From: Andrew Tropin <andrew@trop.in>
To: Maxime Devos <maximedevos@telenet.be>, 54762@debbugs.gnu.org
Subject: [bug#54762] [PATCH] home: symlink-manager: Use no-follow version of file-exists?.
Date: Fri, 08 Apr 2022 07:23:34 +0300 [thread overview]
Message-ID: <878rsg5hkp.fsf@trop.in> (raw)
In-Reply-To: <be6efed627587bf2a962db2f76615b8de538c2ba.camel@telenet.be>
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On 2022-04-07 20:21, Maxime Devos wrote:
> Andrew Tropin schreef op do 07-04-2022 om 20:01 [+0300]:
>> Idk how file-exists? works internally, but still expect it to be more
>> efficient than lstat. That's why I decided to use lstat only as a
>> "fallback" option in `or` statement.
>
> Here's the definition, from module/ice-9/boot-9.scm (Guile source
> code):
>
> ;; For reference, Emacs file-exists-p uses stat in this same way.
> (define file-exists?
> (if (provided? 'posix)
> (lambda (str)
> (->bool (stat str #f)))
> [non-POSIX code that's not relevant to Guix]))
>
> 'file-exists?' just calls 'stat', a variant of 'lstat', so I don't
> think there are performance gains to be had here. Well, the
> (stat ... #f) might not need to install an exception handler since it
> is written in C, but that seems at most a micro-optimisation to me.
>
> Greetings,
> Maxime.
Updated the implementation, which behaves similiar to file-exists?, but
not follow symlinks.
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From 92ee52a96d536cba2b3b473f99e8f36646da81fd Mon Sep 17 00:00:00 2001
From: Andrew Tropin <andrew@trop.in>
Date: Thu, 7 Apr 2022 11:22:48 +0300
Subject: [PATCH v2] home: symlink-manager: Use no-follow version of
file-exists?.
* gnu/home/services/symlink-manager.scm (update-symlinks-script): Use
no-follow version of file-exists?.
---
gnu/home/services/symlink-manager.scm | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/gnu/home/services/symlink-manager.scm b/gnu/home/services/symlink-manager.scm
index 6d19258ec7..e4c931fbee 100644
--- a/gnu/home/services/symlink-manager.scm
+++ b/gnu/home/services/symlink-manager.scm
@@ -85,6 +85,10 @@ (define (target-file file)
;; such as "config/fontconfig/fonts.conf" or "bashrc".
(string-append home-directory "/" (preprocess-file file)))
+ (define (no-follow-file-exists? file)
+ "Return #t if file exists, even if it's a dangling symlink."
+ (->bool (false-if-exception (lstat file))))
+
(define (symlink-to-store? file)
(catch 'system-error
(lambda ()
@@ -123,7 +127,7 @@ (define (strip file)
(const #t)
(lambda (file stat _) ;leaf
(let ((file (target-file (strip file))))
- (when (file-exists? file)
+ (when (no-follow-file-exists? file)
;; DO NOT remove the file if it is no longer a symlink to
;; the store, it will be backed up later during
;; create-symlinks phase.
@@ -183,7 +187,7 @@ (define (source-file file)
(lambda (file stat result) ;leaf
(let ((source (source-file (strip file)))
(target (target-file (strip file))))
- (when (file-exists? target)
+ (when (no-follow-file-exists? target)
(backup-file (strip file)))
(format #t (G_ "Symlinking ~a -> ~a...")
target source)
@@ -192,7 +196,7 @@ (define (source-file file)
(lambda (directory stat result) ;down
(unless (string=? directory config-file-directory)
(let ((target (target-file (strip directory))))
- (when (and (file-exists? target)
+ (when (and (no-follow-file-exists? target)
(not (file-is-directory? target)))
(backup-file (strip directory)))
--
2.34.0
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--
Best regards,
Andrew Tropin
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next prev parent reply other threads:[~2022-04-08 4:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 8:22 [bug#54762] [PATCH] home: symlink-manager: Use no-follow version of file-exists? Andrew Tropin
2022-04-07 12:28 ` Maxime Devos
2022-04-07 17:01 ` Andrew Tropin
2022-04-07 18:17 ` Maxime Devos
2022-04-07 18:21 ` Maxime Devos
2022-04-08 4:23 ` Andrew Tropin [this message]
2022-04-09 21:57 ` bug#54762: " Ludovic Courtès
2022-04-11 5:26 ` [bug#54762] " Andrew Tropin
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