/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/*! \file */

#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include <isc/lex.h>
#include <isc/log.h>
#include <isc/symtab.h>
#include <isc/util.h>

#include <isccfg/cfg.h>
#include <isccfg/grammar.h>

/*!
 * Pass one of these flags to cfg_parser_error() to include the
 * token text in log message.
 */
#define CFG_LOG_NEAR    0x00000001      /*%< Say "near <token>" */
#define CFG_LOG_BEFORE  0x00000002      /*%< Say "before <token>" */
#define CFG_LOG_NOPREP  0x00000004      /*%< Say just "<token>" */

isc_logcategory_t cfg_category = { "config",     0 };
isc_logmodule_t cfg_module = { "isccfg/parser",      0 };

/* Shorthand */
#define CAT &cfg_category
#define MOD &cfg_module

#define MAP_SYM 1       /* Unique type for isc_symtab */

#define TOKEN_STRING(pctx) (pctx->token.value.as_textregion.base)

#define CFG_LEXOPT_QSTRING (ISC_LEXOPT_QSTRING | ISC_LEXOPT_QSTRINGMULTILINE)

/* Check a return value. */
#define CHECK(op)                                               \
        do { result = (op);                                     \
                if (result != ISC_R_SUCCESS) goto cleanup;      \
        } while (0)

/* Clean up a configuration object if non-NULL. */
#define CLEANUP_OBJ(obj) \
        do { if ((obj) != NULL) cfg_obj_destroy(pctx, &(obj)); } while (0)

/* Forward declarations of variables */
cfg_rep_t cfg_rep_string;
cfg_rep_t cfg_rep_list;

cfg_type_t cfg_type_qstring;
cfg_type_t cfg_type_sstring;
cfg_type_t cfg_type_token;
cfg_type_t cfg_type_unsupported;

/*
 * Forward declarations of static functions.
 */

static isc_result_t
cfg_gettoken(cfg_parser_t *pctx, int options);

static isc_result_t
cfg_peektoken(cfg_parser_t *pctx, int options);

static void
cfg_ungettoken(cfg_parser_t *pctx);

static isc_result_t
cfg_create_obj(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **objp);

static isc_result_t
cfg_parse_qstring(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret);

static isc_result_t
cfg_parse_astring(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret);

static isc_result_t
cfg_parse_sstring(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret);

static isc_result_t
cfg_parse_special(cfg_parser_t *pctx, int special);
/*%< Parse a required special character 'special'. */

static isc_result_t
cfg_create_list(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **objp);

static isc_result_t
cfg_parse_listelt(cfg_parser_t *pctx, const cfg_type_t *elttype,
                  cfg_listelt_t **ret);

static isc_result_t
cfg_parse_map(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret);

static isc_result_t
cfg_parse_obj(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret);

static void
cfg_parser_error(cfg_parser_t *pctx, unsigned int flags,
                 const char *fmt, ...) __attribute__((__format__(__printf__, 3, 4)));

static void
free_list(cfg_parser_t *pctx, cfg_obj_t *obj);

static isc_result_t
create_listelt(cfg_parser_t *pctx, cfg_listelt_t **eltp);

static isc_result_t
create_string(cfg_parser_t *pctx, const char *contents, const cfg_type_t *type,
              cfg_obj_t **ret);

static void
free_string(cfg_parser_t *pctx, cfg_obj_t *obj);

static isc_result_t
create_map(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **objp);

static void
free_map(cfg_parser_t *pctx, cfg_obj_t *obj);

static isc_result_t
parse_symtab_elt(cfg_parser_t *pctx, const char *name,
                 cfg_type_t *elttype, isc_symtab_t *symtab);

static isc_result_t
cfg_getstringtoken(cfg_parser_t *pctx);

static void
parser_complain(cfg_parser_t *pctx, int is_warning,
                unsigned int flags, const char *format, va_list args);

/*
 * Data representations.  These correspond to members of the
 * "value" union in struct cfg_obj (except "void", which does
 * not need a union member).
 */

cfg_rep_t cfg_rep_string = { "string", free_string };
cfg_rep_t cfg_rep_map = { "map", free_map };
cfg_rep_t cfg_rep_list = { "list", free_list };

