Re: [Libguestfs] [PATCH] inspect: improve UsrMove detection (RHBZ#1186935)

On Thu, Mar 17, 2016 at 12:25:18PM +0100, Pino Toscano wrote: > In case /usr is a symlink to /usr/bin, then we cannot rely on /usr/bin > to exist, since /usr might be in a different partition. Thus, in case > /bin is a symlink, check it points to "usr/bin". > --- > src/inspect-fs.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/src/inspect-fs.c b/src/inspect-fs.c > index 02fdb2a..0714ae1 100644 > --- a/src/inspect-fs.c > +++ b/src/inspect-fs.c > @@ -43,6 +43,7 @@ static int check_filesystem (guestfs_h *g, const char *mountable, > int whole_device); > static void extend_fses (guestfs_h *g); > static int get_partition_context (guestfs_h *g, const char *partition, int *partnum_ret, int *nr_partitions_ret); > +static int is_symlink_to (guestfs_h *g, const char *file, const char *wanted_target); > > /* Find out if 'device' contains a filesystem. If it does, add > * another entry in g->fses. > @@ -215,8 +216,7 @@ check_filesystem (guestfs_h *g, const char *mountable, > /* Linux root? */ > else if (is_dir_etc && > (is_dir_bin || > - (guestfs_is_symlink (g, "/bin") > 0 && > - guestfs_is_dir (g, "/usr/bin") > 0)) && > + is_symlink_to (g, "/bin", "usr/bin") > 0) && > guestfs_is_file (g, "/etc/fstab") > 0) { > fs->is_root = 1; > fs->format = OS_FORMAT_INSTALLED; > @@ -366,6 +366,22 @@ get_partition_context (guestfs_h *g, const char *partition, > return 0; > } > > +static int > +is_symlink_to (guestfs_h *g, const char *file, const char *wanted_target) > +{ > + CLEANUP_FREE char *target = NULL; > + > + if (guestfs_is_symlink (g, file) == 0) > + return 0; > + > + target = guestfs_readlink (g, file); > + /* This should not fail, but play safe. */ > + if (target == NULL) > + return 0; > + > + return STREQ (target, wanted_target); > +} > + > int > guestfs_int_is_file_nocase (guestfs_h *g, const char *path) > { Yup, pretty good solution. ACK. However, worth checking what Debian is doing now, since they implemented UsrMove madness just recently.