nstat: add json output format

New command line flag to output statistics in JSON format.
In our envrionment, we have scripts that parse output of commands.
It is better to use a format supported by existing parsers.

diff --git a/misc/nstat.c b/misc/nstat.c
index b68597870c1df75eda8484038fcf29a91cf9f2f2..5a4cfe94471bb271ebe3709e3c934141e3da748d 100644 (file)
--- a/misc/nstat.c
+++ b/misc/nstat.c
@@ -33,6 +33,7 @@ int dump_zeros = 0;
 int reset_history = 0;
 int ignore_history = 0;
 int no_output = 0;
+int json_output = 0;
 int no_update = 0;
 int scan_interval = 0;
 int time_constant = 0;
@@ -255,11 +256,17 @@ static void load_netstat(void)
        }
 }
 
+
 static void dump_kern_db(FILE *fp, int to_hist)
 {
        struct nstat_ent *n, *h;
+       const char *eol = "\n";
+
        h = hist_db;
-       fprintf(fp, "#%s\n", info_source);
+       if (json_output)
+               fprintf(fp, "{ \"%s\": [", info_source);
+       else
+               fprintf(fp, "#%s\n", info_source);
        for (n=kern_db; n; n=n->next) {
                unsigned long long val = n->val;
                if (!dump_zeros && !val && !n->rate)
@@ -276,15 +283,30 @@ static void dump_kern_db(FILE *fp, int to_hist)
                                }
                        }
                }
-               fprintf(fp, "%-32s%-16llu%6.1f\n", n->id, val, n->rate);
+
+               if (json_output) {
+                       fprintf(fp, "%s    { \"id\":\"%s\", \"val\":%llu,"
+                               " \"rate\":%.1f }",
+                               eol, n->id, val, n->rate);
+                       eol = ",\n";
+               } else
+                       fprintf(fp, "%-32s%-16llu%6.1f\n", n->id, val, n->rate);
        }
+       if (json_output)
+               fprintf(fp, "\n] }\n");
 }
 
 static void dump_incr_db(FILE *fp)
 {
        struct nstat_ent *n, *h;
+       const char *eol = "\n";
+
        h = hist_db;
-       fprintf(fp, "#%s\n", info_source);
+       if (json_output)
+               fprintf(fp, "{ \"%s\": [", info_source);
+       else
+               fprintf(fp, "#%s\n", info_source);
+
        for (n=kern_db; n; n=n->next) {
                int ovfl = 0;
                unsigned long long val = n->val;
@@ -304,9 +326,18 @@ static void dump_incr_db(FILE *fp)
                        continue;
                if (!match(n->id))
                        continue;
-               fprintf(fp, "%-32s%-16llu%6.1f%s\n", n->id, val,
-                       n->rate, ovfl?" (overflow)":"");
+
+               if (json_output) {
+                       fprintf(fp, "%s    { \"id\":\"%s\", \"val\":%llu,"
+                               " \"rate\":%.1f, \"overflow\":%d }",
+                               eol, n->id, val, n->rate, ovfl);
+                       eol = ",\n";
+               } else
+                       fprintf(fp, "%-32s%-16llu%6.1f%s\n", n->id, val,
+                               n->rate, ovfl?" (overflow)":"");
        }
+       if (json_output)
+               fprintf(fp, "\n] }\n");
 }
 
 static int children;
@@ -451,7 +482,7 @@ int main(int argc, char *argv[])
        int ch;
        int fd;
 
-       while ((ch = getopt(argc, argv, "h?vVzrnasd:t:")) != EOF) {
+       while ((ch = getopt(argc, argv, "h?vVzrnasd:t:j")) != EOF) {
                switch(ch) {
                case 'z':
                        dump_zeros = 1;
@@ -478,6 +509,9 @@ int main(int argc, char *argv[])
                                exit(-1);
                        }
                        break;
+               case 'j':
+                       json_output = 1;
+                       break;
                case 'v':
                case 'V':
                        printf("nstat utility, iproute2-ss%s\n", SNAPSHOT);