mox!

vendor/go.etcd.io/bbolt/unsafe.go

@@ -0,0 +1,39 @@
+package bbolt
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+func unsafeAdd(base unsafe.Pointer, offset uintptr) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(base) + offset)
+}
+
+func unsafeIndex(base unsafe.Pointer, offset uintptr, elemsz uintptr, n int) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(base) + offset + uintptr(n)*elemsz)
+}
+
+func unsafeByteSlice(base unsafe.Pointer, offset uintptr, i, j int) []byte {
+	// See: https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
+	//
+	// This memory is not allocated from C, but it is unmanaged by Go's
+	// garbage collector and should behave similarly, and the compiler
+	// should produce similar code.  Note that this conversion allows a
+	// subslice to begin after the base address, with an optional offset,
+	// while the URL above does not cover this case and only slices from
+	// index 0.  However, the wiki never says that the address must be to
+	// the beginning of a C allocation (or even that malloc was used at
+	// 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)
+	s.Data = uintptr(data)
+	s.Cap = len
+	s.Len = len
+}