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Call callbacks from a pcall
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Lua errors (including allocation failures) would `longjmp` out of the
callbacks, bypassing cleanup in libmosquitto.

This commit changes errors from undefined behaviour (that luckily used
to get reported) to silently discarding errors.

Closes #23
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@daurnimator
daurnimator committed May 22, 2018
1 parent 2633d51 commit b9c12c8
Showing 1 changed file with 122 additions and 46 deletions.
168 changes: 122 additions & 46 deletions lua-mosquitto.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -522,12 +522,9 @@ static int ctx_want_write(lua_State *L)
return 1;
}

static void ctx_on_connect(
struct mosquitto *mosq,
void *obj,
int rc)
{
ctx_t *ctx = obj;
static int ctx_on_connect_safe(lua_State *L) {
int ref = lua_tointeger(L, 1);
int rc = lua_tointeger(L, 2);
bool success = false;
char *str = "reserved for future use";

Expand Down Expand Up @@ -562,22 +559,37 @@ static void ctx_on_connect(
break;
}

lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_connect);
lua_rawgeti(L, LUA_REGISTRYINDEX, ref);

lua_pushboolean(ctx->L, success);
lua_pushinteger(ctx->L, rc);
lua_pushstring(ctx->L, str);
lua_pushboolean(L, success);
lua_pushinteger(L, rc);
lua_pushstring(L, str);

lua_call(ctx->L, 3, 0);
}
lua_call(L, 3, 0);

return 0;
}

static void ctx_on_disconnect(
static void ctx_on_connect(
struct mosquitto *mosq,
void *obj,
int rc)
{
ctx_t *ctx = obj;
lua_State *L = ctx->L;
lua_pushcfunction(L, ctx_on_connect_safe);
lua_pushinteger(L, ctx->on_connect);
lua_pushinteger(L, rc);
if (lua_pcall(L, 2, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}


static int ctx_on_disconnect_safe(lua_State *L) {
int ref = lua_tointeger(L, 1);
int rc = lua_tointeger(L, 2);
bool success = true;
char *str = "client-initiated disconnect";

Expand All @@ -586,13 +598,31 @@ static void ctx_on_disconnect(
str = "unexpected disconnect";
}

lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_disconnect);
lua_rawgeti(L, LUA_REGISTRYINDEX, ref);

lua_pushboolean(ctx->L, success);
lua_pushinteger(ctx->L, rc);
lua_pushstring(ctx->L, str);
lua_pushboolean(L, success);
lua_pushinteger(L, rc);
lua_pushstring(L, str);

lua_call(ctx->L, 3, 0);
lua_call(L, 3, 0);

return 0;
}

static void ctx_on_disconnect(
struct mosquitto *mosq,
void *obj,
int rc)
{
ctx_t *ctx = obj;
lua_State *L = ctx->L;
lua_pushcfunction(L, ctx_on_disconnect_safe);
lua_pushinteger(L, ctx->on_disconnect);
lua_pushinteger(L, rc);
if (lua_pcall(L, 2, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}

static void ctx_on_publish(
Expand All @@ -601,10 +631,31 @@ static void ctx_on_publish(
int mid)
{
ctx_t *ctx = obj;
lua_State *L = ctx->L;
lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->on_publish);
lua_pushinteger(L, mid);
if (lua_pcall(L, 1, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}

static int ctx_on_message_safe(lua_State *L) {
int ref = lua_tointeger(L, 1);
const struct mosquitto_message *msg = lua_touserdata(L, 2);

/* push registered Lua callback function onto the stack */
lua_rawgeti(L, LUA_REGISTRYINDEX, ref);
/* push function args */
lua_pushinteger(L, msg->mid);
lua_pushstring(L, msg->topic);
lua_pushlstring(L, msg->payload, msg->payloadlen);
lua_pushinteger(L, msg->qos);
lua_pushboolean(L, msg->retain);

lua_call(L, 5, 0); /* args: mid, topic, payload, qos, retain */

lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_publish);
lua_pushinteger(ctx->L, mid);
lua_call(ctx->L, 1, 0);
return 0;
}

static void ctx_on_message(
Expand All @@ -613,17 +664,14 @@ static void ctx_on_message(
const struct mosquitto_message *msg)
{
ctx_t *ctx = obj;

/* push registered Lua callback function onto the stack */
lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_message);
/* push function args */
lua_pushinteger(ctx->L, msg->mid);
lua_pushstring(ctx->L, msg->topic);
lua_pushlstring(ctx->L, msg->payload, msg->payloadlen);
lua_pushinteger(ctx->L, msg->qos);
lua_pushboolean(ctx->L, msg->retain);

lua_call(ctx->L, 5, 0); /* args: mid, topic, payload, qos, retain */
lua_State *L = ctx->L;
lua_pushcfunction(L, ctx_on_message_safe);
lua_pushinteger(L, ctx->on_message);
lua_pushlightuserdata(L, (void*)msg);
if (lua_pcall(L, 2, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}

static void ctx_on_subscribe(
Expand All @@ -634,16 +682,24 @@ static void ctx_on_subscribe(
const int *granted_qos)
{
ctx_t *ctx = obj;
lua_State *L = ctx->L;
int i;

lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_subscribe);
lua_pushinteger(ctx->L, mid);
if (!lua_checkstack(L, qos_count + 2)) {
/* can't allocate enough stack space */
return;
}

lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->on_subscribe);
lua_pushinteger(L, mid);
for (i = 0; i < qos_count; i++) {
lua_pushinteger(ctx->L, granted_qos[i]);
lua_pushinteger(L, granted_qos[i]);
}

lua_call(ctx->L, qos_count + 1, 0);
if (lua_pcall(L, qos_count + 1, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}

static void ctx_on_unsubscribe(
Expand All @@ -652,10 +708,28 @@ static void ctx_on_unsubscribe(
int mid)
{
ctx_t *ctx = obj;
lua_State *L = ctx->L;
lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->on_unsubscribe);
lua_pushinteger(L, mid);
if (lua_pcall(L, 1, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}

static int ctx_on_log_safe(lua_State *L) {
int ref = lua_tointeger(L, 1);
int level = lua_tointeger(L, 2);
const char *str = lua_touserdata(L, 3);

lua_rawgeti(L, LUA_REGISTRYINDEX, ref);

lua_pushinteger(L, level);
lua_pushstring(L, str);

lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_unsubscribe);
lua_pushinteger(ctx->L, mid);
lua_call(ctx->L, 1, 0);
lua_call(L, 2, 0);

return 0;
}

static void ctx_on_log(
Expand All @@ -665,13 +739,15 @@ static void ctx_on_log(
const char *str)
{
ctx_t *ctx = obj;

lua_rawgeti(ctx->L, LUA_REGISTRYINDEX, ctx->on_log);

lua_pushinteger(ctx->L, level);
lua_pushstring(ctx->L, str);

lua_call(ctx->L, 2, 0);
lua_State *L = ctx->L;
lua_pushcfunction(L, ctx_on_log_safe);
lua_pushinteger(L, ctx->on_log);
lua_pushinteger(L, level);
lua_pushlightuserdata(L, (void*)str);
if (lua_pcall(L, 3, 0, 0)) {
/* pop error message */
lua_pop(L, 1);
}
}

static int callback_type_from_string(const char *);
Expand Down

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