https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116834
--- Comment #2 from Kacper Michajłow <kasper93 at gmail dot com> ---
static inline struct bstr bstr0(const char *s)
{
return (struct bstr){(unsigned char *)s, s ? strlen(s) : 0};
}
void bstr_xappend_vasprintf(void *talloc_ctx, bstr *s, const char *fmt,
va_list ap)
{
int size;
va_list copy;
va_copy(copy, ap);
size_t avail = talloc_get_size(s->start) - s->len;
char *dest = s->start ? s->start + s->len : NULL;
size = vsnprintf(dest, avail, fmt, copy);
va_end(copy);
if (size < 0) {
bstr_xappend(talloc_ctx, s, bstr0("format error: "));
bstr_xappend(talloc_ctx, s, bstr0(fmt));
return;
}
if (avail < 1 || size + 1 > avail) {
resize_append(talloc_ctx, s, size + 1);
vsnprintf(s->start + s->len, size + 1, fmt, ap);
}
s->len += size;
}
If you want whole thing
https://github.com/mpv-player/mpv/blob/ad7012284eaaaf2064e52668d9243465f5188dd2/misc/bstr.c
