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syscalls: 'define-c-struct' properly align reads. 

* guix/build/syscalls.scm (alignof*, align): New macros.
  (write-types, read-types): Use 'align' to compute the actual offset to
  read/write a value of TYPE0.
This commit is contained in:
Ludovic Courtès 2015-07-25 12:41:08 +02:00
parent 3ca337699a
commit 573b4c1ff3
1 changed files with 29 additions and 4 deletions
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33
guix/build/syscalls.scm
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@ -363,6 +363,26 @@ system to PUT-OLD."
(_ val))))))
v))))
(define-syntax alignof*
;; XXX: This duplicates 'compile-time-value'.
(syntax-rules (int128)
((_ int128)
16)
((_ type)
(let-syntax ((v (lambda (s)
(let ((val (alignof type)))
(syntax-case s ()
(_ val))))))
v))))
(define-syntax align ;as found in (system foreign)
(syntax-rules (~)
"Add to OFFSET whatever it takes to get proper alignment for TYPE."
((_ offset (type ~ endianness))
(align offset type))
((_ offset type)
(1+ (logior (1- offset) (1- (alignof* type)))))))
(define-syntax type-size
(syntax-rules (~)
((_ (type ~ order))
@ -385,8 +405,9 @@ system to PUT-OLD."
#t)
((_ bv offset (type0 types ...) (field0 fields ...))
(begin
(write-type bv offset type0 field0)
(write-types bv (+ offset (type-size type0))
(write-type bv (align offset type0) type0 field0)
(write-types bv
(+ (align offset type0) (type-size type0))
(types ...) (fields ...))))))
(define-syntax read-type
@ -408,8 +429,12 @@ system to PUT-OLD."
(return values ...))
((_ return bv offset (type0 types ...) (values ...))
(read-types return
bv (+ offset (type-size type0)) (types ...)
(values ... (read-type bv offset type0))))))
bv
(+ (align offset type0) (type-size type0))
(types ...)
(values ... (read-type bv
(align offset type0)
type0))))))
(define-syntax define-c-struct
(syntax-rules ()