Re: [PATCH v2] tests: A SANITY test prereq for testing if we're root

On Mon, Aug 9, 2010 at 16:55, Junio C Hamano [off-list ref] wrote:

Ævar Arnfjörð Bjarmason  [off-list ref] writes:

quoted

+ - SANITY
+
+   Test is not run by root user, and an attempt to write to an
+   unwritable file is expected to fail correctly.

As I said in the previous round, I am indeed in favor of having a single
"running as root---code that expects that the normal UNIXy permission
based protection to apply, aka 'running in sane environment', will not
work correctly" prerequisite token, rather than having separate "can I
expect an unwritable file to be unwritable?"  "can I expect an unreadble
file to be unreadable?" bits.

I probably shouldn't have used your docs as-is, you're right. It could
be explained better.

The name of the token _might_ be subject to debate (I am fine with
either SANITY or NOROOT), but the explanation should mention this is
defined to be a bit more broad than "unWRITABLE", I think.

NOROOT is better I think,.

"test -w /" is a traditional way to approximately check if you are
running as root (technically, it only checks if you are running with
unduly high privilege---your sysadm _could_ have done "chmod 2775 /"
and made it owned by the admin group).

Initially I wrote it as:

     # test whether the filesystem supports symbolic links
     ln -s x y 2>/dev/null && test -h y 2>/dev/null && test_set_prereq SYMLINKS
     rm -f y
    +
    +# test whether we can make read-only files
    +mkdir hla
    +chmod -w hla
    +touch hla/gh >/dev/null 2>&1
    +test -f hla/gh || test_set_prereq SANITY
    +rm -rf hla

But then I saw your old "test -w /" implementation and figured it was
good enough without doing all this work on setup. I can submit another
patch with that fixup if you like, maybe it'll prevent odd failures on
someone's odd system.