services: shepherd: Remove ‘dynamic-wind’ in ‘call-with-*-file’.

Fixes <https://issues.guix.gnu.org/64653>.

The ‘dynamic-wind’ was causing files to be closed prematurely when
leaving the dynamic extent of PROC for instance via a delimited
continuation, using Fibers (that ‘dynamic-wind’ call was also
semantically incorrect in the first place).

* gnu/services/shepherd.scm (shepherd-configuration-file)
[config](call-with-file): Remove.
(call-with-input-file, call-with-output-file): Rewrite in terms of
‘call-with-port’.

Change-Id: Ica8af71a04f525a15be99985552063cb98cd6ee8

1 files changed, 5 insertions, 16 deletions

diff --git a/gnu/services/shepherd.scm b/gnu/services/shepherd.scm
index e9d3a631c2..8e122f1aab 100644
--- a/gnu/services/shepherd.scm
+++ b/gnu/services/shepherd.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013-2016, 2018-2023 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013-2016, 2018-2024 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Clément Lassieur <clement@lassieur.org>
 ;;; Copyright © 2018 Carlo Zancanaro <carlo@zancanaro.id.au>
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
@@ -371,17 +371,6 @@ as shepherd package."
           (use-modules (srfi srfi-34)
                        (system repl error-handling))
 
-          (define (call-with-file file flags proc)
-            (let ((port #f))
-              (dynamic-wind
-                (lambda ()
-                  (set! port (open file flags)))
-                (lambda ()
-                  (proc port))
-                (lambda ()
-                  (close-port port)
-                  (set! port #f)))))
-
           ;; There's code run from shepherd that uses 'call-with-input-file' &
           ;; co.--e.g., the 'urandom-seed' service.  Starting from Shepherd
           ;; 0.9.2, users need to make sure not to leak non-close-on-exec file
@@ -389,12 +378,12 @@ as shepherd package."
           ;; standard bindings with O_CLOEXEC variants.
           (set! call-with-input-file
                 (lambda (file proc)
-                  (call-with-file file (logior O_RDONLY O_CLOEXEC)
-                                  proc)))
+                  (call-with-port (open file (logior O_RDONLY O_CLOEXEC))
+                    proc)))
           (set! call-with-output-file
                 (lambda (file proc)
-                  (call-with-file file (logior O_WRONLY O_CREAT O_CLOEXEC)
-                                  proc)))
+                  (call-with-port (open file (logior O_WRONLY O_CREAT O_CLOEXEC))
+                    proc)))
 
           ;; Specify the default environment visible to all the services.
           ;; Without this statement, all the environment variables of PID 1