From da382a3978d3db2380c7e9a69207545562dfd727 Mon Sep 17 00:00:00 2001 From: "Bryan C. Mills" Date: Thu, 30 Apr 2020 17:05:59 -0400 Subject: internal/unsafeheader: consolidate stringHeader and sliceHeader declarations into an internal package The new package "internal/unsafeheader" depends only on "unsafe", and provides declarations equivalent to reflect.StringHeader and reflect.SliceHeader but with Data fields of the proper unsafe.Pointer type (instead of uintptr). Unlike the types it replaces, the "internal/unsafeheader" package has a regression test to ensure that its header types remain equivalent to the declarations provided by the "reflect" package. Since "internal/unsafeheader" has almost no dependencies, it can be used in other low-level packages such as "syscall" and "reflect". This change is based on the corresponding x/sys change in CL 231177. Fixes #37805 Updates #19367 Change-Id: I7a6d93ef8dd6e235bcab94e7c47270aad047af31 Reviewed-on: https://go-review.googlesource.com/c/go/+/231223 Reviewed-by: Ian Lance Taylor --- src/internal/reflectlite/swapper.go | 7 +++++-- src/internal/reflectlite/type.go | 5 +++-- src/internal/reflectlite/value.go | 18 +++--------------- 3 files changed, 11 insertions(+), 19 deletions(-) (limited to 'src/internal/reflectlite') diff --git a/src/internal/reflectlite/swapper.go b/src/internal/reflectlite/swapper.go index 4594fb5ee2..6330ab2d34 100644 --- a/src/internal/reflectlite/swapper.go +++ b/src/internal/reflectlite/swapper.go @@ -4,7 +4,10 @@ package reflectlite -import "unsafe" +import ( + "internal/unsafeheader" + "unsafe" +) // Swapper returns a function that swaps the elements in the provided // slice. @@ -58,7 +61,7 @@ func Swapper(slice interface{}) func(i, j int) { } } - s := (*sliceHeader)(v.ptr) + s := (*unsafeheader.Slice)(v.ptr) tmp := unsafe_New(typ) // swap scratch space return func(i, j int) { diff --git a/src/internal/reflectlite/type.go b/src/internal/reflectlite/type.go index 49a03ac1e1..eb7f1a4b78 100644 --- a/src/internal/reflectlite/type.go +++ b/src/internal/reflectlite/type.go @@ -7,6 +7,7 @@ package reflectlite import ( + "internal/unsafeheader" "unsafe" ) @@ -338,7 +339,7 @@ func (n name) name() (s string) { } b := (*[4]byte)(unsafe.Pointer(n.bytes)) - hdr := (*stringHeader)(unsafe.Pointer(&s)) + hdr := (*unsafeheader.String)(unsafe.Pointer(&s)) hdr.Data = unsafe.Pointer(&b[3]) hdr.Len = int(b[1])<<8 | int(b[2]) return s @@ -350,7 +351,7 @@ func (n name) tag() (s string) { return "" } nl := n.nameLen() - hdr := (*stringHeader)(unsafe.Pointer(&s)) + hdr := (*unsafeheader.String)(unsafe.Pointer(&s)) hdr.Data = unsafe.Pointer(n.data(3+nl+2, "non-empty string")) hdr.Len = tl return s diff --git a/src/internal/reflectlite/value.go b/src/internal/reflectlite/value.go index 6a493938f5..85beea606c 100644 --- a/src/internal/reflectlite/value.go +++ b/src/internal/reflectlite/value.go @@ -5,6 +5,7 @@ package reflectlite import ( + "internal/unsafeheader" "runtime" "unsafe" ) @@ -335,10 +336,10 @@ func (v Value) Len() int { return maplen(v.pointer()) case Slice: // Slice is bigger than a word; assume flagIndir. - return (*sliceHeader)(v.ptr).Len + return (*unsafeheader.Slice)(v.ptr).Len case String: // String is bigger than a word; assume flagIndir. - return (*stringHeader)(v.ptr).Len + return (*unsafeheader.String)(v.ptr).Len } panic(&ValueError{"reflect.Value.Len", v.kind()}) } @@ -379,19 +380,6 @@ func (v Value) Type() Type { return v.typ } -// stringHeader is a safe version of StringHeader used within this package. -type stringHeader struct { - Data unsafe.Pointer - Len int -} - -// sliceHeader is a safe version of SliceHeader used within this package. -type sliceHeader struct { - Data unsafe.Pointer - Len int - Cap int -} - /* * constructors */ -- cgit v1.2.1