Re: [PATCH 3/4] src/t_immutable: Allow setting flags on existing files

[Amir Goldstein <amir73il@gmail.com>]

On Sun, Jan 24, 2021 at 5:14 PM Eryu Guan <guan@eryu.me> wrote:
>
> On Sat, Jan 16, 2021 at 06:56:18PM +0200, Amir Goldstein wrote:
> > For overlayfs tests we need to be able to setflags on existing
> > (lower) files.
> >
> > t_immutable -C test_dir
> >
> > Creates the test area and sets flags, but it also allows setting flags
> > on an existing test area.
> >
> > t_immutable -R test_dir
> >
> > Removes the flags from existing test area, but does not remove the files
> > in the test area.
> >
> > To setup a test area with file without flags, need to run the -C and -R
> > commands.
> >
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> >  src/t_immutable.c | 30 ++++++++++++++++++++++++------
> >  1 file changed, 24 insertions(+), 6 deletions(-)
> >
> > diff --git a/src/t_immutable.c b/src/t_immutable.c
> > index b6a76af0..a2e6796d 100644
> > --- a/src/t_immutable.c
> > +++ b/src/t_immutable.c
> > @@ -1898,6 +1898,8 @@ static int check_test_area(const char *dir)
> >       return 0;
> >  }
> >
> > +static int allow_existing;
> > +
> >  static int create_dir(char **ppath, const char *fmt, const char *dir)
> >  {
> >       const char *path;
> > @@ -1908,6 +1910,9 @@ static int create_dir(char **ppath, const char *fmt, const char *dir)
> >       }
> >       path = *ppath;
> >       if (stat(path, &st) == 0) {
> > +       if (allow_existing && S_ISDIR(st.st_mode)) {
> > +            return 0;
> > +       }
> >         fprintf(stderr, "%s: Test area directory %s must not exist for test area creation.\n",
> >                 __progname, path);
> >         return 1;
> > @@ -1921,6 +1926,7 @@ static int create_dir(char **ppath, const char *fmt, const char *dir)
> >
> >  static int create_file(char **ppath, const char *fmt, const char *dir)
> >  {
> > +     int flags = O_WRONLY|O_CREAT | (allow_existing ? 0 : O_EXCL);
> >       const char *path;
> >       int fd;
> >
> > @@ -1928,7 +1934,7 @@ static int create_file(char **ppath, const char *fmt, const char *dir)
> >         return -1;
> >       }
> >       path = *ppath;
> > -     if ((fd = open(path, O_WRONLY|O_CREAT|O_EXCL, 0666)) == -1) {
> > +     if ((fd = open(path, flags, 0666)) == -1) {
> >         fprintf(stderr, "%s: error creating file %s: %s\n", __progname, path, strerror(errno));
> >            return -1;
> >       }
> > @@ -1937,13 +1943,15 @@ static int create_file(char **ppath, const char *fmt, const char *dir)
> >
> >  static int create_xattrs(int fd)
> >  {
> > -     if (fsetxattr(fd, "trusted.test", "readonly", strlen("readonly"), XATTR_CREATE) != 0) {
> > +     int flags = allow_existing ? 0 : XATTR_CREATE;
> > +
> > +     if (fsetxattr(fd, "trusted.test", "readonly", strlen("readonly"), flags) != 0) {
> >         if (errno != EOPNOTSUPP) {
> >              perror("setxattr");
> >              return 1;
> >         }
> >       }
> > -     if (fsetxattr(fd, "user.test", "readonly", strlen("readonly"), XATTR_CREATE) != 0) {
> > +     if (fsetxattr(fd, "user.test", "readonly", strlen("readonly"), flags) != 0) {
> >         if (errno != EOPNOTSUPP) {
> >              perror("setxattr");
> >              return 1;
> > @@ -2214,6 +2222,10 @@ static int remove_test_area(const char *dir)
> >         return 1;
> >       }
> >
> > +     if (allow_existing) {
> > +          return 0;
> > +     }
> > +
> >       pid = fork();
> >       if (!pid) {
> >         execl("/bin/rm", "rm", "-rf", dir, NULL);
> > @@ -2236,7 +2248,7 @@ int main(int argc, char **argv)
> >  /* this arg parsing is gross, but who cares, its a test program */
> >
> >       if (argc < 2) {
> > -       fprintf(stderr, "usage: t_immutable [-C|-c|-r] test_area_dir\n");
> > +       fprintf(stderr, "usage: t_immutable [-C|-c|-R|-r] test_area_dir\n");
> >         return 1;
> >       }
> >
> > @@ -2246,18 +2258,24 @@ int main(int argc, char **argv)
> >         /* Prepare test area without running tests */
> >         create = 1;
> >         runtest = 0;
> > +       /* With existing test area, only setflags */
> > +       allow_existing = 1;
> >       } else if (!strcmp(argv[1], "-r")) {
> >         remove = 1;
> > +     } else if (!strcmp(argv[1], "-R")) {
> > +       /* Cleanup flags on test area but leave the files */
> > +       remove = 1;
> > +       allow_existing = 1;
> >       }
> >
> >       if (argc != 2 + (create | remove)) {
> > -       fprintf(stderr, "usage: t_immutable [-C|-c|-r] test_area_dir\n");
> > +       fprintf(stderr, "usage: t_immutable [-C|-c|-R|-r] test_area_dir\n");
> >         return 1;
> >       }
> >
> >       if (create) {
> >         ret = create_test_area(argv[argc-1]);
> > -       if (ret || !runtest) {
> > +       if (ret || allow_existing) {
>
> With this change, compiler warns about 'runtest' is set but not used,
> and 'allow_existing' now indicates '!runtest' implicitly, which seems
> subtle. I think it's better to keep 'runtest' as the indicator to
> actually run the test?
>

Sure, I removed it by mistake.

Thanks,
Amir.