[PATCH v2 12/19] cutils: Allow NULL str in qemu_strtosz

[Eric Blake <eblake@redhat.com>]

All the other qemu_strto* and parse_uint allow a NULL str.  Having
qemu_strtosz crash on qemu_strtosz(NULL, NULL, &value) is an easy fix
that adds some consistency between our string parsers.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/unit/test-cutils.c | 3 +++
 util/cutils.c            | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/tests/unit/test-cutils.c b/tests/unit/test-cutils.c
index 5c9ed78be93..1936c7b5795 100644
--- a/tests/unit/test-cutils.c
+++ b/tests/unit/test-cutils.c
@@ -3260,6 +3260,9 @@ static void test_qemu_strtosz_float(void)

 static void test_qemu_strtosz_invalid(void)
 {
+    do_strtosz(NULL, -EINVAL, 0xbaadf00d, 0);
+
+    /* Must parse at least one digit */
     do_strtosz("", -EINVAL, 0xbaadf00d, 0);
     do_strtosz(" \t ", -EINVAL, 0xbaadf00d, 0);
     do_strtosz("crap", -EINVAL, 0xbaadf00d, 0);
diff --git a/util/cutils.c b/util/cutils.c
index e599924a0c4..91c90673aba 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -306,7 +306,7 @@ static int do_strtosz(const char *nptr, const char **end,
 out:
     if (end) {
         *end = endptr;
-    } else if (*endptr) {
+    } else if (nptr && *endptr) {
         retval = -EINVAL;
     }
     if (retval == 0) {
-- 
2.40.1