diff options
| -rw-r--r-- | guix/build/syscalls.scm | 52 |
1 files changed, 35 insertions, 17 deletions
diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm index 7c32e25971..468dc7eca2 100644 --- a/guix/build/syscalls.scm +++ b/guix/build/syscalls.scm @@ -145,6 +145,27 @@ ((_ type) (sizeof* type)))) +(define-syntax struct-alignment + (syntax-rules () + "Compute the alignment for the aggregate made of TYPES at OFFSET. The +result is the alignment of the \"most strictly aligned component\"." + ((_ offset types ...) + (max (align offset types) ...)))) + +(define-syntax struct-size + (syntax-rules () + "Return the size in bytes of the structure made of TYPES." + ((_ offset (types-processed ...)) + ;; The SysV ABI P.S. says: "Aggregates (structures and arrays) and unions + ;; assume the alignment of their most strictly aligned component." As an + ;; example, a struct such as "int32, int16" has size 8, not 6. + (1+ (logior (1- offset) + (1- (struct-alignment offset types-processed ...))))) + ((_ offset (types-processed ...) type0 types ...) + (struct-size (+ (type-size type0) (align offset type0)) + (type0 types-processed ...) + types ...)))) + (define-syntax write-type (syntax-rules (~) ((_ bv offset (type ~ order) value) @@ -193,10 +214,13 @@ (define-syntax define-c-struct (syntax-rules () - "Define READ as a deserializer and WRITE! as a serializer for the C -structure with the given TYPES. READ uses WRAP-FIELDS to return its value." - ((_ name wrap-fields read write! (fields types) ...) + "Define SIZE as the size in bytes of the C structure made of FIELDS. READ +as a deserializer and WRITE! as a serializer for the C structure with the +given TYPES. READ uses WRAP-FIELDS to return its value." + ((_ name size wrap-fields read write! (fields types) ...) (begin + (define size + (struct-size 0 () types ...)) (define (write! bv offset fields ...) (write-types bv offset (types ...) (fields ...))) (define* (read bv #:optional (offset 0)) @@ -559,6 +583,7 @@ system to PUT-OLD." 32)) (define-c-struct sockaddr-in ;<linux/in.h> + sizeof-sockaddrin (lambda (family port address) (make-socket-address family address port)) read-sockaddr-in @@ -568,6 +593,7 @@ system to PUT-OLD." (address (int32 ~ big))) (define-c-struct sockaddr-in6 ;<linux/in6.h> + sizeof-sockaddr-in6 (lambda (family port flowinfo address scopeid) (make-socket-address family address port flowinfo scopeid)) read-sockaddr-in6 @@ -832,6 +858,7 @@ an <interface> object, and whose cdr is the pointer NEXT." next)) (define-c-struct ifaddrs ;<ifaddrs.h> + %sizeof-ifaddrs values->interface read-ifaddrs write-ifaddrs! @@ -843,14 +870,6 @@ an <interface> object, and whose cdr is the pointer NEXT." (broadcastaddr '*) (data '*)) -(define-syntax %struct-ifaddrs-type - (identifier-syntax - `(* * ,unsigned-int * * * *))) - -(define-syntax %sizeof-ifaddrs - (identifier-syntax - (sizeof* %struct-ifaddrs-type))) - (define (unfold-interface-list ptr) "Call 'read-ifaddrs' on PTR and all its 'next' fields, recursively, and return the list of resulting <interface> objects." @@ -901,6 +920,7 @@ network interface. This is implemented using the 'getifaddrs' libc function." (y-pixels window-size-y-pixels)) (define-c-struct winsize ;<bits/ioctl-types.h> + sizeof-winsize window-size read-winsize write-winsize! @@ -909,18 +929,16 @@ network interface. This is implemented using the 'getifaddrs' libc function." (x-pixels unsigned-short) (y-pixels unsigned-short)) -(define winsize-struct - (list unsigned-short unsigned-short unsigned-short unsigned-short)) - (define* (terminal-window-size #:optional (port (current-output-port))) "Return a <window-size> structure describing the terminal at PORT, or raise a 'system-error' if PORT is not backed by a terminal. This procedure corresponds to the TIOCGWINSZ ioctl." - (let* ((size (make-c-struct winsize-struct '(0 0 0 0))) - (ret (%ioctl (fileno port) TIOCGWINSZ size)) + (let* ((size (make-bytevector sizeof-winsize)) + (ret (%ioctl (fileno port) TIOCGWINSZ + (bytevector->pointer size))) (err (errno))) (if (zero? ret) - (read-winsize (pointer->bytevector size (sizeof winsize-struct))) + (read-winsize size) (throw 'system-error "terminal-window-size" "~A" (list (strerror err)) (list err))))) |