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-rw-r--r--guix/utils.scm28
1 files changed, 22 insertions, 6 deletions
diff --git a/guix/utils.scm b/guix/utils.scm
index 7306c6011d..84cb5ae983 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -377,14 +377,30 @@ closed as soon as PROC's dynamic extent is entered."
(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.
+(define errno
(if %libc-errno-pointer
(let ((bv (pointer->bytevector %libc-errno-pointer (sizeof int))))
- (bytevector-sint-ref bv 0 (native-endianness) (sizeof int)))
- 0))
+ (lambda ()
+ "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.
+
+ ;; Use one of the fixed-size native-ref procedures because they are
+ ;; optimized down to a single VM instruction, which reduces the risk
+ ;; that we fiddle with 'errno' (needed on Guile 2.0.5, libc 2.11.)
+ (let-syntax ((ref (lambda (s)
+ (syntax-case s ()
+ ((_ bv)
+ (case (sizeof int)
+ ((4)
+ #'(bytevector-s32-native-ref bv 0))
+ ((8)
+ #'(bytevector-s64-native-ref bv 0))
+ (else
+ (error "unsupported 'int' size"
+ (sizeof int)))))))))
+ (ref bv))))
+ (lambda () 0)))
(define fcntl-flock
(let* ((ptr (dynamic-func "fcntl" (dynamic-link)))