfield(L, -2, "BYTES");
lua_pushinteger(L, PB_KIND_ENUM); lua_setfield(L, -2, "ENUM");
lua_pushinteger(L, PB_KIND_MESSAGE); lua_setfield(L, -2, "MESSAGE");
lua_pushinteger(L, PB_KIND_MAP); lua_setfield(L, -2, "MAP");
lua_setfield(L, -2, "KIND");
lua_createtable(L, 0, 4);
lua_pushinteger(L, PB_WIRE_VARINT); lua_setfield(L, -2, "VARINT");
lua_pushinteger(L, PB_WIRE_I64); lua_setfield(L, -2, "I64");
lua_pushinteger(L, PB_WIRE_LEN); lua_setfield(L, -2, "LEN");
lua_pushinteger(L, PB_WIRE_I32); lua_setfield(L, -2, "I32");
lua_setfield(L, -2, "WIRE");
return 1;
}