Add context propagation to rclone

- Change rclone/fs interfaces to accept context.Context
- Update interface implementations to use context.Context
- Change top level usage to propagate context to lover level functions

Context propagation is needed for stopping transfers and passing other
request-scoped values.

fs/fs.go

@@ -2,6 +2,7 @@
 package fs
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -245,11 +246,11 @@ type Fs interface {
 	//
 	// This should return ErrDirNotFound if the directory isn't
 	// found.
-	List(dir string) (entries DirEntries, err error)
+	List(ctx context.Context, dir string) (entries DirEntries, err error)
 
 	// NewObject finds the Object at remote.  If it can't be found
 	// it returns the error ErrorObjectNotFound.
-	NewObject(remote string) (Object, error)
+	NewObject(ctx context.Context, remote string) (Object, error)
 
 	// Put in to the remote path with the modTime given of the given size
 	//
@@ -260,17 +261,17 @@ type Fs interface {
 	// May create the object even if it returns an error - if so
 	// will return the object and the error, otherwise will return
 	// nil and the error
-	Put(in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
+	Put(ctx context.Context, in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
 
 	// Mkdir makes the directory (container, bucket)
 	//
 	// Shouldn't return an error if it already exists
-	Mkdir(dir string) error
+	Mkdir(ctx context.Context, dir string) error
 
 	// Rmdir removes the directory (container, bucket) if empty
 	//
 	// Return an error if it doesn't exist or isn't empty
-	Rmdir(dir string) error
+	Rmdir(ctx context.Context, dir string) error
 }
 
 // Info provides a read only interface to information about a filesystem.
@@ -299,20 +300,20 @@ type Object interface {
 	ObjectInfo
 
 	// SetModTime sets the metadata on the object to set the modification date
-	SetModTime(time.Time) error
+	SetModTime(ctx context.Context, t time.Time) error
 
 	// Open opens the file for read.  Call Close() on the returned io.ReadCloser
-	Open(options ...OpenOption) (io.ReadCloser, error)
+	Open(ctx context.Context, options ...OpenOption) (io.ReadCloser, error)
 
 	// Update in to the object with the modTime given of the given size
 	//
 	// When called from outside a Fs by rclone, src.Size() will always be >= 0.
 	// But for unknown-sized objects (indicated by src.Size() == -1), Upload should either
 	// return an error or update the object properly (rather than e.g. calling panic).
-	Update(in io.Reader, src ObjectInfo, options ...OpenOption) error
+	Update(ctx context.Context, in io.Reader, src ObjectInfo, options ...OpenOption) error
 
 	// Removes this object
-	Remove() error
+	Remove(ctx context.Context) error
 }
 
 // ObjectInfo provides read only information about an object.
@@ -324,7 +325,7 @@ type ObjectInfo interface {
 
 	// Hash returns the selected checksum of the file
 	// If no checksum is available it returns ""
-	Hash(hash.Type) (string, error)
+	Hash(ctx context.Context, ty hash.Type) (string, error)
 
 	// Storable says whether this object can be stored
 	Storable() bool
@@ -342,7 +343,7 @@ type DirEntry interface {
 
 	// ModTime returns the modification date of the file
 	// It should return a best guess if one isn't available
-	ModTime() time.Time
+	ModTime(context.Context) time.Time
 
 	// Size returns the size of the file
 	Size() int64
@@ -365,7 +366,7 @@ type Directory interface {
 type MimeTyper interface {
 	// MimeType returns the content type of the Object if
 	// known, or "" if not
-	MimeType() string
+	MimeType(ctx context.Context) string
 }
 
 // IDer is an optional interface for Object
@@ -430,7 +431,7 @@ func ObjectOptionalInterfaces(o Object) (supported, unsupported []string) {
 type ListRCallback func(entries DirEntries) error
 
 // ListRFn is defines the call used to recursively list a directory
-type ListRFn func(dir string, callback ListRCallback) error
+type ListRFn func(ctx context.Context, dir string, callback ListRCallback) error
 
 // NewUsageValue makes a valid value
 func NewUsageValue(value int64) *int64 {
@@ -476,7 +477,7 @@ type Features struct {
 	// quicker than just running Remove() on the result of List()
 	//
 	// Return an error if it doesn't exist
-	Purge func() error
+	Purge func(ctx context.Context) error
 
