[bug#65033] [PATCH] guix: read-derivation-from-file: Use less open files.

[Christopher Baines]

The Guix derivation graph isn't that deep, so I don't think this generally
opens lots of files, but I think it's still unnecessary to keep more files
than needed open.

* guix/derivations.scm (read-derivation-from-file): Read each derivation to a
string, which is passed as a port to read-derivation.
---
 guix/derivations.scm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/guix/derivations.scm b/guix/derivations.scm
index 9fec7f4f0b..2154bd76f6 100644
--- a/guix/derivations.scm
+++ b/guix/derivations.scm
@@ -31,6 +31,7 @@ (define-module (guix derivations)
   #:use-module (ice-9 match)
   #:use-module (ice-9 rdelim)
   #:use-module (ice-9 vlist)
+  #:use-module (ice-9 textual-ports)
   #:use-module (guix store)
   #:use-module (guix utils)
   #:use-module (guix base16)
@@ -556,7 +557,14 @@ (define (read-derivation-from-file file)
   ;; and because the same argument is read more than 15 times on average
   ;; during something like (package-derivation s gdb).
   (or (and file (hash-ref %derivation-cache file))
-      (let ((drv (call-with-input-file file read-derivation)))
+      (let ((drv
+             ;; read-derivation can call read-derivation-from-file, so to
+             ;; avoid having multiple open files when reading a derivation
+             ;; with inputs, read it in to a string first.
+             (call-with-input-string
+                 (call-with-input-file file
+                   get-string-all)
+               read-derivation)))
         (hash-set! %derivation-cache file drv)
         drv)))
 

base-commit: fe3e05d8b3dbb255179d3f85aca870e6085bb71a
prerequisite-patch-id: 2322b3b5ce79bdaa763075cdbb96e760168d4c63
-- 
2.41.0