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//
// Copyright (c) SAS Institute Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package comdoc
import (
"bytes"
"encoding/binary"
"errors"
"strings"
)
// Add or replace a named stream with the given contents. Only streams within
// the root storage are currently supported.
func (r *ComDoc) AddFile(name string, contents []byte) error {
if r.writer == nil {
return errors.New("file is not open for writing")
}
if err := r.DeleteFile(name); err != nil {
return err
}
// store contents
isShort := len(contents) < int(r.Header.MinStdStreamSize)
nextSector, err := r.addStream(contents, isShort)
if err != nil {
return err
}
// create new dirent
dirent, err := r.newDirEnt(name, uint32(len(contents)), nextSector)
if err != nil {
return err
}
r.rootFiles = append(r.rootFiles, dirent.Index)
r.changed = true
return nil
}
// Delete a file from the root storage if it exists
func (r *ComDoc) DeleteFile(name string) error {
keepFiles := make([]int, 0, len(r.rootFiles))
for _, index := range r.rootFiles {
item := &r.Files[index]
if !strings.EqualFold(item.name, name) {
keepFiles = append(keepFiles, index)
continue
}
if item.Type != DirStream {
return errors.New("can't delete or replace storages")
}
// free storage
if item.StreamSize < r.Header.MinStdStreamSize {
freeSectors(r.SSAT, item.NextSector)
} else {
freeSectors(r.SAT, item.NextSector)
}
// blank out the dirent
*item = DirEnt{}
r.changed = true
}
r.rootFiles = keepFiles
return nil
}
// Close the CDF and, if open for writing, commit the remainder of structures
// to disk.
func (r *ComDoc) Close() error {
if !r.changed {
if r.closer != nil {
r.closer.Close()
r.closer = nil
}
return nil
}
if err := r.writeShortSAT(); err != nil {
return err
}
if err := r.writeDirStream(); err != nil {
return err
}
// Write MSAT and SAT
r.allocSectorTables()
if err := r.writeSAT(); err != nil {
return err
}
if err := r.writeMSAT(); err != nil {
return err
}
// Write file header
copy(r.Header.Magic[:], fileMagic)
r.Header.ByteOrder = byteOrderMarker
r.Header.SATSectors = uint32(len(r.MSAT))
r.Header.MSATSectorCount = uint32(len(r.msatList))
buf := bytes.NewBuffer(make([]byte, 0, 512))
_ = binary.Write(buf, binary.LittleEndian, r.Header)
if _, err := r.writer.WriteAt(buf.Bytes(), 0); err != nil {
return err
}
// Truncate past last sector. Trailing garbage will cause validation to fail.
for i := len(r.SAT) - 1; i >= 0; i-- {
if r.SAT[i] != SecIDFree {
if err := r.writer.Truncate(r.sectorToOffset(SecID(i + 1))); err != nil {
return err
}
break
}
}
if r.closer != nil {
r.closer.Close()
r.closer = nil
}
return nil
}
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