Re: cpio -m does not preserve timestamps for symlinks

[Pavel Raiskup]

On Tuesday, February 4, 2020 7:05:21 PM CET Carl Edquist wrote:
> Hi all,
> 
> >It seems that for a cpio archive that contains symlinks, the timestamps 
> >for those symlinks are not getting preserved, even with the '-m' option.
> 
> I believe I found the issue -
> 
> in copyin.c, copyin_regular_file() and copyin_device() both make calls to 
> set file times (if '-m' was specified), but copyin_link() does not.
> 
> I was able to fix it by adding a call to set_file_times() in copyin_link() 
> if retain_time_flag is set, just like is done in copyin_device(), and 
> additionally adding the AT_SYMLINK_NOFOLLOW flag to the utimensat() call 
> in fdutimens(), which does the right thing for symlinks and does not 
> change the behavior for non-symlinks.
> 
> Here is a patch of what I used to get it working:
> 
>       https://github.com/edquist/cpio/commit/c2ccb84d5e.patch
> 
> (Patch text also pasted below.)
> 
> Would you maintainers consider applying this enhancement/fix?
> 
> Thanks..!
> Carl

Patch is also proposed here:
https://www.mail-archive.com/address@hidden/msg00605.html

Pavel

> 
> ---
>   gnu/utimens.c | 2 +-
>   src/copyin.c  | 3 +++
>   2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/gnu/utimens.c b/gnu/utimens.c
> index e2bb702..2e870bc 100644
> --- a/gnu/utimens.c
> +++ b/gnu/utimens.c
> @@ -244,7 +244,7 @@ fdutimens (int fd, char const *file, struct timespec 
> const timespec[2])
>   # if HAVE_UTIMENSAT
>         if (fd < 0)
>           {
> -          result = utimensat (AT_FDCWD, file, ts, 0);
> +          result = utimensat (AT_FDCWD, file, ts, AT_SYMLINK_NOFOLLOW);
>   #  ifdef __linux__
>             /* Work around a kernel bug:
>                http://bugzilla.redhat.com/442352
> diff --git a/src/copyin.c b/src/copyin.c
> index b29f348..eb40e99 100644
> --- a/src/copyin.c
> +++ b/src/copyin.c
> @@ -669,6 +669,9 @@ copyin_link (struct cpio_file_stat *file_hdr, int 
> in_file_des)
>         && errno != EPERM)
>       chown_error_details (file_hdr->c_name, uid, gid);
>       }
> +  if (retain_time_flag)
> +    set_file_times (-1, file_hdr->c_name, file_hdr->c_mtime,
> +                 file_hdr->c_mtime);
>     free (link_name);
>   }
> 
>