From 47e4bd92b864f8f92d14710f0ff01a3e35568e85 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Mon, 10 Jul 2023 19:59:24 -0700
Subject: [PATCH] return context error if the context was canceled mid-way
 (#1852)

fixes #1850
---
 api-list.go            | 53 ++++++++++++++++++++++++++++++++++++++----
 api-put-object_test.go |  3 ---
 functional_tests.go    | 12 ++++++----
 3 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/api-list.go b/api-list.go
index cd2355ca3..3b50f61d3 100644
--- a/api-list.go
+++ b/api-list.go
@@ -97,7 +97,15 @@ func (c *Client) listObjectsV2(ctx context.Context, bucketName string, opts List
 
 	// Initiate list objects goroutine here.
 	go func(objectStatCh chan<- ObjectInfo) {
-		defer close(objectStatCh)
+		defer func() {
+			if contextCanceled(ctx) {
+				objectStatCh <- ObjectInfo{
+					Err: ctx.Err(),
+				}
+			}
+			close(objectStatCh)
+		}()
+
 		// Save continuationToken for next request.
 		var continuationToken string
 		for {
@@ -304,7 +312,14 @@ func (c *Client) listObjects(ctx context.Context, bucketName string, opts ListOb
 
 	// Initiate list objects goroutine here.
 	go func(objectStatCh chan<- ObjectInfo) {
-		defer close(objectStatCh)
+		defer func() {
+			if contextCanceled(ctx) {
+				objectStatCh <- ObjectInfo{
+					Err: ctx.Err(),
+				}
+			}
+			close(objectStatCh)
+		}()
 
 		marker := opts.StartAfter
 		for {
@@ -321,6 +336,7 @@ func (c *Client) listObjects(ctx context.Context, bucketName string, opts ListOb
 			for _, object := range result.Contents {
 				// Save the marker.
 				marker = object.Key
+				object.ETag = trimEtag(object.ETag)
 				select {
 				// Send object content.
 				case objectStatCh <- object:
@@ -393,7 +409,14 @@ func (c *Client) listObjectVersions(ctx context.Context, bucketName string, opts
 
 	// Initiate list objects goroutine here.
 	go func(resultCh chan<- ObjectInfo) {
-		defer close(resultCh)
+		defer func() {
+			if contextCanceled(ctx) {
+				resultCh <- ObjectInfo{
+					Err: ctx.Err(),
+				}
+			}
+			close(resultCh)
+		}()
 
 		var (
 			keyMarker       = ""
@@ -699,6 +722,10 @@ func (o *ListObjectsOptions) Set(key, value string) {
 //	for object := range api.ListObjects(ctx, "mytestbucket", minio.ListObjectsOptions{Prefix: "starthere", Recursive:true}) {
 //	    fmt.Println(object)
 //	}
+//
+// If caller cancels the context, then the last entry on the 'chan ObjectInfo' will be the context.Error()
+// caller must drain the channel entirely and wait until channel is closed before proceeding, without
+// waiting on the channel to be closed completely you might leak goroutines.
 func (c *Client) ListObjects(ctx context.Context, bucketName string, opts ListObjectsOptions) <-chan ObjectInfo {
 	if opts.WithVersions {
 		return c.listObjectVersions(ctx, bucketName, opts)
@@ -739,6 +766,16 @@ func (c *Client) ListIncompleteUploads(ctx context.Context, bucketName, objectPr
 	return c.listIncompleteUploads(ctx, bucketName, objectPrefix, recursive)
 }
 
+// contextCanceled returns whether a context is canceled.
+func contextCanceled(ctx context.Context) bool {
+	select {
+	case <-ctx.Done():
+		return true
+	default:
+		return false
+	}
+}
+
 // listIncompleteUploads lists all incomplete uploads.
 func (c *Client) listIncompleteUploads(ctx context.Context, bucketName, objectPrefix string, recursive bool) <-chan ObjectMultipartInfo {
 	// Allocate channel for multipart uploads.
@@ -766,7 +803,15 @@ func (c *Client) listIncompleteUploads(ctx context.Context, bucketName, objectPr
 		return objectMultipartStatCh
 	}
 	go func(objectMultipartStatCh chan<- ObjectMultipartInfo) {
-		defer close(objectMultipartStatCh)
+		defer func() {
+			if contextCanceled(ctx) {
+				objectMultipartStatCh <- ObjectMultipartInfo{
+					Err: ctx.Err(),
+				}
+			}
+			close(objectMultipartStatCh)
+		}()
+
 		// object and upload ID marker for future requests.
 		var objectMarker string
 		var uploadIDMarker string
diff --git a/api-put-object_test.go b/api-put-object_test.go
index ca35b12ed..dde4777ee 100644
--- a/api-put-object_test.go
+++ b/api-put-object_test.go
@@ -82,7 +82,6 @@ func Test_SSEHeaders(t *testing.T) {
 	c, err := New("s3.amazonaws.com", &Options{
 		Transport: rt,
 	})
-
 	if err != nil {
 		t.Error(err)
 	}
@@ -147,7 +146,6 @@ func Test_SSEHeaders(t *testing.T) {
 				uploadID:   "upId",
 				sse:        opts.ServerSideEncryption,
 			})
-
 			if err != nil {
 				t.Error(err)
 			}
@@ -167,5 +165,4 @@ func Test_SSEHeaders(t *testing.T) {
 			}
 		})
 	}
-
 }
diff --git a/functional_tests.go b/functional_tests.go
index 2bc6b8645..3c83d6f64 100644
--- a/functional_tests.go
+++ b/functional_tests.go
@@ -2471,7 +2471,8 @@ func testTrailingChecksums() {
 		PO             minio.PutObjectOptions
 	}{
 		// Currently there is no way to override the checksum type.
-		{header: "x-amz-checksum-crc32c",
+		{
+			header:         "x-amz-checksum-crc32c",
 			hasher:         crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 			ChecksumCRC32C: "set",
 			PO: minio.PutObjectOptions{
@@ -2481,7 +2482,8 @@ func testTrailingChecksums() {
 				PartSize:             5 << 20,
 			},
 		},
-		{header: "x-amz-checksum-crc32c",
+		{
+			header:         "x-amz-checksum-crc32c",
 			hasher:         crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 			ChecksumCRC32C: "set",
 			PO: minio.PutObjectOptions{
@@ -2491,7 +2493,8 @@ func testTrailingChecksums() {
 				PartSize:             6_645_654, // Rather arbitrary size
 			},
 		},
-		{header: "x-amz-checksum-crc32c",
+		{
+			header:         "x-amz-checksum-crc32c",
 			hasher:         crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 			ChecksumCRC32C: "set",
 			PO: minio.PutObjectOptions{
@@ -2501,7 +2504,8 @@ func testTrailingChecksums() {
 				PartSize:             5 << 20,
 			},
 		},
-		{header: "x-amz-checksum-crc32c",
+		{
+			header:         "x-amz-checksum-crc32c",
 			hasher:         crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 			ChecksumCRC32C: "set",
 			PO: minio.PutObjectOptions{