settings: Add flex/bison based parser for strongswan.conf
This parser features several improvements over the existing one.
For instance, quoted strings (with escape sequences), unlimited includes,
relaxed newline handling (e.g. at the end of files or before/after { and }),
and the difference between empty and unset values (key = vs. key = "").
It also complains a lot more about invalid syntax. The current one accepts
pretty odd stuff (like settings or sections without name) without any
errors or warnings.
This commit is contained in:
Tobias Brunner
@@ -0,0 +1,299 @@
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%{
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/*
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* Copyright (C) 2014 Tobias Brunner
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#define _GNU_SOURCE /* for asprintf() */
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#include <stdio.h>
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#include "settings_parser.h"
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#include <library.h>
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#include <collections/array.h>
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#include <settings/settings_types.h>
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#include <utils/parser_helper.h>
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#define YYDEBUG 1
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/**
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* Defined by the lexer
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*/
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int settings_parser_lex(YYSTYPE *lvalp, void *scanner);
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int settings_parser_lex_init_extra(parser_helper_t *extra, void *scanner);
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int settings_parser_lex_destroy(void *scanner);
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int settings_parser_set_in(FILE *in, void *scanner);
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void settings_parser_set_debug(int debug, void *scanner);
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char *settings_parser_get_text(void *scanner);
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int settings_parser_get_leng(void *scanner);
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int settings_parser_get_lineno(void *scanner);
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/* Custom functions in lexer */
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bool settings_parser_open_next_file(parser_helper_t *ctx);
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/**
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* Forward declarations
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*/
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static void settings_parser_error(parser_helper_t *ctx, const char *s);
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static section_t *push_section(parser_helper_t *ctx, char *name);
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static section_t *pop_section(parser_helper_t *ctx);
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static void add_section(parser_helper_t *ctx, section_t *section);
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static void add_setting(parser_helper_t *ctx, kv_t *kv);
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/**
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* Make sure the generated parser code passes the correct object to the lexer
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*/
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#define YYLEX_PARAM ctx->scanner
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%}
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%debug
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/* generate verbose error messages */
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%error-verbose
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/* generate a reentrant parser */
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%define api.pure
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/* prefix function/variable declarations */
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%name-prefix "settings_parser_"
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/* interact properly with the reentrant lexer */
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%lex-param {void *scanner}
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%parse-param {parser_helper_t *ctx}
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/* types for terminal symbols... (can't use the typedef'd types) */
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%union {
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char *s;
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struct section_t *sec;
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struct kv_t *kv;
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}
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%token <s> NAME STRING
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%token NEWLINE
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/* ...and other symbols */
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%type <s> value valuepart
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%type <sec> section_start section
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%type <kv> setting
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/* properly destroy string tokens that are strdup()ed on error */
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%destructor { free($$); } NAME STRING value valuepart
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/* properly destroy parse results on error */
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%destructor { pop_section(ctx); settings_section_destroy($$); } section_start section
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%destructor { settings_kv_destroy($$); } setting
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/* there are two shift/reduce conflicts because of the "NAME = NAME" and
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* "NAME {" ambiguity, and the "NAME =" rule) */
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%expect 2
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%%
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/**
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* strongswan.conf grammar rules
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*/
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statements:
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/* empty */
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| statements NEWLINE
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| statements statement
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;
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statement:
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section
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{
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add_section(ctx, $section);
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}
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| setting
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{
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add_setting(ctx, $setting);
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}
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;
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section:
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section_start statements '}'
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{
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pop_section(ctx);
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$$ = $section_start;
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}
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;
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section_start:
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NAME '{'
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{
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$$ = push_section(ctx, $NAME);
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}
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NAME NEWLINE '{'
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{
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$$ = push_section(ctx, $NAME);
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}
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;
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setting:
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NAME '=' value
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{
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$$ = settings_kv_create($NAME, $value);
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}
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NAME '='
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{
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$$ = settings_kv_create($NAME, NULL);
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}
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;
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value:
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valuepart
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| value valuepart
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{ /* just put a single space between them, use strings for more */
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if (asprintf(&$$, "%s %s", $1, $2) < 0)
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{
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free($1);
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free($2);
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YYERROR;
