Re: [Libguestfs] [PATCH guestfs-tools] diff: Don't compare st_dev or st_ino fields

On 7/20/23 16:15, Richard W.M. Jones wrote: > See comment for details. > > Link: https://listman.redhat.com/archives/libguestfs/2023-July/032061.html > --- > diff/diff.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/diff/diff.c b/diff/diff.c > index fb66a2bbd3..b6344b4ec2 100644 > --- a/diff/diff.c > +++ b/diff/diff.c > @@ -717,8 +717,20 @@ changed (guestfs_h *g1, struct file *file1, > output_string ("changed:"); > #define COMPARE_STAT(n) \ > if (file1->stat->n != file2->stat->n) output_string (#n) > - COMPARE_STAT (st_dev); > - COMPARE_STAT (st_ino); > + /* Comparing st_dev and st_ino is disabled for now, see the longer > + * discussion here: > + * https://listman.redhat.com/archives/libguestfs/2023-July/032061.html > + * Even if we fixed the libguestfs API to do translation of this > + * field correctly, it seems unlikely that there would ever be a > + * meaningful difference in the st_dev or st_ino fields. We > + * already know the fields refer to the same filename. Is it > + * interesting that the file might have moved to a different disk? > + * Everything else is comparing the content or direct metadata of > + * the file, but st_dev and st_ino represent the metadata of the > + * filesystem which is (arguably) different. > + */ > +// COMPARE_STAT (st_dev); > +// COMPARE_STAT (st_ino); > COMPARE_STAT (st_mode); > COMPARE_STAT (st_nlink); > COMPARE_STAT (st_uid); This seems to remain compatible with the existent virt-diff(1) manual, which says: https://libguestfs.org/virt-diff.1.html > This tool will find differences in filenames, file sizes, checksums, > extended attributes, file content and more from a virtual machine or > disk image. However it does not look at the boot loader, unused space > between partitions or within filesystems, "hidden" sectors and so on. > In other words, it is not a security or forensics tool. Acked-by: Laszlo Ersek <lersek(a)redhat.com&gt;