 	// Copy src to this remote using server side copy operations.
 	//
@@ -487,7 +488,7 @@ type Features struct {
 	// Will only be called if src.Fs().Name() == f.Name()
 	//
 	// If it isn't possible then return fs.ErrorCantCopy
-	Copy func(src Object, remote string) (Object, error)
+	Copy func(ctx context.Context, src Object, remote string) (Object, error)
 
 	// Move src to this remote using server side move operations.
 	//
@@ -498,7 +499,7 @@ type Features struct {
 	// Will only be called if src.Fs().Name() == f.Name()
 	//
 	// If it isn't possible then return fs.ErrorCantMove
-	Move func(src Object, remote string) (Object, error)
+	Move func(ctx context.Context, src Object, remote string) (Object, error)
 
 	// DirMove moves src, srcRemote to this remote at dstRemote
 	// using server side move operations.
@@ -508,12 +509,12 @@ type Features struct {
 	// If it isn't possible then return fs.ErrorCantDirMove
 	//
 	// If destination exists then return fs.ErrorDirExists
-	DirMove func(src Fs, srcRemote, dstRemote string) error
+	DirMove func(ctx context.Context, src Fs, srcRemote, dstRemote string) error
 
 	// ChangeNotify calls the passed function with a path
 	// that has had changes. If the implementation
 	// uses polling, it should adhere to the given interval.
-	ChangeNotify func(func(string, EntryType), <-chan time.Duration)
+	ChangeNotify func(context.Context, func(string, EntryType), <-chan time.Duration)
 
 	// UnWrap returns the Fs that this Fs is wrapping
 	UnWrap func() Fs
@@ -529,7 +530,7 @@ type Features struct {
 	DirCacheFlush func()
 
 	// PublicLink generates a public link to the remote path (usually readable by anyone)
-	PublicLink func(remote string) (string, error)
+	PublicLink func(ctx context.Context, remote string) (string, error)
 
 	// Put in to the remote path with the modTime given of the given size
 	//
@@ -539,24 +540,24 @@ type Features struct {
 	//
 	// May create duplicates or return errors if src already
 	// exists.
-	PutUnchecked func(in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
+	PutUnchecked func(ctx context.Context, in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
 
 	// PutStream uploads to the remote path with the modTime given of indeterminate size
 	//
 	// May create the object even if it returns an error - if so
 	// will return the object and the error, otherwise will return
 	// nil and the error
-	PutStream func(in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
+	PutStream func(ctx context.Context, in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
 
 	// MergeDirs merges the contents of all the directories passed
 	// in into the first one and rmdirs the other directories.
-	MergeDirs func([]Directory) error
+	MergeDirs func(ctx context.Context, dirs []Directory) error
 
 	// CleanUp the trash in the Fs
 	//
 	// Implement this if you have a way of emptying the trash or
 	// otherwise cleaning up old versions of files.
-	CleanUp func() error
+	CleanUp func(ctx context.Context) error
 
 	// ListR lists the objects and directories of the Fs starting
 	// from dir recursively into out.
@@ -577,14 +578,14 @@ type Features struct {
 	ListR ListRFn
 
 	// About gets quota information from the Fs
-	About func() (*Usage, error)
+	About func(ctx context.Context) (*Usage, error)
 
 	// OpenWriterAt opens with a handle for random access writes
 	//
 	// Pass in the remote desired and the size if known.
 	//
 	// It truncates any existing object
-	OpenWriterAt func(remote string, size int64) (WriterAtCloser, error)
+	OpenWriterAt func(ctx context.Context, remote string, size int64) (WriterAtCloser, error)
 }
 
 // Disable nil's out the named feature.  If it isn't found then it
@@ -803,7 +804,7 @@ type Purger interface {
 	// quicker than just running Remove() on the result of List()
 	//
 	// Return an error if it doesn't exist
-	Purge() error
+	Purge(ctx context.Context) error
 }
 
 // Copier is an optional interface for Fs
@@ -817,7 +818,7 @@ type Copier interface {
 	// Will only be called if src.Fs().Name() == f.Name()
 	//
 	// If it isn't possible then return fs.ErrorCantCopy
-	Copy(src Object, remote string) (Object, error)
+	Copy(ctx context.Context, src Object, remote string) (Object, error)
 }
 
 // Mover is an optional interface for Fs
@@ -831,7 +832,7 @@ type Mover interface {
 	// Will only be called if src.Fs().Name() == f.Name()
 	//
 	// If it isn't possible then return fs.ErrorCantMove
-	Move(src Object, remote string) (Object, error)
+	Move(ctx context.Context, src Object, remote string) (Object, error)
 }
 