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}
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free($1);
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free($2);
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}
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;
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valuepart:
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NAME
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| STRING
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;
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%%
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/**
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* Referenced by the generated parser
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*/
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static void settings_parser_error(parser_helper_t *ctx, const char *s)
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{
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char *text = settings_parser_get_text(ctx->scanner);
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int len = settings_parser_get_leng(ctx->scanner);
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if (len && text[len-1] == '\n')
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{ /* cut off newline at the end to avoid muti-line log messages */
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len--;
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}
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PARSER_DBG1(ctx, "%s [%.*s]", s, len, text);
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}
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/**
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* Create a section and push it to the stack (the name is adopted), returns
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* the created section
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*/
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static section_t *push_section(parser_helper_t *ctx, char *name)
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{
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array_t *sections = (array_t*)ctx->context;
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section_t *section;
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section = settings_section_create(name);
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array_insert(sections, ARRAY_TAIL, section);
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return section;
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}
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/**
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* Removes the top section of the stack and returns it
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*/
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static section_t *pop_section(parser_helper_t *ctx)
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{
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array_t *sections = (array_t*)ctx->context;
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section_t *section;
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array_remove(sections, ARRAY_TAIL, §ion);
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return section;
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}
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/**
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* Adds the given section to the section on top of the stack
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*/
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static void add_section(parser_helper_t *ctx, section_t *section)
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{
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array_t *sections = (array_t*)ctx->context;
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section_t *parent, *existing;
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array_get(sections, ARRAY_TAIL, &parent);
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if (array_bsearch(parent->sections, section->name, settings_section_find,
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&existing) == -1)
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{
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array_insert_create(&parent->sections, ARRAY_TAIL, section);
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array_sort(parent->sections, settings_section_sort, NULL);
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}
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else
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{ /* extend the existing section */
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settings_section_extend(existing, section);
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settings_section_destroy(section);
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}
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}
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/**
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* Adds the given key/value pair to the section on top of the stack
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*/
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static void add_setting(parser_helper_t *ctx, kv_t *kv)
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{
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array_t *sections = (array_t*)ctx->context;
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section_t *section;
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kv_t *existing;
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array_get(sections, ARRAY_TAIL, §ion);
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if (array_bsearch(section->kv, kv->key, settings_kv_find, &existing) == -1)
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{
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array_insert_create(§ion->kv, ARRAY_TAIL, kv);
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array_sort(section->kv, settings_kv_sort, NULL);
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}
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else
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{ /* move value to existing object */
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free(existing->value);
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existing->value = kv->value;
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kv->value = NULL;
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settings_kv_destroy(kv);
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}
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}
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/**
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* Parse the given file and add all sections and key/value pairs to the
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* given section.
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*/
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bool settings_parser_parse_file(section_t *root, char *name)
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{
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parser_helper_t *helper;
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array_t *sections = NULL;
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bool success = FALSE;
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array_insert_create(§ions, ARRAY_TAIL, root);
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helper = parser_helper_create(sections);
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helper->get_lineno = settings_parser_get_lineno;
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if (settings_parser_lex_init_extra(helper, &helper->scanner) != 0)
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{
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helper->destroy(helper);
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array_destroy(sections);
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return FALSE;
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}
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helper->file_include(helper, name);
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if (!settings_parser_open_next_file(helper))
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{
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DBG1(DBG_CFG, "failed to open config file '%s'", name);
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}
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else
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{
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if (getenv("DEBUG_SETTINGS_PARSER"))
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{
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yydebug = 1;
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settings_parser_set_debug(1, helper->scanner);
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}
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success = yyparse(helper) == 0;
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if (!success)
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{
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DBG1(DBG_CFG, "invalid config file '%s'", name);
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}
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}
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array_destroy(sections);
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settings_parser_lex_destroy(helper->scanner);
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helper->destroy(helper);
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return success;
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}
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