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authorLudovic Courtès <ludo@gnu.org>2019-10-05 21:54:31 +0200
committerLudovic Courtès <ludo@gnu.org>2019-10-05 22:05:02 +0200
commit5e5f7167943b408ae55736a44908a82056c87780 (patch)
treeb62ed56427ad1274b05edc2a4d995263034b62a9
parentaace6f6dba3a0e7dd46146f5c7947b11e1076e5d (diff)
downloadguix-5e5f7167943b408ae55736a44908a82056c87780.tar
guix-5e5f7167943b408ae55736a44908a82056c87780.tar.gz
syscalls: Add 'add-to-entropy-count'.
* guix/build/syscalls.scm (RNDADDTOENTCNT): New variable. (add-to-entropy-count): New procedure. * tests/syscalls.scm ("add-to-entropy-count"): New test.
-rw-r--r--guix/build/syscalls.scm28
-rw-r--r--tests/syscalls.scm13
2 files changed, 41 insertions, 0 deletions
diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm
index f2fdb4d9d1..bbf2531c79 100644
--- a/guix/build/syscalls.scm
+++ b/guix/build/syscalls.scm
@@ -68,6 +68,7 @@
statfs
free-disk-space
device-in-use?
+ add-to-entropy-count
processes
mkdtemp!
@@ -708,6 +709,33 @@ backend device."
;;;
+;;; Random.
+;;;
+
+;; From <uapi/linux/random.h>.
+(define RNDADDTOENTCNT #x40045201)
+
+(define (add-to-entropy-count port-or-fd n)
+ "Add N to the kernel's entropy count (the value that can be read from
+/proc/sys/kernel/random/entropy_avail). PORT-OR-FD must correspond to
+/dev/urandom or /dev/random. Raise to 'system-error with EPERM when the
+caller lacks root privileges."
+ (let ((fd (if (port? port-or-fd)
+ (fileno port-or-fd)
+ port-or-fd))
+ (box (make-bytevector (sizeof int))))
+ (bytevector-sint-set! box 0 n (native-endianness)
+ (sizeof int))
+ (let-values (((ret err)
+ (%ioctl fd RNDADDTOENTCNT
+ (bytevector->pointer box))))
+ (unless (zero? err)
+ (throw 'system-error "add-to-entropy-count" "~A"
+ (list (strerror err))
+ (list err))))))
+
+
+;;;
;;; Containers.
;;;
diff --git a/tests/syscalls.scm b/tests/syscalls.scm
index eeb223b950..1b3121e503 100644
--- a/tests/syscalls.scm
+++ b/tests/syscalls.scm
@@ -567,6 +567,19 @@
(let ((result (call-with-input-file "/var/run/utmpx" read-utmpx)))
(or (utmpx? result) (eof-object? result))))
+(when (zero? (getuid))
+ (test-skip 1))
+(test-equal "add-to-entropy-count"
+ EPERM
+ (call-with-output-file "/dev/urandom"
+ (lambda (port)
+ (catch 'system-error
+ (lambda ()
+ (add-to-entropy-count port 77)
+ #f)
+ (lambda args
+ (system-error-errno args))))))
+
(test-end)
(false-if-exception (delete-file temp-file))