substitute-binary: Implement `--substitute'.

This allows build outputs to be transparently downloaded from
http://hydra.gnu.org, for example.

* config-daemon.ac: Check for `gzip', `bzip2', and `xz'.
* guix/config.scm.in (%gzip, %bzip2, %xz): New variable.
* guix/scripts/substitute-binary.scm (fetch): Return SIZE as a second value.
  (<narinfo>): Change `url' to `uri'.
  (make-narinfo): Rename to...
  (narinfo-maker): ... this.  Handle relative URLs.
  (fetch-narinfo): Adjust accordingly.
  (filtered-port, decompressed-port): New procedures.
  (guix-substitute-binary): Implement the `--substitute' case.
* tests/store.scm ("substitute query"): Use (%store-prefix) instead
  of (getenv "NIX_STORE_DIR").
  ("substitute"): New test.

1 files changed, 8 insertions, 0 deletions

diff --git a/config-daemon.ac b/config-daemon.ac
index eed1e23f9e5..7c51f2b95c5 100644
--- a/config-daemon.ac
+++ b/config-daemon.ac
@@ -11,6 +11,14 @@ if test "x$guix_build_daemon" = "xyes"; then
   AC_PROG_RANLIB
   AC_CONFIG_HEADER([nix/config.h])
 
+  dnl Decompressors, for use by the substituter.
+  AC_PATH_PROG([GZIP], [gzip])
+  AC_PATH_PROG([BZIP2], [bzip2])
+  AC_PATH_PROG([XZ], [xz])
+  AC_SUBST([GZIP])
+  AC_SUBST([BZIP2])
+  AC_SUBST([XZ])
+
   dnl Use 64-bit file system calls so that we can support files > 2 GiB.
   AC_SYS_LARGEFILE