/*
 * Configuration type definitions.
 */

/* Functions. */

static isc_result_t
cfg_parse_obj(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(type != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        result = type->parse(pctx, type, ret);
        if (result != ISC_R_SUCCESS)
                return (result);
        ENSURE(*ret != NULL);
        return (ISC_R_SUCCESS);
}

static isc_result_t
cfg_parse_special(cfg_parser_t *pctx, int special) {
        isc_result_t result;

        REQUIRE(pctx != NULL);

        CHECK(cfg_gettoken(pctx, 0));
        if (pctx->token.type == isc_tokentype_special &&
            pctx->token.value.as_char == special)
                return (ISC_R_SUCCESS);

        cfg_parser_error(pctx, CFG_LOG_NEAR, "'%c' expected", special);
        return (ISC_R_UNEXPECTEDTOKEN);
 cleanup:
        return (result);
}

/*
 * Parse a required semicolon.  If it is not there, log
 * an error and increment the error count but continue
 * parsing.  Since the next token is pushed back,
 * care must be taken to make sure it is eventually
 * consumed or an infinite loop may result.
 */
static isc_result_t
parse_semicolon(cfg_parser_t *pctx) {
        isc_result_t result;

        CHECK(cfg_gettoken(pctx, 0));
        if (pctx->token.type == isc_tokentype_special &&
            pctx->token.value.as_char == ';')
                return (ISC_R_SUCCESS);

        cfg_parser_error(pctx, CFG_LOG_BEFORE, "missing ';'");
        cfg_ungettoken(pctx);
 cleanup:
        return (result);
}

/*
 * Parse EOF, logging and returning an error if not there.
 */
static isc_result_t
parse_eof(cfg_parser_t *pctx) {
        isc_result_t result;

        CHECK(cfg_gettoken(pctx, 0));

        if (pctx->token.type == isc_tokentype_eof)
                return (ISC_R_SUCCESS);

        cfg_parser_error(pctx, CFG_LOG_NEAR, "syntax error");
        return (ISC_R_UNEXPECTEDTOKEN);
 cleanup:
        return (result);
}

/* A list of files, used internally for pctx->files. */

static cfg_type_t cfg_type_filelist = {
        "filelist", NULL, &cfg_rep_list,
        &cfg_type_qstring
};

isc_result_t
cfg_parser_create(isc_log_t *lctx, cfg_parser_t **ret) {
        isc_result_t result;
        cfg_parser_t *pctx;
        isc_lexspecials_t specials;

        REQUIRE(ret != NULL && *ret == NULL);

        pctx = malloc(sizeof(*pctx));
        if (pctx == NULL)
                return (ISC_R_NOMEMORY);

        pctx->lctx = lctx;
        pctx->lexer = NULL;
        pctx->seen_eof = 0;
        pctx->ungotten = 0;
        pctx->errors = 0;
        pctx->open_files = NULL;
        pctx->closed_files = NULL;
        pctx->line = 0;
        pctx->token.type = isc_tokentype_unknown;
        pctx->flags = 0;

        memset(specials, 0, sizeof(specials));
        specials['{'] = 1;
        specials['}'] = 1;
        specials[';'] = 1;
        specials['/'] = 1;
        specials['"'] = 1;
        specials['!'] = 1;

        CHECK(isc_lex_create(1024, &pctx->lexer));

        isc_lex_setspecials(pctx->lexer, specials);
        isc_lex_setcomments(pctx->lexer, (ISC_LEXCOMMENT_C |
                                         ISC_LEXCOMMENT_CPLUSPLUS |
                                         ISC_LEXCOMMENT_SHELL));

        CHECK(cfg_create_list(pctx, &cfg_type_filelist, &pctx->open_files));
        CHECK(cfg_create_list(pctx, &cfg_type_filelist, &pctx->closed_files));

        *ret = pctx;
        return (ISC_R_SUCCESS);

 cleanup:
        if (pctx->lexer != NULL)
                isc_lex_destroy(&pctx->lexer);
        CLEANUP_OBJ(pctx->open_files);
        CLEANUP_OBJ(pctx->closed_files);
        free(pctx);
        return (result);
}

static isc_result_t
parser_openfile(cfg_parser_t *pctx, const char *filename) {
        isc_result_t result;
        cfg_listelt_t *elt = NULL;
        cfg_obj_t *stringobj = NULL;

        result = isc_lex_openfile(pctx->lexer, filename);
        if (result != ISC_R_SUCCESS) {
                cfg_parser_error(pctx, 0, "open: %s: %s",
                             filename, isc_result_totext(result));
                goto cleanup;
        }

