From patchwork Thu Jun 25 19:24:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Lunn X-Patchwork-Id: 217114 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8ECADC433E0 for ; Thu, 25 Jun 2020 19:25:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 626D1206B7 for ; Thu, 25 Jun 2020 19:25:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406434AbgFYTZI (ORCPT ); Thu, 25 Jun 2020 15:25:08 -0400 Received: from vps0.lunn.ch ([185.16.172.187]:60906 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404019AbgFYTZE (ORCPT ); Thu, 25 Jun 2020 15:25:04 -0400 Received: from andrew by vps0.lunn.ch with local (Exim 4.94) (envelope-from ) id 1joXUX-002FO5-4p; Thu, 25 Jun 2020 21:24:57 +0200 From: Andrew Lunn To: Michal Kubecek Cc: netdev , Chris Healy , Andrew Lunn , Stephen Hemminger Subject: [PATCH ethtool v3 3/6] json_writer/json_print: Import the iproute2 helper code for JSON output Date: Thu, 25 Jun 2020 21:24:43 +0200 Message-Id: <20200625192446.535754-4-andrew@lunn.ch> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200625192446.535754-1-andrew@lunn.ch> References: <20200625192446.535754-1-andrew@lunn.ch> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In general, Linux network tools use JSON for machine readable output. See for example -json for iproute2 and devlink. In order to support JSON output from ethtool, import the iproute2 helper code. Acked-by: Stephen Hemminger Signed-off-by: Andrew Lunn --- Makefile.am | 3 +- json_print.c | 229 +++++++++++++++++++++++++++++ json_print.h | 67 +++++++++ json_writer.c | 389 ++++++++++++++++++++++++++++++++++++++++++++++++++ json_writer.h | 76 ++++++++++ 5 files changed, 763 insertions(+), 1 deletion(-) create mode 100644 json_print.c create mode 100644 json_print.h create mode 100644 json_writer.c create mode 100644 json_writer.h diff --git a/Makefile.am b/Makefile.am index a818cf8..a736237 100644 --- a/Makefile.am +++ b/Makefile.am @@ -7,7 +7,8 @@ EXTRA_DIST = LICENSE ethtool.8 ethtool.spec.in aclocal.m4 ChangeLog autogen.sh sbin_PROGRAMS = ethtool ethtool_SOURCES = ethtool.c uapi/linux/ethtool.h internal.h \ - uapi/linux/net_tstamp.h rxclass.c common.c common.h + uapi/linux/net_tstamp.h rxclass.c common.c common.h \ + json_writer.c json_writer.h json_print.c json_print.h if ETHTOOL_ENABLE_PRETTY_DUMP ethtool_SOURCES += \ amd8111e.c de2104x.c dsa.c e100.c e1000.c et131x.c igb.c \ diff --git a/json_print.c b/json_print.c new file mode 100644 index 0000000..1ce2e69 --- /dev/null +++ b/json_print.c @@ -0,0 +1,229 @@ +/* + * json_print.c "print regular or json output, based on json_writer". + * + * 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: Julien Fortin, + */ + +#include +#include +#include +#include + +#include "json_print.h" + +#define SPRINT_BSIZE 64 +#define SPRINT_BUF(x) char x[SPRINT_BSIZE] + +static json_writer_t *_jw; + +#define _IS_JSON_CONTEXT(type) ((type & PRINT_JSON || type & PRINT_ANY) && _jw) +#define _IS_FP_CONTEXT(type) (!_jw && (type & PRINT_FP || type & PRINT_ANY)) + +void new_json_obj(int json) +{ + if (json) { + _jw = jsonw_new(stdout); + if (!_jw) { + perror("json object"); + exit(1); + } + jsonw_pretty(_jw, true); + jsonw_start_array(_jw); + } +} + +void delete_json_obj(void) +{ + if (_jw) { + jsonw_end_array(_jw); + jsonw_destroy(&_jw); + } +} + +bool is_json_context(void) +{ + return _jw != NULL; +} + +json_writer_t *get_json_writer(void) +{ + return _jw; +} + +void open_json_object(const char *str) +{ + if (_IS_JSON_CONTEXT(PRINT_JSON)) { + if (str) + jsonw_name(_jw, str); + jsonw_start_object(_jw); + } +} + +void close_json_object(void) +{ + if (_IS_JSON_CONTEXT(PRINT_JSON)) + jsonw_end_object(_jw); +} + +/* + * Start json array or string array using + * the provided