fix(drivers): stop the upload retry loop when the context is canceled (#2892)

The 115 and pikpak multipart uploaders checked for cancellation with a
`case <-ctx.Done()` inside a select, and a break there only leaves the
select, not the enclosing `for retry := 0; retry < 3; retry++` loop.
Cancelling an upload therefore ran all three attempts for every
remaining chunk, each allocating a chunk-sized buffer and reading it
off disk before firing a request that could not succeed, and reported
a transport error instead of the cancellation.

Move the check ahead of the select and use utils.IsCanceled, matching
the pattern the other drivers already use. Assigning ctx.Err() to err
is load-bearing: without it a cancelled chunk takes the success branch,
counts toward progress, and appends a zero-value UploadPart.

Found with staticcheck (SA4011).

Co-authored-by: Pikachu Ren <40362270+PIKACHUIM@users.noreply.github.com>

Author: beardthelion

drivers/115/util.go

@@ -337,9 +337,11 @@ func (d *Pan115) UploadByMultipart(ctx context.Context, params *driver115.Upload
 			for chunk := range chunksCh {
 				var part oss.UploadPart // 出现错误就继续尝试，共尝试3次
 				for retry := 0; retry < 3; retry++ {
-					select {
-					case <-ctx.Done():
+					if utils.IsCanceled(ctx) {
+						err = ctx.Err()
 						break
+					}
+					select {
 					case <-ticker.C:
 						if ossToken, err = d.client.GetOSSToken(); err != nil { // 到时重新获取ossToken
 							errCh <- errors.Wrap(err, "刷新token时出现错误")

drivers/pikpak/util.go

@@ -503,9 +503,11 @@ func (d *PikPak) UploadByMultipart(ctx context.Context, params *S3Params, fileSi
 			for chunk := range chunksCh {
 				var part oss.UploadPart // 出现错误就继续尝试，共尝试3次
 				for retry := 0; retry < 3; retry++ {
-					select {
-					case <-ctx.Done():
+					if utils.IsCanceled(ctx) {
+						err = ctx.Err()
 						break
+					}
+					select {
 					case <-ticker.C:
 						errCh <- errors.Wrap(err, "ossToken 过期")
 					default: