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linux/tools/bpf/bpftool/json_writer.c
Quentin Monnet 8918dc42dc tools: bpftool: move "__printf()" attributes to header file 
Some functions in bpftool have a "__printf()" format attributes to tell
the compiler they should expect printf()-like arguments. But because
these attributes are not used for the function prototypes in the header
files, the compiler does not run the checks everywhere the functions are
used, and some mistakes on format string and corresponding arguments
slipped in over time.

Let's move the __printf() attributes to the correct places.

Note: We add guards around the definition of GCC_VERSION in
tools/include/linux/compiler-gcc.h to prevent a conflict in jit_disasm.c
on GCC_VERSION from headers pulled via libbfd.

Fixes: c101189bc9 ("tools: bpftool: fix -Wmissing declaration warnings")
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-08-15 22:06:46 -07:00

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// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
/*
* Simple streaming JSON writer
*
* This takes care of the annoying bits of JSON syntax like the commas
* after elements
*
* 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_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
{
jsonw_eor(self);
putc('"', self->out);
vfprintf(self->out, fmt, ap);
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
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