vendor: Add github.com/cznic/lldb and friends (new recursive dependency)

vendor/github.com/cznic/lldb/memfiler.go

@@ -0,0 +1,107 @@
+// Copyright 2014 The lldb Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// A memory-only implementation of Filer.
+
+package lldb
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/cznic/internal/file"
+)
+
+const (
+	pgBits = 16
+	pgSize = 1 << pgBits
+	pgMask = pgSize - 1
+)
+
+var _ Filer = &MemFiler{}
+
+// MemFiler is a memory backed Filer. It implements BeginUpdate, EndUpdate and
+// Rollback as no-ops. MemFiler is not automatically persistent, but it has
+// ReadFrom and WriteTo methods.
+type MemFiler struct {
+	fi   file.Interface
+	nest int
+}
+
+// NewMemFiler returns a new MemFiler.
+func NewMemFiler() *MemFiler {
+	fi, err := file.OpenMem("")
+	if err != nil {
+		return nil
+	}
+
+	return &MemFiler{fi: fi}
+}
+
+// BeginUpdate implements Filer.
+func (f *MemFiler) BeginUpdate() error {
+	f.nest++
+	return nil
+}
+
+// Close implements Filer.
+func (f *MemFiler) Close() (err error) {
+	if f.nest != 0 {
+		return &ErrPERM{(f.Name() + ":Close")}
+	}
+
+	return f.fi.Close()
+}
+
+// EndUpdate implements Filer.
+func (f *MemFiler) EndUpdate() (err error) {
+	if f.nest == 0 {
+		return &ErrPERM{(f.Name() + ": EndUpdate")}
+	}
+
+	f.nest--
+	return
+}
+
+// Name implements Filer.
+func (f *MemFiler) Name() string { return fmt.Sprintf("%p.memfiler", f) }
+
+// PunchHole implements Filer.
+func (f *MemFiler) PunchHole(off, size int64) (err error) { return nil }
+
+// ReadAt implements Filer.
+func (f *MemFiler) ReadAt(b []byte, off int64) (n int, err error) { return f.fi.ReadAt(b, off) }
+
+// ReadFrom is a helper to populate MemFiler's content from r.  'n' reports the
+// number of bytes read from 'r'.
+func (f *MemFiler) ReadFrom(r io.Reader) (n int64, err error) { return f.fi.ReadFrom(r) }
+
+// Rollback implements Filer.
+func (f *MemFiler) Rollback() (err error) { return nil }
+
+// Size implements Filer.
+func (f *MemFiler) Size() (int64, error) {
+	info, err := f.fi.Stat()
+	if err != nil {
+		return 0, err
+	}
+
+	return info.Size(), nil
+}
+
+// Sync implements Filer.
+func (f *MemFiler) Sync() error { return nil }
+
+// Truncate implements Filer.
+func (f *MemFiler) Truncate(size int64) (err error) { return f.fi.Truncate(size) }
+
+// WriteAt implements Filer.
+func (f *MemFiler) WriteAt(b []byte, off int64) (n int, err error) { return f.fi.WriteAt(b, off) }
+
+// WriteTo is a helper to copy/persist MemFiler's content to w.  If w is also
+// an io.WriterAt then WriteTo may attempt to _not_ write any big, for some
+// value of big, runs of zeros, i.e. it will attempt to punch holes, where
+// possible, in `w` if that happens to be a freshly created or to zero length
+// truncated OS file.  'n' reports the number of bytes written to 'w'.
+func (f *MemFiler) WriteTo(w io.Writer) (n int64, err error) { return f.fi.WriteTo(w) }