operations: copy: generate stable partial suffix

docs/content/docs.md

@@ -1347,11 +1347,12 @@ flag set) such as:
 - local
 - ftp
 - sftp
+- pcloud
 
 Without `--inplace` (the default) rclone will first upload to a
 temporary file with an extension like this, where `XXXXXX` represents a
-random string and `.partial` is [--partial-suffix](#partial-suffix) value
-(`.partial` by default).
+hash of the source file's fingerprint and `.partial` is 
+[--partial-suffix](#partial-suffix) value (`.partial` by default).
 
     original-file-name.XXXXXX.partial
 

fs/operations/copy.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"hash/crc32"
 	"io"
 	"path"
 	"strings"
@@ -20,7 +21,6 @@ import (
 	"github.com/rclone/rclone/fs/hash"
 	"github.com/rclone/rclone/lib/atexit"
 	"github.com/rclone/rclone/lib/pacer"
-	"github.com/rclone/rclone/lib/random"
 )
 
 // State of the copy
@@ -87,7 +87,7 @@ func TruncateString(s string, n int) string {
 }
 
 // Check to see if we should be using a partial name and return the name for the copy and the inplace flag
-func (c *copy) checkPartial() (remoteForCopy string, inplace bool, err error) {
+func (c *copy) checkPartial(ctx context.Context) (remoteForCopy string, inplace bool, err error) {
 	remoteForCopy = c.remote
 	if c.ci.Inplace || c.dstFeatures.Move == nil || !c.dstFeatures.PartialUploads || strings.HasSuffix(c.remote, ".rclonelink") {
 		return remoteForCopy, true, nil
@@ -97,7 +97,11 @@ func (c *copy) checkPartial() (remoteForCopy string, inplace bool, err error) {
 	}
 	// Avoid making the leaf name longer if it's already lengthy to avoid
 	// trouble with file name length limits.
-	suffix := "." + random.String(8) + c.ci.PartialSuffix
+
+	// generate a stable random suffix by hashing the fingerprint
+	hash := crc32.ChecksumIEEE([]byte(fs.Fingerprint(ctx, c.src, true)))
+
+	suffix := fmt.Sprintf(".%x%s", hash, c.ci.PartialSuffix)
 	base := path.Base(remoteForCopy)
 	if len(base) > 100 {
 		remoteForCopy = TruncateString(remoteForCopy, len(remoteForCopy)-len(suffix)) + suffix
@@ -400,7 +404,7 @@ func Copy(ctx context.Context, f fs.Fs, dst fs.Object, remote string, src fs.Obj
 	// Are we using partials?
 	//
 	// If so set the flag and update the name we use for the copy
-	c.remoteForCopy, c.inplace, err = c.checkPartial()
+	c.remoteForCopy, c.inplace, err = c.checkPartial(ctx)
 	if err != nil {
 		return nil, err
 	}