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authorLudovic Courtès <ludo@gnu.org>2014-03-06 21:41:51 +0100
committerLudovic Courtès <ludo@gnu.org>2014-03-06 21:42:24 +0100
commit9ea3ef26551a754df502e03002a73052f3c2fbc6 (patch)
tree2a04e53e14cedd66a606922445ba226995982f42
parentf326fef8a89d02b481d7e900ef791d0108381f3f (diff)
downloadpatches-9ea3ef26551a754df502e03002a73052f3c2fbc6.tar
patches-9ea3ef26551a754df502e03002a73052f3c2fbc6.tar.gz
utils: 'fcntl-flock' passes an errno when throwing an exception.
* guix/utils.scm (%libc-errno-pointer, errno): New procedures. (fcntl-flock): Use it as the exception's argument.
-rw-r--r--guix/utils.scm18
1 files changed, 17 insertions, 1 deletions
diff --git a/guix/utils.scm b/guix/utils.scm
index 5fda2116de..38f9ad0f61 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -252,6 +252,22 @@ buffered data is lost."
((string-contains %host-type "linux") #(0 1 2)) ; *-linux-gnu
(else #(1 2 3))))) ; *-gnu*
+(define %libc-errno-pointer
+ ;; Glibc's 'errno' pointer.
+ (let ((errno-loc (dynamic-func "__errno_location" (dynamic-link))))
+ (and errno-loc
+ (let ((proc (pointer->procedure '* errno-loc '())))
+ (proc)))))
+
+(define (errno)
+ "Return the current errno."
+ ;; XXX: We assume that nothing changes 'errno' while we're doing all this.
+ ;; In particular, that means that no async must be running here.
+ (if %libc-errno-pointer
+ (let ((bv (pointer->bytevector %libc-errno-pointer (sizeof int))))
+ (bytevector-sint-ref bv 0 (native-endianness) (sizeof int)))
+ 0))
+
(define fcntl-flock
(let* ((ptr (dynamic-func "fcntl" (dynamic-link)))
(proc (pointer->procedure int ptr `(,int ,int *))))
@@ -282,7 +298,7 @@ must be a symbol, one of 'read-lock, 'write-lock, or 'unlock."
(or (zero? err)
;; Presumably we got EAGAIN or so.
- (throw 'flock-error fd))))))
+ (throw 'flock-error (errno)))))))
;;;