        CHECK(create_string(pctx, filename, &cfg_type_qstring, &stringobj));
        CHECK(create_listelt(pctx, &elt));
        elt->obj = stringobj;
        ISC_LIST_APPEND(pctx->open_files->value.list, elt, link);

        return (ISC_R_SUCCESS);
 cleanup:
        CLEANUP_OBJ(stringobj);
        return (result);
}

/*
 * Parse a configuration using a pctx where a lexer has already
 * been set up with a source.
 */
static isc_result_t
parse2(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        isc_result_t result;
        cfg_obj_t *obj = NULL;

        result = cfg_parse_obj(pctx, type, &obj);

        if (pctx->errors != 0) {
                /* Errors have been logged. */
                if (result == ISC_R_SUCCESS)
                        result = ISC_R_FAILURE;
                goto cleanup;
        }

        if (result != ISC_R_SUCCESS) {
                /* Parsing failed but no errors have been logged. */
                cfg_parser_error(pctx, 0, "parsing failed: %s",
                                 isc_result_totext(result));
                goto cleanup;
        }

        CHECK(parse_eof(pctx));

        *ret = obj;
        return (ISC_R_SUCCESS);

 cleanup:
        CLEANUP_OBJ(obj);
        return (result);
}

isc_result_t
cfg_parse_file(cfg_parser_t *pctx, const char *filename,
               const cfg_type_t *type, cfg_obj_t **ret)
{
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(filename != NULL);
        REQUIRE(type != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        CHECK(parser_openfile(pctx, filename));
        CHECK(parse2(pctx, type, ret));
 cleanup:
        return (result);
}

void
cfg_parser_destroy(cfg_parser_t **pctxp) {
        cfg_parser_t *pctx;

        REQUIRE(pctxp != NULL && *pctxp != NULL);

        pctx = *pctxp;
        *pctxp = NULL;

        isc_lex_destroy(&pctx->lexer);
        /*
         * Cleaning up open_files does not
         * close the files; that was already done
         * by closing the lexer.
         */
        CLEANUP_OBJ(pctx->open_files);
        CLEANUP_OBJ(pctx->closed_files);
        free(pctx);
}

/*
 * qstring (quoted string), ustring (unquoted string), astring
 * (any string)
 */

/* Create a string object from a null-terminated C string. */
static isc_result_t
create_string(cfg_parser_t *pctx, const char *contents, const cfg_type_t *type,
              cfg_obj_t **ret)
{
        isc_result_t result;
        cfg_obj_t *obj = NULL;
        int len;

        CHECK(cfg_create_obj(pctx, type, &obj));
        len = strlen(contents);
        obj->value.string.length = len;
        obj->value.string.base = malloc(len + 1);
        if (obj->value.string.base == NULL) {
                free(obj);
                return (ISC_R_NOMEMORY);
        }
        memmove(obj->value.string.base, contents, len);
        obj->value.string.base[len] = '\0';

        *ret = obj;
 cleanup:
        return (result);
}

static isc_result_t
cfg_parse_qstring(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        UNUSED(type);

        CHECK(cfg_gettoken(pctx, CFG_LEXOPT_QSTRING));
        if (pctx->token.type != isc_tokentype_qstring) {
                cfg_parser_error(pctx, CFG_LOG_NEAR, "expected quoted string");
                return (ISC_R_UNEXPECTEDTOKEN);
        }
        return (create_string(pctx, TOKEN_STRING(pctx),
                              &cfg_type_qstring, ret));
 cleanup:
        return (result);
}

static isc_result_t
cfg_parse_astring(cfg_parser_t *pctx, const cfg_type_t *type,
                  cfg_obj_t **ret)
{
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        UNUSED(type);

        CHECK(cfg_getstringtoken(pctx));
        return (create_string(pctx,
                              TOKEN_STRING(pctx),
                              &cfg_type_qstring,
                              ret));
 cleanup:
        return (result);
}

static isc_result_t
cfg_parse_sstring(cfg_parser_t *pctx, const cfg_type_t *type,
                  cfg_obj_t **ret)
{
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        UNUSED(type);

