tools: bpftool: introduce --json and --pretty options

These two options can be used to ask for a JSON output (--j or -json),
and to make this JSON human-readable (-p or --pretty).

A json_writer object is created when JSON is required, and will be used
in follow-up commits to produce JSON output.

Note that --pretty implies --json.

Update for the manual pages and interactive help messages comes in a
later patch of the series.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 613e3c7..14bfc17 100644 (file)
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -51,6 +51,9 @@ const char *bin_name;
 static int last_argc;
 static char **last_argv;
 static int (*last_do_help)(int argc, char **argv);
+json_writer_t *json_wtr;
+bool pretty_output;
+bool json_output;
 
 void usage(void)
 {
@@ -217,22 +220,32 @@ err_close:
 int main(int argc, char **argv)
 {
        static const struct option options[] = {
+               { "json",       no_argument,    NULL,   'j' },
                { "help",       no_argument,    NULL,   'h' },
+               { "pretty",     no_argument,    NULL,   'p' },
                { "version",    no_argument,    NULL,   'V' },
                { 0 }
        };
-       int opt;
+       int opt, ret;
 
        last_do_help = do_help;
+       pretty_output = false;
+       json_output = false;
        bin_name = argv[0];
 
-       while ((opt = getopt_long(argc, argv, "Vh",
+       while ((opt = getopt_long(argc, argv, "Vhpj",
                                  options, NULL)) >= 0) {
                switch (opt) {
                case 'V':
                        return do_version(argc, argv);
                case 'h':
                        return do_help(argc, argv);
+               case 'p':
+                       pretty_output = true;
+                       /* fall through */
+               case 'j':
+                       json_output = true;
+                       break;
                default:
                        usage();
                }
@@ -243,7 +256,21 @@ int main(int argc, char **argv)
        if (argc < 0)
                usage();
 
+       if (json_output) {
+               json_wtr = jsonw_new(stdout);
+               if (!json_wtr) {
+                       err("failed to create JSON writer\n");
+                       return -1;
+               }
+               jsonw_pretty(json_wtr, pretty_output);
+       }
+
        bfd_init();
 
-       return cmd_select(cmds, argc, argv, do_help);
+       ret = cmd_select(cmds, argc, argv, do_help);
+
+       if (json_output)
+               jsonw_destroy(&json_wtr);
+
+       return ret;
 }

diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 41e6c7d..15927fc 100644 (file)
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -43,6 +43,8 @@
 #include <linux/bpf.h>
 #include <linux/kernel.h>
 
+#include "json_writer.h"
+
 #define err(msg...)    fprintf(stderr, "Error: " msg)
 #define warn(msg...)   fprintf(stderr, "Warning: " msg)
 #define info(msg...)   fprintf(stderr, msg)
@@ -66,6 +68,9 @@ enum bpf_obj_type {
 
 extern const char *bin_name;
 
+extern json_writer_t *json_wtr;
+extern bool json_output;
+
 bool is_prefix(const char *pfx, const char *str);
 void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep);
 void usage(void) __attribute__((noreturn));