Re: [PATCH v2] nfsd: Disable NFSv2 timestamp workaround for NFSv3+

["Andreas Grünbacher" <andreas.gruenbacher@gmail.com>]

Here's a little test for this:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <utime.h>
#include <grp.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

static int touch(const char *path, mode_t mode, bool current_time)
{
        if (current_time)
                return utime(path, NULL);
        else {
                time_t now = time(NULL);
                struct utimbuf times = {
                        .actime = now,
                        .modtime = now,
                };
                return utime(path, &times);
        }
}

static int su(uid_t uid, gid_t gid)
{
        int ret;

        ret = seteuid(0);
        if (ret != 0)
                return ret;
        ret = setegid(gid);
        if (ret != 0)
                return ret;
        ret = setgroups(0, NULL);
        if (ret != 0)
                return ret;
        ret = seteuid(uid);
        return ret;
}

static void die(const char *str)
{
        perror(str);
        exit(1);
}

void cleanup(void)
{
        su(0, 0);
        unlink("foo");
}

int main(void)
{
        int ret;

        atexit(cleanup);

        ret = creat("foo", 0600);
        if (ret < 0)
                die("foo");
        close(ret);
        ret = chown("foo", 0, 12345);
        if (ret != 0)
                die("foo");

        ret = su(12345, 12345);
        if (ret != 0)
                die("su");
        errno = 0;
        ret = touch("foo", 0660, true);
        if (ret == 0)
                die("touch should have failed");

        ret = su(0, 0);
        if (ret != 0)
                die("su");
        ret = chmod("foo", 0660);
        if (ret != 0)
                die("foo");

        ret = su(12345, 12345);
        if (ret != 0)
                die("su");
        errno = 0;
        ret = touch("foo", 0660, true);
        if (ret != 0)
                die("touch should have succeeded");

        ret = touch("foo", 0660, false);
        if (ret == 0)
                die("touch should fail on NFSv3+");

        return 0;
}