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Clobbering of MT slots #1439

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Clobbering of MT slots #1439

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72f9add
Return fd to lua on device open and for every event add an additional…
mapinguari Dec 9, 2021
582a5c2
clang-formated
mapinguari Dec 9, 2021
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23 changes: 14 additions & 9 deletions input/input.c
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,7 @@ static int openInputDevice(lua_State* L)

// We're done w/ inputdevice, pop it
lua_settop(L, 0);
lua_pushnumber(L, inputfds[fd_idx]);

// Compute select's nfds argument.
// That's not the actual number of fds in the set, like poll(),
Expand All @@ -161,7 +162,7 @@ static int openInputDevice(lua_State* L)
// That, on the other hand, *is* the number of open fds ;).
fd_idx++;

return 0;
return 1;
}

static int closeInputDevices(lua_State* L __attribute__((unused)))
Expand Down Expand Up @@ -203,8 +204,8 @@ static int closeInputDevices(lua_State* L __attribute__((unused)))
static int fakeTapInput(lua_State* L)
{
const char* restrict inputdevice = luaL_checkstring(L, 1);
int x = luaL_checkint(L, 2);
int y = luaL_checkint(L, 3);
int x = luaL_checkint(L, 2);
int y = luaL_checkint(L, 3);

int inputfd = open(inputdevice, O_WRONLY | O_NONBLOCK);
if (inputfd == -1) {
Expand Down Expand Up @@ -271,9 +272,9 @@ static int fakeTapInput(lua_State* L)
return 0;
}

static inline void set_event_table(lua_State* L, const struct input_event* input)
static inline void set_event_table(lua_State* L, const struct input_event* input, int fd)
{
lua_createtable(L, 0, 4); // ev = {} (pre-allocated for its four fields)
lua_createtable(L, 0, 5); // ev = {} (pre-allocated for its five fields)
lua_pushstring(L, "type");
lua_pushinteger(L, input->type); // uint16_t
// NOTE: rawset does t[k] = v, with v @ -1, k @ -2 and t at the specified index, here, that's ev @ -3.
Expand All @@ -286,6 +287,10 @@ static inline void set_event_table(lua_State* L, const struct input_event* input
lua_pushinteger(L, input->value); // int32_t
lua_rawset(L, -3); // ev.value = input.value

lua_pushstring(L, "fd");
lua_pushinteger(L, fd); // int
lua_rawset(L, -3); // ev.fd = fd

lua_pushstring(L, "time");
// NOTE: This is TimeVal-like, but it doesn't feature its metatable!
// The frontend (device/input.lua) will convert it to a proper TimeVal object.
Expand All @@ -299,7 +304,7 @@ static inline void set_event_table(lua_State* L, const struct input_event* input
lua_rawset(L, -3); // ev.time = time
}

static inline size_t drain_input_queue(lua_State* L, struct input_event* input_queue, size_t ev_count, size_t j)
static inline size_t drain_input_queue(lua_State* L, struct input_event* input_queue, size_t ev_count, int fd, size_t j)
{
if (lua_gettop(L) == 1) {
// Only a single element in the stack? (that would be our `true` bool)?
Expand All @@ -312,7 +317,7 @@ static inline size_t drain_input_queue(lua_State* L, struct input_event* input_q

// Iterate over every input event in the queue buffer
for (const struct input_event* event = input_queue; event < input_queue + ev_count; event++) {
set_event_table(L, event); // Pushed a new ev table all filled up at the top of the stack (that's -1)
set_event_table(L, event, fd); // Pushed a new ev table all filled up at the top of the stack (that's -1)
// NOTE: Here, rawseti basically inserts -1 in -2 @ [j]. We ensure that j always points at the tail.
lua_rawseti(L, -2, ++j); // table.insert(ev_array, ev) [, j]
}
Expand Down Expand Up @@ -406,7 +411,7 @@ static int waitForInput(lua_State* L)

if ((size_t) len == queue_available_size) {
// If we're out of buffer space in the queue, drain it *now*
j = drain_input_queue(L, input_queue, ev_count, j);
j = drain_input_queue(L, input_queue, ev_count, inputfds[i], j);
// Rewind to the start of the queue to recycle the buffer
queue_pos = input_queue;
queue_available_size = sizeof(input_queue);
Expand All @@ -418,7 +423,7 @@ static int waitForInput(lua_State* L)
}
}
// We've drained the kernel's input queue, now drain our buffer
j = drain_input_queue(L, input_queue, ev_count, j);
j = drain_input_queue(L, input_queue, ev_count, inputfds[i], j);
return 2; // true, ev_array
}
}
Expand Down