From 07c3a429bfed433e49018cb0f78a52145d4bedeb Mon Sep 17 00:00:00 2001
From: M Alvee <alvee.developer@gmail.com>
Date: Sun, 7 Sep 2025 09:13:09 -0700
Subject: [PATCH] fix: conditional checks write for multipart (#21567)

---
 cmd/erasure-multipart.go         | 12 ++++++++++++
 cmd/erasure-object.go            |  5 +++--
 cmd/object-api-interface.go      |  1 +
 cmd/object-handlers.go           |  3 +++
 cmd/object-multipart-handlers.go |  6 ++++++
 5 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/cmd/erasure-multipart.go b/cmd/erasure-multipart.go
index 0a2f527b7..f748f1f3e 100644
--- a/cmd/erasure-multipart.go
+++ b/cmd/erasure-multipart.go
@@ -393,6 +393,12 @@ func (er erasureObjects) newMultipartUpload(ctx context.Context, bucket string,
 		if err != nil && !isErrVersionNotFound(err) && !isErrObjectNotFound(err) && !isErrReadQuorum(err) {
 			return nil, err
 		}
+
+		// if object doesn't exist and not a replication request return error for If-Match conditional requests
+		// If-None-Match should be allowed to proceed for non-existent objects
+		if err != nil && !opts.ReplicationRequest && opts.HasIfMatch && (isErrObjectNotFound(err) || isErrVersionNotFound(err)) {
+			return nil, err
+		}
 	}
 
 	userDefined := cloneMSS(opts.UserDefined)
@@ -1111,6 +1117,12 @@ func (er erasureObjects) CompleteMultipartUpload(ctx context.Context, bucket str
 		if err != nil && !isErrVersionNotFound(err) && !isErrObjectNotFound(err) && !isErrReadQuorum(err) {
 			return ObjectInfo{}, err
 		}
+
+		// if object doesn't exist and not a replication request return error for If-Match conditional requests
+		// If-None-Match should be allowed to proceed for non-existent objects
+		if err != nil && !opts.ReplicationRequest && opts.HasIfMatch && (isErrObjectNotFound(err) || isErrVersionNotFound(err)) {
+			return ObjectInfo{}, err
+		}
 	}
 
 	fi, partsMetadata, err := er.checkUploadIDExists(ctx, bucket, object, uploadID, true)
diff --git a/cmd/erasure-object.go b/cmd/erasure-object.go
index 6f603564c..26ca3022b 100644
--- a/cmd/erasure-object.go
+++ b/cmd/erasure-object.go
@@ -1278,8 +1278,9 @@ func (er erasureObjects) putObject(ctx context.Context, bucket string, object st
 			return objInfo, err
 		}
 
-		// if object doesn't exist and not a replication request return error for conditional requests
-		if err != nil && !opts.ReplicationRequest {
+		// if object doesn't exist and not a replication request return error for If-Match conditional requests
+		// If-None-Match should be allowed to proceed for non-existent objects
+		if err != nil && !opts.ReplicationRequest && opts.HasIfMatch && (isErrObjectNotFound(err) || isErrVersionNotFound(err)) {
 			return objInfo, err
 		}
 	}
diff --git a/cmd/object-api-interface.go b/cmd/object-api-interface.go
index 501fa3a94..603cc38f2 100644
--- a/cmd/object-api-interface.go
+++ b/cmd/object-api-interface.go
@@ -91,6 +91,7 @@ type ObjectOptions struct {
 	NoDecryption                        bool      // indicates if the stream must be decrypted.
 	PreserveETag                        string    // preserves this etag during a PUT call.
 	NoLock                              bool      // indicates to lower layers if the caller is expecting to hold locks.
+	HasIfMatch                          bool      // indicates if the request has If-Match header
 	ProxyRequest                        bool      // only set for GET/HEAD in active-active replication scenario
 	ProxyHeaderSet                      bool      // only set for GET/HEAD in active-active replication scenario
 	ReplicationRequest                  bool      // true only if replication request
diff --git a/cmd/object-handlers.go b/cmd/object-handlers.go
index 7879300be..9663e99b4 100644
--- a/cmd/object-handlers.go
+++ b/cmd/object-handlers.go
@@ -2014,6 +2014,9 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	pReader := NewPutObjReader(rawReader)
 	opts.IndexCB = idxCb
 
+	if r.Header.Get(xhttp.IfMatch) != "" {
+		opts.HasIfMatch = true
+	}
 	if opts.PreserveETag != "" ||
 		r.Header.Get(xhttp.IfMatch) != "" ||
 		r.Header.Get(xhttp.IfNoneMatch) != "" {
diff --git a/cmd/object-multipart-handlers.go b/cmd/object-multipart-handlers.go
index c7edaf76f..12a99b312 100644
--- a/cmd/object-multipart-handlers.go
+++ b/cmd/object-multipart-handlers.go
@@ -200,6 +200,9 @@ func (api objectAPIHandlers) NewMultipartUploadHandler(w http.ResponseWriter, r
 		return
 	}
 
+	if r.Header.Get(xhttp.IfMatch) != "" {
+		opts.HasIfMatch = true
+	}
 	if opts.PreserveETag != "" ||
 		r.Header.Get(xhttp.IfMatch) != "" ||
 		r.Header.Get(xhttp.IfNoneMatch) != "" {
@@ -1014,6 +1017,9 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 	multipartETag := etag.Multipart(completeETags...)
 	opts.UserDefined["etag"] = multipartETag.String()
 
+	if r.Header.Get(xhttp.IfMatch) != "" {
+		opts.HasIfMatch = true
+	}
 	if opts.PreserveETag != "" ||
 		r.Header.Get(xhttp.IfMatch) != "" ||
 		r.Header.Get(xhttp.IfNoneMatch) != "" {