MINOR: tools: make memvprintf() never pass a NULL target to vsnprintf()
Most modern platforms don't touch the output buffer when the size
argument is null, but there exist a few old ones (like AIX 5 and
possibly Tru64) where the output will be dereferenced anyway, probably
to write the trailing null, crashing the process. memprintf() uses this
to measure the desired length.
There is a very simple workaround to this consisting in passing a pointer
to a character instead of a NULL pointer. It was confirmed to fix the issue
on AIX 5.1.
diff --git a/src/standard.c b/src/standard.c
index 03072b9..09bc155 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -3577,12 +3577,14 @@
return NULL;
do {
+ char buf1;
+
/* vsnprintf() will return the required length even when the
* target buffer is NULL. We do this in a loop just in case
* intermediate evaluations get wrong.
*/
va_copy(args, orig_args);
- needed = vsnprintf(ret, allocated, format, args);
+ needed = vsnprintf(ret ? ret : &buf1, allocated, format, args);
va_end(args);
if (needed < allocated) {
/* Note: on Solaris 8, the first iteration always