string as json key (if not null) + * or as array delimiter in non-json context. + */ +void open_json_array(enum output_type type, const char *str) +{ + if (_IS_JSON_CONTEXT(type)) { + if (str) + jsonw_name(_jw, str); + jsonw_start_array(_jw); + } else if (_IS_FP_CONTEXT(type)) { + printf("%s", str); + } +} + +/* + * End json array or string array + */ +void close_json_array(enum output_type type, const char *str) +{ + if (_IS_JSON_CONTEXT(type)) { + jsonw_end_array(_jw); + } else if (_IS_FP_CONTEXT(type)) { + printf("%s", str); + } +} + +/* + * pre-processor directive to generate similar + * functions handling different types + */ +#define _PRINT_FUNC(type_name, type) \ + __attribute__((format(printf, 3, 0))) \ + void print_##type_name(enum output_type t, \ + const char *key, \ + const char *fmt, \ + type value) \ + { \ + if (_IS_JSON_CONTEXT(t)) { \ + if (!key) \ + jsonw_##type_name(_jw, value); \ + else \ + jsonw_##type_name##_field(_jw, key, value); \ + } else if (_IS_FP_CONTEXT(t)) { \ + fprintf(stdout, fmt, value); \ + } \ + } +_PRINT_FUNC(int, int); +_PRINT_FUNC(s64, int64_t); +_PRINT_FUNC(hhu, unsigned char); +_PRINT_FUNC(hu, unsigned short); +_PRINT_FUNC(uint, unsigned int); +_PRINT_FUNC(u64, uint64_t); +_PRINT_FUNC(luint, unsigned long); +_PRINT_FUNC(lluint, unsigned long long); +_PRINT_FUNC(float, double); +#undef _PRINT_FUNC + +void print_string(enum output_type type, + const char *key, + const char *fmt, + const char *value) +{ + if (_IS_JSON_CONTEXT(type)) { + if (key && !value) + jsonw_name(_jw, key); + else if (!key && value) + jsonw_string(_jw, value); + else + jsonw_string_field(_jw, key, value); + } else if (_IS_FP_CONTEXT(type)) { + fprintf(stdout, fmt, value); + } +} + +/* + * value's type is bool. When using this function in FP context you can't pass + * a value to it, you will need to use "is_json_context()" to have different + * branch for json and regular output. grep -r "print_bool" for example + */ +void print_bool(enum output_type type, + const char *key, + const char *fmt, + bool value) +{ + if (_IS_JSON_CONTEXT(type)) { + if (key) + jsonw_bool_field(_jw, key, value); + else + jsonw_bool(_jw, value); + } else if (_IS_FP_CONTEXT(type)) { + fprintf(stdout, fmt, value ? "true" : "false"); + } +} + +/* + * In JSON context uses hardcode %#x format: 42 -> 0x2a + */ +void print_0xhex(enum output_type type, + const char *key, + const char *fmt, + unsigned long long hex) +{ + if (_IS_JSON_CONTEXT(type)) { + SPRINT_BUF(b1); + + snprintf(b1, sizeof(b1), "%#llx", hex); + print_string(PRINT_JSON, key, NULL, b1); + } else if (_IS_FP_CONTEXT(type)) { + fprintf(stdout, fmt, hex); + } +} + +void print_hex(enum output_type type, + const char *key, + const char *fmt, + unsigned int hex) +{ + if (_IS_JSON_CONTEXT(type)) { + SPRINT_BUF(b1); + + snprintf(b1, sizeof(b1), "%x", hex); + if (key) + jsonw_string_field(_jw, key, b1); + else + jsonw_string(_jw, b1); + } else if (_IS_FP_CONTEXT(type)) { + fprintf(stdout, fmt, hex); + } +} + +/* + * In JSON context we don't use the argument "value" we simply call jsonw_null + * whereas FP context can use "value" to output anything + */ +void print_null(enum output_type type, + const char *key, + const char *fmt, + const char *value) +{ + if (_IS_JSON_CONTEXT(type)) { + if (key) + jsonw_null_field(_jw, key); + else + jsonw_null(_jw); + } else if (_IS_FP_CONTEXT(type)) { + fprintf(stdout, fmt, value); + } +} + +/* Print line seperator (if not in JSON mode) */ +void print_nl(void) +{ + if (!