From ee0c1cc1e4b87bde73f1eba3212ab93b1c379c6c Mon Sep 17 00:00:00 2001 From: Igor Ryzhov Date: Mon, 5 Feb 2024 19:04:39 +0200 Subject: [PATCH] lib: fix __darr_in_vsprintf If the initial darr capacity is not enough for the output, the `ap` is reused multiple times, which is wrong, because it may be altered by `vsnprintf`. Make a copy of `ap` each time instead of reusing. Signed-off-by: Igor Ryzhov --- lib/darr.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/lib/darr.c b/lib/darr.c index f7a64fc3943f..4f3bd9fb67ab 100644 --- a/lib/darr.c +++ b/lib/darr.c @@ -58,6 +58,7 @@ char *__darr_in_vsprintf(char **sp, bool concat, const char *fmt, va_list ap) size_t inlen = concat ? darr_strlen(*sp) : 0; size_t capcount = strlen(fmt) + MIN(inlen + 64, 128); ssize_t len; + va_list ap_copy; darr_ensure_cap(*sp, capcount); @@ -68,7 +69,9 @@ char *__darr_in_vsprintf(char **sp, bool concat, const char *fmt, va_list ap) if (darr_len(*sp) == 0) *darr_append(*sp) = 0; again: - len = vsnprintf(darr_last(*sp), darr_avail(*sp), fmt, ap); + va_copy(ap_copy, ap); + len = vsnprintf(darr_last(*sp), darr_avail(*sp), fmt, ap_copy); + va_end(ap_copy); if (len < 0) darr_in_strcat(*sp, fmt); else if ((size_t)len < darr_avail(*sp))