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x: make wid_get_text_prop robust against race

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The property being fetched might change between x_get_prop_info and
actually fetching the property. So instead we do this all in one request
by setting the length to UINT_MAX.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
This commit is contained in:
Yuxuan Shui 2024-06-27 16:09:58 +01:00
parent 667084d6c9
commit 90954b62d5
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GPG key ID: D3A4405BE6CC17F4
1 changed files with 20 additions and 24 deletions
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44
src/x.c
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@ -334,39 +334,35 @@ xcb_window_t wid_get_prop_window(struct x_connection *c, xcb_window_t wid,
*/
bool wid_get_text_prop(struct x_connection *c, struct atom *atoms, xcb_window_t wid,
xcb_atom_t prop, char ***pstrlst, int *pnstr) {
auto prop_info = x_get_prop_info(c, wid, prop);
auto type = prop_info.type;
auto format = prop_info.format;
auto length = prop_info.length;
if (type == XCB_ATOM_NONE) {
return false;
}
if (!x_is_type_string(atoms, type)) {
log_warn("Text property %d of window %#010x has unsupported type: %d",
prop, wid, type);
return false;
}
if (format != 8) {
log_warn("Text property %d of window %#010x has unexpected format: %d",
prop, wid, format);
return false;
}
xcb_generic_error_t *e = NULL;
auto word_count = (length + 4 - 1) / 4;
auto r = xcb_get_property_reply(
c->c, xcb_get_property(c->c, 0, wid, prop, type, 0, word_count), &e);
c->c, xcb_get_property(c->c, 0, wid, prop, XCB_ATOM_ANY, 0, UINT_MAX), &e);
if (!r) {
log_debug_x_error(e, "Failed to get window property for %#010x", wid);
free(e);
return false;
}
assert(length == (uint32_t)xcb_get_property_value_length(r));
if (r->type == XCB_ATOM_NONE) {
free(r);
return false;
}
if (!x_is_type_string(atoms, r->type)) {
log_warn("Text property %d of window %#010x has unsupported type: %d",
prop, wid, r->type);
free(r);
return false;
}
if (r->format != 8) {
log_warn("Text property %d of window %#010x has unexpected format: %d",
prop, wid, r->format);
free(r);
return false;
}
uint32_t length = to_u32_checked(xcb_get_property_value_length(r));
void *data = xcb_get_property_value(r);
unsigned int nstr = 0;
uint32_t current_offset = 0;