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mirror of https://git.tartarus.org/simon/putty.git synced 2025-07-03 04:22:47 -05:00

Make dupcat() into a variadic macro.

Up until now, it's been a variadic _function_, whose argument list
consists of 'const char *' ASCIZ strings to concatenate, terminated by
one containing a null pointer. Now, that function is dupcat_fn(), and
it's wrapped by a C99 variadic _macro_ called dupcat(), which
automatically suffixes the null-pointer terminating argument.

This has three benefits. Firstly, it's just less effort at every call
site. Secondly, it protects against the risk of accidentally leaving
off the NULL, causing arbitrary words of stack memory to be
dereferenced as char pointers. And thirdly, it protects against the
more subtle risk of writing a bare 'NULL' as the terminating argument,
instead of casting it explicitly to a pointer. That last one is
necessary because C permits the macro NULL to expand to an integer
constant such as 0, so NULL by itself may not have pointer type, and
worse, it may not be marshalled in a variadic argument list in the
same way as a pointer. (For example, on a 64-bit machine it might only
occupy 32 bits. And yet, on another 64-bit platform, it might work
just fine, so that you don't notice the mistake!)

I was inspired to do this by happening to notice one of those bare
NULL terminators, and thinking I'd better check if there were any
more. Turned out there were quite a few. Now there are none.
This commit is contained in:
Simon Tatham
2019-10-14 19:42:37 +01:00
parent 283bd541a6
commit 1547c9c1ec
27 changed files with 73 additions and 85 deletions

View File

@ -235,7 +235,7 @@ static void post_fatal_message_box(void *vctx, int result)
static void common_connfatal_message_box(
GtkFrontend *inst, const char *msg, post_dialog_fn_t postfn)
{
char *title = dupcat(appname, " Fatal Error", NULL);
char *title = dupcat(appname, " Fatal Error");
GtkWidget *dialog = create_message_box(
inst->window, title, msg,
string_width("REASONABLY LONG LINE OF TEXT FOR BASIC SANITY"),
@ -661,7 +661,7 @@ gint delete_window(GtkWidget *widget, GdkEvent *event, GtkFrontend *inst)
* case we'll just re-emphasise that one.
*/
if (!find_and_raise_dialog(inst, DIALOG_SLOT_WARN_ON_CLOSE)) {
char *title = dupcat(appname, " Exit Confirmation", NULL);
char *title = dupcat(appname, " Exit Confirmation");
GtkWidget *dialog = create_message_box(
inst->window, title,
"Are you sure you want to close this session?",
@ -1080,8 +1080,7 @@ gint key_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
char *old = state_string;
state_string = dupcat(state_string,
state_string[0] ? "|" : "",
mod_bits[i].name,
(char *)NULL);
mod_bits[i].name);
sfree(old);
val &= ~mod_bits[i].mod_bit;
@ -4596,7 +4595,7 @@ void change_settings_menuitem(GtkMenuItem *item, gpointer data)
if (find_and_raise_dialog(inst, DIALOG_SLOT_RECONFIGURE))
return;
title = dupcat(appname, " Reconfiguration", NULL);
title = dupcat(appname, " Reconfiguration");
ctx = snew(struct after_change_settings_dialog_ctx);
ctx->inst = inst;
@ -5489,7 +5488,7 @@ void new_session_window(Conf *conf, const char *geometry_string)
paste_clipboard_menuitem);
MKMENUITEM("Copy All", copy_all_menuitem);
MKSEP();
s = dupcat("About ", appname, NULL);
s = dupcat("About ", appname);
MKMENUITEM(s, about_menuitem);
sfree(s);
#undef MKMENUITEM