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c2: use UINT32_MAX as GetProperty length
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Previously we do 2-step property fetch - get length first, then get the
whole property. If the property changes in between, this breaks.

Now we just pass UINT32_MAX as the length, we also stop tracking the max
indices of a property in rules - we just always fetch the whole
property. This makes the code simpler.

Signed-off-by: Yuxuan Shui <[email protected]>
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@yshui
yshui committed Oct 10, 2024
1 parent 35f64b3 commit dadfe5a
Showing 1 changed file with 5 additions and 56 deletions.
61 changes: 5 additions & 56 deletions src/c2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -69,16 +69,12 @@ struct c2_tracked_property {
UT_hash_handle hh;
struct c2_tracked_property_key key;
unsigned int id;
/// Highest indices of this property that
/// are tracked. -1 mean all indices are tracked.
int max_indices;
};

struct c2_state {
struct c2_tracked_property *tracked_properties;
struct atom *atoms;
xcb_get_property_cookie_t *cookies;
uint32_t *propert_lengths;
};

// TODO(yshui) this has some overlap with winprop_t, consider merging them.
Expand Down Expand Up @@ -470,7 +466,6 @@ TEST_CASE(c2_parse) {
HASH_ITER2(state->tracked_properties, prop) {
TEST_EQUAL(prop->key.property,
get_atom_with_nul(state->atoms, "_GTK_FRAME_EXTENTS", NULL));
TEST_EQUAL(prop->max_indices, 0);
}
c2_state_free(state);
destroy_atoms(atoms);
Expand Down Expand Up @@ -1225,11 +1220,6 @@ c2_l_postprocess(struct c2_state *state, xcb_connection_t *c, c2_condition_node_
property->id = HASH_COUNT(state->tracked_properties);
HASH_ADD_KEYPTR(hh, state->tracked_properties, &property->key,
sizeof(property->key), property);
property->max_indices = pleaf->index;
} else if (pleaf->index == -1) {
property->max_indices = -1;
} else if (property->max_indices >= 0 && pleaf->index > property->max_indices) {
property->max_indices = pleaf->index;
}
pleaf->target_id = property->id;
}
Expand Down Expand Up @@ -1976,7 +1966,6 @@ void c2_state_free(struct c2_state *state) {
HASH_DEL(state->tracked_properties, property);
free(property);
}
free(state->propert_lengths);
free(state->cookies);
free(state);
}
Expand Down Expand Up @@ -2136,7 +2125,7 @@ c2_window_state_update_one_from_reply(struct c2_state *state,
static void c2_window_state_update_from_replies(struct c2_state *state,
struct c2_window_state *window_state,
xcb_connection_t *c, xcb_window_t client_win,
xcb_window_t frame_win, bool refetch) {
xcb_window_t frame_win) {
HASH_ITER2(state->tracked_properties, p) {
if (!window_state->values[p->id].needs_update) {
continue;
Expand All @@ -2152,25 +2141,8 @@ static void c2_window_state_update_from_replies(struct c2_state *state,
window_state->values[p->id].needs_update = false;
continue;
}
bool property_is_string = x_is_type_string(state->atoms, reply->type);
if (reply->bytes_after > 0 && (property_is_string || p->max_indices < 0)) {
if (!refetch) {
log_warn("Did property %d for window %#010x change while "
"we were fetching it? some window rules might "
"not work.",
p->id, window);
window_state->values[p->id].valid = false;
window_state->values[p->id].needs_update = false;
} else {
state->propert_lengths[p->id] += reply->bytes_after;
state->cookies[p->id] = xcb_get_property(
c, 0, window, p->key.property, XCB_GET_PROPERTY_TYPE_ANY,
0, (state->propert_lengths[p->id] + 3) / 4);
}
} else {
c2_window_state_update_one_from_reply(
state, &window_state->values[p->id], p->key.property, reply, c);
}
c2_window_state_update_one_from_reply(state, &window_state->values[p->id],
p->key.property, reply, c);
free(reply);
}
}
Expand All @@ -2182,47 +2154,24 @@ void c2_window_state_update(struct c2_state *state, struct c2_window_state *wind
if (!state->cookies) {
state->cookies = ccalloc(property_count, xcb_get_property_cookie_t);
}
if (!state->propert_lengths) {
state->propert_lengths = ccalloc(property_count, uint32_t);
}
memset(state->cookies, 0, property_count * sizeof(xcb_get_property_cookie_t));

log_verbose("Updating c2 window state for window %#010x (frame %#010x)",
client_win, frame_win);

// Because we don't know the length of all properties (i.e. if they are string
// properties, or for properties matched with `[*]`). We do this in 3 steps:
// 1. Send requests to all properties we need. Use `max_indices` to determine
// the length, or use 0 if it's unknown.
// 2. From the replies to (1), for properties we know the length of, we update
// the values. For those we don't, use the length information from the
// replies to send a new request with the correct length.
// 3. Update the rest of the properties.

// Step 1
HASH_ITER2(state->tracked_properties, p) {
if (!window_state->values[p->id].needs_update) {
continue;
}
uint32_t length = 0;
if (p->max_indices >= 0) {
// length is in 4 bytes units
length = (uint32_t)p->max_indices + 1;
}

xcb_window_t window = p->key.is_on_client ? client_win : frame_win;
// xcb_get_property long_length is in units of 4-byte,
// so use `ceil(length / 4)`. same below.
state->cookies[p->id] = xcb_get_property(
c, 0, window, p->key.property, XCB_GET_PROPERTY_TYPE_ANY, 0, length);
state->propert_lengths[p->id] = length * 4;
c, 0, window, p->key.property, XCB_GET_PROPERTY_TYPE_ANY, 0, UINT32_MAX);
}

// Step 2
c2_window_state_update_from_replies(state, window_state, c, client_win, frame_win, true);
// Step 3
c2_window_state_update_from_replies(state, window_state, c, client_win, frame_win,
false);
c2_window_state_update_from_replies(state, window_state, c, client_win, frame_win);
}

bool c2_state_is_property_tracked(struct c2_state *state, xcb_atom_t property) {
Expand Down

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