tools: bpftool: copy JSON writer from iproute2 repository

In prevision of following commits, supposed to add JSON output to the
tool, two files are copied from the iproute2 repository (taken at commit
268a9eee985f): lib/json_writer.c and include/json_writer.h.

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>

1 files changed, 348 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c
new file mode 100644
index 000000000000..6b77d288cce2
--- /dev/null
+++ b/tools/bpf/bpftool/json_writer.c
@@ -0,0 +1,348 @@
+/*
+ * Simple streaming JSON writer
+ *
+ * This takes care of the annoying bits of JSON syntax like the commas
+ * after elements
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors:     Stephen Hemminger <stephen@networkplumber.org>
+ */
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <assert.h>
+#include <malloc.h>
+#include <inttypes.h>
+#include <stdint.h>
+
+#include "json_writer.h"
+
+struct json_writer {
+        FILE            *out;   /* output file */
+        unsigned        depth;  /* nesting */
+        bool            pretty; /* optional whitepace */
+        char            sep;    /* either nul or comma */
+};
+
+/* indentation for pretty print */
+static void jsonw_indent(json_writer_t *self)
+{
+        unsigned i;
+        for (i = 0; i < self->depth; ++i)
+                fputs("    ", self->out);
+}
+
+/* end current line and indent if pretty printing */
+static void jsonw_eol(json_writer_t *self)
+{
+        if (!self->pretty)
+                return;
+
+        putc('\n', self->out);
+        jsonw_indent(self);
+}
+
+/* If current object is not empty print a comma */
+static void jsonw_eor(json_writer_t *self)
+{
+        if (self->sep != '\0')
+                putc(self->sep, self->out);
+        self->sep = ',';
+}
+
+
+/* Output JSON encoded string */
+/* Handles C escapes, does not do Unicode */
+static void jsonw_puts(json_writer_t *self, const char *str)
+{
+        putc('"', self->out);
+        for (; *str; ++str)
+                switch (*str) {
+                case '\t':
+                        fputs("\\t", self->out);
+                        break;
+                case '\n':
+                        fputs("\\n", self->out);
+                        break;
+                case '\r':
+                        fputs("\\r", self->out);
+                        break;
+                case '\f':
+                        fputs("\\f", self->out);
+                        break;
+                case '\b':
+                        fputs("\\b", self->out);
+                        break;
+                case '\\':
+                        fputs("\\n", self->out);
+                        break;
+                case '"':
+                        fputs("\\\"", self->out);
+                        break;
+                case '\'':
+                        fputs("\\\'", self->out);
+                        break;
+                default:
+                        putc(*str, self->out);
+                }
+        putc('"', self->out);
+}
+
+/* Create a new JSON stream */
+json_writer_t *jsonw_new(FILE *f)
+{
+        json_writer_t *self = malloc(sizeof(*self));
+        if (self) {
+                self->out = f;
+                self->depth = 0;
+                self->pretty = false;
+                self->sep = '\0';
+        }
+        return self;
+}
+
+/* End output to JSON stream */
+void jsonw_destroy(json_writer_t **self_p)
+{
+        json_writer_t *self = *self_p;
+
+        assert(self->depth == 0);
+        fputs("\n", self->out);
+        fflush(self->out);
+        free(self);
+        *self_p = NULL;
+}
+
+void jsonw_pretty(json_writer_t *self, bool on)
+{
+        self->pretty = on;
+}
+
+/* Basic blocks */
+static void jsonw_begin(json_writer_t *self, int c)
+{
+        jsonw_eor(self);
+        putc(c, self->out);
+        ++self->depth;
+        self->sep = '\0';
+}
+
+static void jsonw_end(json_writer_t *self, int c)
+{
+        assert(self->depth > 0);
+
+        --self->depth;
+        if (self->sep != '\0')
+                jsonw_eol(self);
+        putc(c, self->out);
+        self->sep = ',';
+}
+
+
+/* Add a JSON property name */
+void jsonw_name(json_writer_t *self, const char *name)
+{
+        jsonw_eor(self);
+        jsonw_eol(self);
+        self->sep = '\0';
+        jsonw_puts(self, name);
+        putc(':', self->out);
+        if (self->pretty)
+                putc(' ', self->out);
+}
+
