Merge 31bfe87edc into f9f629a1d0
This commit is contained in:
Dmitri Shuralyov
commit
a41f134455
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@ -0,0 +1,131 @@
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/*
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* Copyright (c) 2013 Dave Collins <dave@davec.name>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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// +build !appengine
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package spew
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import (
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"reflect"
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"unsafe"
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)
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const (
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// ptrSize is the size of a pointer on the current arch.
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ptrSize = unsafe.Sizeof((*byte)(nil))
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)
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var (
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// offsetPtr, offsetScalar, and offsetFlag are the offsets for the
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// internal reflect.Value fields. These values are valid before golang
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// commit ecccf07e7f9d which changed the format. The are also valid
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// after commit 82f48826c6c7 which changed the format again to mirror
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// the original format. Code in the init function updates these offsets
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// as necessary.
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offsetPtr = uintptr(ptrSize)
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offsetScalar = uintptr(0)
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offsetFlag = uintptr(ptrSize * 2)
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// flagKindWidth and flagKindShift indicate various bits that the
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// reflect package uses internally to track kind information.
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//
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// flagRO indicates whether or not the value field of a reflect.Value is
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// read-only.
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//
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// flagIndir indicates whether the value field of a reflect.Value is
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// the actual data or a pointer to the data.
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//
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// These values are valid before golang commit 90a7c3c86944 which
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// changed their positions. Code in the init function updates these
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// flags as necessary.
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flagKindWidth = uintptr(5)
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flagKindShift = uintptr(flagKindWidth - 1)
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flagRO = uintptr(1 << 0)
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flagIndir = uintptr(1 << 1)
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)
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func init() {
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// Older versions of reflect.Value stored small integers directly in the
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// ptr field (which is named val in the older versions). Versions
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// between commits ecccf07e7f9d and 82f48826c6c7 added a new field named
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// scalar for this purpose which unfortunately came before the flag
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// field, so the offset of the flag field is different for those
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// versions.
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//
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// This code constructs a new reflect.Value from a known small integer
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// and checks if the size of the reflect.Value struct indicates it has
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// the scalar field. When it does, the offsets are updated accordingly.
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vv := reflect.ValueOf(0xf00)
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if unsafe.Sizeof(vv) == (ptrSize * 4) {
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offsetScalar = ptrSize * 2
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offsetFlag = ptrSize * 3
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}
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// Commit 90a7c3c86944 changed the flag positions such that the low
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// order bits are the kind. This code extracts the kind from the flags
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// field and ensures it's the correct type. When it's not, the flag
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// order has been changed to the newer format, so the flags are updated
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// accordingly.
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upf := unsafe.Pointer(uintptr(unsafe.Pointer(&vv)) + offsetFlag)
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upfv := *(*uintptr)(upf)
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flagKindMask := uintptr((1<<flagKindWidth - 1) << flagKindShift)
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if (upfv&flagKindMask)>>flagKindShift != uintptr(reflect.Int) {
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flagKindShift = 0
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flagRO = 1 << 5
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flagIndir = 1 << 6
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}
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}
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// unsafeReflectValue converts the passed reflect.Value into a one that bypasses
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// the typical safety restrictions preventing access to unaddressable and
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// unexported data. It works by digging the raw pointer to the underlying
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// value out of the protected value and generating a new unprotected (unsafe)
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// reflect.Value to it.
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//
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// This allows us to check for implementations of the Stringer and error
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// interfaces to be used for pretty printing ordinarily unaddressable and
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// inaccessible values such as unexported struct fields.
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func unsafeReflectValue(v reflect.Value) (rv reflect.Value) {
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indirects := 1
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vt := v.Type()
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upv := unsafe.Pointer(uintptr(unsafe.Pointer(&v)) + offsetPtr)
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rvf := *(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&v)) + offsetFlag))
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if rvf&flagIndir != 0 {
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vt = reflect.PtrTo(v.Type())
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indirects++
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} else if offsetScalar != 0 {
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// The value is in the scalar field when it's not one of the
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// reference types.
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switch vt.Kind() {
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case reflect.Uintptr:
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case reflect.Chan:
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case reflect.Func:
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case reflect.Map:
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case reflect.Ptr:
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case reflect.UnsafePointer:
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default:
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upv = unsafe.Pointer(uintptr(unsafe.Pointer(&v)) +
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offsetScalar)
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}
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}
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pv := reflect.NewAt(vt, upv)
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rv = pv
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for i := 0; i < indirects; i++ {
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rv = rv.Elem()
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}
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return rv
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}
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@ -0,0 +1,26 @@
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/*
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* Copyright (c) 2013 Dave Collins <dave@davec.name>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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// +build appengine
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package spew
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import "reflect"
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func UnsafeReflectValue(v reflect.Value) reflect.Value {
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// This is just a stub, since "unsafe" is unavailable.
