Remove UnsafeSlice and use unsafe.Slice

References:
- #713
- #566

Signed-off-by: Chun-Hung Tseng <henrybear327@gmail.com>

freelist.go

@@ -282,9 +282,8 @@ func (f *freelist) read(p *page) {
 	if count == 0 {
 		f.ids = nil
 	} else {
-		var ids []pgid
-		data := unsafeIndex(unsafe.Pointer(p), unsafe.Sizeof(*p), unsafe.Sizeof(ids[0]), idx)
-		unsafeSlice(unsafe.Pointer(&ids), data, count)
+		data := unsafeIndex(unsafe.Pointer(p), unsafe.Sizeof(*p), unsafe.Sizeof(pgid(0)), idx)
+		ids := unsafe.Slice((*pgid)(data), count)
 
 		// copy the ids, so we don't modify on the freelist page directly
 		idsCopy := make([]pgid, count)
@@ -322,15 +321,13 @@ func (f *freelist) write(p *page) error {
 		p.count = uint16(l)
 	} else if l < 0xFFFF {
 		p.count = uint16(l)
-		var ids []pgid
 		data := unsafeAdd(unsafe.Pointer(p), unsafe.Sizeof(*p))
-		unsafeSlice(unsafe.Pointer(&ids), data, l)
+		ids := unsafe.Slice((*pgid)(data), l)
 		f.copyall(ids)
 	} else {
 		p.count = 0xFFFF
-		var ids []pgid
 		data := unsafeAdd(unsafe.Pointer(p), unsafe.Sizeof(*p))
-		unsafeSlice(unsafe.Pointer(&ids), data, l+1)
+		ids := unsafe.Slice((*pgid)(data), l+1)
 		ids[0] = pgid(l)
 		f.copyall(ids[1:])
 	}

page.go

@@ -74,9 +74,8 @@ func (p *page) leafPageElements() []leafPageElement {
 	if p.count == 0 {
 		return nil
 	}
-	var elems []leafPageElement
 	data := unsafeAdd(unsafe.Pointer(p), unsafe.Sizeof(*p))
-	unsafeSlice(unsafe.Pointer(&elems), data, int(p.count))
+	elems := unsafe.Slice((*leafPageElement)(data), int(p.count))
 	return elems
 }
 
@@ -91,9 +90,8 @@ func (p *page) branchPageElements() []branchPageElement {
 	if p.count == 0 {
 		return nil
 	}
-	var elems []branchPageElement
 	data := unsafeAdd(unsafe.Pointer(p), unsafe.Sizeof(*p))
-	unsafeSlice(unsafe.Pointer(&elems), data, int(p.count))
+	elems := unsafe.Slice((*branchPageElement)(data), int(p.count))
 	return elems
 }
 

unsafe.go

@@ -1,7 +1,6 @@
 package bbolt
 
 import (
-	"reflect"
 	"unsafe"
 )
 
@@ -26,14 +25,3 @@ func unsafeByteSlice(base unsafe.Pointer, offset uintptr, i, j int) []byte {
 	// all), so this is believed to be correct.
 	return (*[maxAllocSize]byte)(unsafeAdd(base, offset))[i:j:j]
 }
-
-// unsafeSlice modifies the data, len, and cap of a slice variable pointed to by
-// the slice parameter.  This helper should be used over other direct
-// manipulation of reflect.SliceHeader to prevent misuse, namely, converting
-// from reflect.SliceHeader to a Go slice type.
-func unsafeSlice(slice, data unsafe.Pointer, len int) {
-	s := (*reflect.SliceHeader)(slice) //nolint:staticcheck
-	s.Data = uintptr(data)
-	s.Cap = len
-	s.Len = len
-}