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install: Validate symlink target in evaluate-populate-directive.

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* 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.
This commit is contained in:
Maxim Cournoyer 2022-10-25 23:17:09 -04:00
parent 8934827014
commit 0bb872b379
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GPG key ID: 1260E46482E63562
1 changed files with 40 additions and 20 deletions
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60
gnu/build/install.scm
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@ -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.