> On Mon, Jul 03, 2023 at 04:06:47PM +0800, Zhangjin Wu wrote:
> > > > /* get absolute path of myself, nolibc has no realpath() currently */
> > > > #ifndef NOLIBC
> > > > realpath(argv[0], exe);
> > > > #else
> > > > /* assume absolute path has no "./" */
> > > > if (strncmp(argv[0], "./", 2) != 0)
> > > > strncat(exe, argv[0], strlen(argv[0]) + 1);
> > > > else {
> > > > pwd = getenv("PWD");
> > > > /* skip the ending '\0' */
> > > > strncat(exe, getenv("PWD"), strlen(pwd));
> > > > /* skip the first '.' */
> > > > strncat(exe, argv[0] + 1, strlen(argv[0]));
> > > > }
> > > > #endif
> > >
> > > No, please, not like this. Just copy argv[0] (the pointer not the
> > > contents) and you're fine:
> > >
> > > static const char *argv0;
> > >
> > > int main(int argc, char **argv, char **envp)
> > > {
> > > argv0 = argv[0];
> > > ...
> > > }
> > >
> > > Nothing more, nothing less. Your program will always have its correct
> > > path when being called unless someone purposely forces it to something
> > > different, which is not our concern at all since this is a test program.
> > > And I'd rather call it "argv0" which exactly tells us what it contains
> > > than "exe" which can be misleading for that precise reason.
> > >
> >
> > Yeah, locally, I just used a global argv0 pointer directly, but
> > chroot_exe("./nolibc-test") not work when run 'libc-test' in host
> > system, that is why I tried to get an absolute path ;-)
> >
> > CASE_TEST(chroot_exe); EXPECT_SYSER(1, chroot(exe), -1, ENOTDIR); break;
> >
> > -->
> >
> > 19 chroot_exe = -1 ENOENT != (-1 ENOTDIR) [FAIL]
>
> Then we have a problem somewhere else and the test should be debugger
> instead. Are you sure there isn't a successful chdir() test before it
> for example, that would change the directory ? If so maybe we just need
> to save the current dir before calling it and restore it later.
>
Yes, as Thomas pointed out, the chdir test cases changed current
directory to "/" just before chroot_exe(), so, restore it with
chdir(getenv("PWD")) solves the issue.
> > I removed the "proc ?" check manually to test if it also work with
> > CONFIG_PROC_FS=n. it doesn't work, without absolute path, we need to add
> > the ENOENT errno back to the errno check list.
>
> Same as above.
>
> > I'm not sure if the other syscalls require an absolute path, so, the
> > realpath() is called in this proposed method.
>
> No, please do not overengineer tests. That's only hiding the dust under
> the carpet and people adding more tests later that will randomly fail
> will have a very hard time trying to figure what's happening under the
> hood. If a test doesn't work as expected, we must not try to work around
> it, but arrange to fix it.
That's right, thanks.
Best regards,
Zhangjin
>
> Thanks,
> Willy
