support if-match/if-none-match with s3 uploads (#16551)

cmd/object-handlers-common.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2015-2021 MinIO, Inc.
+// Copyright (c) 2015-2023 MinIO, Inc.
 //
 // This file is part of MinIO Object Storage stack
 //
@@ -165,6 +165,30 @@ func checkPreconditionsPUT(ctx context.Context, w http.ResponseWriter, r *http.R
 		}
 	}
 
+	// If-Match : Return the object only if its entity tag (ETag) is the same as the one specified;
+	// otherwise return a 412 (precondition failed).
+	ifMatchETagHeader := r.Header.Get(xhttp.IfMatch)
+	if ifMatchETagHeader != "" {
+		if !isETagEqual(objInfo.ETag, ifMatchETagHeader) {
+			// If the object ETag does not match with the specified ETag.
+			writeHeaders()
+			writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrPreconditionFailed), r.URL)
+			return true
+		}
+	}
+
+	// If-None-Match : Return the object only if its entity tag (ETag) is different from the
+	// one specified otherwise, return a 304 (not modified).
+	ifNoneMatchETagHeader := r.Header.Get(xhttp.IfNoneMatch)
+	if ifNoneMatchETagHeader != "" {
+		if isETagEqual(objInfo.ETag, ifNoneMatchETagHeader) {
+			// If the object ETag matches with the specified ETag.
+			writeHeaders()
+			w.WriteHeader(http.StatusNotModified)
+			return true
+		}
+	}
+
 	etagMatch := opts.PreserveETag != "" && isETagEqual(objInfo.ETag, opts.PreserveETag)
 	vidMatch := opts.VersionID != "" && opts.VersionID == objInfo.VersionID
 	mtimeMatch := !opts.MTime.IsZero() && objInfo.ModTime.Unix() >= opts.MTime.Unix()

cmd/object-handlers.go

@@ -1769,7 +1769,9 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	}
 	opts.IndexCB = idxCb
 
-	if !opts.MTime.IsZero() && opts.PreserveETag != "" {
+	if (!opts.MTime.IsZero() && opts.PreserveETag != "") ||
+		r.Header.Get(xhttp.IfMatch) != "" ||
+		r.Header.Get(xhttp.IfNoneMatch) != "" {
 		opts.CheckPrecondFn = func(oi ObjectInfo) bool {
 			if _, err := DecryptObjectInfo(&oi, r); err != nil {
 				writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)