        CHECK(cfg_getstringtoken(pctx));
        return (create_string(pctx,
                              TOKEN_STRING(pctx),
                              &cfg_type_sstring,
                              ret));
 cleanup:
        return (result);
}

static void
free_string(cfg_parser_t *pctx, cfg_obj_t *obj) {
        UNUSED(pctx);
        free(obj->value.string.base);
}

const char *
cfg_obj_asstring(const cfg_obj_t *obj) {
        REQUIRE(obj != NULL && obj->type->rep == &cfg_rep_string);
        return (obj->value.string.base);
}

/* Quoted string only */
cfg_type_t cfg_type_qstring = {
        "quoted_string", cfg_parse_qstring, &cfg_rep_string, NULL
};

/* Any string (quoted or unquoted); printed with quotes */
cfg_type_t cfg_type_astring = {
        "string", cfg_parse_astring, &cfg_rep_string, NULL
};

/*
 * Any string (quoted or unquoted); printed with quotes.
 * If CFG_PRINTER_XKEY is set when printing the string will be '?' out.
 */
cfg_type_t cfg_type_sstring = {
        "string", cfg_parse_sstring, &cfg_rep_string, NULL
};

/*
 * Booleans
 */

/*
 * Lists.
 */

static isc_result_t
cfg_create_list(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **obj) {
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(type != NULL);
        REQUIRE(obj != NULL && *obj == NULL);

        CHECK(cfg_create_obj(pctx, type, obj));
        ISC_LIST_INIT((*obj)->value.list);
 cleanup:
        return (result);
}

static isc_result_t
create_listelt(cfg_parser_t *pctx, cfg_listelt_t **eltp) {
        UNUSED(pctx);
        cfg_listelt_t *elt;

        elt = malloc(sizeof(*elt));
        if (elt == NULL)
                return (ISC_R_NOMEMORY);
        elt->obj = NULL;
        ISC_LINK_INIT(elt, link);
        *eltp = elt;
        return (ISC_R_SUCCESS);
}

static void
free_list_elt(cfg_parser_t *pctx, cfg_listelt_t *elt) {
        cfg_obj_destroy(pctx, &elt->obj);
        free(elt);
}

static void
free_list(cfg_parser_t *pctx, cfg_obj_t *obj) {
        cfg_listelt_t *elt, *next;
        for (elt = ISC_LIST_HEAD(obj->value.list);
             elt != NULL;
             elt = next)
        {
                next = ISC_LIST_NEXT(elt, link);
                free_list_elt(pctx, elt);
        }
}

static isc_result_t
cfg_parse_listelt(cfg_parser_t *pctx, const cfg_type_t *elttype,
                  cfg_listelt_t **ret)
{
        isc_result_t result;
        cfg_listelt_t *elt = NULL;
        cfg_obj_t *value = NULL;

        REQUIRE(pctx != NULL);
        REQUIRE(elttype != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        CHECK(create_listelt(pctx, &elt));

        result = cfg_parse_obj(pctx, elttype, &value);
        if (result != ISC_R_SUCCESS)
                goto cleanup;

        elt->obj = value;

        *ret = elt;
        return (ISC_R_SUCCESS);

 cleanup:
        free(elt);
        return (result);
}

/*
 * Maps.
 */

/*
 * Parse a map body.  That's something like
 *
 *   "foo 1; bar { glub; }; zap true; zap false;"
 *
 * i.e., a sequence of option names followed by values and
 * terminated by semicolons.  Used for the top level of
 * the named.conf syntax, as well as for the body of the
 * options, view, zone, and other statements.
 */
isc_result_t
cfg_parse_mapbody(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret)
{
        const cfg_clausedef_t * const *clausesets = type->of;
        isc_result_t result;
        const cfg_clausedef_t * const *clauseset;
        const cfg_clausedef_t *clause;
        cfg_obj_t *value = NULL;
        cfg_obj_t *obj = NULL;
        cfg_obj_t *eltobj = NULL;
        cfg_obj_t *includename = NULL;
        isc_symvalue_t symval;

        REQUIRE(pctx != NULL);
        REQUIRE(type != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        CHECK(create_map(pctx, type, &obj));

        obj->value.map.clausesets = clausesets;

        for (;;) {
        redo:
                /*
                 * Parse the option name and see if it is known.
                 */
                CHECK(cfg_gettoken(pctx, 0));

                if (pctx->token.type != isc_tokentype_string) {
                        cfg_ungettoken(pctx);
                        break;
                }

