vendor: Add dependencies for discosrv

vendor/github.com/cznic/fileutil/storage/mem.go

@@ -0,0 +1,161 @@
+// Copyright (c) 2011 CZ.NIC z.s.p.o. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// blame: jnml, labs.nic.cz
+
+package storage
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"math"
+	"os"
+)
+
+//TODO -> exported type w/ exported fields
+type memaccessor struct {
+	f  *os.File
+	fi *FileInfo
+	b  []byte
+}
+
+// Implementation of Accessor.
+func (m *memaccessor) BeginUpdate() error { return nil }
+
+// Implementation of Accessor.
+func (f *memaccessor) EndUpdate() error { return nil }
+
+// NewMem returns a new Accessor backed by an os.File.  The returned Accessor
+// keeps all of the store content in memory.  The memory and file images are
+// synced only by Sync and Close.  Recomended for small amounts of data only
+// and content which may be lost on process kill/crash.  NewMem return the
+// Accessor or an error of any.
+//
+// NOTE: The returned Accessor implements BeginUpdate and EndUpdate as a no op.
+func NewMem(f *os.File) (store Accessor, err error) {
+	a := &memaccessor{f: f}
+	if err = f.Truncate(0); err != nil {
+		return
+	}
+
+	var fi os.FileInfo
+	if fi, err = a.f.Stat(); err != nil {
+		return
+	}
+
+	a.fi = NewFileInfo(fi, a)
+	store = a
+	return
+}
+
+// OpenMem return a new Accessor backed by an os.File.  The store content is
+// loaded from f.  The returned Accessor keeps all of the store content in
+// memory.  The memory and file images are synced only Sync and Close.
+// Recomended for small amounts of data only and content which may be lost on
+// process kill/crash.  OpenMem return the Accessor or an error of any.
+//
+// NOTE: The returned Accessor implements BeginUpdate and EndUpdate as a no op.
+func OpenMem(f *os.File) (store Accessor, err error) {
+	a := &memaccessor{f: f}
+	if a.b, err = ioutil.ReadAll(a.f); err != nil {
+		a.f.Close()
+		return
+	}
+
+	var fi os.FileInfo
+	if fi, err = a.f.Stat(); err != nil {
+		a.f.Close()
+		return
+	}
+
+	a.fi = NewFileInfo(fi, a)
+	store = a
+	return
+}
+
+// Close implements Accessor. Specifically it synchronizes the memory and file images.
+func (a *memaccessor) Close() (err error) {
+	defer func() {
+		a.b = nil
+		if a.f != nil {
+			if e := a.f.Close(); e != nil && err == nil {
+				err = e
+			}
+		}
+		a.f = nil
+	}()
+
+	return a.Sync()
+}
+
+func (a *memaccessor) Name() string {
+	return a.f.Name()
+}
+
+func (a *memaccessor) ReadAt(b []byte, off int64) (n int, err error) {
+	if off < 0 || off > math.MaxInt32 {
+		return -1, fmt.Errorf("ReadAt: illegal offset %#x", off)
+	}
+
+	rq, fp := len(b), int(off)
+	if fp+rq > len(a.b) {
+		return -1, fmt.Errorf("ReadAt: illegal rq %#x @ offset %#x, len %#x", rq, fp, len(a.b))
+	}
+
+	copy(b, a.b[fp:])
+	return
+}
+
+func (a *memaccessor) Stat() (fi os.FileInfo, err error) {
+	i := a.fi
+	i.FSize = int64(len(a.b))
+	fi = i
+	return
+}
+
+// Sync implements Accessor. Specifically it synchronizes the memory and file images.
+func (a *memaccessor) Sync() (err error) {
+	var n int
+	if n, err = a.f.WriteAt(a.b, 0); n != len(a.b) {
+		return
+	}
+
+	return a.f.Truncate(int64(len(a.b)))
+}
+
+func (a *memaccessor) Truncate(size int64) (err error) {
+	defer func() {
+		if e := recover(); e != nil {
+			err = e.(error)
+		}
+	}()
+
+	if size > math.MaxInt32 {
+		panic(errors.New("truncate: illegal size"))
+	}
+
+	a.b = a.b[:int(size)]
+	return
+}
+
+func (a *memaccessor) WriteAt(b []byte, off int64) (n int, err error) {
+	if off < 0 || off > math.MaxInt32 {
+		return -1, errors.New("WriteAt: illegal offset")
+	}
+
+	rq, fp, size := len(b), int(off), len(a.b)
+	if need := rq + fp; need > size {
+		if need <= cap(a.b) {
+			a.b = a.b[:need]
+		} else {
+			nb := make([]byte, need, 2*need)
+			copy(nb, a.b)
+			a.b = nb
+		}
+	}
+
+	copy(a.b[int(off):], b)
+	return
+}