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

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

@@ -0,0 +1,99 @@
+// 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 basic os.File backed Filer.
+
+package lldb
+
+import (
+	"os"
+
+	"github.com/cznic/internal/file"
+)
+
+var _ Filer = &SimpleFileFiler{}
+
+// SimpleFileFiler is an os.File backed Filer intended for use where structural
+// consistency can be reached by other means (SimpleFileFiler is for example
+// wrapped in eg. an RollbackFiler or ACIDFiler0) or where persistence is not
+// required (temporary/working data sets).
+//
+// SimpleFileFiler is the most simple os.File backed Filer implementation as it
+// does not really implement BeginUpdate and EndUpdate/Rollback in any way
+// which would protect the structural integrity of data. If misused e.g. as a
+// real database storage w/o other measures, it can easily cause data loss
+// when, for example, a power outage occurs or the updating process terminates
+// abruptly.
+type SimpleFileFiler struct {
+	fi   file.Interface
+	name string
+	nest int
+}
+
+// NewSimpleFileFiler returns a new SimpleFileFiler.
+func NewSimpleFileFiler(f *os.File) *SimpleFileFiler {
+	fi, err := file.Open(f)
+	if err != nil {
+		return nil
+	}
+
+	sf := &SimpleFileFiler{fi: fi, name: f.Name()}
+	return sf
+}
+
+// BeginUpdate implements Filer.
+func (f *SimpleFileFiler) BeginUpdate() error {
+	f.nest++
+	return nil
+}
+
+// Close implements Filer.
+func (f *SimpleFileFiler) Close() (err error) {
+	if f.nest != 0 {
+		return &ErrPERM{(f.Name() + ":Close")}
+	}
+
+	return f.fi.Close()
+}
+
+// EndUpdate implements Filer.
+func (f *SimpleFileFiler) EndUpdate() (err error) {
+	if f.nest == 0 {
+		return &ErrPERM{(f.Name() + ":EndUpdate")}
+	}
+
+	f.nest--
+	return
+}
+
+// Name implements Filer.
+func (f *SimpleFileFiler) Name() string { return f.name }
+
+// PunchHole implements Filer.
+func (f *SimpleFileFiler) PunchHole(off, size int64) (err error) { return nil }
+
+// ReadAt implements Filer.
+func (f *SimpleFileFiler) ReadAt(b []byte, off int64) (n int, err error) { return f.fi.ReadAt(b, off) }
+
+// Rollback implements Filer.
+func (f *SimpleFileFiler) Rollback() (err error) { return nil }
+
+// Size implements Filer.
+func (f *SimpleFileFiler) Size() (int64, error) {
+	info, err := f.fi.Stat()
+	if err != nil {
+		return 0, err
+	}
+
+	return info.Size(), nil
+}
+
+// Sync implements Filer.
+func (f *SimpleFileFiler) Sync() error { return f.fi.Sync() }
+
+// Truncate implements Filer.
+func (f *SimpleFileFiler) Truncate(size int64) (err error) { return f.fi.Truncate(size) }
+
+// WriteAt implements Filer.
+func (f *SimpleFileFiler) WriteAt(b []byte, off int64) (n int, err error) { return f.fi.WriteAt(b, off) }