                /*
                 * We accept "include" statements wherever a map body
                 * clause can occur.
                 */
                if (strcasecmp(TOKEN_STRING(pctx), "include") == 0) {
                        /*
                         * Turn the file name into a temporary configuration
                         * object just so that it is not overwritten by the
                         * semicolon token.
                         */
                        CHECK(cfg_parse_obj(pctx, &cfg_type_qstring, &includename));
                        CHECK(parse_semicolon(pctx));
                        CHECK(parser_openfile(pctx, includename->
                                              value.string.base));
                         cfg_obj_destroy(pctx, &includename);
                         goto redo;
                }

                clause = NULL;
                for (clauseset = clausesets; *clauseset != NULL; clauseset++) {
                        for (clause = *clauseset;
                             clause->name != NULL;
                             clause++) {
                                if (strcasecmp(TOKEN_STRING(pctx),
                                           clause->name) == 0)
                                        goto done;
                        }
                }
        done:
                if (clause == NULL || clause->name == NULL) {
                        cfg_parser_error(pctx, CFG_LOG_NOPREP,
                                         "unknown option");
                        /*
                         * Try to recover by parsing this option as an unknown
                         * option and discarding it.
                         */
                        CHECK(cfg_parse_obj(pctx, &cfg_type_unsupported,
                                            &eltobj));
                        cfg_obj_destroy(pctx, &eltobj);
                        CHECK(parse_semicolon(pctx));
                        continue;
                }

                /* Clause is known. */

                /* See if the clause already has a value; if not create one. */
                result = isc_symtab_lookup(obj->value.map.symtab,
                                           clause->name, 0, &symval);

                /* Single-valued clause */
                if (result == ISC_R_NOTFOUND) {
                        CHECK(parse_symtab_elt(pctx, clause->name,
                                               clause->type,
                                               obj->value.map.symtab));
                        CHECK(parse_semicolon(pctx));
                } else if (result == ISC_R_SUCCESS) {
                        cfg_parser_error(pctx, CFG_LOG_NEAR, "'%s' redefined",
                                     clause->name);
                        result = ISC_R_EXISTS;
                        goto cleanup;
                } else {
                        cfg_parser_error(pctx, CFG_LOG_NEAR,
                                     "isc_symtab_define() failed");
                        goto cleanup;
                }
        }

        *ret = obj;
        return (ISC_R_SUCCESS);

 cleanup:
        CLEANUP_OBJ(value);
        CLEANUP_OBJ(obj);
        CLEANUP_OBJ(eltobj);
        CLEANUP_OBJ(includename);
        return (result);
}

static isc_result_t
parse_symtab_elt(cfg_parser_t *pctx, const char *name,
                 cfg_type_t *elttype, isc_symtab_t *symtab)
{
        isc_result_t result;
        cfg_obj_t *obj = NULL;
        isc_symvalue_t symval;

        CHECK(cfg_parse_obj(pctx, elttype, &obj));

        symval.as_pointer = obj;
        CHECK(isc_symtab_define(symtab, name,
                                1, symval,
                                isc_symexists_reject));
        return (ISC_R_SUCCESS);

 cleanup:
        CLEANUP_OBJ(obj);
        return (result);
}

/*
 * Parse a map; e.g., "{ foo 1; bar { glub; }; zap true; zap false; }"
 */
static isc_result_t
cfg_parse_map(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        isc_result_t result;

        REQUIRE(pctx != NULL);
        REQUIRE(type != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        CHECK(cfg_parse_special(pctx, '{'));
        CHECK(cfg_parse_mapbody(pctx, type, ret));
        CHECK(cfg_parse_special(pctx, '}'));
 cleanup:
        return (result);
}

/*
 * Subroutine for cfg_parse_named_map() and cfg_parse_addressed_map().
 */
static isc_result_t
parse_any_named_map(cfg_parser_t *pctx, cfg_type_t *nametype,
                    const cfg_type_t *type, cfg_obj_t **ret)
{
        isc_result_t result;
        cfg_obj_t *idobj = NULL;
        cfg_obj_t *mapobj = NULL;

