On Mon, Nov 13, 2023 at 02:54:06PM +0100, наб wrote:
> Package: libncurses6
> Version: 6.4-4
> Severity: normal
> Tags: patch
...
> I see "while ((*str != '\0') && (n-- > 0)) {" is in the wrong order,
> and ought to be "(n-- > 0) && (*str != '\0')" ‒ only reading from str
> when it's not past the end.
It's a little more complicated than that. The problem was introduced here:
20201205
+ eliminate an additional strlen and wsclen.
+ eliminate an unnecessary strlen in waddnstr() (suggested by Benjamin
Abendroth).
The null terminator should be checked only for the special case where
the passed-in length is negative. I overlooked this case when eliminating
the strlen's. Here's what I have in mind (using a flag to short-circuit
past the test for null terminator):
diff -u -r1.58 lib_addstr.c
--- lib_addstr.c 2022/06/11 20:12:04 1.58
+++ lib_addstr.c 2023/11/14 01:09:13
@@ -55,16 +55,18 @@
T((T_CALLED("waddnstr(%p,%s,%d)"), (void *) win, _nc_visbufn(astr, n), n));
- if (win && (str != 0)) {
+ if (win && (str != 0) && (n != 0)) {
+ bool explicit = (n > 0);
+
TR(TRACE_VIRTPUT | TRACE_ATTRS,
("... current %s", _traceattr(WINDOW_ATTRS(win))));
code = OK;
TR(TRACE_VIRTPUT, ("str is not null, length = %d",
- ((n > 0) ? n : (int) strlen(str))));
- if (n < 0)
+ (explicit ? n : (int) strlen(str))));
+ if (!explicit)
n = INT_MAX;
- while ((*str != '\0') && (n-- > 0)) {
+ while ((explicit || (*str != '\0')) && (n-- > 0)) {
NCURSES_CH_T ch;
TR(TRACE_VIRTPUT, ("*str = %#o", UChar(*str)));
SetChar(ch, UChar(*str++), A_NORMAL);
@@ -228,16 +230,18 @@
T((T_CALLED("waddnwstr(%p,%s,%d)"), (void *) win, _nc_viswbufn(str, n),
n));
- if (win && (str != 0)) {
+ if (win && (str != 0) && (n != 0)) {
+ bool explicit = (n > 0);
+
TR(TRACE_VIRTPUT | TRACE_ATTRS,
("... current %s", _traceattr(WINDOW_ATTRS(win))));
code = OK;
TR(TRACE_VIRTPUT, ("str is not null, length = %d",
- ((n > 0) ? n : (int) wcslen(str))));
- if (n < 0)
+ (explicit ? n : (int) wcslen(str))));
+ if (!explicit)
n = INT_MAX;
- while ((*str != L('\0')) && (n-- > 0)) {
+ while ((explicit || (*str != L('\0'))) && (n-- > 0)) {
NCURSES_CH_T ch;
TR(TRACE_VIRTPUT, ("*str[0] = %#lx", (unsigned long) *str));
SetChar(ch, *str++, A_NORMAL);
--
Thomas E. Dickey <dic...@invisible-island.net>
https://invisible-island.net
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