[GitHub] [nifi-minifi-cpp] phrocker commented on a change in pull request #499: MINIFICPP-748 - Nanofi: add custom C processor example

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phrocker commented on a change in pull request #499: MINIFICPP-748 - Nanofi: add custom C processor example
URL: https://github.com/apache/nifi-minifi-cpp/pull/499#discussion_r263540080
 
 

 ##########
 File path: nanofi/examples/hash_file.c
 ##########
 @@ -0,0 +1,121 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+    *
+    *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+*/
+
+#ifdef OPENSSL_SUPPORT
+
+#include "api/nanofi.h"
+#include <openssl/md5.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+
+void custom_processor_logic(processor_session * ps, processor_context * ctx) {
+  flow_file_record * ffr = get(ps, ctx);
+  if(ffr == NULL) {
+    return;
+  }
+  uint8_t * buffer = (uint8_t*)malloc(ffr->size* sizeof(uint8_t));
+
+  get_content(ffr, buffer, ffr->size);
+
+
+  MD5_CTX context;
+  MD5_Init(&context);
+  MD5_Update(&context, buffer, ffr->size);
+
+  free(buffer);
+
+  unsigned char digest[MD5_DIGEST_LENGTH];
+  MD5_Final(digest, &context);
+
+  char md5string[33];
+  for(int i = 0; i < 16; ++i) {
+    sprintf(&md5string[i*2], "%02x", (unsigned int)digest[i]);
+  }
+
+  char prop_value[50];
+
+  if(get_property(ctx, "checksum_attr_name", prop_value, 50) != 0) {
+    return; // Attr name not found
+  }
+
+  add_attribute(ffr, prop_value, (void*)md5string, strlen(md5string));
+
+  transfer_to_relationship(ffr, ps, SUCCESS_RELATIONSHIP);
+
+  free_flowfile(ffr);
+}
+
+int main(int argc, char **argv) {
+
+  if (argc < 2) {
+    printf("Error: must run ./hash_file <file>\n");
+    exit(1);
+  }
+
+  char *file = argv[1];
+
+  if(access( file, F_OK ) == -1) {
+    printf("Error: %s doesn't exist!\n", file);
+    exit(1);
+  }
+
+  struct stat stats;
+  stat(file, &stats);
+
+  // Check for file existence
+  if (S_ISDIR(stats.st_mode)){
+    printf("Error: %s is a directory!\n", file);
+    exit(1);
+  }
+
+  add_custom_processor("md5proc", custom_processor_logic);
+
+  standalone_processor *standalone_proc = create_processor("md5proc");
+
+  const char * checksum_attr_name = "md5attr";
+
+  set_standalone_property(standalone_proc, "checksum_attr_name", checksum_attr_name);
+
+
+  flow_file_record * ffr = create_flowfile(file, strlen(file));
+
+  flow_file_record * new_ff = invoke_ff(standalone_proc, ffr);
+
+  free_flowfile(ffr);
+
+  attribute attr;
+  attr.key = checksum_attr_name;
+  attr.value_size = 0;
+  get_attribute(new_ff, &attr);
+
+  char md5value[50];
+
+  snprintf(md5value, attr.value_size, "%s", (const char*)attr.value+1);
 
 Review comment:
   Totally agree -- and no objection from my side since it's an internal struct and assignment likely wouldn't cause any impact to currently existing code. 
   
   You're right though, I do think there may be a JIRA for it.

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