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return v
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}
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108
spew/common.go
108
spew/common.go
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@ -23,116 +23,8 @@ import (
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"reflect"
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"sort"
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"strconv"
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"unsafe"
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)
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const (
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// ptrSize is the size of a pointer on the current arch.
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ptrSize = unsafe.Sizeof((*byte)(nil))
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)
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var (
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// offsetPtr, offsetScalar, and offsetFlag are the offsets for the
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// internal reflect.Value fields. These values are valid before golang
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// commit ecccf07e7f9d which changed the format. The are also valid
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// after commit 82f48826c6c7 which changed the format again to mirror
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// the original format. Code in the init function updates these offsets
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// as necessary.
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offsetPtr = uintptr(ptrSize)
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offsetScalar = uintptr(0)
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offsetFlag = uintptr(ptrSize * 2)
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// flagKindWidth and flagKindShift indicate various bits that the
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// reflect package uses internally to track kind information.
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//
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// flagRO indicates whether or not the value field of a reflect.Value is
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// read-only.
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//
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// flagIndir indicates whether the value field of a reflect.Value is
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// the actual data or a pointer to the data.
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//
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// These values are valid before golang commit 90a7c3c86944 which
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// changed their positions. Code in the init function updates these
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// flags as necessary.
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flagKindWidth = uintptr(5)
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flagKindShift = uintptr(flagKindWidth - 1)
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flagRO = uintptr(1 << 0)
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flagIndir = uintptr(1 << 1)
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)
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func init() {
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// Older versions of reflect.Value stored small integers directly in the
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// ptr field (which is named val in the older versions). Versions
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// between commits ecccf07e7f9d and 82f48826c6c7 added a new field named
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// scalar for this purpose which unfortunately came before the flag
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// field, so the offset of the flag field is different for those
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// versions.
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//
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// This code constructs a new reflect.Value from a known small integer
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// and checks if the size of the reflect.Value struct indicates it has
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// the scalar field. When it does, the offsets are updated accordingly.
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vv := reflect.ValueOf(0xf00)
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if unsafe.Sizeof(vv) == (ptrSize * 4) {
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offsetScalar = ptrSize * 2
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offsetFlag = ptrSize * 3
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}
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// Commit 90a7c3c86944 changed the flag positions such that the low
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// order bits are the kind. This code extracts the kind from the flags
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// field and ensures it's the correct type. When it's not, the flag
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// order has been changed to the newer format, so the flags are updated
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// accordingly.
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upf := unsafe.Pointer(uintptr(unsafe.Pointer(&vv)) + offsetFlag)
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upfv := *(*uintptr)(upf)
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flagKindMask := uintptr((1<<flagKindWidth - 1) << flagKindShift)
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if (upfv&flagKindMask)>>flagKindShift != uintptr(reflect.Int) {
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flagKindShift = 0
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flagRO = 1 << 5
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flagIndir = 1 << 6
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}
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}
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// unsafeReflectValue converts the passed reflect.Value into a one that bypasses
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// the typical safety restrictions preventing access to unaddressable and
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// unexported data. It works by digging the raw pointer to the underlying
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// value out of the protected value and generating a new unprotected (unsafe)
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// reflect.Value to it.
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//
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// This allows us to check for implementations of the Stringer and error
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// interfaces to be used for pretty printing ordinarily unaddressable and
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// inaccessible values such as unexported struct fields.
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func unsafeReflectValue(v reflect.Value) (rv reflect.Value) {
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indirects := 1
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vt := v.Type()
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upv := unsafe.Pointer(uintptr(unsafe.Pointer(&v)) + offsetPtr)
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rvf := *(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&v)) + offsetFlag))
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if rvf&flagIndir != 0 {
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vt = reflect.PtrTo(v.Type())
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indirects++
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} else if offsetScalar != 0 {
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// The value is in the scalar field when it's not one of the
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// reference types.
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switch vt.Kind() {
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case reflect.Uintptr:
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case reflect.Chan:
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case reflect.Func:
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case reflect.Map:
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case reflect.Ptr:
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case reflect.UnsafePointer:
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default:
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upv = unsafe.Pointer(uintptr(unsafe.Pointer(&v)) +
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offsetScalar)
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}
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}
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pv := reflect.NewAt(vt, upv)
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rv = pv
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for i := 0; i < indirects; i++ {
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rv = rv.Elem()
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}
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return rv
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}
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// Some constants in the form of bytes to avoid string overhead. This mirrors
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// the technique used in the fmt package.
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var (
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|
|
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|||
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