rclone/fs.go

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// File system interface
package main
import (
"io"
"time"
)
// A Filesystem, describes the local filesystem and the remote object store
type Fs interface {
List() FsObjectsChan
NewFsObject(remote string) FsObject
Put(src FsObject)
Mkdir() error
Rmdir() error
}
// FIXME make f.Debugf...
// A filesystem like object which can either be a remote object or a
// local file/directory
type FsObject interface {
Remote() string
Debugf(string, ...interface{})
Md5sum() (string, error)
ModTime() (time.Time, error)
SetModTime(time.Time)
Size() int64
Open() (io.ReadCloser, error)
Storable() bool
// Exists() bool
Remove() error
}
type FsObjectsChan chan FsObject
type FsObjects []FsObject
// NewFs makes a new Fs object from the path
//
// FIXME make more generic in future
func NewFs(path string) (Fs, error) {
if swiftMatch.MatchString(path) {
return NewFsSwift(path)
}
return NewFsLocal(path)
}
// checkClose is a utility function used to check the return from
// Close in a defer statement.
func checkClose(c io.Closer, err *error) {
cerr := c.Close()
if *err == nil {
*err = cerr
}
}
// Checks to see if the src and dst objects are equal by looking at
// size, mtime and MD5SUM
//
// If the src and dst size are different then it is considered to be
// not equal.
//
// If the size is the same and the mtime is the same then it is
// considered to be equal. This is the heuristic rsync uses when
// not using --checksum.
//
// If the size is the same and and mtime is different or unreadable
// and the MD5SUM is the same then the file is considered to be equal.
// In this case the mtime on the dst is updated.
//
// Otherwise the file is considered to be not equal including if there
// were errors reading info.
func Equal(src, dst FsObject) bool {
if src.Size() != dst.Size() {
src.Debugf("Sizes differ")
return false
}
// Size the same so check the mtime
srcModTime, err := src.ModTime()
if err != nil {
src.Debugf("Failed to read src mtime: %s", err)
} else {
dstModTime, err := dst.ModTime()
if err != nil {
dst.Debugf("Failed to read dst mtime: %s", err)
} else if !dstModTime.Equal(srcModTime) {
src.Debugf("Modification times differ")
} else {
src.Debugf("Size and modification time the same")
return true
}
}
// mtime is unreadable or different but size is the same so
// check the MD5SUM
srcMd5, err := src.Md5sum()
if err != nil {
src.Debugf("Failed to calculate src md5: %s", err)
return false
}
dstMd5, err := dst.Md5sum()
if err != nil {
dst.Debugf("Failed to calculate dst md5: %s", err)
return false
}
// fs.Debugf("Src MD5 %s", srcMd5)
// fs.Debugf("Dst MD5 %s", obj.Hash)
if srcMd5 != dstMd5 {
src.Debugf("Md5sums differ")
return false
}
// Size and MD5 the same but mtime different so update the
// mtime of the dst object here
dst.SetModTime(srcModTime)
src.Debugf("Size and MD5SUM of src and dst objects identical")
return true
}