        REQUIRE(pctx != NULL);
        REQUIRE(nametype != NULL);
        REQUIRE(type != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        CHECK(cfg_parse_obj(pctx, nametype, &idobj));
        CHECK(cfg_parse_map(pctx, type, &mapobj));
        mapobj->value.map.id = idobj;
        *ret = mapobj;
        return (result);
 cleanup:
        CLEANUP_OBJ(idobj);
        CLEANUP_OBJ(mapobj);
        return (result);
}

/*
 * Parse a map identified by a string name.  E.g., "name { foo 1; }".
 * Used for the "key" and "channel" statements.
 */
isc_result_t
cfg_parse_named_map(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        return (parse_any_named_map(pctx, &cfg_type_astring, type, ret));
}

isc_result_t
cfg_map_get(const cfg_obj_t *mapobj, const char* name, const cfg_obj_t **obj) {
        isc_result_t result;
        isc_symvalue_t val;
        const cfg_map_t *map;

        REQUIRE(mapobj != NULL && mapobj->type->rep == &cfg_rep_map);
        REQUIRE(name != NULL);
        REQUIRE(obj != NULL && *obj == NULL);

        map = &mapobj->value.map;

        result = isc_symtab_lookup(map->symtab, name, MAP_SYM, &val);
        if (result != ISC_R_SUCCESS)
                return (result);
        *obj = val.as_pointer;
        return (ISC_R_SUCCESS);
}

const cfg_obj_t *
cfg_map_getname(const cfg_obj_t *mapobj) {
        REQUIRE(mapobj != NULL && mapobj->type->rep == &cfg_rep_map);
        return (mapobj->value.map.id);
}

/* Parse an arbitrary token, storing its raw text representation. */
static isc_result_t
parse_token(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        cfg_obj_t *obj = NULL;
        isc_result_t result;
        isc_region_t r;

        UNUSED(type);

        CHECK(cfg_create_obj(pctx, &cfg_type_token, &obj));
        CHECK(cfg_gettoken(pctx, CFG_LEXOPT_QSTRING));
        if (pctx->token.type == isc_tokentype_eof) {
                cfg_ungettoken(pctx);
                result = ISC_R_EOF;
                goto cleanup;
        }

        isc_lex_getlasttokentext(pctx->lexer, &pctx->token, &r);

        obj->value.string.base = malloc(r.length + 1);
        if (obj->value.string.base == NULL) {
                result = ISC_R_NOMEMORY;
                goto cleanup;
        }
        obj->value.string.length = r.length;
        memmove(obj->value.string.base, r.base, r.length);
        obj->value.string.base[r.length] = '\0';
        *ret = obj;
        return (result);

 cleanup:
        if (obj != NULL)
                free(obj);
        return (result);
}

cfg_type_t cfg_type_token = {
        "token", parse_token, &cfg_rep_string, NULL
};

/*
 * An unsupported option.  This is just a list of tokens with balanced braces
 * ending in a semicolon.
 */

static isc_result_t
parse_unsupported(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        cfg_obj_t *listobj = NULL;
        isc_result_t result;
        int braces = 0;

        CHECK(cfg_create_list(pctx, type, &listobj));

        for (;;) {
                cfg_listelt_t *elt = NULL;

                CHECK(cfg_peektoken(pctx, 0));
                if (pctx->token.type == isc_tokentype_special) {
                        if (pctx->token.value.as_char == '{')
                                braces++;
                        else if (pctx->token.value.as_char == '}')
                                braces--;
                        else if (pctx->token.value.as_char == ';')
                                if (braces == 0)
                                        break;
                }
                if (pctx->token.type == isc_tokentype_eof || braces < 0) {
                        cfg_parser_error(pctx, CFG_LOG_NEAR, "unexpected token");
                        result = ISC_R_UNEXPECTEDTOKEN;
                        goto cleanup;
                }

                CHECK(cfg_parse_listelt(pctx, &cfg_type_token, &elt));
                ISC_LIST_APPEND(listobj->value.list, elt, link);
        }
        INSIST(braces == 0);
        *ret = listobj;
        return (ISC_R_SUCCESS);

 cleanup:
        CLEANUP_OBJ(listobj);
        return (result);
}

cfg_type_t cfg_type_unsupported = {
        "unsupported", parse_unsupported, &cfg_rep_list, NULL
};

static isc_result_t
cfg_gettoken(cfg_parser_t *pctx, int options) {
        isc_result_t result;

