Libguestfs - Feb 2016 - [PATCH] inspect: check also /etc/hosts for detecting Linux root (RHBZ#1203898)

Use /etc/hosts as alternative of /etc/fstab to detect whether a partition
represents the root of a Linux installation; the latter might not exist
in smaller/special installations like Docker images.
---
 src/inspect-fs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/inspect-fs.c b/src/inspect-fs.c
index 02fdb2a..ad175f8 100644
--- a/src/inspect-fs.c
+++ b/src/inspect-fs.c
@@ -217,7 +217,8 @@ check_filesystem (guestfs_h *g, const char *mountable,
            (is_dir_bin ||
             (guestfs_is_symlink (g, "/bin") > 0 &&
              guestfs_is_dir (g, "/usr/bin") > 0)) &&
-           guestfs_is_file (g, "/etc/fstab") > 0) {
+           (guestfs_is_file (g, "/etc/fstab") > 0 ||
+            guestfs_is_file (g, "/etc/hosts") > 0)) {
     fs->is_root = 1;
     fs->format = OS_FORMAT_INSTALLED;
     if (guestfs_int_check_linux_root (g, fs) == -1)
-- 
2.5.0

On Wed, Feb 24, 2016 at 05:31:32PM +0100, Pino Toscano
wrote:
> Use /etc/hosts as alternative of /etc/fstab to detect whether a partition
> represents the root of a Linux installation; the latter might not exist
> in smaller/special installations like Docker images.
> ---
>  src/inspect-fs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/src/inspect-fs.c b/src/inspect-fs.c
> index 02fdb2a..ad175f8 100644
> --- a/src/inspect-fs.c
> +++ b/src/inspect-fs.c
> @@ -217,7 +217,8 @@ check_filesystem (guestfs_h *g, const char *mountable,
>             (is_dir_bin ||
>              (guestfs_is_symlink (g, "/bin") > 0 &&
>               guestfs_is_dir (g, "/usr/bin") > 0)) &&
> -           guestfs_is_file (g, "/etc/fstab") > 0) {
> +           (guestfs_is_file (g, "/etc/fstab") > 0 ||
> +            guestfs_is_file (g, "/etc/hosts") > 0)) {
/etc/hosts could be present on any UNIX pretty much  (so could /etc/fstab
for that matter).

If you want Linux then how about /lib/ld-linux.so.2  which exists
on any Linux with ELF library support.
>      fs->is_root = 1;
>      fs->format = OS_FORMAT_INSTALLED;
>      if (guestfs_int_check_linux_root (g, fs) == -1)
Regards,
Daniel
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On Wednesday 24 February 2016 16:38:59 Daniel P. Berrange
wrote:
> On Wed, Feb 24, 2016 at 05:31:32PM +0100, Pino Toscano wrote:
> > Use /etc/hosts as alternative of /etc/fstab to detect whether a
partition
> > represents the root of a Linux installation; the latter might not
exist
> > in smaller/special installations like Docker images.
> > ---
> >  src/inspect-fs.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/src/inspect-fs.c b/src/inspect-fs.c
> > index 02fdb2a..ad175f8 100644
> > --- a/src/inspect-fs.c
> > +++ b/src/inspect-fs.c
> > @@ -217,7 +217,8 @@ check_filesystem (guestfs_h *g, const char
*mountable,
> >             (is_dir_bin ||
> >              (guestfs_is_symlink (g, "/bin") > 0
&&
> >               guestfs_is_dir (g, "/usr/bin") > 0))
&&
> > -           guestfs_is_file (g, "/etc/fstab") > 0) {
> > +           (guestfs_is_file (g, "/etc/fstab") > 0 ||
> > +            guestfs_is_file (g, "/etc/hosts") > 0)) {
> 
> /etc/hosts could be present on any UNIX pretty much  (so could /etc/fstab
> for that matter).
I know -- the case here was about Docker images without /etc/fstab.
> If you want Linux then how about /lib/ld-linux.so.2  which exists
> on any Linux with ELF library support.
Well, that is not universally available: on my Fedora 23 it doesn't
exist, and indeed:

  $ env LC_ALL=C readelf -l /bin/ls \
    | perl -n -e 'if (/program interpreter: (.*)]/) { print $1 .
"\n"; }'
  /lib64/ld-linux-x86-64.so.2

-- 
Pino Toscano