_jw) + printf("%s", "\n"); +} diff --git a/json_print.h b/json_print.h new file mode 100644 index 0000000..d035ba2 --- /dev/null +++ b/json_print.h @@ -0,0 +1,67 @@ +/* + * json_print.h "print regular or json output, based on json_writer". + * + * 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: Julien Fortin, + */ + +#ifndef _JSON_PRINT_H_ +#define _JSON_PRINT_H_ + +#include "json_writer.h" + +json_writer_t *get_json_writer(void); + +/* + * use: + * - PRINT_ANY for context based output + * - PRINT_FP for non json specific output + * - PRINT_JSON for json specific output + */ +enum output_type { + PRINT_FP = 1, + PRINT_JSON = 2, + PRINT_ANY = 4, +}; + +void new_json_obj(int json); +void delete_json_obj(void); + +bool is_json_context(void); + +void fflush_fp(void); + +void open_json_object(const char *str); +void close_json_object(void); +void open_json_array(enum output_type type, const char *delim); +void close_json_array(enum output_type type, const char *delim); + +void print_nl(void); + +#define _PRINT_FUNC(type_name, type) \ + void print_##type_name(enum output_type t, \ + const char *key, \ + const char *fmt, \ + type value); \ + +_PRINT_FUNC(int, int); +_PRINT_FUNC(s64, int64_t); +_PRINT_FUNC(bool, bool); +_PRINT_FUNC(null, const char*); +_PRINT_FUNC(string, const char*); +_PRINT_FUNC(uint, unsigned int); +_PRINT_FUNC(u64, uint64_t); +_PRINT_FUNC(hhu, unsigned char); +_PRINT_FUNC(hu, unsigned short); +_PRINT_FUNC(hex, unsigned int); +_PRINT_FUNC(0xhex, unsigned long long); +_PRINT_FUNC(luint, unsigned long); +_PRINT_FUNC(lluint, unsigned long long); +_PRINT_FUNC(float, double); +#undef _PRINT_FUNC + +#endif /* _JSON_PRINT_H_ */ diff --git a/json_writer.c b/json_writer.c new file mode 100644 index 0000000..88c5eb8 --- /dev/null +++ b/json_writer.c @@ -0,0 +1,389 @@ +/* SPDX-License-Identifier: (GPL-2.0 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 + */ + +#include +#include +#include +#include +#include +#include +#include + +#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("\\\\", 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); +} + +__attribute__((format(printf, 2, 3))) +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, '['); + if (self->pretty) + putc(' ', self->out); +} + +void jsonw_end_array(json_writer_t *self) +{ + if (self->pretty && self->sep) + putc(' ', self->out); + self->sep = '\0'; + 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(json_writer_t *self, double num) +{ + jsonw_printf(self, "%g", num); +} + +void jsonw_hhu(json_writer_t *self, unsigned char num) +{ + jsonw_printf(self, "%hhu", num); +} + +void jsonw_hu(json_writer_t *self, unsigned short num) +{ + jsonw_printf(self, "%hu", num); +} + +void jsonw_uint(json_writer_t *self, unsigned int num) +{ + jsonw_printf(self, "%u", num); +} + +void jsonw_u64(json_writer_t *self, uint64_t num) +{ + jsonw_printf(self, "%"PRIu64, num); +} + +void jsonw_xint(json_writer_t *self, uint64_t num) +{ + jsonw_printf(self, "%"PRIx64, num); +} + +void jsonw_luint(json_writer_t *self, unsigned long num) +{ + jsonw_printf(self, "%lu", num); +} + +void jsonw_lluint(json_writer_t *self, unsigned long long num) +{ + jsonw_printf(self, "%llu", num); +} + +void jsonw_int(json_writer_t *self, int num) +{ + jsonw_printf(self, "%d", num); +} + +void jsonw_s64(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); +} + +void jsonw_float_field(json_writer_t *self, const char *prop, double val) +{ + jsonw_name(self, prop); + jsonw_float(self, val); +} + +void jsonw_uint_field(json_writer_t *self, const char *prop, unsigned int num) +{ + jsonw_name(self, prop); + jsonw_uint(self, num); +} + +void jsonw_u64_field(json_writer_t *self, const char *prop, uint64_t num) +{ + jsonw_name(self, prop); + jsonw_u64(self, num); +} + +void jsonw_xint_field(json_writer_t *self, const char *prop, uint64_t num) +{ + jsonw_name(self, prop); + jsonw_xint(self, num); +} + +void jsonw_hhu_field(json_writer_t *self, const