--- src/rrd_tool.c.orig	2012-01-24 08:08:48.000000000 -0200
+++ src/rrd_tool.c	2012-05-11 15:57:51.000000000 -0300
@@ -57,7 +57,7 @@
         N_
         ("Valid commands: create, update, updatev, graph, graphv,  dump, restore,\n"
          "\t\tlast, lastupdate, first, info, fetch, tune,\n"
-         "\t\tresize, xport, flushcached\n");
+         "\t\tresize, xport, json, flushcached\n");
 
     const char *help_listremote =
         N_("Valid remote commands: quit, ls, cd, mkdir, pwd\n");
@@ -210,6 +210,13 @@
            "\t\t[--enumds] [--json]\n" "\t\t[DEF:vname=rrd:ds-name:CF]\n"
            "\t\t[CDEF:vname=rpn-expression]\n"
            "\t\t[XPORT:vname:legend]\n");
+    const char *help_json =
+        N_("* json - generate JSON dump from one or several RRD\n\n"
+           "\trrdtool json [-s|--start seconds] [-e|--end seconds]\n"
+           "\t\t[-m|--maxrows rows]\n" "\t\t[--step seconds]\n"
+           "\t\t[DEF:vname=rrd:ds-name:CF]\n"
+           "\t\t[CDEF:vname=rpn-expression]\n"
+           "\t\t[XPORT:vname:legend]\n");
     const char *help_quit =
         N_(" * quit - closing a session in remote mode\n\n"
            "\trrdtool quit\n");
@@ -232,7 +239,7 @@
     enum { C_NONE, C_CREATE, C_DUMP, C_INFO, C_RESTORE, C_LAST,
         C_LASTUPDATE, C_FIRST, C_UPDATE, C_FETCH, C_GRAPH, C_GRAPHV,
         C_TUNE,
-        C_RESIZE, C_XPORT, C_QUIT, C_LS, C_CD, C_MKDIR, C_PWD,
+        C_RESIZE, C_XPORT, C_JSON, C_QUIT, C_LS, C_CD, C_MKDIR, C_PWD,
         C_UPDATEV, C_FLUSHCACHED
     };
     int       help_cmd = C_NONE;
@@ -270,6 +277,8 @@
             help_cmd = C_RESIZE;
         else if (!strcmp(cmd, "xport"))
             help_cmd = C_XPORT;
+        else if (!strcmp(cmd, "json"))
+            help_cmd = C_JSON;
         else if (!strcmp(cmd, "quit"))
             help_cmd = C_QUIT;
         else if (!strcmp(cmd, "ls"))
@@ -345,6 +354,9 @@
     case C_XPORT:
         puts(_(help_xport));
         break;
+    case C_JSON:
+        puts(_(help_json));
+        break;
     case C_QUIT:
         puts(_(help_quit));
         break;
@@ -844,6 +856,58 @@
             setlocale(LC_NUMERIC, old_locale);
         }
         free(vtag);
+    } else if (strcmp("json", argv[1]) == 0) {
+        int       xxsize;
+        unsigned long int j = 0;
+        time_t    start, end, ti;
+        unsigned long step, col_cnt;
+        rrd_value_t *data, *ptr;
+        char    **legend_v;
+        int       i;
+
+        if (rrd_xport
+            (argc - 1, &argv[1], &xxsize, &start, &end, &step, &col_cnt,
+             &legend_v, &data) != -1) {
+            char *old_locale = setlocale(LC_NUMERIC, "C");
+            printf("[\n");
+            for (j = 0; j < col_cnt; j++) {
+                char     *entry = NULL;
+                ptr = j + data;
+                entry = legend_v[j];
+
+                printf("\t{\n\t\t\"%s\": {\n", entry);
+                free(entry);
+                printf("\t\t\t\"%s\": %lld,\n", META_START_TAG,
+                      (long long int) start + step);
+                printf("\t\t\t\"%s\": %lu,\n", META_STEP_TAG, step);
+                printf("\t\t\t\"%s\": %lld,\n", META_END_TAG, (long long int) end);
+                printf("\t\t\t\"data_points\": [\n");
+
+                for (ti = start + step; ti <= end; ti += step) {
+                  rrd_value_t newval = DNAN;
+                    newval = *ptr;
+                    if (isnan(newval)) {
+                        printf("null");
+                    } else {
+                        printf("%0.5f", newval);
+                    };
+                    if (ti < end) {
+                      printf(", ");
+                    }
+                    ptr+=col_cnt;
+                }
+
+                printf("\n\t\t\t]\n");
+                printf("\t\t}\n");
+
+                printf("\t}%s\n", (j<col_cnt-1) ? "," : "");
+            }
+            free(legend_v);
+
+            free(data);
+            printf("]\n");
+            setlocale(LC_NUMERIC, old_locale);
+        }
 #else
         rrd_set_error("the instance of rrdtool has been compiled without graphics");
 #endif