Messages in this thread | | | From | Alexander Potapenko <> | Date | Wed, 12 Apr 2023 14:34:00 +0200 | Subject | Re: [PATCH 3/9] string: Add Kunit tests for strcat() family |
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On Fri, Apr 7, 2023 at 1:07 AM Kees Cook <keescook@chromium.org> wrote: > > On Thu, Apr 06, 2023 at 11:11:09AM +0200, Alexander Potapenko wrote: > > > +static void strncat_test(struct kunit *test) > > > +{ > > > + char dest[8]; > > > + > > > + /* Destination is terminated. */ > > > + memset(dest, 0, sizeof(dest)); > > > + KUNIT_EXPECT_EQ(test, strlen(dest), 0); > > > + /* Empty copy of size 0 does nothing. */ > > > + KUNIT_EXPECT_TRUE(test, strncat(dest, "", 0) == dest); > > > + KUNIT_EXPECT_STREQ(test, dest, ""); > > > + /* Empty copy of size 1 does nothing too. */ > > > + KUNIT_EXPECT_TRUE(test, strncat(dest, "", 1) == dest); > > > + KUNIT_EXPECT_STREQ(test, dest, ""); > > > + /* Copy of max 0 characters should do nothing. */ > > > + KUNIT_EXPECT_TRUE(test, strncat(dest, "asdf", 0) == dest); > > > + KUNIT_EXPECT_STREQ(test, dest, ""); > > > + > > > + /* 4 characters copied in, even if max is 8. */ > > > + KUNIT_EXPECT_TRUE(test, strncat(dest, "four\000123", 8) == dest); > > > + KUNIT_EXPECT_STREQ(test, dest, "four"); > > > + KUNIT_EXPECT_EQ(test, dest[5], '\0'); > > > > Maybe also add a test case for strncat(dest, "four", 4) that checks > > that the fourth byte of dest is not 0? > > I think I don't understand what state you want to test for? The line > above (STREQ is checking dest is "four". Maybe I should check for > dest[6] being 0 as well as dest[5]. But if that's not what you mean, I'm > not sure. Is it something here:
Sorry, not sure why I wrote "strncat" here, I was thinking about strncpy, which is handled in a different patch. Please disregard.
> char dest[16]; > memset(dest, 0, sizeof(dest)); > // dest == "" > strncat(dest, "four", 4); > // dest == "four" > strncat(dest, "four", 4); > // dest == "fourfour" > > strncat's "n" is how much to reach from source -- dest will always be > terminated. > > -- > Kees Cook
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