        REQUIRE(pctx != NULL);

        if (pctx->seen_eof)
                return (ISC_R_SUCCESS);

        options |= (ISC_LEXOPT_EOF | ISC_LEXOPT_NOMORE);

 redo:
        pctx->token.type = isc_tokentype_unknown;
        result = isc_lex_gettoken(pctx->lexer, options, &pctx->token);
        pctx->ungotten = 0;
        pctx->line = isc_lex_getsourceline(pctx->lexer);

        switch (result) {
        case ISC_R_SUCCESS:
                if (pctx->token.type == isc_tokentype_eof) {
                        result = isc_lex_close(pctx->lexer);
                        INSIST(result == ISC_R_NOMORE ||
                               result == ISC_R_SUCCESS);

                        if (isc_lex_getsourcename(pctx->lexer) != NULL) {
                                /*
                                 * Closed an included file, not the main file.
                                 */
                                cfg_listelt_t *elt;
                                elt = ISC_LIST_TAIL(pctx->open_files->
                                                    value.list);
                                INSIST(elt != NULL);
                                ISC_LIST_UNLINK(pctx->open_files->
                                                value.list, elt, link);
                                ISC_LIST_APPEND(pctx->closed_files->
                                                value.list, elt, link);
                                goto redo;
                        }
                        pctx->seen_eof = 1;
                }
                break;

        case ISC_R_NOSPACE:
                /* More understandable than "ran out of space". */
                cfg_parser_error(pctx, CFG_LOG_NEAR, "token too big");
                break;

        case ISC_R_IOERROR:
                cfg_parser_error(pctx, 0, "%s",
                                 isc_result_totext(result));
                break;

        default:
                cfg_parser_error(pctx, CFG_LOG_NEAR, "%s",
                                 isc_result_totext(result));
                break;
        }
        return (result);
}

static void
cfg_ungettoken(cfg_parser_t *pctx) {
        REQUIRE(pctx != NULL);

        if (pctx->seen_eof)
                return;
        isc_lex_ungettoken(pctx->lexer, &pctx->token);
        pctx->ungotten = 1;
}

static isc_result_t
cfg_peektoken(cfg_parser_t *pctx, int options) {
        isc_result_t result;

        REQUIRE(pctx != NULL);

        CHECK(cfg_gettoken(pctx, options));
        cfg_ungettoken(pctx);
 cleanup:
        return (result);
}

/*
 * Get a string token, accepting both the quoted and the unquoted form.
 * Log an error if the next token is not a string.
 */
static isc_result_t
cfg_getstringtoken(cfg_parser_t *pctx) {
        isc_result_t result;

        result = cfg_gettoken(pctx, CFG_LEXOPT_QSTRING);
        if (result != ISC_R_SUCCESS)
                return (result);

        if (pctx->token.type != isc_tokentype_string &&
            pctx->token.type != isc_tokentype_qstring) {
                cfg_parser_error(pctx, CFG_LOG_NEAR, "expected string");
                return (ISC_R_UNEXPECTEDTOKEN);
        }
        return (ISC_R_SUCCESS);
}

static void
cfg_parser_error(cfg_parser_t *pctx, unsigned int flags, const char *fmt, ...) {
        va_list args;

        REQUIRE(pctx != NULL);
        REQUIRE(fmt != NULL);

        va_start(args, fmt);
        parser_complain(pctx, 0, flags, fmt, args);
        va_end(args);
        pctx->errors++;
}

#define MAX_LOG_TOKEN 30 /* How much of a token to quote in log messages. */

static int
have_current_file(cfg_parser_t *pctx) {
        cfg_listelt_t *elt;
        if (pctx->open_files == NULL)
                return (0);

        elt = ISC_LIST_TAIL(pctx->open_files->value.list);
        if (elt == NULL)
              return (0);

        return (1);
}

static char *
current_file(cfg_parser_t *pctx) {
        static char none[] = "none";
        cfg_listelt_t *elt;
        cfg_obj_t *fileobj;

        if (!have_current_file(pctx))
                return (none);

        elt = ISC_LIST_TAIL(pctx->open_files->value.list);
        if (elt == NULL)        /* shouldn't be possible, but... */
              return (none);

        fileobj = elt->obj;
        INSIST(fileobj->type == &cfg_type_qstring);
        return (fileobj->value.string.base);
}

