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Better protection against stale clipboard_data_instances.

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I had a segfault on OS X today at Pterm.app shutdown. I wasn't able to
reproduce it in a debugger, but the cause seemed to be that
clipboard_clear called term_deselect (this was from before the patch
series that renamed that function) when inst->term was already NULL.

This must be because a clipboard_data_instance outlived its associated
inst->term, and quite likely its associated inst as well. But we can't
free those structures when a gui_data is freed, because GTK callbacks
will still depend on them; so instead we must have each gui_data keep
a list of active cdis pointing at it, and then at destruction time,
walk along the list nulling out each one's pointer to part of itself.
This commit is contained in:
Simon Tatham 2017-12-17 20:12:52 +00:00
parent 2a76f8d4a2
commit 1af9c425ba
1 changed files with 55 additions and 23 deletions
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78
unix/gtkwin.c
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@ -52,7 +52,23 @@
GdkAtom compound_text_atom, utf8_string_atom;
struct clipboard_data_instance;
#ifdef JUST_USE_GTK_CLIPBOARD_UTF8
/*
* Because calling gtk_clipboard_set_with_data triggers a call to the
* clipboard_clear function from the last time, we need to arrange a
* way to distinguish a real call to clipboard_clear for the _new_
* instance of the clipboard data from the leftover call for the
* outgoing one. We do this by setting the user data field in our
* gtk_clipboard_set_with_data() call, instead of the obvious pointer
* to 'inst', to one of these.
*/
struct clipboard_data_instance {
char *pasteout_data_utf8;
int pasteout_data_utf8_len;
struct clipboard_state *state;
struct clipboard_data_instance *next, *prev;
};
#endif
struct clipboard_state {
struct gui_data *inst;
@ -115,6 +131,12 @@ struct gui_data {
#endif
int direct_to_font;
struct clipboard_state clipstates[N_CLIPBOARDS];
#ifdef JUST_USE_GTK_CLIPBOARD_UTF8
/* Remember all clipboard_data_instance structures currently
* associated with this gui_data, in case they're still around
* when it gets destroyed */
struct clipboard_data_instance cdi_headtail;
#endif
int clipboard_ctrlshiftins, clipboard_ctrlshiftcv;
int font_width, font_height;
int width, height;
@ -2298,6 +2320,21 @@ static void delete_inst(struct gui_data *inst)
inst->logctx = NULL;
}
#ifdef JUST_USE_GTK_CLIPBOARD_UTF8
/*
* Clear up any in-flight clipboard_data_instances. We can't
* actually _free_ them, but we detach them from the inst that's
* about to be destroyed.
*/
while (inst->cdi_headtail.next != &inst->cdi_headtail) {
struct clipboard_data_instance *cdi = inst->cdi_headtail.next;
cdi->state = NULL;
cdi->next->prev = cdi->prev;
cdi->prev->next = cdi->next;
cdi->next = cdi->prev = cdi;
}
#endif
/*
* Delete any top-level callbacks associated with inst, which
* would otherwise become stale-pointer dereferences waiting to
@ -2647,30 +2684,14 @@ int init_clipboard(struct gui_data *inst)
return TRUE;
}
/*
* Because calling gtk_clipboard_set_with_data triggers a call to the
* clipboard_clear function from the last time, we need to arrange a
* way to distinguish a real call to clipboard_clear for the _new_
* instance of the clipboard data from the leftover call for the
* outgoing one. We do this by setting the user data field in our
* gtk_clipboard_set_with_data() call, instead of the obvious pointer
* to 'inst', to one of these.
*/
struct clipboard_data_instance {
char *pasteout_data_utf8;
int pasteout_data_utf8_len;
};
static void clipboard_provide_data(GtkClipboard *clipboard,
GtkSelectionData *selection_data,
guint info, gpointer data)
{
struct clipboard_data_instance *cdi =
(struct clipboard_data_instance *)data;
struct clipboard_state *state = (struct clipboard_state *)
g_object_get_data(G_OBJECT(clipboard), "user-data");
if (state->current_cdi == cdi) {
if (cdi->state && cdi->state->current_cdi == cdi) {
gtk_selection_data_set_text(selection_data, cdi->pasteout_data_utf8,
cdi->pasteout_data_utf8_len);
}
@ -2680,14 +2701,17 @@ static void clipboard_clear(GtkClipboard *clipboard, gpointer data)
{
struct clipboard_data_instance *cdi =
(struct clipboard_data_instance *)data;
struct clipboard_state *state = (struct clipboard_state *)
g_object_get_data(G_OBJECT(clipboard), "user-data");
if (state->current_cdi == cdi) {
term_lost_clipboard_ownership(state->inst->term, state->clipboard);
state->current_cdi = NULL;
if (cdi->state && cdi->state->current_cdi == cdi) {
if (cdi->state->inst && cdi->state->inst->term) {
term_lost_clipboard_ownership(cdi->state->inst->term,
cdi->state->clipboard);
}
cdi->state->current_cdi = NULL;
}
sfree(cdi->pasteout_data_utf8);
cdi->next->prev = cdi->next;
cdi->prev->next = cdi->prev;
sfree(cdi);
}
@ -2712,8 +2736,13 @@ void write_clip(void *frontend, int clipboard,
return;
cdi = snew(struct clipboard_data_instance);
cdi->state = state;
state->current_cdi = cdi;
cdi->pasteout_data_utf8 = snewn(len*6, char);
cdi->prev = inst->cdi_headtail.prev;
cdi->next = &inst->cdi_headtail;
cdi->next->prev = cdi;
cdi->prev->next = cdi;
{
const wchar_t *tmp = data;
int tmplen = len;
@ -4897,6 +4926,9 @@ void new_session_window(Conf *conf, const char *geometry_string)
*/
inst = snew(struct gui_data);
memset(inst, 0, sizeof(*inst));
#ifdef JUST_USE_GTK_CLIPBOARD_UTF8
inst->cdi_headtail.next = inst->cdi_headtail.prev = &inst->cdi_headtail;
#endif
inst->alt_keycode = -1; /* this one needs _not_ to be zero */
inst->busy_status = BUSY_NOT;
inst->conf = conf;