[PATCH v2 2/4] install: Validate symlink target in evaluate-populate-directive.
(address . guix-patches@gnu.org)(name . Maxim Cournoyer)(address . maxim.cournoyer@gmail.com)
20221110042351.829-2-maxim.cournoyer@gmail.com
* gnu/build/install.scm (evaluate-populate-directive): By default, error when
the target of a symlink doesn't exist. Always ensure TARGET ends with "/".
(populate-root-file-system): Call evaluate-populate-directive with
#:error-on-dangling-symlink #t and add comment.
---
gnu/build/install.scm | 60 ++++++++++++++++++++++++++++---------------
1 file changed, 40 insertions(+), 20 deletions(-)
Toggle diff (109 lines)
diff --git a/gnu/build/install.scm b/gnu/build/install.scm
index f5c8407b89..33a9616c0d 100644
--- a/gnu/build/install.scm
+++ b/gnu/build/install.scm
@@ -1,6 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
+;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -56,19 +57,24 @@ (define (install-boot-config bootcfg bootcfg-location mount-point)
(define* (evaluate-populate-directive directive target
#:key
(default-gid 0)
- (default-uid 0))
+ (default-uid 0)
+ (error-on-dangling-symlink? #t))
"Evaluate DIRECTIVE, an sexp describing a file or directory to create under
directory TARGET. DEFAULT-UID and DEFAULT-GID are the default UID and GID in
the context of the caller. If the directive matches those defaults then,
-'chown' won't be run."
+'chown' won't be run. When ERROR-ON-DANGLING-SYMLINK? is true, abort with an
+error when a dangling symlink would be created."
+ (define target* (if (string-suffix? "/" target)
+ target
+ (string-append target "/")))
(let loop ((directive directive))
(catch 'system-error
(lambda ()
(match directive
(('directory name)
- (mkdir-p (string-append target name)))
+ (mkdir-p (string-append target* name)))
(('directory name uid gid)
- (let ((dir (string-append target name)))
+ (let ((dir (string-append target* name)))
(mkdir-p dir)
;; If called from a context without "root" permissions, "chown"
;; to root will fail. In that case, do not try to run "chown"
@@ -78,27 +84,38 @@ (define* (evaluate-populate-directive directive target
(chown dir uid gid))))
(('directory name uid gid mode)
(loop `(directory ,name ,uid ,gid))
- (chmod (string-append target name) mode))
+ (chmod (string-append target* name) mode))
(('file name)
- (call-with-output-file (string-append target name)
+ (call-with-output-file (string-append target* name)
(const #t)))
(('file name (? string? content))
- (call-with-output-file (string-append target name)
+ (call-with-output-file (string-append target* name)
(lambda (port)
(display content port))))
((new '-> old)
- (let try ()
- (catch 'system-error
- (lambda ()
- (symlink old (string-append target new)))
- (lambda args
- ;; When doing 'guix system init' on the current '/', some
- ;; symlinks may already exists. Override them.
- (if (= EEXIST (system-error-errno args))
- (begin
- (delete-file (string-append target new))
- (try))
- (apply throw args))))))))
+ (let ((new* (string-append target* new)))
+ (let try ()
+ (catch 'system-error
+ (lambda ()
+ (when error-on-dangling-symlink?
+ ;; When the symbolic link points to a relative path,
+ ;; checking if its target exists must be done relatively
+ ;; to the link location.
+ (unless (if (string-prefix? "/" old)
+ (file-exists? old)
+ (with-directory-excursion (dirname new*)
+ (file-exists? old)))
+ (error (format #f "symlink `~a' points to nonexistent \
+file `~a'" new* old))))
+ (symlink old new*))
+ (lambda args
+ ;; When doing 'guix system init' on the current '/', some
+ ;; symlinks may already exists. Override them.
+ (if (= EEXIST (system-error-errno args))
+ (begin
+ (delete-file new*)
+ (try))
+ (apply throw args)))))))))
(lambda args
;; Usually we can only get here when installing to an existing root,
;; as with 'guix system init foo.scm /'.
@@ -142,7 +159,10 @@ (define* (populate-root-file-system system target
includes /etc, /var, /run, /bin/sh, etc., and all the symlinks to SYSTEM.
EXTRAS is a list of directives appended to the built-in directives to populate
TARGET."
- (for-each (cut evaluate-populate-directive <> target)
+ ;; It's expected that some symbolic link targets do not exist yet, so do not
+ ;; error on dangling links.
+ (for-each (cut evaluate-populate-directive <> target
+ #:error-on-dangling-symlink? #f)
(append (directives (%store-directory)) extras))
;; Add system generation 1.
--
2.37.3