| // Copyright 2014 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package reflect |
| |
| import ( |
| "runtime" |
| "unsafe" |
| ) |
| |
| // The ffi function, written in C, allocates an FFI closure. It |
| // returns the code and data pointers. When the code pointer is |
| // called, it will call callback. CIF is an FFI data structure |
| // allocated as part of the closure, and is returned to ensure that |
| // the GC retains it. |
| func ffi(ftyp *funcType, callback func(unsafe.Pointer, unsafe.Pointer)) (code uintptr, data uintptr, cif unsafe.Pointer) |
| |
| // The ffiFree function, written in C, releases the FFI closure. |
| func ffiFree(uintptr) |
| |
| // An ffiData holds the information needed to preserve an FFI closure |
| // for the garbage collector. |
| type ffiData struct { |
| code uintptr |
| data uintptr |
| cif unsafe.Pointer |
| callback func(unsafe.Pointer, unsafe.Pointer) |
| } |
| |
| // The makeFuncFFI function uses libffi closures to implement |
| // reflect.MakeFunc. This is used for processors for which we don't |
| // have more efficient support. |
| func makeFuncFFI(ftyp *funcType, fn func(args []Value) (results []Value)) (uintptr, *ffiData) { |
| callback := func(params, results unsafe.Pointer) { |
| ffiCall(ftyp, fn, params, results) |
| } |
| |
| code, data, cif := ffi(ftyp, callback) |
| |
| c := &ffiData{code: code, data: data, cif: cif, callback: callback} |
| |
| runtime.SetFinalizer(c, |
| func(p *ffiData) { |
| ffiFree(p.data) |
| }) |
| |
| return code, c |
| } |
| |
| // ffiCall takes pointers to the parameters, calls the function, and |
| // stores the results back into memory. |
| func ffiCall(ftyp *funcType, fn func([]Value) []Value, params unsafe.Pointer, results unsafe.Pointer) { |
| in := make([]Value, 0, len(ftyp.in)) |
| ap := params |
| for _, rt := range ftyp.in { |
| p := unsafe_New(rt) |
| memmove(p, *(*unsafe.Pointer)(ap), rt.size) |
| v := Value{rt, p, flag(rt.Kind()<<flagKindShift) | flagIndir} |
| in = append(in, v) |
| ap = (unsafe.Pointer)(uintptr(ap) + ptrSize) |
| } |
| |
| out := fn(in) |
| |
| off := uintptr(0) |
| for i, typ := range ftyp.out { |
| v := out[i] |
| if v.typ != typ { |
| panic("reflect: function created by MakeFunc using " + funcName(fn) + |
| " returned wrong type: have " + |
| out[i].typ.String() + " for " + typ.String()) |
| } |
| if v.flag&flagRO != 0 { |
| panic("reflect: function created by MakeFunc using " + funcName(fn) + |
| " returned value obtained from unexported field") |
| } |
| |
| off = align(off, uintptr(typ.fieldAlign)) |
| addr := unsafe.Pointer(uintptr(results) + off) |
| if v.flag&flagIndir == 0 && (v.kind() == Ptr || v.kind() == UnsafePointer) { |
| *(*unsafe.Pointer)(addr) = v.ptr |
| } else { |
| memmove(addr, v.ptr, typ.size) |
| } |
| off += typ.size |
| } |
| } |