Alex Vorobiev <alexander.vorobiev@gmail.com> writes:

> Hi,
> I have built guix-0.8.2 and specified both --with-store-dir and --
> localstatedir (both directories are world-writable) but when I started 
> guix-daemon (as myself) and tried to install a package I got:
>
> $ guix package -i mc
> guix package: error: build failed: creating directory `/gnu': Permission 
> denied
>
> Am I doing anything wrong? Why would it want to go to /gnu? I am using 
> RHEL-6.5.
>
> Thanks,
> Alex

The local state dir would be 'var' (e.g. /var, /usr/var, /usr/local/var,
depending on the value for $prefix), and I've used that option before
and believe it works fine.  (At the very least I've seen --prefix affect
its default value.)

So I believe your problem is about --with-store-dir only.

I've grepped a fresh guix clone for the raw string '/gnu/store' in .c,
.cc, .scm, and .sh files, and outside of comments and docstrings, found
the following:

guix/build/utils.scm:

  (define (%store-directory)
    "Return the directory name of the store."
    (or (getenv "NIX_STORE")
        "/gnu/store"))

guix/packages.scm (patch-and-repack):

  (let* ((store     (or (getenv "NIX_STORE") "/gnu/store"))

gnu/packages/busybox.scm (busybox):

  (substitute* "testsuite/cpio.tests"
     (("/usr/bin") "/gnu/store")
     (("usr") "gnu"))

(There are also some matches in the tests/ directory but I think they're
harmless.)

Those should probably use %store-directory from (guix config).  Here's a
patch doing that, but note that:

- In the busybox recipe, the "gnu" is replaced by (car (filter (negate
  string-null?) (string-split (%store-directory) #\/))) meaning it
  assumes (%store-directory) not to be the root directory.  (Note that
  this uses the %store-directory procedure from (guix build utils); see
  next point.)

- (guix build utils) has its own %store-directory bound to a procedure
  doing environment variable look-up on NIX_STORE instead of
  NIX_STORE_DIR (which determines the value of %store-directory from
  (guix config)); I preserved this semantics by importing
  %store-directory from (guix config) with a rename and falling back to
  it only if NIX_STORE is unset.

- Similarly, packages.scm checks NIX_STORE and not NIX_STORE_DIR, and I
  preserved this semantics by falling back to %store-directory only if
  NIX_STORE is unset.

Are these decisions right?

The patch: