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Add %n$s support for sudo_lbuf_append_v1

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Brilliant Hanabi
2023-06-09 22:42:06 +08:00
committed by moehanabi
parent c7070b0475
commit 932339ed9f
1 changed files with 33 additions and 1 deletions
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34
lib/util/lbuf.c
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@@ -270,7 +270,7 @@ done:
}
/*
* Parse the format and append strings, only %s and %% escapes are supported.
* Parse the format and append strings, only %s, %n$s and %% escapes are supported.
*/
bool
sudo_lbuf_append_v1(struct sudo_lbuf *lbuf, const char *fmt, ...)
@@ -287,6 +287,38 @@ sudo_lbuf_append_v1(struct sudo_lbuf *lbuf, const char *fmt, ...)
va_start(ap, fmt);
while (*fmt != '\0') {
if (fmt[0] == '%' && isdigit(fmt[1])) {
const char *num_start = fmt + 1;
const char *num_end;
int arg_num;
/* Find the end of the numeric part */
for (num_end = num_start; isdigit(*num_end); num_end++)
;
if (num_end[0] == '$' && num_end[1] == 's' && num_end > num_start) {
/* Convert the numeric part to an integer */
char num_str[num_end - num_start + 1];
memcpy(num_str, num_start, num_end - num_start);
num_str[num_end - num_start] = '\0';
arg_num = atoi(num_str);
if (arg_num > 0) {
va_list arg_copy;
va_copy(arg_copy, ap);
for (int i = 1; i < arg_num; i++) {
(void)va_arg(arg_copy, char *);
}
if ((s = va_arg(arg_copy, char *)) == NULL)
s = "(NULL)";
len = strlen(s);
if (!sudo_lbuf_expand(lbuf, len))
goto done;
memcpy(lbuf->buf + lbuf->len, s, len);
lbuf->len += len;
fmt = num_end + 2;
va_end(arg_copy);
continue;
}
}
}
if (fmt[0] == '%' && fmt[1] == 's') {
if ((s = va_arg(ap, char *)) == NULL)
s = "(NULL)";