Adding capability to take max upload size per request.

src/main/java/org/apache/commons/fileupload/FileUploadBase.java

@@ -205,6 +205,16 @@ public long getSizeMax() {
         return sizeMax;
     }
 
+    /**
+     * Gets allowed max size for current upload, subclasses can override this method
+     * to calculate allowed size per request
+     * @param ctx requestContext - provides information related to current upload request.
+     * @return max size allowed for current request
+     */
+    public long getSizeMaxForThisRequest(RequestContext ctx) {
+        return sizeMax;
+    }
+
     /**
      * Sets the maximum allowed size of a complete request, as opposed
      * to {@link #setFileSizeMax(long)}.
@@ -969,15 +979,16 @@ public void setHeaders(FileItemHeaders pHeaders) {
                                      // CHECKSTYLE:ON
 
             InputStream input; // N.B. this is eventually closed in MultipartStream processing
-            if (sizeMax >= 0) {
-                if (requestSize != -1 && requestSize > sizeMax) {
+            long sizeMaxForThisRequest = getSizeMaxForThisRequest(ctx);
+            if (sizeMaxForThisRequest >= 0) {
+                if (requestSize != -1 && requestSize > sizeMaxForThisRequest) {
                     throw new SizeLimitExceededException(
                         format("the request was rejected because its size (%s) exceeds the configured maximum (%s)",
-                                Long.valueOf(requestSize), Long.valueOf(sizeMax)),
-                               requestSize, sizeMax);
+                                Long.valueOf(requestSize), Long.valueOf(sizeMaxForThisRequest)),
+                               requestSize, sizeMaxForThisRequest);
                 }
                 // N.B. this is eventually closed in MultipartStream processing
-                input = new LimitedInputStream(ctx.getInputStream(), sizeMax) {
+                input = new LimitedInputStream(ctx.getInputStream(), sizeMaxForThisRequest) {
                     @Override
                     protected void raiseError(long pSizeMax, long pCount)
                             throws IOException {

src/main/java/org/apache/commons/fileupload/servlet/ServletRequestContext.java

@@ -127,4 +127,13 @@ public String toString() {
                 this.getContentType());
     }
 
+    /**
+     * Gets underlying HttpServletRequest, this method can be used in subclasses of @{@link FileUploadBase}
+     * while adding support for max upload size per request.
+     * @return
+     */
+    public HttpServletRequest getRequest(){
+        return this.request;
+    }
+
 }