04/06: substitute: Gracefully handle invalid store file names.

[Ludovic Courtès]

civodul pushed a commit to branch master
in repository guix.

commit 30d4bc0434aa5d438c2d433f39c80e1f4a25bcac
Author: Ludovic Courtès <address@hidden>
Date:   Fri May 20 17:18:58 2016 +0200

    substitute: Gracefully handle invalid store file names.
    
    Before, something like:
    
      echo have /gnu/foo | ./test-env guix substitute --query
    
    would lead to an ugly backtrace.
    
    * guix/scripts/substitute.scm (narinfo-cache-file): Call 'leave' when
    'store-hash-part' returns #f.
---
 guix/scripts/substitute.scm |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/guix/scripts/substitute.scm b/guix/scripts/substitute.scm
index d46d610..5cdc55f 100755
--- a/guix/scripts/substitute.scm
+++ b/guix/scripts/substitute.scm
@@ -440,9 +440,15 @@ the cache STR originates form."
 (define (narinfo-cache-file cache-url path)
   "Return the name of the local file that contains an entry for PATH.  The
 entry is stored in a sub-directory specific to CACHE-URL."
-  (string-append %narinfo-cache-directory "/"
-                 (bytevector->base32-string (sha256 (string->utf8 cache-url)))
-                 "/" (store-path-hash-part path)))
+  ;; The daemon does not sanitize its input, so PATH could be something like
+  ;; "/gnu/store/foo".  Gracefully handle that.
+  (match (store-path-hash-part path)
+    (#f
+     (leave (_ "'~a' does not name a store item~%") path))
+    ((? string? hash-part)
+     (string-append %narinfo-cache-directory "/"
+                    (bytevector->base32-string (sha256 (string->utf8 
cache-url)))
+                    "/" hash-part))))
 
 (define (cached-narinfo cache-url path)
   "Check locally if we have valid info about PATH coming from CACHE-URL.