malloc(0) can legitimately return NULL; it does on some systems and
not others. Force the size to 1 byte if the size is 0 coming in,
except for realloc() where this is legitimate and equivalent to
free().
Since this is an abnormal case, and can't even happen with most C
libraries, handle it on the error path, after we already got back a
NULL pointer.
Reported-by: Ozkan Sezer <sezeroz@gmail.com>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
5bb35772b3