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01/01: build: syscalls: Add pivot-root.
From: |
David Thompson |
Subject: |
01/01: build: syscalls: Add pivot-root. |
Date: |
Wed, 08 Jul 2015 01:18:00 +0000 |
davexunit pushed a commit to branch master
in repository guix.
commit df3ce5c123929b690672cfc6adb3323a8033ec44
Author: David Thompson <address@hidden>
Date: Thu Jun 25 20:17:46 2015 -0400
build: syscalls: Add pivot-root.
* guix/build/syscalls.scm (pivot-root): New procedure.
* tests/syscalls.scm ("pivot-root"): New test.
---
guix/build/syscalls.scm | 15 +++++++++++++++
tests/syscalls.scm | 29 +++++++++++++++++++++++++++++
2 files changed, 44 insertions(+), 0 deletions(-)
diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm
index 3f0a0c9..dcca5fc 100644
--- a/guix/build/syscalls.scm
+++ b/guix/build/syscalls.scm
@@ -46,6 +46,7 @@
swapoff
processes
mkdtemp!
+ pivot-root
CLONE_NEWNS
CLONE_NEWUTS
@@ -329,6 +330,20 @@ there is no such limitation."
(list fdes nstype (strerror err))
(list err)))))))
+(define pivot-root
+ (let* ((ptr (dynamic-func "pivot_root" (dynamic-link)))
+ (proc (pointer->procedure int ptr (list '* '*))))
+ (lambda (new-root put-old)
+ "Change the root file system to NEW-ROOT and move the current root file
+system to PUT-OLD."
+ (let ((ret (proc (string->pointer new-root)
+ (string->pointer put-old)))
+ (err (errno)))
+ (unless (zero? ret)
+ (throw 'system-error "pivot_root" "~S ~S: ~A"
+ (list new-root put-old (strerror err))
+ (list err)))))))
+
;;;
;;; Packed structures.
diff --git a/tests/syscalls.scm b/tests/syscalls.scm
index 9b8ac9e..8598f74 100644
--- a/tests/syscalls.scm
+++ b/tests/syscalls.scm
@@ -18,6 +18,7 @@
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (test-syscalls)
+ #:use-module (guix utils)
#:use-module (guix build syscalls)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
@@ -117,6 +118,34 @@
(waitpid fork-pid)
result))))))))
+(test-assert "pivot-root"
+ (match (pipe)
+ ((in . out)
+ (match (clone (logior CLONE_NEWUSER CLONE_NEWNS SIGCHLD))
+ (0
+ (close in)
+ (call-with-temporary-directory
+ (lambda (root)
+ (let ((put-old (string-append root "/real-root")))
+ (mount "none" root "tmpfs")
+ (mkdir put-old)
+ (call-with-output-file (string-append root "/test")
+ (lambda (port)
+ (display "testing\n" port)))
+ (pivot-root root put-old)
+ ;; The test file should now be located inside the root directory.
+ (write (file-exists? "/test") out)
+ (close out))))
+ (primitive-exit 0))
+ (pid
+ (close out)
+ (let ((result (read in)))
+ (close in)
+ (and (zero? (match (waitpid pid)
+ ((_ . status)
+ (status:exit-val status))))
+ (eq? #t result))))))))
+
(test-assert "all-network-interfaces"
(match (all-network-interfaces)
(((? string? names) ..1)