Added -O option: print offsets

kafkacat.c

@@ -52,6 +52,7 @@ static struct conf {
         char    mode;
 	int     flags;
 #define CONF_F_KEY_DELIM  0x2
+#define CONF_F_OFFSET     0x4 /* Print offsets */
         int     delim;
 	int     key_delim;
         int     msg_size;
@@ -76,6 +77,7 @@ static struct conf {
         .partition = RD_KAFKA_PARTITION_UA,
         .msg_size = 1024*1024,
         .delim = '\n',
+	.key_delim = '\t',
 };
 
 
@@ -195,7 +197,8 @@ static ssize_t produce_file (const char *path) {
                 return -1;
         }
 
-        INFO(4, "Producing file %s (%"PRIdMAX" bytes)\n", path, (intmax_t)st.st_size);
+        INFO(4, "Producing file %s (%"PRIdMAX" bytes)\n",
+	     path, (intmax_t)st.st_size);
         produce(ptr, st.st_size, NULL, 0, RD_KAFKA_MSG_F_COPY);
 
         munmap(ptr, st.st_size);
@@ -363,6 +366,10 @@ static void consume_cb (rd_kafka_message_t *rkmessage, void *opaque) {
                       rd_kafka_message_errstr(rkmessage));
         }
 
+	/* Print offset (using key delim), if desired */
+	if (conf.flags & CONF_F_OFFSET)
+		fprintf(fp, "%"PRId64"%c", rkmessage->offset, conf.key_delim);
+
 	/* Print key, if desired */
 	if (conf.flags & CONF_F_KEY_DELIM)
 		fprintf(fp, "%.*s%c",
@@ -669,6 +676,7 @@ static void __attribute__((noreturn)) usage (const char *argv0, int exitcode,
                "  -D <delim>         Delimiter to separate messages on output\n"
 	       "  -K <delim>         Print message keys prefixing the message\n"
 	       "                     with specified delimiter.\n"
+	       "  -O                 Print message offset using -K delimiter\n"
                "  -c <cnt>           Exit after consuming this number "
                "of messages\n"
                "  -u                 Unbuffered output\n"
@@ -727,7 +735,7 @@ static void argparse (int argc, char **argv) {
         int opt;
 
 	while ((opt = getopt(argc, argv,
-			     "PCLt:p:b:z:o:eD:K:d:qvX:c:u")) != -1) {
+			     "PCLt:p:b:z:o:eD:K:Od:qvX:c:u")) != -1) {
 		switch (opt) {
 		case 'P':
 		case 'C':
@@ -773,6 +781,9 @@ static void argparse (int argc, char **argv) {
 			conf.key_delim = parse_delim(optarg);
 			conf.flags |= CONF_F_KEY_DELIM;
 			break;
+		case 'O':
+			conf.flags |= CONF_F_OFFSET;
+			break;
                 case 'c':
                         conf.msg_cnt = strtoll(optarg, NULL, 10);
                         break;