char *prop, unsigned char num) +{ + jsonw_name(self, prop); + jsonw_hhu(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_luint_field(json_writer_t *self, + const char *prop, + unsigned long num) +{ + jsonw_name(self, prop); + jsonw_luint(self, num); +} + +void jsonw_lluint_field(json_writer_t *self, + const char *prop, + unsigned long long num) +{ + jsonw_name(self, prop); + jsonw_lluint(self, num); +} + +void jsonw_int_field(json_writer_t *self, const char *prop, int num) +{ + jsonw_name(self, prop); + jsonw_int(self, num); +} + +void jsonw_s64_field(json_writer_t *self, const char *prop, int64_t num) +{ + jsonw_name(self, prop); + jsonw_s64(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 diff --git a/json_writer.h b/json_writer.h new file mode 100644 index 0000000..b52dc2d --- /dev/null +++ b/json_writer.h @@ -0,0 +1,76 @@ +/* SPDX-License-Identifier: (GPL-2.0 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 + */ + +#ifndef _JSON_WRITER_H_ +#define _JSON_WRITER_H_ + +#include +#include + +/* Opaque class structure */ +typedef struct json_writer json_writer_t; + +/* Create a new JSON stream */ +json_writer_t *jsonw_new(FILE *f); +/* End output to JSON stream */ +void jsonw_destroy(json_writer_t **self_p); + +/* Cause output to have pretty whitespace */ +void jsonw_pretty(json_writer_t *self, bool on); + +/* Add property name */ +void jsonw_name(json_writer_t *self, const char *name); + +/* Add value */ +__attribute__((format(printf, 2, 3))) +void jsonw_printf(json_writer_t *self, const char *fmt, ...); +void jsonw_string(json_writer_t *self, const char *value); +void jsonw_bool(json_writer_t *self, bool value); +void jsonw_float(json_writer_t *self, double number); +void jsonw_float_fmt(json_writer_t *self, const char *fmt, double num); +void jsonw_uint(json_writer_t *self, unsigned int number); +void jsonw_u64(json_writer_t *self, uint64_t number); +void jsonw_xint(json_writer_t *self, uint64_t number); +void jsonw_hhu(json_writer_t *self, unsigned char num); +void jsonw_hu(json_writer_t *self, unsigned short number); +void jsonw_int(json_writer_t *self, int number); +void jsonw_s64(json_writer_t *self, int64_t number); +void jsonw_null(json_writer_t *self); +void jsonw_luint(json_writer_t *self, unsigned long num); +void jsonw_lluint(json_writer_t *self, unsigned long long num); + +/* Useful Combinations of name and value */ +void jsonw_string_field(json_writer_t *self, const char *prop, const char *val); +void jsonw_bool_field(json_writer_t *self, const char *prop, bool value); +void jsonw_float_field(json_writer_t *self, const char *prop, double num); +void jsonw_uint_field(json_writer_t *self, const char *prop, unsigned int num); +void jsonw_u64_field(json_writer_t *self, const char *prop, uint64_t num); +void jsonw_xint_field(json_writer_t *self, const char *prop, uint64_t num); +void jsonw_hhu_field(json_writer_t *self, const char *prop, unsigned char num); +void jsonw_hu_field(json_writer_t *self, const char *prop, unsigned short num); +void jsonw_int_field(json_writer_t *self, const char *prop, int num); +void jsonw_s64_field(json_writer_t *self, const char *prop, int64_t num); +void jsonw_null_field(json_writer_t *self, const char *prop); +void jsonw_luint_field(json_writer_t *self, const char *prop, + unsigned long num); +void jsonw_lluint_field(json_writer_t *self, const char *prop, + unsigned long long num); + +/* Collections */ +void jsonw_start_object(json_writer_t *self); +void jsonw_end_object(json_writer_t *self); + +void jsonw_start_array(json_writer_t *self); +void jsonw_end_array(json_writer_t *self); + +/* Override default exception handling */ +typedef void (jsonw_err_handler_fn)(const char *); + +#endif /* _JSON_WRITER_H_ */