store: Add 'register-path' procedure.

* guix/store.scm (register-path): New procedure.
* tests/store.scm ("register-path"): New test.
* guix/config.scm.in (%guix-register-program): New variable.
* configure.ac: Compute and substitute 'guix_sbindir'.  Compute
  'guix_prefix'.
* pre-inst-env.in: Define 'GUIX_REGISTER'.

2 files changed, 30 insertions, 0 deletions

diff --git a/guix/config.scm.in b/guix/config.scm.in
index 3a5c50e00a..5edb4ced30 100644
--- a/guix/config.scm.in
+++ b/guix/config.scm.in
@@ -24,6 +24,7 @@
             %store-directory
             %state-directory
             %config-directory
+            %guix-register-program
             %system
             %libgcrypt
             %nixpkgs
@@ -62,6 +63,10 @@
   ;; This must match `NIX_CONF_DIR' as defined in `daemon.am'.
   (or (getenv "NIX_CONF_DIR") "@guix_sysconfdir@/guix"))
 
+(define %guix-register-program
+  ;; The 'guix-register' program.
+  (or (getenv "GUIX_REGISTER") "@guix_sbindir@/guix-register"))
+
 (define %system
   "@guix_system@")
 
diff --git a/guix/store.scm b/guix/store.scm
index 8ad32b2fd5..393eee8d1b 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -33,6 +33,7 @@
   #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
   #:use-module (ice-9 vlist)
+  #:use-module (ice-9 popen)
   #:export (%daemon-socket-file
 
             nix-server?
@@ -85,6 +86,8 @@
 
             current-build-output-port
 
+            register-path
+
             %store-prefix
             store-path?
             direct-store-path?
@@ -694,6 +697,28 @@ is true."
          (and (export-path server head port #:sign? sign?)
               (loop tail)))))))
 
+(define* (register-path path
+                        #:key (references '()) deriver)
+  "Register PATH as a valid store file, with REFERENCES as its list of
+references, and DERIVER as its deriver (.drv that led to it.)  Return #t on
+success.
+
+Use with care as it directly modifies the store!  This is primarily meant to
+be used internally by the daemon's build hook."
+  ;; Currently this is implemented by calling out to the fine C++ blob.
+  (catch 'system-error
+    (lambda ()
+      (let ((pipe (open-pipe* OPEN_WRITE %guix-register-program)))
+        (and pipe
+             (begin
+               (format pipe "~a~%~a~%~a~%"
+                       path (or deriver "") (length references))
+               (for-each (cut format pipe "~a~%" <>) references)
+               (zero? (close-pipe pipe))))))
+    (lambda args
+      ;; Failed to run %GUIX-REGISTER-PROGRAM.
+      #f)))
+
 
 ;;;
 ;;; Store paths.