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syscalls: Add 'network-interface-flags'.

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* guix/build/syscalls.scm (SIOCGIFFLAGS, IFF_UP, IFF_BROADCAST,
  IFF_LOOPBACK, IF_NAMESIZE): New variables.
  (network-interface-flags, loopback-network-interface?): New
  procedures.
* tests/syscalls.scm ("network-interface-flags",
  "loopback-network-interface?"): New tests.
This commit is contained in:
Ludovic Courtès 2014-09-14 22:12:35 +02:00
parent 7585016f53
commit 973eea3478
2 changed files with 67 additions and 3 deletions
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53
guix/build/syscalls.scm
View file

@ -31,7 +31,13 @@ (define-module (guix build syscalls)
mount
umount
processes
network-interfaces))
IFF_UP
IFF_BROADCAST
IFF_LOOPBACK
network-interfaces
network-interface-flags
loopback-network-interface?))
;;; Commentary:
;;;
@ -190,6 +196,18 @@ (define SIOCGIFCONF ;from <bits/ioctls.h>
(if (string-contains %host-type "linux")
#x8912 ;GNU/Linux
#xf00801a4)) ;GNU/Hurd
(define SIOCGIFFLAGS
(if (string-contains %host-type "linux")
#x8913 ;GNU/Linux
#xc4804191)) ;GNU/Hurd
;; Flags and constants from <net/if.h>.
(define IFF_UP #x1) ;Interface is up
(define IFF_BROADCAST #x2) ;Broadcast address valid.
(define IFF_LOOPBACK #x8) ;Is a loopback net.
(define IF_NAMESIZE 16) ;maximum interface name size
(define ifconf-struct
;; 'struct ifconf', from <net/if.h>.
@ -197,8 +215,9 @@ (define ifconf-struct
'*)) ;struct ifreq *ifc_ifcu
(define ifreq-struct-size
;; 'struct ifreq' begins with a char array containing the interface name,
;; followed by a bunch of stuff. This is its size in bytes.
;; 'struct ifreq' begins with an array of IF_NAMESIZE bytes containing the
;; interface name (nul-terminated), followed by a bunch of stuff. This is
;; its size in bytes.
(if (= 8 (sizeof '*))
40
32))
@ -245,4 +264,32 @@ (define* (network-interfaces #:optional sock)
(list (strerror err))
(list err)))))
(define (network-interface-flags socket name)
"Return a number that is the bit-wise or of 'IFF*' flags for network
interface NAME."
(let ((req (make-bytevector ifreq-struct-size)))
(bytevector-copy! (string->utf8 name) 0 req 0
(min (string-length name) (- IF_NAMESIZE 1)))
(let* ((ret (%ioctl (fileno socket) SIOCGIFFLAGS
(bytevector->pointer req)))
(err (errno)))
(if (zero? ret)
;; The 'ifr_flags' field is IF_NAMESIZE bytes after the beginning of
;; 'struct ifreq', and it's a short int.
(bytevector-sint-ref req IF_NAMESIZE (native-endianness)
(sizeof short))
(throw 'system-error "network-interface-flags"
"network-interface-flags on ~A: ~A"
(list name (strerror err))
(list err))))))
(define (loopback-network-interface? name)
"Return true if NAME designates a loopback network interface."
(let* ((sock (socket SOCK_STREAM AF_INET 0))
(flags (network-interface-flags sock name)))
(close-port sock)
(not (zero? (logand flags IFF_LOOPBACK)))))
;;; syscalls.scm ends here

17
tests/syscalls.scm
View file

@ -48,6 +48,23 @@ (define-module (test-syscalls)
(((? string? names) ..1)
(member "lo" names))))
(test-assert "network-interface-flags"
(let* ((sock (socket SOCK_STREAM AF_INET 0))
(flags (network-interface-flags sock "lo")))
(close-port sock)
(and (not (zero? (logand flags IFF_LOOPBACK)))
(not (zero? (logand flags IFF_UP))))))
(test-equal "loopback-network-interface?"
ENODEV
(and (loopback-network-interface? "lo")
(catch 'system-error
(lambda ()
(loopback-network-interface? "nonexistent")
#f)
(lambda args
(system-error-errno args)))))
(test-end)