On 08.05.23 22:03, Eric Blake wrote:
Add some more strings that the user might send our way. In
particular, some of these additions include FIXME comments showing
where our parser doesn't quite behave the way we want.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
tests/unit/test-cutils.c | 226 +++++++++++++++++++++++++++++++++++++--
1 file changed, 215 insertions(+), 11 deletions(-)
diff --git a/tests/unit/test-cutils.c b/tests/unit/test-cutils.c
index afae2ee5331..9fa6fb042e8 100644
--- a/tests/unit/test-cutils.c
+++ b/tests/unit/test-cutils.c
[...]
@@ -2875,6 +3056,20 @@ static void test_qemu_strtosz_trailing(void)
err = qemu_strtosz(str, NULL, &res);
g_assert_cmpint(err, ==, -EINVAL);
g_assert_cmphex(res, ==, 0xbaadf00d);
+
+ /* FIXME overflow in fraction is buggy */
+ str = "1.5E999";
+ endptr = NULL;
+ res = 0xbaadf00d;
+ err = qemu_strtosz(str, &endptr, &res);
+ g_assert_cmpint(err, ==, 0);
+ g_assert_cmpuint(res, ==, EiB /* FIXME EiB * 1.5 */);
+ g_assert(endptr == str + 9 /* FIXME + 4 */);
+
+ res = 0xbaadf00d;
+ err = qemu_strtosz(str, NULL, &res);
+ g_assert_cmpint(err, ==, -EINVAL);
+ g_assert_cmphex(res, ==, 0xbaadf00d);
Got it now!
Our problem is that `endptr` is beyond the end of the string, precisely
as gcc complains. The data there is undefined, and depending on the
value in the g_assert_cmpuint() (which is converted to strings for the
potential error message) it sometimes is "endptr == str + 9" (the one in
the g_assert()) and sometimes isn’t.
If it is "endptr == str + 9", then the 'e' is taken as a suffix, which
makes `res == EiB`, and `endptr == "ndptr == str + 9"`.
If it isn’t, well, it might be anything, so there often is no valid
suffix, making `res == 1`.
So the solution is to set `str = "1.5E999\0\0"`, so we don’t get out of
bounds and know exactly what will be parsed. Then, at str[8] there is
no valid suffix (it’s \0), so `res == 1` and `endptr == str + 8`. This
will then lead to the qemu_strtosz(str, NULL, &res) below succeed,
because, well, it’s a valid number. I suppose it failed on your end
because the out-of-bounds `str[9]` value was not '\0'.
That was a fun debugging session.
Hanna