static void
parser_complain(cfg_parser_t *pctx, int is_warning,
                unsigned int flags, const char *format,
                va_list args)
{
        char tokenbuf[MAX_LOG_TOKEN + 10];
        static char where[PATH_MAX + 100];
        static char message[2048];
        int level = ISC_LOG_ERROR;
        const char *prep = "";
        size_t len;

        if (is_warning)
                level = ISC_LOG_WARNING;

        where[0] = '\0';
        if (have_current_file(pctx))
                snprintf(where, sizeof(where), "%s:%u: ",
                         current_file(pctx), pctx->line);

        len = vsnprintf(message, sizeof(message), format, args);
#define ELIPSIS " ... "
        if (len >= sizeof(message)) {
                message[sizeof(message) - sizeof(ELIPSIS)] = 0;
                strlcat(message, ELIPSIS, sizeof(message));
        }

        if ((flags & (CFG_LOG_NEAR|CFG_LOG_BEFORE|CFG_LOG_NOPREP)) != 0) {
                isc_region_t r;

                if (pctx->ungotten)
                        (void)cfg_gettoken(pctx, 0);

                if (pctx->token.type == isc_tokentype_eof) {
                        snprintf(tokenbuf, sizeof(tokenbuf), "end of file");
                } else if (pctx->token.type == isc_tokentype_unknown) {
                        flags = 0;
                        tokenbuf[0] = '\0';
                } else {
                        isc_lex_getlasttokentext(pctx->lexer,
                                                 &pctx->token, &r);
                        if (r.length > MAX_LOG_TOKEN)
                                snprintf(tokenbuf, sizeof(tokenbuf),
                                         "'%.*s...'", MAX_LOG_TOKEN, r.base);
                        else
                                snprintf(tokenbuf, sizeof(tokenbuf),
                                         "'%.*s'", (int)r.length, r.base);
                }

                /* Choose a preposition. */
                if (flags & CFG_LOG_NEAR)
                        prep = " near ";
                else if (flags & CFG_LOG_BEFORE)
                        prep = " before ";
                else
                        prep = " ";
        } else {
                tokenbuf[0] = '\0';
        }
        isc_log_write(pctx->lctx, CAT, MOD, level,
                      "%s%s%s%s", where, message, prep, tokenbuf);
}

static isc_result_t
cfg_create_obj(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        cfg_obj_t *obj;

        REQUIRE(pctx != NULL);
        REQUIRE(type != NULL);
        REQUIRE(ret != NULL && *ret == NULL);

        obj = malloc(sizeof(cfg_obj_t));
        if (obj == NULL)
                return (ISC_R_NOMEMORY);
        obj->type = type;
        obj->file = current_file(pctx);
        obj->line = pctx->line;
        *ret = obj;
        return (ISC_R_SUCCESS);
}

static void
map_symtabitem_destroy(char *key, unsigned int type,
                       isc_symvalue_t symval, void *userarg)
{
        cfg_obj_t *obj = symval.as_pointer;
        cfg_parser_t *pctx = (cfg_parser_t *)userarg;

        UNUSED(key);
        UNUSED(type);

        cfg_obj_destroy(pctx, &obj);
}

static isc_result_t
create_map(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {
        isc_result_t result;
        isc_symtab_t *symtab = NULL;
        cfg_obj_t *obj = NULL;

        CHECK(cfg_create_obj(pctx, type, &obj));
        CHECK(isc_symtab_create(5, /* XXX */
                                map_symtabitem_destroy,
                                pctx, 0, &symtab));
        obj->value.map.symtab = symtab;
        obj->value.map.id = NULL;

        *ret = obj;
        return (ISC_R_SUCCESS);

 cleanup:
        if (obj != NULL)
                free(obj);
        return (result);
}

static void
free_map(cfg_parser_t *pctx, cfg_obj_t *obj) {
        CLEANUP_OBJ(obj->value.map.id);
        isc_symtab_destroy(&obj->value.map.symtab);
}

/*
 * Destroy 'obj', a configuration object created in 'pctx'.
 */
void
cfg_obj_destroy(cfg_parser_t *pctx, cfg_obj_t **objp) {
        cfg_obj_t *obj;

        REQUIRE(objp != NULL && *objp != NULL);
        REQUIRE(pctx != NULL);

        obj = *objp;

        obj->type->rep->free(pctx, obj);
        free(obj);
        *objp = NULL;
}