+void jsonw_printf(json_writer_t *self, const char *fmt, ...)
+{
+        va_list ap;
+
+        va_start(ap, fmt);
+        jsonw_eor(self);
+        vfprintf(self->out, fmt, ap);
+        va_end(ap);
+}
+
+/* Collections */
+void jsonw_start_object(json_writer_t *self)
+{
+        jsonw_begin(self, '{');
+}
+
+void jsonw_end_object(json_writer_t *self)
+{
+        jsonw_end(self, '}');
+}
+
+void jsonw_start_array(json_writer_t *self)
+{
+        jsonw_begin(self, '[');
+}
+
+void jsonw_end_array(json_writer_t *self)
+{
+        jsonw_end(self, ']');
+}
+
+/* JSON value types */
+void jsonw_string(json_writer_t *self, const char *value)
+{
+        jsonw_eor(self);
+        jsonw_puts(self, value);
+}
+
+void jsonw_bool(json_writer_t *self, bool val)
+{
+        jsonw_printf(self, "%s", val ? "true" : "false");
+}
+
+void jsonw_null(json_writer_t *self)
+{
+        jsonw_printf(self, "null");
+}
+
+void jsonw_float_fmt(json_writer_t *self, const char *fmt, double num)
+{
+        jsonw_printf(self, fmt, num);
+}
+
+#ifdef notused
+void jsonw_float(json_writer_t *self, double num)
+{
+        jsonw_printf(self, "%g", num);
+}
+#endif
+
+void jsonw_hu(json_writer_t *self, unsigned short num)
+{
+        jsonw_printf(self, "%hu", num);
+}
+
+void jsonw_uint(json_writer_t *self, uint64_t num)
+{
+        jsonw_printf(self, "%"PRIu64, num);
+}
+
+void jsonw_lluint(json_writer_t *self, unsigned long long int num)
+{
+        jsonw_printf(self, "%llu", num);
+}
+
+void jsonw_int(json_writer_t *self, int64_t num)
+{
+        jsonw_printf(self, "%"PRId64, num);
+}
+
+/* Basic name/value objects */
+void jsonw_string_field(json_writer_t *self, const char *prop, const char *val)
+{
+        jsonw_name(self, prop);
+        jsonw_string(self, val);
+}
+
+void jsonw_bool_field(json_writer_t *self, const char *prop, bool val)
+{
+        jsonw_name(self, prop);
+        jsonw_bool(self, val);
+}
+
+#ifdef notused
+void jsonw_float_field(json_writer_t *self, const char *prop, double val)
+{
+        jsonw_name(self, prop);
+        jsonw_float(self, val);
+}
+#endif
+
+void jsonw_float_field_fmt(json_writer_t *self,
+                           const char *prop,
+                           const char *fmt,
+                           double val)
+{
+        jsonw_name(self, prop);
+        jsonw_float_fmt(self, fmt, val);
+}
+
+void jsonw_uint_field(json_writer_t *self, const char *prop, uint64_t num)
+{
+        jsonw_name(self, prop);
+        jsonw_uint(self, num);
+}
+
+void jsonw_hu_field(json_writer_t *self, const char *prop, unsigned short num)
+{
+        jsonw_name(self, prop);
+        jsonw_hu(self, num);
+}
+
+void jsonw_lluint_field(json_writer_t *self,
+                        const char *prop,
+                        unsigned long long int num)
+{
+        jsonw_name(self, prop);
+        jsonw_lluint(self, num);
+}
+
+void jsonw_int_field(json_writer_t *self, const char *prop, int64_t num)
+{
+        jsonw_name(self, prop);
+        jsonw_int(self, num);
+}
+
+void jsonw_null_field(json_writer_t *self, const char *prop)
+{
+        jsonw_name(self, prop);
+        jsonw_null(self);
+}
+
+#ifdef TEST
+int main(int argc, char **argv)
+{
+        json_writer_t *wr = jsonw_new(stdout);
+
+        jsonw_start_object(wr);
+        jsonw_pretty(wr, true);
+        jsonw_name(wr, "Vyatta");
+        jsonw_start_object(wr);
+        jsonw_string_field(wr, "url", "http://vyatta.com");
+        jsonw_uint_field(wr, "downloads", 2000000ul);
+        jsonw_float_field(wr, "stock", 8.16);
+
+        jsonw_name(wr, "ARGV");
+        jsonw_start_array(wr);
+        while (--argc)
+                jsonw_string(wr, *++argv);
+        jsonw_end_array(wr);
+
+        jsonw_name(wr, "empty");
+        jsonw_start_array(wr);
+        jsonw_end_array(wr);
+
+        jsonw_name(wr, "NIL");
+        jsonw_start_object(wr);
+        jsonw_end_object(wr);
+
+        jsonw_null_field(wr, "my_null");
+
+        jsonw_name(wr, "special chars");
+        jsonw_start_array(wr);
+        jsonw_string_field(wr, "slash", "/");
+        jsonw_string_field(wr, "newline", "\n");
+        jsonw_string_field(wr, "tab", "\t");
+        jsonw_string_field(wr, "ff", "\f");
+        jsonw_string_field(wr, "quote", "\"");
+        jsonw_string_field(wr, "tick", "\'");
+        jsonw_string_field(wr, "backslash", "\\");
+        jsonw_end_array(wr);
+
+        jsonw_end_object(wr);
+
+        jsonw_end_object(wr);
+        jsonw_destroy(&wr);
+        return 0;
+}
+
+#endif