 // DirMover is an optional interface for Fs
@@ -844,7 +845,7 @@ type DirMover interface {
 	// If it isn't possible then return fs.ErrorCantDirMove
 	//
 	// If destination exists then return fs.ErrorDirExists
-	DirMove(src Fs, srcRemote, dstRemote string) error
+	DirMove(ctx context.Context, src Fs, srcRemote, dstRemote string) error
 }
 
 // ChangeNotifier is an optional interface for Fs
@@ -858,7 +859,7 @@ type ChangeNotifier interface {
 	// The ChangeNotify implementation must empty the channel
 	// regularly. When the channel gets closed, the implementation
 	// should stop polling and release resources.
-	ChangeNotify(func(string, EntryType), <-chan time.Duration)
+	ChangeNotify(context.Context, func(string, EntryType), <-chan time.Duration)
 }
 
 // UnWrapper is an optional interfaces for Fs
@@ -892,7 +893,7 @@ type PutUncheckeder interface {
 	//
 	// May create duplicates or return errors if src already
 	// exists.
-	PutUnchecked(in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
+	PutUnchecked(ctx context.Context, in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
 }
 
 // PutStreamer is an optional interface for Fs
@@ -902,20 +903,20 @@ type PutStreamer interface {
 	// May create the object even if it returns an error - if so
 	// will return the object and the error, otherwise will return
 	// nil and the error
-	PutStream(in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
+	PutStream(ctx context.Context, in io.Reader, src ObjectInfo, options ...OpenOption) (Object, error)
 }
 
 // PublicLinker is an optional interface for Fs
 type PublicLinker interface {
 	// PublicLink generates a public link to the remote path (usually readable by anyone)
-	PublicLink(remote string) (string, error)
+	PublicLink(ctx context.Context, remote string) (string, error)
 }
 
 // MergeDirser is an option interface for Fs
 type MergeDirser interface {
 	// MergeDirs merges the contents of all the directories passed
 	// in into the first one and rmdirs the other directories.
-	MergeDirs([]Directory) error
+	MergeDirs(ctx context.Context, dirs []Directory) error
 }
 
 // CleanUpper is an optional interfaces for Fs
@@ -924,7 +925,7 @@ type CleanUpper interface {
 	//
 	// Implement this if you have a way of emptying the trash or
 	// otherwise cleaning up old versions of files.
-	CleanUp() error
+	CleanUp(ctx context.Context) error
 }
 
 // ListRer is an optional interfaces for Fs
@@ -945,7 +946,7 @@ type ListRer interface {
 	//
 	// Don't implement this unless you have a more efficient way
 	// of listing recursively that doing a directory traversal.
-	ListR(dir string, callback ListRCallback) error
+	ListR(ctx context.Context, dir string, callback ListRCallback) error
 }
 
 // RangeSeeker is the interface that wraps the RangeSeek method.
@@ -958,13 +959,13 @@ type RangeSeeker interface {
 	// limiting the total length to limit.
 	//
 	// RangeSeek with a limit of < 0 is equivalent to a regular Seek.
-	RangeSeek(offset int64, whence int, length int64) (int64, error)
+	RangeSeek(ctx context.Context, offset int64, whence int, length int64) (int64, error)
 }
 
 // Abouter is an optional interface for Fs
 type Abouter interface {
 	// About gets quota information from the Fs
-	About() (*Usage, error)
+	About(ctx context.Context) (*Usage, error)
 }
 
 // OpenWriterAter is an optional interface for Fs
@@ -974,7 +975,7 @@ type OpenWriterAter interface {
 	// Pass in the remote desired and the size if known.
 	//
 	// It truncates any existing object
-	OpenWriterAt(remote string, size int64) (WriterAtCloser, error)
+	OpenWriterAt(ctx context.Context, remote string, size int64) (WriterAtCloser, error)
 }
 
 // ObjectsChan is a channel of Objects
@@ -1195,8 +1196,8 @@ func CheckClose(c io.Closer, err *error) {
 
 // FileExists returns true if a file remote exists.
 // If remote is a directory, FileExists returns false.
-func FileExists(fs Fs, remote string) (bool, error) {
-	_, err := fs.NewObject(remote)
+func FileExists(ctx context.Context, fs Fs, remote string) (bool, error) {
+	_, err := fs.NewObject(ctx, remote)
 	if err != nil {
 		if err == ErrorObjectNotFound || err == ErrorNotAFile || err == ErrorPermissionDenied {
 			return false, nil