diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm index ddf6117b67..527c51cea0 100644 --- a/gnu/build/file-systems.scm +++ b/gnu/build/file-systems.scm @@ -1,5 +1,5 @@ ;;; GNU Guix --- Functional package management for GNU -;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2020 Ludovic Courtès +;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2020, 2021 Ludovic Courtès ;;; Copyright © 2016, 2017 David Craven ;;; Copyright © 2017 Mathieu Othacehe ;;; Copyright © 2019 Guillaume Le Vaillant @@ -36,6 +36,7 @@ #:use-module (system foreign) #:autoload (system repl repl) (start-repl) #:use-module (srfi srfi-1) + #:use-module (srfi srfi-9) #:use-module (srfi srfi-26) #:export (disk-partitions partition-label-predicate @@ -886,6 +887,98 @@ corresponds to the symbols listed in FLAGS." (() 0)))) +;; Mount point information. +(define-record-type + (%mount source point devno type options) + mount? + (devno mount-device-number) ;st_dev + (source mount-source) ;string + (point mount-point) ;string + (type mount-type) ;string + (options mount-options)) ;string + +(define (option-string->mount-flags str) + "Parse the \"option string\" STR as it appears in /proc/mounts and similar, +and return two values: a mount bitmask (inclusive or of MS_* constants), and +the remaining unprocessed options." + (define not-comma + (char-set-complement (char-set #\,))) + + (define lst + (string-tokenize str not-comma)) + + (let loop ((options lst) + (mask 0) + (remainder '())) + (match options + (() + (values mask (string-concatenate-reverse remainder))) + ((head . tail) + (letrec-syntax ((match-options (syntax-rules (=>) + ((_) + (loop tail mask + (cons head remainder))) + ((_ (str => bit) rest ...) + (if (string=? str head) + (loop tail (logior bit mask) + remainder) + (match-options rest ...)))))) + ;; TODO: Add MS_RELATIME and more flags. + (match-options ("ro" => MS_RDONLY) + ("nosuid" => MS_NOSUID) + ("nodev" => MS_NODEV) + ("noexec" => MS_NOEXEC) + ("noatime" => MS_NOATIME))))))) + +(define (mount-flags mount) + "Return the mount flags of MOUNT, a record, as an inclusive or of +MS_* constants." + (option-string->mount-flags (mount-options mount))) + +(define (octal-decode str) + "Decode octal escapes from STR and return the corresponding string. STR may +look like this: \"white\\040space\", which is decoded as \"white space\"." + (define char-set:octal + (char-set #\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7)) + (define (octal? c) + (char-set-contains? char-set:octal c)) + + (let loop ((chars (string->list str)) + (result '())) + (match chars + (() + (list->string (reverse result))) + ((#\\ (? octal? a) (? octal? b) (? octal? c) . rest) + (loop rest + (cons (integer->char + (string->number (list->string (list a b c)) 8)) + result))) + ((head . tail) + (loop tail (cons head result)))))) + +(define (mounts) + "Return the list of mounts ( records) visible in the namespace of the +current process." + (define (string->device-number str) + (match (string-split str #\:) + (((= string->number major) (= string->number minor)) + (+ (* major 256) minor)))) + + (call-with-input-file "/proc/self/mountinfo" + (lambda (port) + (let loop ((result '())) + (let ((line (read-line port))) + (if (eof-object? line) + (reverse result) + (match (string-tokenize line) + ((id parent-id major:minor root mount-point + options _ type source _ ...) + (let ((devno (string->device-number major:minor))) + (loop (cons (%mount (octal-decode source) + (octal-decode mount-point) + devno type options) + result))))))))))) + (define* (mount-file-system fs #:key (root "/root")) "Mount the file system described by FS, a object, under ROOT." @@ -894,8 +987,8 @@ corresponds to the symbols listed in FLAGS." (host-part (string-take source idx)) ;; Strip [] from around host if present (host (match (string-split host-part (string->char-set "[]")) - (("" h "") h) - ((h) h))) + (("" h "") h) + ((h) h))) (aa (match (getaddrinfo host "nfs") ((x . _) x))) (sa (addrinfo:addr aa)) (inet-addr (inet-ntop (sockaddr:fam sa) @@ -909,12 +1002,22 @@ corresponds to the symbols listed in FLAGS." (if options (string-append "," options) ""))))) - (let ((type (file-system-type fs)) - (options (file-system-options fs)) - (source (canonicalize-device-spec (file-system-device fs))) - (mount-point (string-append root "/" - (file-system-mount-point fs))) - (flags (mount-flags->bit-mask (file-system-flags fs)))) + (let* ((type (file-system-type fs)) + (source (canonicalize-device-spec (file-system-device fs))) + (target (string-append root "/" + (file-system-mount-point fs))) + (flags (logior (mount-flags->bit-mask (file-system-flags fs)) + (if (memq 'bind-mount (file-system-flags fs)) + (or (and=> (find (let ((devno (stat:dev + (lstat source)))) + (lambda (mount) + (= (mount-device-number mount) + devno))) + (mounts)) + mount-flags) + 0) + 0))) + (options (file-system-options fs))) (when (file-system-check? fs) (check-file-system source type)) @@ -925,24 +1028,24 @@ corresponds to the symbols listed in FLAGS." ;; needed. (if (and (= MS_BIND (logand flags MS_BIND)) (not (file-is-directory? source))) - (unless (file-exists? mount-point) - (mkdir-p (dirname mount-point)) - (call-with-output-file mount-point (const #t))) - (mkdir-p mount-point)) + (unless (file-exists? target) + (mkdir-p (dirname target)) + (call-with-output-file target (const #t))) + (mkdir-p target)) (cond ((string-prefix? "nfs" type) - (mount-nfs source mount-point type flags options)) + (mount-nfs source target type flags options)) (else - (mount source mount-point type flags options))) + (mount source target type flags options))) ;; For read-only bind mounts, an extra remount is needed, as per ;; , which still applies to Linux ;; 4.0. (when (and (= MS_BIND (logand flags MS_BIND)) (= MS_RDONLY (logand flags MS_RDONLY))) - (let ((flags (logior MS_BIND MS_REMOUNT MS_RDONLY))) - (mount source mount-point type flags #f)))) + (let ((flags (logior MS_REMOUNT flags))) + (mount source target type flags options)))) (lambda args (or (file-system-mount-may-fail? fs) (apply throw args))))))