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-rw-r--r--guix/store.scm57
1 files changed, 56 insertions, 1 deletions
diff --git a/guix/store.scm b/guix/store.scm
index 8e7f09678e..ee47703a55 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -23,7 +23,8 @@
#:use-module (guix serialization)
#:use-module (guix monads)
#:use-module (guix base16)
- #:autoload (guix base32) (bytevector->base32-string)
+ #:use-module (guix base32)
+ #:use-module (guix hash)
#:autoload (guix build syscalls) (terminal-columns)
#:use-module (rnrs bytevectors)
#:use-module (ice-9 binary-ports)
@@ -133,6 +134,9 @@
interned-file
%store-prefix
+ store-path
+ output-path
+ fixed-output-path
store-path?
direct-store-path?
derivation-path?
@@ -1347,6 +1351,57 @@ connection, and return the result."
;; Absolute path to the Nix store.
(make-parameter %store-directory))
+(define (compressed-hash bv size) ; `compressHash'
+ "Given the hash stored in BV, return a compressed version thereof that fits
+in SIZE bytes."
+ (define new (make-bytevector size 0))
+ (define old-size (bytevector-length bv))
+ (let loop ((i 0))
+ (if (= i old-size)
+ new
+ (let* ((j (modulo i size))
+ (o (bytevector-u8-ref new j)))
+ (bytevector-u8-set! new j
+ (logxor o (bytevector-u8-ref bv i)))
+ (loop (+ 1 i))))))
+
+(define (store-path type hash name) ; makeStorePath
+ "Return the store path for NAME/HASH/TYPE."
+ (let* ((s (string-append type ":sha256:"
+ (bytevector->base16-string hash) ":"
+ (%store-prefix) ":" name))
+ (h (sha256 (string->utf8 s)))
+ (c (compressed-hash h 20)))
+ (string-append (%store-prefix) "/"
+ (bytevector->nix-base32-string c) "-"
+ name)))
+
+(define (output-path output hash name) ; makeOutputPath
+ "Return an output path for OUTPUT (the name of the output as a string) of
+the derivation called NAME with hash HASH."
+ (store-path (string-append "output:" output) hash
+ (if (string=? output "out")
+ name
+ (string-append name "-" output))))
+
+(define* (fixed-output-path name hash
+ #:key
+ (output "out")
+ (hash-algo 'sha256)
+ (recursive? #t))
+ "Return an output path for the fixed output OUTPUT defined by HASH of type
+HASH-ALGO, of the derivation NAME. RECURSIVE? has the same meaning as for
+'add-to-store'."
+ (if (and recursive? (eq? hash-algo 'sha256))
+ (store-path "source" hash name)
+ (let ((tag (string-append "fixed:" output ":"
+ (if recursive? "r:" "")
+ (symbol->string hash-algo) ":"
+ (bytevector->base16-string hash) ":")))
+ (store-path (string-append "output:" output)
+ (sha256 (string->utf8 tag))
+ name))))
+
(define (store-path? path)
"Return #t if PATH is a store path."
;; This is a lightweight check, compared to using a regexp, but this has to